Biochem Lecture 11-17

Front 1

Anabolic Pathway

Back 1

synthesizes macromolecules

aka biosynthetic pathway

an energy-requiring or energy-consuming

pathway

use energy derived from catabolic pathways

endergonic rxn (delta G > 0)

ex: glycogenesis, gluconeogenesis

delta G = +ve

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Catabolic pathway

Back 2

aka degradative pathway

breaking down of complex molecules to simpler ones that results in energy release captured by formation of high energy compounds such as ATP

energy-generating or energy-releasing pathway

exergonic rxn (delta G < 0)

example: glycolysis, complete oxidation of glucose to CO2 and H20

delta G = -ve

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metabolism

Back 3

the sum of all of the chemical reactions that occur within an organism in order to maintain life

Front 4

the metabolic activities of cells are dictated by two major goals:

Back 4

1) the cell has to synthesize it macromolecules: proteins have to be made from amino acids, carbs from monosaccharides, membrane lipids form fatty acids, nucleic acids from nucleotides

2) the cell has to generate metabolic energy: nutrients must be oxidized to supply the energy for biosynthesis, active membrane transport, cell motility, and muscle contraction.

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intermediary/ energy metabolim

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reactions concerned with generating or storing energy; using that energy for biosynthesis of small molecules (maintenance of cellular ATP and blood glucose levels)

combined activities of all the metabolic pathways that inter-convert precursors, metabolites etc

these processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments

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most amino acids can be converted to

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glucose

Front 7

glucose can be converted to

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amino acids and fatty acids

Front 8

2 alternative fates of a nutrient molecule entering a cell:

Back 8

it is either used for the synthesis of a macromolecule or

it is oxidized to CO2 and H2O for the generation of ATP through various metabolic pathways

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the direction in which the pathway proceeds depends on...

Back 9

the sum of the free energy changes of the individual reactions

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a metabolic pathway is a :

Back 10

series of chemical reactions occurring within a cell

Front 11

metabolic pathways are:

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compartmentalized

driven by the net free energy change of the sum of individual reactions

regulated

Front 12

cytosol/ cytoplasm

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contains both anabolic and catabolic pathways such as glycolysis, glycogen metabolism, pentose phosphate pathway, and it is also the place where glycogen and fat are stored as energy reserves

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ER and golgi apparatus

Back 13

concerned with the synthesis and processing of proteins and membrane lipids

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mitochondria

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the powerhouse of the cell, generating >90% of ATP synthesis by oxidate phosphorylation

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lysosomes

Back 15

are hydrolytic enzymes for the degradation of macromolecules. they hydrolyze cellular macromolecules

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peroxisomes

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specialized organelles for oxidative reactions such as reactions forming hydrogen peroxide as a byproduct

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Nucleolus

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synthesis of ribosomal RNA, assembly of ribosomal subunits

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nucleus

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central databank,

DNA and RNA synthesis

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Free energy

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the component of the total energy of a system that can do woe at constant temperature and pressure

Front 20

free energy change

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the amount of free energy released or absorbed in a rxn at constant temperature and pressure

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exergonic reaction

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when delta G is negative (the product has lower free energy than the substrate), process or chemical run proceeds spontaneously in the forward direction

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endergonic reaction

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when delta G is positive (the reaction does not go spontaneously), the process proceeds spontaneously in the reverse

Front 23

delta G = zero

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the process is in equilibrium, with no net change taking place over time

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under aerobic conditions, [NAD+] is ...

Back 24

always higher than [NADH]

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in the cell, [GTP] concentration is ...

Back 25

almost 100 times higher than [GMP]

Front 26

Cells respond to signals from _____ to adjust their metabolism

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nutrients

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cells have 3 options for the regulation of their metabolic pathways

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1) long term at the DNA level: the amt of enzyme is adjusted by a change in its synthesis or degradation... SLOW

2) short term at protein level: some enzymes are modified covalently by phosphorylation. this requires a protein kinase and protein phosphatase... FAST

3) allosteric effectors: VERY FAST

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phosphorylation

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formation of a phosphate derivative

Front 29

dephosphorylation

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removal of phosphate groups from a biomolecule

Front 30

the protein kinases and protein pho sphatases are regulated by:

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metabolites or hormones

Front 31

metabolic enzymes are also subject to competitive inhibition in the form of :

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product inhibition - meaning the product of the reaction competes with the substrate for the active site of the enzyme.

Front 32

hormones can regulate both the synthesis and degradation of metabolic enzyme and their phosphorylation by :

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protein kinase

Front 33

most biosynthetic pathways are inhibited by :

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high concentrations of their end product (feedback inhibition)

Front 34

regulation of anabolic pathway

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regulation by feedback inhibition

Front 35

regulation of catabolic pathway

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regulation by ATP and ADP, Pi

Front 36

regulation of catabolic pathway

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regulation by feedforward stimulation

Front 37

in energy-producing catabolic pathways, the important product is :

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ATP

Front 38

the ATP level is inversely related to:

Back 38

the concentrations of ADP and AMP.

ADP and /or AMP act opposite to ATP in the regulation of many catabolic pathways

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feedback inhibition

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the regulated enzyme is inhibited by a product of the pathway

Front 40

feedforward stimulation

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a substrate stimulates the pathway by which it is utilized

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a regulated enzyme must be present in:

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lower activity than the other enzymes in the pathway

Front 42

the regulated enzyme should serve :

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an essential function in only one metabolic pathway

Front 43

the regulated enzyme should catalyze:

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the first irreversible reaction ( the committed step) in the pathway

Front 44

regulation of the committed step ensures:

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that only the substrate of the pathway accumulates when the regulated enzyme is inhibited.

if a later reaction would be inhibited, metabolic intermediates would accumulate causing possible toxic effects.

Front 45

inherited enzyme deficiencies cause

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metabolic diseases

Front 46

when an enzyme is missing as a result of a genetic defect, the immediate effects are always:

Back 46

the accumulation of the substrate in blood and the lack of the product

Front 47

deficiency of an enzyme in a catabolic pathway, ATP producing pathway causes:

Back 47

a serious problem

Front 48

if the intracellular degradation of a macromolecule by hydrolytic enzymes is blocked...

