BIOL 240 Lecture Notes - Lecture 10: Citric Acid Cycle, Acetyl-Coa, Oxidative Phosphorylation

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azuremole431

24 Oct 2018

School

University of San Diego

Department

Biology Courses

Course

BIOL 240

Professor

Lisa Baird

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Document Summary

The product of the reaction slows down/inhibits that reaction. After pyruvate is oxidized, the citric acid cycle completes the energy-yielding oxidation of organic molecules. In the presence of o2, pyruvate enters a mitochondrion . (in eukaryotic cells) where the oxidation of glucose is completed. Before the citric cycle can begin, pyruvate must be converted to acetyl coenzyme a (acetyl coa), which links glycolysis to the citric acid cycle. This step is carried out by a multienzyme complex that catalyzes 3 reactions. Combination of the remaining 2-carbon fragment and coenzyme a to form acetyl coa. The citric acid cycle, aka the krebs cycle, completes the breakdown of pyruvate to co2. The cycle oxidizes organic fuel derived from pyruvate. Generates 1 atp, 3 nadh, 1 fadh per turn. The citric acid cycle has 8 steps, each catalyzed by a specific enzyme. The acetyl group of acetyl coa joins the cycle by combining with oxaloacetate (4 carbons), forming citrate (6 carbons)

Related Questions

1. Choose the TWO correct statements describing the citrate cycle.

	ATP is an indirect product of the citric acid cycle
	Acetyl CoA can increase the pool of citric acid cycle intermediates
	Fatty acids can increase the pool of citric acid cycle intermediates
	ADP inhibits Î±-ketoglutarate dehydrogenase
	The pool of mitochondrial oxaloacetate can be increased by pyruvate
	All enzymes of the citric acid cycle are found soluble and free in the mitochondrial matrix

2.Which molecule in the net reaction of the citrate cycle contributes to the inhibition of pyruvate dehydrogenase?

	NADH
	H⁺
	H₂O
	FAD

3. How would a high NADH to NAD⁺ ratio be expected to affect the pyruvate dehydrogenase reaction?

	The E1 subunit is phosphorylated by pyruvate dehydrogenase kinase, and the catalytic activity of pyruvate dehydrogenase decreases.
	The last step of the pyruvate dehydrogenase reaction is blocked, resulting in a decrease in activity.
	The pyruvate dehydrogenase phosphatase-1 enzyme would increase, resulting in pyruvate dehydrogenase activation at an accelerated rate.
	The pyruvate dehydrogenase kinase enzyme activity would increase, resulting in an increase in pyruvate dehydrogenase activity.

1. Integrated metabolism

A. A molecule of glucose that you eat can eventually be transformed into part of a fatty acid that you store. Circle the pathways/cycles below that are part of this overall flow of carbon atoms. Cross out any that are not.

Gluconeogenesis, beta-oxidation, citric acid cycle, glycolysis, urea cycle, fatty acid synthesis

B. Trace the metabolic path of this glucose molecule through the enzymes it encounters along the way to being made into fat. Write all the enzymes in the list below into the proper places in the figure below. If the enzyme is not used, write its name in a ânot used" column. If it is used, write the enzyme in the order that the carbon atoms from glucose encounter the enzymes.

Pyruvate dehydrogenase, fumarase, aldolase, lactate dehydrogenase, pyruvate kinase, acetyl CoA carboxylase, fatty acid synthase, hexokinase, carnitine acyltransferase, ATP synthase

B. What is the minimum number of glucose molecules that would be necessary to be the carbon source for synthesis of a 16-carbon fatty acid through this pathway?

C. How many net glucose can be made from one molecule of a 16-carbon fatty acid?

2. Describe each cycle/transport system (compounds, compartments, tissues) and explain its purpose:

A. citrate transport system

B. Cori cycle

C. glucose/alanine cycle

Explain the logic of these pathway regulations:

A. Phosphofructokinase, not hexokinase, is the main regulation site of glycolysis.

B. SuccinylCoA inhibits the entry of acetyl CoA into the citric acid cycle.

C. NADH inhibits pyruvate dehydrogenase.

D. Citrate inhibits the citric acid cycle and activates acetyl-CoA carboxylase.

E. Insulin leads to activation of glycogen synthase.

ochrereindeer904

Consider the process of ATP synthesis via aerobic cellular respiration.

In a series of bullet point lists, provide the following information for each of the step in aerobiccellular respiration:
Inputs, Outputs, Energy stored or generated (if it is ATP is it by substrate level phosphorylation or oxidative phosphorylation) and where within a eukaryotic cell the process is located (specifically).

I will be looking for the items listed above in the bullet points you create for each step of aerobiccellular respiration (glycolysis, transition reaction (pyruvate to acetyl-CoA), Citric Acid Cycle, Electron Transport Chain and ATPsynthase).

I don't need paragraphs, just bullet point lists showing what is what.

BIOL 240 Lecture Notes - Lecture 10: Citric Acid Cycle, Acetyl-Coa, Oxidative Phosphorylation

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