Biochemistry Ii

Front 1

Where does CAC take place?

Back 1

mitochondria

Front 2

Can CAC occur anaerobically?

Back 2

No, NADH and FADH2 would accumulate if O2 were not available for the electron transport chain

Front 3

What is the primary function of CAC?

Back 3

oxidation of acetyl CoA to carbon dioxide

Front 4

What energy resovoirs are used by CAC?

Back 4

NADH, FADH2, and GTP

Front 5

What is the major control enzyme?

Back 5

Isocitrate dehydrogenase

Front 6

What activates isocitrate dehydrogenase and what inhibits it?

Back 6

Activated by: ADP
Inhibited by: NADH

Front 7

To what enzyme is alpha-Ketoglutarate dehydrogenase similar?

Back 7

pyruvate dehydrogenase complex

Front 8

What does lack of thaimine slow?

Back 8

oxidation of acetyl CoA in the citric acid cycle

Front 9

What does alpha-Ketodehydrogenase need?

Back 9

thiamine, lipoic acid, CoA, FAD and NAD

Front 10

What does succinyl CoA synthetase catalyze?

Back 10

substrate-level phosphorylation of GDP to GTP

Front 11

Where is succinate dehydrogenase found?

Back 11

inner mitochondrial membrane

Front 12

What does succinate dehydrogenase function as?

Back 12

complex II of the electron transport chain

Front 13

Where is the majority of O2 in tissue consumed?

Back 13

in the electron transport chain

Front 14

What is the main function of O2?

Back 14

accept electrons at the end of the chain

Front 15

What oxidizes NADH?

Back 15

NADH dehydrogenase (Complex I)

(delivering its electrons to the chain and returning as NAD to enzymes that require it)

Front 16

Across which membrane is the proton gradient kept?

Back 16

inner membrane

Front 17

How does CAC function?

Back 17

catalytically

Front 18

What does citrate do?

Back 18

it carries acetyl CoA into cytolasm for fatty acid synthesis

Front 19

Where does electron transport and oxidative phosphorylation occur?

Back 19

mitochondrial inner membrane
(cell membrane in prokaryotes)

Front 20

What do you call reactions leading to TCA intermediates?

Back 20

anaplerotic reactions

Front 21

How many carbons are lost when going from citrate to oxaloacetate?

Back 21

two

Citrate 6 carbon atoms
Oxaloacetate 4 carbon atoms

Front 22

What is used to reform citrate from oxaloacetate?

Back 22

Acetyl CoA

Front 23

Which one can be transported across the mitochondrial membrane, malate or OAA?

Back 23

malate

Front 24

What does PEP carboxykinase do?

Back 24

synthesizes PEP from OAA

Front 25

What are the three names for CAC?

Back 25

Citric Acid Cycle
Tricarboxylic Acid Cycle
Krebs Cycle

Front 26

What is the input in CAC?

Back 26

acetyl units

Front 27

What is the output in CAC?

Back 27

CO2, ATP or GTP, reduced cofactors

Front 28

In CAC, what is the only five carbon intermediate?

Back 28

alpha-ketoglutarate

Front 29

For alpha-ketoglutarate to proceed to the 4-carbon stage what must the alpha-ketoglutarate release?

Back 29

CO2

Front 30

What is seen in the last four intermediates (succinate, fumarate, malate, and oxaloacetate)?

Back 30

progressive oxidation

Front 31

What happens to carbon 2 in succinate?

Back 31

it changes from CH2 to C=O

yielding a loss of 4 electrons

Front 32

The regulating enzymes of the TCA cycle control flux through?

Back 32

1. substrate availability/concentration
2. product inhibition
3. competitive feedback inhibition

Front 33

What are the most crucial regulators of the TCA cyle?

Back 33

its substrates, actyl Coa and OAA and its product NADH

Front 34

Do the concentrations at which Acetyl CoA and OAA are found in the mitrochondria ever saturate citrate synthase?

Back 34

no

Front 35

The metabolic flux in TCA through enzymes varies with what?

Back 35

substrate concentration and is controlled by substrate availability

Front 36

In TCA, NAD+ levels are a measure of what?

Back 36

electron transport activity

Front 37

In TCA, adenine nucleotides are a measure of what?

Back 37

measure of energy charge

Front 38

How many steps are in the CA cycle?

Back 38

8

Front 39

How many are oxidation reactions, which ones?

Back 39

3,4,6,8

Front 40

What is the oxidizing agent in 3,4, and 8?

Back 40

NAD+

Front 41

What is the oxidizing agent in 6?

Back 41

FAD

Front 42

What is special about step 5?

Back 42

a molecule of GDP is phosphorylated to produce GTP, this reaction is equivalent to the production of ATP

Front 43

What are the 2 sources of NADH (reducing equivalents)?

Back 43

CAC metabolism and the cytosol via the shuttle system

Front 44

What does the ETS pathway do?

Back 44

the pathway by which electrons from reduced fuels are transferred to molecular oxygen... reduced cofactors NADH and FADH2 deliver electrons to oxygen to make ATP

Front 45

Outer membrane of mitochondrion, two facts?

Back 45

contains porins and is relatively permeable for molecules smaller than 10,000 Da

Front 46

Inner membrane of mitochondrion, three facts?

Back 46

1. permeable to O2, CO2 and H2O
2. contains transport proteins that control passage of metabolites (ATP, ADP, pyruvate, Ca2+, P...)
3. important for compartmentalization between mitochondria and cytosol

Front 47

What drives phosphate import into mitochondrion?

Back 47

Transmembrane proton gradient

Front 48

In CAC, released CO2 molecules don't coome directly from acetyl-CoA but from ?

Back 48

oxaloacetate

Front 49

How many moles of ATP/mol of glucose are produced aerobically?

Back 49

aerobically-38

Front 50

Metabolon Hypothesis

Back 50

enzyme molecules are noncovalently associated in an assembly called the metabolon that is localized to a particular area in the cytoplasm or in an organelle

Front 51

Amphibolic

Back 51

both anabolic and catabolic

Front 52

Catabolic

Back 52

degradation, energy conservation

Front 53

Anabolic

Back 53

pathways use cyclic intermediates