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"undegraded" macromolecules accumulates mostly within the cells. the result is a "storage disease"

Front 49

vitamin deficiencies

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can affect multiple metabolic pathways.

a vitamin deficiency can prevent a metabolic react by depriving it of an essential coenzyme. most vitaim derived coenzymes (NAD, FAD, CoA), participate in multiple metabolic pathways. al of these pathways are impaired when vitamin deficient

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toxins

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act by inhibiting metabolic enzymes

lead: causes the accumulation of toxic intermediates by inhibiting enzymes of heme biosynthesis

cyanide: blocks cell respiration by inhibiting the mitochondrial cytrochrome oxidase

Front 51

endocrine disorders

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the most complex metabolic diseases because each hormone controls a whole set of metabolic pathways.

diabetes mellitus: insufficient insulin action disrupts a host of pathways in carbohydrate and fat metabolism

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bioenergetics

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the quantitative study of every relationships and energy utilization, and conversions in biological systems, or energy transformations in living organisms

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metabolism

Back 53

the sum of all chemical reactions that occur within an organism in order to maintain life or the entire set of enzyme-catalyzed transformations of organic molecules in living cells (the sum of anabolism and catabolism)

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autotrophs

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aka producers

can use CO2 from the atmosphere as their major source of carbon, from which they construct all their carbon-containing biomolecules, such as photosynthetic bacteria, green algae, and plants

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heterotrophs

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aka consumers

can not use CO2 from the atmosphere and must obtain carbon from their environment in the form of complex organic molecules such as glucose. Multi cellular animals an most micro-organisms are heterotrophic

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free energy source

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cells are isothermal systems - function at constant temp and pressure. autotrophic cells acquire free energy form solar radiation, and heterotrophic cells acquire it from nutrient molecules

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autotrophic organisms are ____ and obtain their energy from ____

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photosynthetic

sunlight

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heterotrophic organisms obtain their energy from ....

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the degradation of organic nutrients produced by autotorphs

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Carbon, oxygen, nitrogen, and water are constantly cycled between the ____ and _____

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autotrophic producers and heterotrophic consumers

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oxidation-reduction

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reactions involving the loss or gain of electrons - one reactant gains electrons and is reduced while the other loses electrons and is oxidized

Front 61

oxidation reactions generally ______ energy and are important in _____

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release

catabolism

Front 62

in many organisms, the oxidation of ____ supplies energy for the production of ____

Back 62

glucose

ATP

Front 63

NAD+ and FAD

Back 63

are a prosthetic group covalently bound in some enzymes

Front 64

NAD+ or NADP+

Back 64

soluble co-factors free to diffuse from one enzyme to another.

Both accept two electrons and one proton

Front 65

FAD or FMN

Back 65

coenzymes derived from the vitamin riboflavin, often tightly bound to specific enzyme called flavoproteins

Front 66

great majority of NAD+/NADH is located in

Back 66

the mitochondria

Front 67

most of the NADP+/NADPH is

Back 67

in the cytosol

Front 68

electron carrier

Back 68

a biomolecule that can reversibly gain and lose electrons

Front 69

NAD+ and NADP+ undergo

Back 69

reduction to NADH and NADPH by accepting a hydride ion from an oxidizable substrate

the hydride ion is added to either the front or back of the nicotinamide ring

Front 70

Reduction of nicotinamide ring produces

Back 70

a new broad ring

NADH at 340 nm

Front 71

NAD+ or NADP+ move readily fro one enzyme to another, acting as a water-soluble electron carriers, derived from

Back 71

vitamin niacin which is synthesized from tryptophan

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Niacin deficiency causes a disease called

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pellagra (rough skin)

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Rossmann fold

Back 73

most dehydrogenates that use NAD or NADP bid the cofactor in a conserved protein domain

it is an NAD-binding site, consisting of : six stranded parallel beta pleated sheets and four alpha helices

Front 74

FAD/FADH2

Back 74

flavoproteins are enzymes that catalyze oxidation-reduction reactions using either FMN or FAD as coenzyme

Front 75

FAD or FMN are coenzyme derived from

Back 75

vitamin B2, riboflavin

Front 76

in a healthy cell: [NAD+]/[NADH]

Back 76

>> 1

due to continuous ATP production (rapid utilization of NADH in the mitochondria)

Front 77

in a healthy cell: [NADP+]/[NADPH]

Back 77

= 0.05

maintains reductive environment in the cytosol (NADPH)

Front 78

ATP is the chemical link between:

Back 78

catabolism and anabolism

and is the energy currency of the living cell

Front 79

NAD and NADP, both are the freely diffusible coenzymes of

Back 79

dehydrogenases

Front 80

total concentration of NAD+ + NADH in tissues is

Back 80

10^ -5 M

Front 81

total concentration of NADP+ + NADPH in tissues is

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10^ -6 M

Front 82

all major nutrients are degraded to

Back 82

acetyl coenzyme A

"activated acetic acid"

Front 83

in the mitochondria, the two carbons of the acetyl group become oxidized to CO2 and produce reduced coenzymes in the

Back 83

tricarboxylic acid (TCA) cycle

Front 84

the deoxidation of the reduced coenzymes produces the bulk of the cellular ATP in the process of

Back 84

oxidative phosphorylation

Front 85

glucose is not only the most abundant monosaccharide in food, but is

Back 85

also produced from other monosaccharides by the breakdown of the storage polysaccharide glycogen

from amino acids and other non-carbohydrate substrates

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dietary sources of glucose

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starch- a glucose polymer

sugar (dimer of glucose and fructose)

milk (lactose, dimer of galactose and glucose)

fruit/ vegetables (a source of glucose and fructose)

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glucose is the principal

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transported carbohydrate in humans and most abundant monosaccharide in dietary carbohydrates

Front 88

glucose can be transported by the

Back 88

blood

Front 89

glucose cannot be stored in

Back 89

the cells

Front 90

glucose storage

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to be stored, it has to be converted to the polysaccharide glycogen

Front 91

glucose is relatively rich in

Back 91

potential energy, and thus a good fuel

Front 92

in many organisms, the oxidation of glucose supplies energy for the production of

Back 92

ATP

Front 93

is glucose lipid soluble

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glucose is not sufficiently lipid soluble to enter in cells by diffusion across the plasma membrane

Front 94

dietary glucose enters the intestinal mucosal cells mainly by

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sodium co-transport, but the uptake of glucose from blood or interstitial fluid into the cells occurs by so-called "facilitate diffusion"

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GLUT 4

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express in muscle, adipose tissue, heart

function: insulin-dependent glucose uptake

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GLUT 4 deposition in the plasma membrane is enhanced by

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insulin

Front 97

during the well-fed state

Back 97

decreased levels of glucagon and elevated levels of insulin

muscle and adipose tissue take up glucose

muscle and adipose do not depend on glucose, but can subsist on fatty acids and other nutrients if needed

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durgin starvation

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elevated levels of glucagon and low levels of insulin develops during fasting. this results in a decrease in the overall rate of glycolysis and an increase in gluconeogenesis

glucose is redirected from muscle and adipose tissue to tissues that depend on glucose - brain, RBCs

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insulin-independent tissues

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utilize glucose independently of the dietary/nutritional status

includes tissues that depend on glucose as a sole source of energy

RBCs, brain, beta cells of the pancreas

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insulin - dependent tissues

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can take up glucose only during the fed state (high insulin) levels

do not depend on glucose as a sole source of energy

muscle, fat

Front 101

glucose metabolism by the liver depends on

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the insulin/glucagon but insulin is NOT required for the entry of glucose into the liver cell

Front 102

glucose absorption from diet leads to

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increase in blood glucose concentrations

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rising blood glucose levels will

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increase liver-mediated glucose consumption by the liver (insulin-independent) - GLUT 2 transporters

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rising glucose triggers the release of

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insulin by the beta cells of the pancreas, which leads to a rapid removal of excess glucose from blood by tissues expressing GLUT 4 transporters (fat and muscle) Insulin-dependent

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blood glucose levels never fall below

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4-5 mM

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falling glucose leads to

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decreased insulin, increased glucagon and cessation of glucose uptake by most tissues

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carbohydrate

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a major source of energy

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glucose

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the major product of carbohydrate digestion

Front 109

some cells depend exclusively on

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glucose for energy

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glucose is stored in cells as

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glycogen (animal starch)

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glucose can be synthesized by cells from

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other metabolites

Front 112

the brain always depends on

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glucose supply.

