Sullivan General Human Physiology Lecture 7

Front 1

Energy and Cellular Metabolism

Back 1

Metabolism:
- Anabolism
- Catabolism

Dynamic equilibrium
- anabolic/catabolic rates are equal

Front 2

3 Metabolic Pathways...

Back 2

are used by cells to transfer the energy released by catabolism:

* Glycolysis
* Krebs Cycle
* Oxidative Phosphorylation

Front 3

Glycolysis

Back 3

* first major pathway in energy metabolism of glucose
* occurs with/without O2 (arobic/anarobic)
* occurs in cytosol
* it is a series of 10 enzymatic reactions beginning with glucose and ending with pyruvic acid or lactic acid (depending on the availibility of oxygen)
* glycolysis yields 2 ATP for each glucose

Front 4

equation for GLYCOLYSIS

Back 4

Glucose + 2 ADP + 2 Pi + 2 NAD+ --> 2 Pyruvate + 2 ATP + 2 NADH + 2 H2O + 2H+

Front 5

What are the ways Pyruvate can proceed?

Back 5

Pyruvate can proceed 2 ways depending on the availibility of o2
... if o2 is availible pyruvate enters the Krebs Cycle
... if o2 is NOT available pyruvate is convertd to LACTATE

Front 6

How is more energy gained?

Back 6

more energy is gained under aerobic (o2) conditions because 2 more H atoms are available to use for energy transfer (rather than transferring then to lactate)

Front 7

Kreb's Cycle

Back 7

* pyruvate must be decarboxylated (releases CO2) and form NADH to enter Kreb's cycle
* the 2 carbon acetyl group remaining is accepted by Coenzyme A
* the Cycle is a circular sequence of 8 reactions thaqt occur in the matrix of mitochondria during which:
**1. 2 CO2 are formed
**2. 4 electrons are transfered to electron-carrier coenzymes (3 to NAD+)(1 to FAD)
**3. 1 ATP is formed
** for each acetyl group

Front 8

Oxidative Phosphorylation

Back 8

* most energy derived
* the energy transferred to ATP is derived from the energy released when hydrogen atoms are oxidized and ultimately form water
* OP mediated by proteins called cytochromes
* at 5 steps electons are transferred to NAD+ or FAD+
* as electrons are transferred from cytochrome to cytochrome the energy released is used to move hydrogen ions (protons) into mitochondria producing a hydrogen ion gradient and thus potential energy
* when these electrons eventually pass to oxygen (oxidative phosphorylation)
*** MOST of the ATP is produced
o2 + 4e- + 4H+ ----> 2H2O
* most energy derived from electron transport is used to phosphorylate ADP to ATP (oxidative phosphorylation)

Front 9

Oxidative Phosphorylation
equation

Back 9

1/2 o2 + NADH + H+ -----> H2O + NAD+ + 53 kcal

Front 10

Oxydative Phosphorylation
Steps:

Back 10

1. the energy released as electrons are transferred is used to pump H ions into the mitochondria
2. this creates a high concentration of H ions inside mitochondria
3. which cause H ions to flow thru ATPase molecules
4. energy from this flow is used to convert ADP ---> ATP
5. newly formed ATP moves out of mitochondria by facilitated diffusion

Front 11

How much energy is released during catabolism of one mole of glucose?

Back 11

686 kcal

Front 12

formula for catabolism of one mole of glucose

Back 12

C6H12O6 + 6O2 ----> 6H2O + 6CO2 + 686 kcal

Front 13

Chemical reactions:

Back 13

1. FORMING chemical bonds (endergonic)
2. BREAKING chemical bonds (exergonic)

Front 14

Energy is measured in ...

Back 14

calories

Front 15

1 calorie =

Back 15

amount of heat energy required to raise the temperature of 1 g of water 1 C

Front 16

Rate of Chemical Reactions

Back 16

1. Concentration of reactants
2. Temperature
3. Activation energy
4. Catalyst

Front 17

Rate of Chemical Reactions

Equation

Back 17

H2CO3 <======> CO2 + H2O + 4Kcal/mol
reactants products energy

Front 18

Reaction rate changes

Back 18

* as concentration of reactants becomes less
* as concentration of products becomes more

Front 19

What determines rate/direction of net reaction?

Back 19

Concentration of reactants and products determines rate/direction of net reaction.

Front 20

Chemical Equalibrium

Back 20

* when rates of forward and reverse reactions becomes EQUAL and concentrations do not change

carbonic anhydrase
H2CO3 <===================> H2O + CO2

Front 21

Where do the 38ish ATP come from?

