Krebs Cycle

Question 1

what is the cuter acid cycle

Answer 1

common path by which all fuel molecules are broken down to carbon dioxide and water

Question 2

What is the first stage

Answer 2

A 2-carbon molecule is condensed with a 4-carbon molecule to form a 6-carbon molecule]
First step is condensation of the acetyl group of Acetyl-CoA with the keto acid oxaloacetate:A number of dehydrogenation steps occur in the TCA cycle
Because keto acids so formed are quite reactive, they can be decarboxylated

Question 3

what is the second stage

Answer 3

The 6-carbon molecule is broken down in stages, finally resulting in formation of a new molecule of the original 4-carbon compound

Question 4

what is the third stage

Answer 4

During this process, two molecules of CO2 and one molecule of GTP are formed.

Question 5

what is the fourth stage

Answer 5

At the same time 3 molecules of NADH and one molecule of FADH2* are formed. –The hydrogen is eventually combined with molecular O2 (forming water) in a process coupled to ATP synthesis

Question 6

what forms FAD (flavin adenine dinucleotide)

Answer 6

from vitamin riboflavin (vitamin b2)

Question 7

what does a deficiency in riboflavin cause

Answer 7

lesions of the mucous membranes

cracked, sore lips and corners of mouth; similar lesions in genital regions; tongue swollen, tender, magenta

Question 8

where do all reactions from the breakdown of pyruvate, including all steps of the citric acid cycle take place

Answer 8

the MATRIX of the mitochondria

Question 9

TRANSLOCATION OF PYRUVATE AND DECARBOXYLATION TO ACETATE

Answer 9

Coenzyme A (CoA) forms a high energy bond with carboxylic acids such as acetate

Question 10

what is CoA

Answer 10

nucleotide that contains the vitamin pantothenic acid

= vitamin B5

Question 11

where does the RESPIRATORY CHAIN = ELECTRON TRANSFER take place

Answer 11

macromolecular assemblies in the inner mitochondrial membrane

Question 12

what does the respiratory chain consist of

Answer 12

three large protein complexes linked together by molecules that act as electron shuttles

Question 13

what feeds electrons into the system at different places

Answer 13

NADH and FADH2

Question 14

the respiratory chai is a target for what agents

Answer 14

retenone - insecticide, piscicide

antimycin - Antibiotic

Question 15

what chemicals can block the final step by which hydrogen combines with oxygen

Answer 15

cyanide and carbon monoxide

Question 16

what makes this chain more efficient

Answer 16

Electrons are passed from one member of the chain to another by passing electrons from NADH or FADH2 to oxygen

Question 17

what is made by the movement of electrons down the respiratory chain

Answer 17

generates a H+ ion (pH) gradient across the inner mitochondrial

Question 18

what is the resulting electrochemical gradient used for

Answer 18

to drive ATP synthesis by way of ATP synthase (= H+-ATPase)

Question 19

respiratory chain summery

Answer 19

Think of it as a system that works in the opposite direction from the sodium pump (Na-K ATPase) in the surface membrane
The sodium pump uses ATP to generate an ion gradient, while the ATP synthase uses an ion gradient to generate ATP
Oxidation of each molecule of NADH produces about 3 molecules of ATP, while each molecule of FADH2 generates 2 ATP molecules