Front 113

blood glucose level must be maintained at

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4-5.5 mmol/liter (70-100 mg/dL)

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the main site for glucose metabolism is

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the liver

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glucose degradation begins in the _____ and ends in the _____

Back 115

cytoplasm

mitochondria

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glucose oxidation:

Back 116

when glucose is oxidized completely to CO2 and H2O, 36 or 38 ATP molecules are generated

Front 117

glycerol phosphate shuttle

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the transfer of electrons from cytoplasmic NADH to the respiratory chain of mitochondria

Front 118

malate- aspartate shuttle

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the reversible shuttling of hydrogen, in the form of malate, across the inner mitochondrial membrane

Front 119

glycolysis

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the catabolic pathway by which a molecule of glucose (6 carbons) is broken down into 2 molecules of 3 carbon compound pyruvate

Front 120

All cells of the body are capable of

Back 120

GLYCOLSIS

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glycolysis produces

Back 121

ATP without consuming oxygen

Front 122

glycolysis functions under

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aerobic or anaerobic conditoins

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many microorganisms are entirely dependent on

Back 123

glycolysis

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where does glycolysis take place

Back 124

in the cytoplasm of the cells

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glycolysis is an essential step for :

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aerobic metabolism of glucose

Front 126

in the liver _____ is the first step in the conversion of carbohydrate to fat

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glycolysis

Front 127

during glycolysis, some of the free energy released from glucose is conserved in the form:

Back 127

of ATP and NADH

Front 128

step 1 of glycolysis

Back 128

glucose is phosphorylated to glucose 6 phosphate catalyzed by glucokinase in the liver or by hexokinase in muslce/ fat

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glycolysis produces a net yield of

Back 129

2 molecules of pyruvate, 2 molecules of ATP, and 2 molecules of NADH per molecule of glucose (aerobic)

2 molecules of lactate, 2 molecules of ATP, and no net product of NADH per molecule of glucose (anaerobic glycolysis)

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2 phases of glycolysis

Back 130

1) energy investment phase (steps 1-5)

phosphorylation of glucose and its conversion to glyceraldehyde 3-phosphate

2) energy generation phase (steps 6-10): oxidative conversion of glyceraldehyde 3-phosphate to pyruvate

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glucokinase

Back 131

(liver and pancreas)

highly specific for glucose

high but variable Km for glucose (10mM)

not saturated at physiological blood glucose [] (4-5mM

inhibited by fructose 6 P, but not glucose- 6- phosphate

induced by insulin (transcriptionally)

Front 132

hexokinase

Back 132

(peripheral tissues)

-low specificity - phosporylates most relevant hexoses

-soluble and cytoplasmic protein

-low Km (0.1mM); saturated at all plasma glucose concentrations

-inhibited by glucose 6 phosphate

-activated by fructose 1 phosphate and glucose

-insulin has no effect on expression

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during glycolysis, some of the energy of the glucose is conserved in ___ while much remains the product ___

Back 133

ATP

pyruvate

Front 134

each molecule of glucose is degraded to :

Back 134

2 molecules of pyruvate

2 molecules of ATP

and 2 molecules of NADH

Front 135

conversion of glucose to pyruvate is

Back 135

exergonic (neg G)

Front 136

formation of ATP from ADP and Pi is

Back 136

endergonic (positive G)

Front 137

what is the most important regulated enzyme of glycolysis

Back 137

phosphofrutokinase (PFK)

Front 138

PFK is stimulated by ____ and inhibited by _____

Back 138

insulin

AMP and ADP

glucagon (in the liver)

citrate

low pH

ATP

Front 139

what inhibits pyruvate kinase

Back 139

ATP

Front 140

in RBCs, rates of glycolysis are regulated by

Back 140

ATP / (AMP + ADP) only

Front 141

hexokinase, phosphofructokinase, and pyruvate kinase reactions are

Back 141

irreversible

Front 142

aldolase and triose phosphate isomerase have very

Back 142

unfavorable equilibria (G>0)

but can still proceed, since fructose 1,6 bisP forms irreversibly, and glyceraldehyde 3P is rapidly consumed in the next react of the pathway bc NAD+ is in excess compared to NADH

Front 143

committed step of glycolysis

Back 143

Phosphofructokinase - commits conversion of glucose to pyruvate

Front 144

fate of 1,3 BPG

Back 144

converted to 3-phosphoglycrerate by phophoglycerate kinase

converted to 2,3- BPG by bisphophoglycerate mutase

2,3 bisphosphoglycerate is converted to 3-phosphoglycerate by bisphophoglycerate phosphatase

Front 145

pyruvate kinase is more active in

Back 145

the fed state than in the fasting state

Front 146

pyruvate kinase is inhibited by

Back 146

ATP

acetyl CoA

alanine

Front 147

pyruvate kinase is activated by

Back 147

fructose 1,6-bisphosphate

Front 148

pyruvate formed by glycolysis, is only the first stage in

Back 148

the complete degradation of glucose

Front 149

acetyl - CoA is formed from

Back 149

carbohydrates through glycolysis and pyruvate dehydrogenase

Front 150

the major fate of acetyl CoA is

Back 150

oxidation in the TCA cycle

Front 151

pasteur effect

Back 151

the stimulation of glycolysis under anaerobic conditions

this is due to a much higher energy yield from glucose metabolism in the presence of oxygen

pasteur effect NOT observed in red blood cells

Front 152

flux of glucose through the glycolytic pathway is dramatically reduced uner

Back 152

aerobic conditions

oxygen appears to "inhibit" glucose metabolism

Front 153

lactate is produced under

Back 153

anaerobic conditions

Front 154

anaerobic glycolysis is only useful under what circumstances:

