Chapter 17

Question 1

citric acid cycle takes place in

Answer 1

mitochondrial matrix

Question 2

Our mitochondria are

Answer 2

“tame” bacteria

Question 3

mitochondria have their own

Answer 3

small genomes, and a double membrane

Question 4

Succinate DH

Answer 4

One enzyme of the citric acid cycle that is membrane bound (part of membrane)

Question 5

most of the enzymes in citric cycle is

Answer 5

dissolved in the matrix

Question 6

TCA cycle oxidizes

Answer 6

acetyl group to CO2, ATP, NADH, FADH2

Question 7

Plants TCA cycly only form

Answer 7

ATP

Question 8

The AcCoA eventually the reduced cofactors will yield energy in the form of

Answer 8

energy in the form of ATP

Question 9

For each AcCoA the yield is

Answer 9

1.0 ATP
1 x FADH2 ~ 1.5 ATP each
3 x NADH ~ 2.5 ATP each
Total: 10 ATP/AcCoA X 2 AcCoA/glucose =
20 ATP!

Question 10

The GTP that is formed by GDP-forming succinyl-CoA synthetase may be utilized by

Answer 10

nucleoside-diphosphate kinaseto form ATP

Question 11

catalyzed reaction of GTP in TCA is

Answer 11

GTP + ADP → GDP + ATP

Question 12

The hydrolysis of Acetyl-CoA is highly

Answer 12

exergonic ∆G= -7.5 (same as ATP)

Question 13

3 food sources that feed into acetyl CoA supply

Answer 13

Fatty acids, Glucose, and amino acids

Question 14

Membrane important to acety CoA

Answer 14

Inner mitochondrial membrane

Question 15

Citric cycle

Answer 15

Acetyle CoA ->
1 ATP
NADH/ FADH2
2 CO2

Question 16

Reduced carriers from citric cycle will

Answer 16

feed the mitochondrial electron transport chain that will eventually yield ATP

Question 17

pyruvate DH complex

Answer 17

Ac-CoA machine that links glycolysis and the the citric acid cycle where pyruvate is turned into acetyl groups.

Question 18

E1 name

Answer 18

Pyruvate dehydrogenase component

Question 19

E2 name

Answer 19

Dihydrolipoyl transacetylase

Question 20

E3 name

Answer 20

Dihydrolipoyl dehydrogenase

Question 21

E1 prosthetic group

Answer 21

TPP

Question 22

E2 Prosthetic group

Answer 22

Lipoamide

Question 23

E3 prosthetic group

Answer 23

FAD

Question 24

pyruvate DH complex structure

Answer 24

Larger than ribosomes and is a little cube made up of tiny spheres

Question 25

Pyruvate dehydrogenase (E1) contains

Answer 25

 mixed alpha helices and beta sheets

Question 26

The pyruvate DH complex needs two new cofactors

Answer 26

TPP and Lipoic acid

Question 27

TPP

Answer 27

5 membered thiazolium ring

Question 28

pyruvate DH complex reaction with cofactors yields

Answer 28

CO2 plus hydroxyethyl-thiamine-pyrophosphate (HE-TPP)

Question 29

PDH Steps

Answer 29

1.) Pyruvate “split in half” a. First half forms CO2 (completely oxidized so done with these carbons). b.The other half is transferred onto TPP to form Hydroxyethyl-TPP 2.) 2C from Hydroxyethyl-TPP transferred to Lipoamide to form acetyllipmoamide 3.) Acetyl group from acetyllipoamide is transferred to CoA-SH to form Acetyl-CoA. a. This is the entry point to TCA cycle b. We also generate lipoamide (reduced) here. The regeneration of the oxidized form generates an FADH2 (from FAD) and these electrons are then transferred to NAD+.

Question 30

The lipoamide arm coordinates

Answer 30

subunits of the PDH complex

Question 31

lipoamide arm steps

Answer 31

1. Pyruvate is decarboxylated in the E1 catalytic site is deep in a channel. CO2 is released 2. E2’s LA arm insterts into the channel of E1 3. Ac is transferred to E2’s LA arm and swings into another monomer of E2 4. Ac is transferred to CoA & released while LA arm swings into E3 subunit 5. LA is re-oxidized by FAD in E3 subunit a. FAD -> FADH2 6. FADH2 transfers H- to NAD+ reforming FAD

Question 32

acetyl CoA + 3 H2O + 3 NAD+ + FAD + ADP + Pi --->

Answer 32

CoA + 2 CO2 + 3 NADH + 2H+ + FADH2 + ATP

Question 33

Irreversible reactions in citric cycle

Answer 33

Step 1: OAA plus AcCoA yield citrate by citrate synthase Step 3: Oxidation and decarboxylation of citrate to 𝛼-KG by isocitrate DH Step 4: Oxidation and decarboxylation of 𝛼-KG to succinyl CoA by 𝛼-KG DH complex

Question 34

You can’t synthesize glucose from AcCoA, so if AcCoA or NADH/H+ builds up

Answer 34

they inhibit the pyruvate DH complex (feedback inhibition

Question 35

If the AcCoA builds up in the mitochondrial matrix, one of 2 things is happening.

Answer 35

1. The organism is too well fed. If so, it should be using pyruvate for gluconeogenesis 2. The organism is not overfed, but the CAC has stopped because the CAC is out of oxaloacetate

Question 36

Too well fed solution

Answer 36

The AcCoA will stimulate pyruvate carboxylase to make OAA for gluconeogenesis.

Question 37

CAC has stopped

Answer 37

use high AcCoA to stimulate pyruvate carboxylase to convert pyruvate into OAA for use as a substrate in the CAC.

Question 38

PDH Is regulated by

Answer 38

phsophorylation

Question 39

Bacterial citrate synthase is also inhibited by

Answer 39

high ATP/ADP

Question 40

Consider exercising after a night’s rest:

Answer 40

1. OAA is low 2. AcCoA is low 3. Energy status is low 4. But, the need for ATP is high.

Question 41

To restart the CAC

Answer 41

1. Available glucose is converted to pyruvate by glycolysis. 2. Pyruvate is carboxylated to OAA by Pyruvate carboxylase in an anaplerotic (filling) reaction. - but first PC needs AcCoA as a positive activator. 3a. Pyruvate is converted to AcCoA by PDH, and 3b. FAs are converted to AcCoA 4. ATP is generated by CAC and OxPhos

Question 42

Beriberi

Answer 42

neurological and cardiac disease caused by thiamine deficiency (Vitamin B1) often found in cultures that consume rice from which the husk (rich in thiamine) has been removed

Question 43

Hg or AsO3 (arsenic trioxide or arsenite) exposure

Answer 43

These block the transacetylase step (E3) of PDH and 𝛼KG DH.

Question 44

in beriberi

Answer 44

neurons are starved for energy due to compromised PDH

Question 45

Heavy metals (Hg & AsO3) treatment

Answer 45

mercaptopropanol