Back 21

2 ATP from Glycolysis
2 ATP from Kreb's Cycle
34 ATP from Oxidative Phosphorylation

Front 22

7 kcal energy to form

Back 22

1 ATP

Front 23

ATP per glucose

Back 23

38

Front 24

7 X 38

Back 24

266 kcal energy transferred

Front 25

686-266

Back 25

420 kcal lost as heat

Front 26

for each 2 electrons that go thru the electron transport chain up to how many ATPs ae synthesized?

Back 26

up to 3 ATP

Front 27

Diagram H atom to ATP

Back 27

Glycolysis 2 ATP
Kreb's Cycle 2 ATP
ETS
20 H atoms
(in ox/red up to 3 ATP/ pair e-) 10 prs x 3 = 30 ATP

4 H atoms
(2 ATP/pair e-) 2 prs x 2= 4 ATP
Total: 38 ATP

Front 28

Enzymes

Back 28

* proteins
* biological catalysts
* react with substrates form products
* specific
* binds to substrate at ACTIVE SITE on enzyme (complementary shape)
* enzymes lower the required activation energy
* 90% of proteins in a cell are enzymes
* 1,000 - 4,000 enzymes/ animal cell

Front 29

Enzymes

Formula

Back 29

S + E <=====> ES <=====> E + P

Front 30

Cofactors

Back 30

1. metal ions
ie: Fe++ on catalase
Fe++, Cu++ on cytochrome oxidase
2. Coenzymes
ie: NAD+ nicotinamide adenine dinucleotide
FAD flavin adenine dinucleotide

Front 31

Cofactors:

Metal Ions

Back 31

* Ca++, Mg++, Mn++, Cu++, Zn++
* inorganic
* attach to enzyme as part of active site/causing conformational changes in enzyme that allow it to combine with the substrate
* allows for better "fit"
* sometimes form part of temporary ES complex
* activators or inhibitors

Front 32

Cofactors:

Coenzymes

Back 32

* organic molecules derived from water-soluble B vitamins (niacin/riboflavin)
* molecule that directly participates as a substrate in the reaction being catalyzed
* catalyze reactions in which atoms (H, CH3, CH3CO) are removed or added to the substrate

Front 33

Cofactor

Equasion

Back 33

R-2H + coenzyme <===> R + coenzyme - 2H

Front 34

CELLULAR METABOLISM
definition

Back 34

many types of enzymatic reactions in a cell do not occur independently but, rather are LINKED together in an interrelated pattern called CELLULAR METABOLISM

Front 35

METABOLIC PATHWAY
definition

Back 35

a SEQUENCE of enzyme-mediated reactions which lead to the formation of products is called METABOLIC PATHWAY

Front 36

BIOENERGETICS

Back 36

The flow of ENERGY in living systems is called BIOENERGETICS

Front 37

LAWS OF THERMODYNAMICS

Back 37

energy in biological systems obeys the LAWS OF THERMODYNAMICS

Front 38

First Law of Thermodynamics

Back 38

* energy can be transformed from one form to another, but can be neither created nor destroyed

Front 39

Second Law of Thermodynamics

Back 39

* the universe and its parts become increasingly disorganized (entropy)
* energy transformations increase entropy in a system
* only energy in an organized state (free energy) can be used to do work.

Front 40

Atoms ORGANIZED IN COMPLEX molecules like glucose have more ..

Back 40

free energy than small molecules like CO2/H2O

Front 41

The ENERGY released by exergonic reactions (catabolism) in a cell are used to form

Back 41

ADENOSINE TRIPHOSPHATE ... ATP

Front 42

ADP / ATP formula

Back 42

ADP + Pi + 7 Kcal <===> ATP + H2O

Front 43

when ATP is hydrolyzed, the removal of the terminal phosphate group yields ...

Back 43

7 kcal of energy

Front 44

Cells use this energy (ATP hydrolysis) by coupling ATP hydrolysis to endergonic reactions for

Back 44

muscle contractions
membrane transport
synthesis of cell structures

Front 45

40% of the energy derived from catabolism ...

Back 45

is transferred to ATP

Front 46

60% of the energy from catabolism ...

Back 46

goes off as heat

Front 47

most of the potential energy carried by glucose is captured by

Back 47

Oxidation - Reduction reactions

Front 48

In OXIDATION-REDUCTION reactions:

Back 48

One molecule GIVES UP electrons (oxidation)
One molecule ACCEPTS electrons (reduction)

Front 49

The electrons are carried by COENZYMES

Back 49

1. Nicotinamide adenine dinucleotide (NAD)
2. Flavin adenine dinucleotide (FAD)

Front 50

Oxidized

Back 50

NAD+
FAD+

Front 51

Reduced

Back 51

NADH
FADH

Front 52

Oxidative Phosphorylation occurs where?

Back 52

* occurs on mitochondrial membrane