Back 154

mature RBCs

vigorously contracting skeletal muscle in which oxygen supply becomes a limiting factor

ischemic tissue

Front 155

warburg effect

Back 155

most cancer cells rely on aerobic glycolysis

Front 156

fructose metabolism occurs primarily in

Back 156

the liver, kidneys, and small intestine

Front 157

in the liver, fructose is converted to

Back 157

fructose 1 phosphate by fructokinase and activates glucokinase

Front 158

essential fructosuria

Back 158

a deficiency of fructokinase

Front 159

hereditary fructose intolerance

Back 159

a deficiency of fructose 1-phosphate metabolism by aldolase B

Front 160

pyruvate

Back 160

produced by glycolysis and further oxidized in the mitochondria under aerobic conditions

Front 161

cellular respiration

Back 161

the aerobic phase of catabolism when cells consume O2 and produce CO2 (and H2O)

Front 162

transport of pyruvate

Back 162

must be transported into the mitochondria,

it diffuses through the pores in the outer mitochondrial membrane into the mitochondria matrix to reach the multi-enzyme complex pyruvate dehydrogenase

Front 163

The TCA cycle is ____ in metabolism

Back 163

"hub"

Front 164

first step of TCA

Back 164

conversion of pyruvate to acetyl groups, then acetyl groups are carried into the TCA cylce

Front 165

3 stages of cellular respiration

Back 165

1) oxidation of fatty acids, glucose, and some amino acids yields acetyl COA

2)oxidation of acetyl groups in TCA cycle includes 4 steps in which electrons are transferred ( 4 pairs of electrons are transferred during one turn of the cycle)

3) electrons carried by NADH and FADH2 enter the respiratory chain - ultimately reducing O2 to H2O and the production of ATP

Front 166

Oxidative Decarboxylation

Back 166

the conversion of pyruvate to Acetyl CoA

Exergonic reaction

catalyzed by pyruvate dehyrogenase complex

NAD+ and CoA-SH are needed as co-substrates

-vitamins: niacin (NAD) and panthotenic acid (CoA)

co-enzymes are lipoid acid and the vitamins thiamin pyrophosphate and riboflavin

Front 167

3 enzymes that make up the PDH complex

Back 167

1) pyruvate dehydrogenase

2) dihydrolipoyl transacetylase

3)dihydrolipoyl dehydrogenase

Front 168

pyruvate dehydrogenase

Back 168

-inhibited by its product NADH and acetyl CoA

-stimulated by AMP

-Inactivated but the phosphorylation

-reactivated by dephosphorylation

Front 169

dihydrolipoyl transacetylase

Back 169

catalyzes the transfer of the acetyl group to coenzyme A, forming Acetyl - CoA

Front 170

dihydrolipoyl dehydrogenase

Back 170

catalyzes the regeneration of the disulfide form of lipoate

Front 171

regualtory enzymes of PDH

Back 171

phosphorylate/dephosphorylate E1 (a kinase and a phophatase)

Front 172

5 cofactors required for PDH

Back 172

-Thiamin pyrophosphate (TPP)

-Lipoic acid (lipase)

-Flavin adenine dinuclueotide, FAD (Riboflavin)

-Nicotinamide adenine dinucleotide, NAD+ (Niacin)

-Coenzyme A, CoA (Pantothenic acid)

Front 173

4 different vitamins required in human nutrition are vital components of PDH complex

Back 173

thiamine (in TPP)

riboflavin (in FAD)

niacin (in NAD)

pantothenate (in CoA)

Front 174

thiamine pyrophosphate (TPP)

Back 174

a coenzyme important in respiration in the TCA cycle, and often plays a role in the removal of carboxyl groups from organic acids

a vitamin B1 derivative produced by the enzyme thiamine

Front 175

thiamine deficiency leads to

Back 175

inability to oxidize pyruvate and thus has a major neurological impact - Beriberi

Front 176

lipoamide

Back 176

lipoate, a prosthetic group of pyruvate dehydrogenase, has two thiol groups that can undergo reversible oxidation to a disulfide bond. because of its capacity to undergo oxidation-reduction reactions, lipase can serve both as an electron carrier and as an acyl carrier.

Front 177

Coenzyme A

Back 177

has a reactive thiol (-SH) group that is critical to the role of CoA as an acyl carrier in metabolic reactions

formed from pantothenic acid and ATP, is necessary for carb, fatty acid synthesis and metabolism, and the oxidation of pyruvate in the TCA cylce

Front 178

PDH complex carries out __________ in the decarboxylation and dehydrogenation of pyruvate

Back 178

five consecutive reactions

Front 179

sources of acetyl - Co A

Back 179

in aerobic organisms, glucose and other sugars, fatty acids, and most amino acids are ultimately oxidized to CO2 and H2O via TCA cycle and respiratory chain

pyruvate, the product of glycolysis is converted to acetyl CoA, the starting material for the TCA cycle, by the PDH complex

Front 180

Regulation of PDH

Back 180

Allosteric: inhibition by ATP, acetyl-CoA and NADH

Activation by AMP, CoA and NAD+

Covalent: Inhibition by phosphorylation of E1 (pyruvate dehydrogenase). A specific kinase (co-substrate: ATP) catalyzes this phosphorylation (PDH kinase)

Activation by dephospho rylation

Front 181

pyruvate is a potent inhibitor of

Back 181

pyruvate dehydrogenase kinase

Front 182

TCA/Krebs cylce

Back 182

the final common pathway for the oxidation of all major nutrients, and plays several roles in metabolism

Front 183

where do TCA and oxidative phosphorylation take place

Back 183

in all cells that contain mitochondria

Front 184

TCA cycle and oxidative phosphorylation are the

Back 184

final common pathway for the oxidation of all major nutrients

Front 185

degradation of acetyl CoA derived form carbs, fatty acids, and amino acids:

Back 185

-produces most of the CO2 generated in tissues

-is the major source of NADH

-allows excess energy to be used for fatty acid biosynthesis

-provides precursors for many metabolites

Front 186

most TCA cycle enzymes are in the

Back 186

mitochondrial matrix, some are in the inner mitochondrial matrix

Front 187

one complete turn of the TCA cycle generates

Back 187

only one GTP, 3 molecules of NADH and one molecule of FADH2 from one acetyl residue

Front 188

TCA: in a series of 7 reactions 2 carbons are released as

Back 188

CO2, regenerating oxaloacetate

Front 189

how many pairs of electrons are transferred during one turn of the TCA cycle

Back 189

4 paris

3 pairs of electrons reducing 3 NAD+ to NADH, and one pair reducing FAD to FADH2

Front 190

one complete turn of the TCA cycle generates ____ ATP

____ NADH

____ FADH2

Back 190

1 ATP in the conversion of succinyl CoA to succinate

3 NADH

1 FADH2

Front 191

oxidation of one NADH leads to formation of ___ ATP

Back 191

3

Front 192

Oxidation fo FADH2 yields ____ ATP

Back 192

2

Front 193

Total ATP generated by one round of TCA cycle from one acetyl residue

Back 193

12ATP

Front 194

Total ATP yield from one molecule of glucose (through glycolysis and TCA)

Back 194

38 ATP

Front 195

The TCA cycle activity is responsive to:

Back 195

energy state of the cell

-redox state of the cell, through flux rate limitation caused when intramitochondrial NAD+ decreses

- availability of energy - rich compounds, through inhibition of relevant enzymes by acetyl CoA or succinyl CoA

Front 196

TCA cycle is an ______ pathway, that serves in ...

