Krebs Cycle Flashcards
what is the cuter acid cycle
common path by which all fuel molecules are broken down to carbon dioxide and water
What is the first stage
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
what is the second stage
The 6-carbon molecule is broken down in stages, finally resulting in formation of a new molecule of the original 4-carbon compound
what is the third stage
During this process, two molecules of CO2 and one molecule of GTP are formed.
what is the fourth stage
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
what forms FAD (flavin adenine dinucleotide)
from vitamin riboflavin (vitamin b2)
what does a deficiency in riboflavin cause
lesions of the mucous membranes
cracked, sore lips and corners of mouth; similar lesions in genital regions; tongue swollen, tender, magenta
where do all reactions from the breakdown of pyruvate, including all steps of the citric acid cycle take place
the MATRIX of the mitochondria
TRANSLOCATION OF PYRUVATE AND DECARBOXYLATION TO ACETATE
Coenzyme A (CoA) forms a high energy bond with carboxylic acids such as acetate
what is CoA
nucleotide that contains the vitamin pantothenic acid
= vitamin B5
where does the RESPIRATORY CHAIN = ELECTRON TRANSFER take place
macromolecular assemblies in the inner mitochondrial membrane
what does the respiratory chain consist of
three large protein complexes linked together by molecules that act as electron shuttles
what feeds electrons into the system at different places
NADH and FADH2
the respiratory chai is a target for what agents
retenone - insecticide, piscicide
antimycin - Antibiotic
what chemicals can block the final step by which hydrogen combines with oxygen
cyanide and carbon monoxide
what makes this chain more efficient
Electrons are passed from one member of the chain to another by passing electrons from NADH or FADH2 to oxygen
what is made by the movement of electrons down the respiratory chain
generates a H+ ion (pH) gradient across the inner mitochondrial
what is the resulting electrochemical gradient used for
to drive ATP synthesis by way of ATP synthase (= H+-ATPase)
respiratory chain summery
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