Back 196

amphibolic pathway that serves in both catabolic and anabolic processes

Front 197

PDH complex is allosterically inhibited when

Back 197

[ATP]/[ADP], [NADH]/[NAD+] and [acetylCoA]/[CoA] ratios are high, indicating an energy sufficient metabolic state

when these ratios decrease, allosteric activation of pyruvate oxidation results

Front 198

the overall rate of the TCA cycle is controlled by

Back 198

the rate of conversion o pyruvate to acetyl CoA

Front 199

In TCA cycle: Citrate synthase is inhibited by

Back 199

ATP

citrate

NADH

succinyl CoA

Front 200

in TCA: isocitrate dehydrogenase is inhibited by

Back 200

ATP and NADH

Front 201

in TCA: alpha keto glutarate dehydrogenase is inhibited by

Back 201

succinyl CoA and NADH

Front 202

TCA cycle intermediates are also used in

Back 202

biosynthetic (anabolic) pathways

Front 203

Anaplertoic reactions

Back 203

biosynthetic reactions tat consume TCA cycle intermediates, must be balanced by reactions that produce them

Front 204

example of anplerotic reactions

Back 204

synthesis of oxaloacetate from pyruvate by pyruvate carboxylase... this is ATP dependent carboxlation reaction, activated by acetyl CoA bound biotin

synthesis of malate form pyruvate by malic enzyme - pro and eukaryotes

synthesis of oxaloacetate from PEP by PEP-CK

- heart and skeletal muscle

Front 205

pyruvate carboxylase defficiency

Back 205

a rare recessively inherited condition

pyruvate accumulates because pyruvate carboxylase is a major consumer of pyruvate

acculated pyruvate is converted to lactate and alanine

Front 206

hypoglycemia

Back 206

caused by the inability to convert pyruvate to glucose

Front 207

neurological deficits and mental retardation can be caused by

Back 207

dysfunction of TCA cycle due to insufficient oxaloacetate

Front 208

Antiporters

Back 208

transport metabolites across the inner mitochondrial membrane

ex: ADP, ATP, pyruvate, phosphate, alanine, aspartate, glutamate, substrates, intermediates, and products of the TCA cycle : except acetyl CoA, oxaloacetate, fumarate, NAD, NADH

Front 209

the mitochondrial translocases are

Back 209

antiporters

they do not hydrolyze ATP, but energy is consumed whenever active maintained ion gradient or the membrane potential is dissipated

Front 210

Can TCA function in anaerobic conditions?

Back 210

NO, unlike glycolysis, TCA cycle cannot function under anaerobic condition

TCA cycles is an aerobic pathway

Front 211

under aerobic conditions, pyruvate is transported to...

Back 211

into the mitochondria, where it is turned into the 2 carbon compound acetyl coenzyme A (CoA)

Front 212

how does Acetyl CoA enter the TCA cycle

Back 212

by reacting with the 4 carbon compound oxaloacetate to form the 6 carbon compound citrate

citrate is converted back to oxaloacetate in the reactions of the TCA cylcw

Front 213

in aerobic organisms, glucose and other sugars, fatty acids and most amino acids are ultimately oxidized to

Back 213

CO2 and H2O via TCA and respiratory chain.

Front 214

what converts pyruvate to acetyl CoA

Back 214

pyruvate dehydrogenase complex

Front 215

FADH2

Back 215

is not free in solution like NAD+ and NADH;

it is tightly bound to enzymes

Front 216

TCA cycle produces ___ molecules of CO2 for each acetyl residue

Back 216

2

Front 217

succinate dehyrogenase

Back 217

is the only membrane bound enzyme in the TCA cycle

Front 218

lipoate (lipoid acid)

Back 218

a prosthetic group of pyruvate dehyrdogenase

Front 219

prosthetic group

Back 219

a metal ion or an organic compound that is covalently bound to a protein an dis essential for its activity

Front 220

pantothenic acid (pantothenate)

Back 220

an essential constituent of coenzyme A, also called vitamin B5, a water soluble vitamin required to sustain life (essential nutrient)

Front 221

TPP

Back 221

thiamine pyrophosphate, a prosthetic group that transfers carboxyla

Front 222

acyl carrier

Back 222

part of the fatty acid synthesizing enzyme complex, which carries acyl groups, including the acetyl group

Front 223

election carriers

Back 223

a protein such as flavoprotein or a cytochrome that can reversibly gain and lose electrons

Front 224

lyase reaction

Back 224

an enzymatic reaction that removes a group non hydrolytic ally from its substrate

Front 225

isomerization

Back 225

convert form one isomer to another

Front 226

condensation

Back 226

a chemical reaction in which two molecules or moieties combine to form one single molecule, with the loss of a small molecule

Front 227

decarboxylation

Back 227

a chemical reaction in which a carboxyl group is split off from a compound as CO2

Front 228

deydration

Back 228

a chemical reaction that involves the loss of water from the reacting moleculeh

Front 229

hydration

Back 229

a chemical reaction involving the loss of water from the reacting molecule

Front 230

dehyrogenation

Back 230

chemical reaction that involves the elimination of H2

Front 231

the respiratory chain is present in

Back 231

the mitochondrial membrane

Front 232

the respiratory chain and oxidative phosphorylation are

Back 232

tightly couple processesin

Front 233

inhibition of the electron transport chain also results in

Back 233

inhibition of ATP synthesis

Front 234

oxidative phosphorylation

Back 234

means ATP synthesis, its the culmination of energy yielding metabolism in aerobic organisms

Front 235

what is the principal source of ATP

Back 235

oxidative phosphorylation

Front 236

where do TCA cycle and oxidative phosphorylation take place?

Back 236

in all cells that contain mitochondria

Front 237

TCA cycle and oxidative phosphorylation are the final..

Back 237

common pathway for the oxidation of all major nutrients

Front 238

failures of oxidative phosphorylation are caused by

Back 238

hypoxia and anoxia

Front 239

oxidative phosphorylation involves the reduction of

Back 239

O2 to H2O with electrons donated by NADH and FADH2

Front 240

oxidative phosphoyrlation involves

Back 240

a "flow of electrons"

Front 241

oxidative phosphorylation begins with

Back 241

the entry of elections into the respiratory chain

Front 242

NADH

Back 242

a water soluble electron carrier that associates reversibly with dehydrogenates

Front 243

energy yields from cytoplasmic NADH depends on

Back 243

the shuttle used

Front 244

complete oxidation of glucose molecule to CO2 yields

Back 244

36 or 38 ATP

only 4 of them are produced by phosphorylation during glycolysis and the TCA cycle, the rest are from oxidative phosphorylation

Front 245

all major catabolic pathways form

Back 245

NADH and or FAHD2

these reduced coenzymes must be re-oxidized to NAD+ and FAD, which are needed as substrates of the pathways and requires the respiratory chain in the inner mitochondria membrane

Front 246

nutrient energy potential (H2) is stored in

Back 246

mitchondrial NADH+, H+/FADH2

Front 247

the transfer of the protons and electrons to oxygen generates the

Back 247

energy required for ATP synthesis

Front 248

none of the functional groups in proteins can transfer

Back 248

hydrogen or electrons

the components of the respiratory chain have to employ metal and ions and coenzymes

Front 249

the respiratory chain contains:

Back 249

flavoproteins

iron-sulfur proteins

cytochromes

ubquinone or coenzyme Q

protein bound copper

* with the exception of Coenzyme Q, all members of this chain are proteins

Front 250

FAD or flavin mononucleotide (FMN) in the flavoproteins can transfer:

Back 250

either one or two electrons at a time

Front 251

electron transfer occurs because:

Back 251

the FAD/FMN has a higher reduction potential than the compound oxidized

Front 252

FAD/FMN accepty hydrogen/electrons from :

Back 252

NADH and donate it to the cytochromes

Front 253

flavoproteins

Back 253

proteins containing flavin adenine dinucleotide (FAD) or FMN as a prosthetic group, participate in hydrogen transfer reactions

Front 254

reduction potential

Back 254

delta E: the measure of tendency of a redox pair reaction

Front 255

cytochromes

Back 255

heme proteins that functions as electron carriers in respiration, photosynthesis, and other oxidation reduction reactions

Front 256

iron-sulfur proteins

Back 256

a large family of electron-transfer proteins in which the electron carrier is one or more iron ions associated with 2 or more sulfur atoms of cysteine residues

aka non-heme proteins

anchored in proteins through cysteine

both the iron sulfur proteins and flavoproteins are integral membrane proteins

Front 257

iron sulfur complexes in proteins

Back 257

iron in these complexes can change its oxidation state reversibly between the ferrous (Fe2+) and ferric (Fe3+) forms

Front 258

cytochromes contain

Back 258

red or brown heme proteins

the heme iron of the cytochrome switches back and forth between ferrous and ferric

one electron carriers

mitochondria contain 3 classes of cytochromes based on wavelengths of the spectral absorption peaks (a, b, c)

all but one are integral membrane proteins

Front 259

cytochrome c

Back 259

is a small and water soluble protein. after its single heme accepts an electron from complex III, cytochrome c moves to complex IV to donate electron to a binuclear copper center.

Front 260

cytochromes consist of

Back 260

4 five membered nitrogen containing rings in a cyclic structure, called a porphyrin

the 4 nitrogen atoms are coordinated with a central Fe ion, either Fe2+ or Fe3+

Front 261

ubiquinone or coenzyme Q

Back 261

a lipid soluble hydrophobic benzoquinione with a long isoprenoid side chain (a long hydrocarbon tail of 10 isoprene units makes it hydrophobic)

a component of the respiratory chain

a hydrogen carrierp

Front 262

protein bound copper

Back 262

participates in the last reaction of the respiratory chain, the transfer of electrons to molecular oxygen. it switches between the Cu+ and Cu 2+ forms during these electron transfers

Front 263

4 components of the respiratory chain are freely diffusible:

Back 263

NADH

ubiquinone

cytochrome c

molecular oxygen

Front 264

the respiratory chain contains

Back 264

large multi protein

four electron carrier complexes, each capable of catalyzing electron transfer: complex I, II, III, IV

Front 265

Complexes I and II

Back 265

catalyze electron transfer to ubiquinone from 2 different electron donors: NADH (complex I) and succinate dehydrogenase (complex II)

Front 266

Complex III

Back 266

carries electrons from reduced ubiquinone to cytochrome C

Front 267

complex IV

Back 267

transferring electrons from cytrochrome c to O2

Front 268

the respiratory proteins are located in

Back 268

the inner mitochondrial membrane

cells with high rates of respiration (heart muscle) have mitochondria with many densely packed cristae.

liver cells have much fewer cristae

Front 269

for each pair of electrons transferred to O2, ___ protons are pumped out by Complex I, ___ by Complex III, and ___ by complex IV

Back 269

4 protons by complex 1

4 protons by complex III

2 protons by complex IV

Front 270

electron transport

Back 270

progressive transport of electrons for NADH+H+/FADH2 through various electron acceptors with increasing reduction potentials, ultimately to O2

Front 271

Complex I

Back 271

aka NADH: ubiquinone oxidoreductase or NADH dehydrogenase, transfers electrons from NADH to ubiquinone, is a large enzyme composed of 42 different polypeptide chains, including FMN-containing flavoprotein and at least 6 iron sulfur centers

electrons are transferred from NADH to flavoprotein (FMN) then iron sulfur centers to ubiquinone

Front 272

amytal, rotenone, and piericidin A inhibit:

Back 272

electron flow from the Fe-S centers of complex I to ubiquinone, and therefore block the overall process of oxidative phosphorylation

Front 273

complex II

Back 273

aka succinate dehyrogenase is the only membrane-bound enzyme in the TCA cycle

contains only 5 cofactors and 4 different protein subunits (A, B, C, D)

contains 3 Fe-S centers, bound FAD

electrons from succinate pass through a flavoprotein and several Fe-S centers to ubiquinone

Front 274

glycerol 3-phosphate donates electrons to

Back 274

a flavoprotein on the outer face of the inner mitochondrial membrane, then pass to ubiquinone

Front 275

acyl CoA dehyrogenase transfers

Back 275

electrons to ETF from which they pass to ubiquinonec

Front 276

complex III

Back 276

(ubiquinone to cytochrome c)

aka cytochrome c oxidoreductase or cytochrome bc1 complex, couples the transfer of electrons from ubiquinol (QH2) to cytochrome c

it contains cytochrome b, an Fe-S protein, and cytochrome c1.

its a dimer of identical monomers, each with 11 different subunits

Front 277

Complex IV

Back 277

(cytochrome c to O2)

the final step of the respiratory chain. aka cytochrome oxidase, carries electrons from cytochrome c to molecular oxygen, reducing it to H2O

a large enzyme of the inner mitochondrial membrane

contains 2 heme groups, each located near a copper ion

oxygen is tightly bound between heme a3, and copper to be released after its reduction to H20 by the transfer of 4 electrons

cytochrome oxidase has a very high affinity for oxygen.

Front 278

complex IV inhibitoin

Back 278

acute cyanide poisoning

Front 279

both iron and copper has been shown

Back 279

to bind cyanide

Front 280

oxidative phosphorylation proceeds in 2 steps

Back 280

1) protons are pumped out of the mitochondria: driven by the redox reactions in resp chain

2)protons are admitted back into the mitochondria via a proton channel: this process drives ATP synthesis

Front 281

ATP is synthesized only when

Back 281

protons flow, and protons can only flow when ATP is synthesized

Front 282

inner mitochondrial membrane acts like a

Back 282

storage battery, is charged by the proton pumps of the respiratory chain

Front 283

proton pumping out of the mitochondria matrix is fueled by

Back 283

the exergonic reactions in the respiratory chain

Front 284

protons move back into the matrix through a proton channel. This proton channel is coupled to

Back 284

an ATP- synthesizing enzyme (ATP synthase).

ATP synthesis is field by the flow of protons down their electrochemical gradient.

Front 285

there is no rate limiting step in:

Back 285

oxidative phosphorylation

Front 286

what does the rate of oxidative phosphorylation depend on

Back 286

substrates availability and an oxidizable metabolite, like NADH and or FADH2

Front 287

ATP synthesis absolutely dependent on

Back 287

continuous electron flow and electron transport occurs only during ATP synthesis

Front 288

what produces most of the ATP

Back 288

oxidative phosphorylation

Front 289

in healthy cells, the level of ATP exceeds that of ADP by a factor of:

Back 289

4-10

Front 290

high demand for ATP, generates:

Back 290

ADP, which stimulates respiration

Front 291

At rest, accumulation of ATP depletes

Back 291

ADP levels and suppresses respiration

Front 292

uncoupler

Back 292

any substance that inhibits ATP synthesis but have no effect on electron transport

means the dissociation of oxidative phosphorylation (not reduction) from ATP synthesis. wh

Front 293

at is the most common uncoupler

Back 293

2,4-dinitrophenol (DNP)

Front 294

Valinomycin

Back 294

an antibiotic that makes the inner mitochondrial membrane permeable for potassium

Front 295

oxygen utilization is maintained as

Back 295

electron transport (H+ pumping) continues

Front 296

ATP synthesis is diminished or inhibited as

Back 296

proton gradient is weak, disrupted, or non-existentt

Front 297

thyroxin

Back 297

a hormone produced by the thyroid glands to regulate metabolism by controlling the rate of oxidation in cells

Front 298

thermogenin

Back 298

a protein of the inner mitochonrial membrane that allows trans-membrane movement of protons, called uncoupling protein, a membrane-spanning protein that forms a natural channel to allow proton return

-increases heat generation

-found in specialized tissues (hairless, hibernators, cold-adapted)

-brown fat (particularly high content of cytrochromes) localized in the neck and upper back

Front 299

oxidative phosphorylation is inhibited by:

Back 299

by many poisons; electron flow through the respiratory chain, can be blocked by:

-rotenone

-amytal

-antimycin A

-cyanide

Front 300

rotenone

Back 300

an insecticide, blocks flow of electrons from Fe-S complexes in the NADH-Q reductase complex to ubiquinone through complex I. blocks transfer of electrons associated with NADH

Front 301

amytal

Back 301

(a barbituate), site of action same as rotenone, also inhibits electron flow through the NADH-Q redutase compile (complex I)

Front 302

antimycin A

Back 302

an antibiotic, that blocks electron flow from cytochrom b to c1 through the cytochrome c oxido-reductase complex (complex III)

Front 303

cyanide

Back 303

binds to cytochrome oxidase (complex IV) and prevents electron transfer ot oxygen. hydrogen sulfide, carbon monoxide and azide also act as cyanide.

Front 304

mitochondrial genome consists of

Back 304

16,569 base pairs that encode:

13 polypeptides

7 subunits of complex I

1 subunit of complex II

3 subunits of complex IV

2 subunits of ATP synthase

22 transfer RNAs

2 RNAs of the mitochondrial ribosomes

Front 305

mutation in mitochondrial DNA can cause

Back 305

-Lebers hereditary optic neuropathy (LHON): blindness, caused by degeneration of the optic nerve

-myoclonic epilepsy and ragged-red fiber disease (MERRF)

-mitochondrial DNA has a higher mutation rate than nuclear DNA

Front 306

reactive oxygen species are formed when?

Back 306

during oxidative metabolism

electrons may "leak out" of the respiratory chain

Front 307

what is the most harmful radical

Back 307

hydroxyl radical

Front 308

enzymes evolved to destroy ROS

Back 308

superoxide dismutase (SOD)

catalase - a heme containing enzyme that destroys H2O2)

peroxidases: glutathione peroxidase

Front 309

examples of metabolites, vitamins, hormones,and phytochemicals that can eliminate free radicals

Back 309

bilirubin

uric acid

ascorbate (vitamin C)

estrogens

Front 310

heart muscle obtains nearly all its ATP from

Back 310

oxidative phosphorylation

Front 311

oxidative phosphorylation and photo-phosphorylation account for

Back 311

most of the ATP synthesized by organisms

Front 312

mitochondria have ___ membranes

Back 312

2: the outer membrane is readily permeable to small molecules, which move freely through transmembrane channels. The inner membrane is impermeable to small molecules and bears the components of the respiratory chain and the ATP synthase.

Front 313

can NADH and NADPH cross the inner mitochondrial membrane

Back 313

NO

Front 314

respiratory chain creates

Back 314

a proton gradient

Front 315

inhibition of ATP synthesis blocks:

Back 315

electron transfer in intact mitochondria

Front 316

glycolysis under anaerobic conditions yields only

Back 316

2 ATP per glucose

Front 317

ATP consumption increases...

Back 317

the rate of electron transfer and oxidative phosphorylation increases

Front 318

mitochondria of heart muscle

Back 318

have much larger are of inner membrane, contain more than 3 times the electron transport systems compared to liver mitochondria

Front 319

electron transport system:

Back 319

movement of electrons from electron donor to electron acceptor molecules, especially from substrates to oxygen, via carriers such as components of the respiratory chain

Front 320

cytochromes

Back 320

heme proteins that functions as electron carriers in respiration, photosynthesis and other oxidation - reduction reactions

Front 321

proton pump

Back 321

proton pumps are integral membrane proteins capable of moving protons across the membrane of a cell, mitochondrion, or other sub-cellular compartment

Front 322

iron-sulfur proteins

Back 322

non-heme iron proteins that participate in electron transfer reactions

Front 323

ATP synthase

Back 323

an enzyme complex that forms ATP from ADP and phosphate during oxidative phosphorylation in the inner mitochondria membrane, and during phosphorylation in chloroplast

Front 324

uncouplers

Back 324

also called uncoupling agents

substances tha uncouple phosphorylatin of ADP from electron transfer,

ex; 2,4 dinitrophenol

Front 325

free radicals

Back 325

molecules with an unpaired electron; most of them are highly reactive

Front 326

the brain alone consumes ____ of glucose

Back 326

120 grams of glucose per day

Front 327

what blood glucose level must be maintained at all times

Back 327

4-5.5 mmol/liter

Front 328

only ____ glycogen can be used to maintain the blood glucose level

Back 328

liver

Front 329

gluconeogenesis produces

Back 329

glucose from amino acids, lactic acid, and glycerol

it is the only source of glucose during prolonged fasting

Front 330

only the liver and kidneys have a ..

Back 330

complete gluconeogenic pathway

Front 331

liver produces ___ times more glucose than kidney, because...

Back 331

10 x

bc the liver is this much larger than the kidney

Front 332

where is glucose stored

Back 332

in the liver and muscle, in the form of glycogen

Front 333

where does gluconeogenesis occur

Back 333

primarily in the cytosol, although some precursors are generated in the mitochondria

Front 334

glucose is a universal

Back 334

fuel and building block in humans, some tissues depend almost completely on glucose for their metabolic energy

Front 335

what is the major gluconeogenic organ of the body

Back 335

LIVER

Front 336

does muscle contribute to gluconeogenesis

Back 336

muscle does NOT contribute, because it has no glucose-6-phospatase and no glucagon receptors

Front 337

gluconeogenesis

Back 337

synthesis of carbohydrate from non carbohydrates such as oxaloacetate or pyruvate

Front 338

gluconeogenesis and glycolysis run in

Back 338

oposite directions

Front 339

3 reactions of glycolysis are irreversible and cannot be used in gluconeogenesis:

Back 339

1. conversion of glucose to glucose 6 phosphate (hexokinase/glucokinase)

2. phosphorylation of fructose 6 phosphate to fructose 1,6 bisphosphate (PFK-1)

3. Conversion of PEP to pyruvate (pyruvate kinase)

Front 340

3 reactions bypassing irreversible reactions of glycolysis in gluconeogenesis

Back 340

1) bypass from pyruvate to PEP. Pyruvate is carboxylated to oxaloacetate by pyruvate carboxylase.

2) the PFK rxn is bypassed by fructose 1,6 bisphosphate which hydrolyzes the phosphate from carbon 1

3) hexokinase reaction is bypassed by glucose 6 phosphate

Front 341

where is glucose 6 phosphate

Back 341

located in the ER and present only i the liver.

Front 342

glucose

Back 342

is an important metabolic substrate for most tissues, and is required fuel for brain and RBCs. normal blood glucose level: 70 to 100 mg/dL

Front 343

in the fasting state, the liver...

Back 343

has to produce glucose by gluconeogenesis and glycogen degradation

Front 344

for each molecule of glucose formed by pyruvate, ___ high-energy phosphate groups are required, ___ from ATP and ___ from GTP

Back 344

6

4

2

Front 345

___ molecules of NADH is required for the reduction of 2 molecules of 1,3 bisphosphoglycerate to glyceraldehyde 3 phosphate

Back 345

2

Front 346

gluconeogenic substrates

Back 346

glucogenic amino acids - all except leucine and lysine

lactate - cori cycle

glycerol

all TCA intermediates except Acetyl CoA

Front 347

Acetyl CoA cannot be converted to glucose, because

Back 347

the PDH reaction is irreversible

Front 348

gluconeogenesis depends on

Back 348

amino acids, lactate, and glycerol

Front 349

fatty acids that are released from adipose tissue during fasting cannot

Back 349

be turned into glucose

Front 350

most important substrates of gluconeogenesis

Back 350

lactate and alanine bc they are readily converted to pyruvate by lactate dehydrogenase and by transamination

Front 351

cori cycle

Back 351

shuttling of glucose and lactate between muscle/ RBC and liver during physical exercise

Front 352

after vigorous exercise, lactate produced by anaerobic glycolysis returns to

Back 352

the liver and is converted to glucose, which moves back to muscle and is converted to glycogen (core cycle)

Front 353

regulation of gluconeogenesis

Back 353

insulin and glucagon

epinephrine and norepinephrine

glucocorticoids

pyruvate kinase

phosphofructokinase and fructose 1,6 bisphosphate

Front 354

insulin

Back 354

released from pancreatic Beta cells in response to hyperglycemia

insulin lower blood glucose level

insulin is needed to convert sugar, starches, and other food into glucose or regulates storage of glycogen in the liver and accelerates oxidation of sugar in cells

Front 355

glucagon

Back 355

a polypeptide hormone from the alpha cells of the pancreas that stimulates the glucose producing pathways of the liver. it is released in response to hyperglycemia

glucagon raises blood glucose level

Front 356

the release of glucagon and insulin is inhibited by

Back 356

somatostatin that is secreted by the pan created delta cells

Front 357

epinephrine and norepinephrine

Back 357

stress hormones that released during physical exertion and cold exposure. in the liver, they promote gluconeogenesis over glycolysis by inducing cAMP

Front 358

glucocorticoids

Back 358

also stress hormones that affect gene transcription.

stimulate gluconeogenesis by inducing gluconeogenic enzymes

Front 359

pyruvate kinase

Back 359

the most important regulated enzyme in the PEP-pyruvate cycle. it is inhibited by ATP and activated by fructose 1,6 bisphosphate

Front 360

phosphofructokinase and fructose 1,6 bisphosphatase

Back 360

in the liver are oppositely regulated. ATP and citrate stimulate fructose 1,6 bisphosphatase but inhibit phosphofructokinase

Front 361

glucose-phosphorylating enzymes in the liver are:

Back 361

hexokinase and glucokinase

Front 362

fructose 2,6 bisphosphate

Back 362

the most potent modulator of phosphofructokinase and fructose 1,6 bisphosphatase

Front 363

fatty acid oxidation is less controlled by _______ _______ than is glucose oxidation

Back 363

feedback inhibition

therefore, levels of ATP and acetyl CoA in the liver are actually elevated during fasting

Front 364

fatty acid oxidation provides the necessary energy required by

Back 364

gluconeogenesis

Front 365

feedback inhibition

Back 365

inhibition of a metabolic pathway by its end product

Front 366

fatty acid oxidation

Back 366

the burning of stored fat

Front 367

gluconeogenesis is inhibited by:

and stimulated by:

Back 367

inhibited by fructose 2,6 bisphospate

stimulated by acetyl CoA

Front 368

liver consumes _____ to maintain _____

Back 368

glucose to maintain blood glucose level

Front 369

muscle consumes

Back 369

glucose for energy production

Front 370

lactate is transported from muscle to...

Back 370

liver for the re-synthesis of glucose in the Cori cycle

Front 371

glycolysis

Back 371

conversion of glucose to pyruvate

Front 372

gluconeogenesis

Back 372

conversation of 2 molecules of pyruvate to one molecule of glucose

Front 373

glycogenesis

Back 373

synthesis of glycogen

Front 374

glycogenolysis

Back 374

breakdown of stored glycogen