Anaerobic Metabolism - the TCA Cycle

Where does the TCA cycle take place?

The TCA cycle takes place in all tissues.

Fill in the blanks below to give a general description of the TCA cycle. 1. [blank_start]Acetyl CoA[blank_end] (2C) combines with [blank_start]oxaloacetate[blank_end] (4C) to form [blank_start]citrate[blank_end] (6C). 2. [blank_start]Citrate[blank_end] is isomerised to [blank_start]isocitrate[blank_end] (6C). 3. Citrate is decarboxylised to [blank_start]a-ketoglutarate[blank_end] (5C) 4. [blank_start]a-ketoglutarate[blank_end] is decarboxylised to [blank_start]succinyl-CoA[blank_end] (4C) 5. [blank_start]Succinyl CoA[blank_end] is converted to [blank_start]succinate[blank_end], then [blank_start]fumarate[blank_end], then [blank_start]malate[blank_end], then finally back to [blank_start]oxaloacetate[blank_end]. 6. The cycle repeats.

Which enzyme carries out the link reaction?

Fill in the blanks below to describe the link reaction. P[blank_start]yruvate[blank_end] reacts with c[blank_start]oenzyme A[blank_end] to form a [blank_start]thioester[blank_end] bond. This forms an a[blank_start]cetyl CoA[blank_end] molecule and a c[blank_start]arbon dioxide molecule[blank_end]. This forms [blank_start]NADH[blank_end] + H+ from NAD. This reaction is catalysed by [blank_start]pyruvate dehydrogenase[blank_end].

What enzyme catalyses the formation of citrate from oxaloacetate and acetyl CoA in the TCA cycle?

What is the function of aconitase in the TCA cycle?

Isocitrate is decarboxylated to what molecule in the TCA cycle?

Which enzyme forms a-ketoglutarate?

NADH + H+ is formed from NAD+ when isocitrate is decarboxylated to a-ketoglutarate.

a-ketoglutarate is decarboxylated by ketoglutatate dehydrognease to what molecule?

NADH + H+ are formed from NAD+ when a-ketoglutarate is decarboxylated to succinyl CoA.

What is formed when succinyl CoA is cleaved to form succinate?

Which enzyme catalysed the cleavage of succinyl CoA to succinate?

What does succinate dehydrognease do?

During which reaction of the TCA cycle is FADH2 formed?

When fumarate is hydrated by fumarase, what molecule is formed?

What enzyme oxidises malate to oxaloacetate in the final stage of the TCA cycle?

NADH + H+ are formed from NAD in the oxidation of malate to oxaloacetate in the TCA cycle.

Fill in the blanks below to summarise each reaction of the TCA cycle based on the type of reaction it is. 1. [blank_start]Condensation[blank_end] 2. [blank_start]Isomerisation[blank_end] 3. [blank_start]Decarboyxlation[blank_end] 4. [blank_start]Decarboxylation[blank_end] 5. [blank_start]Cleavage[blank_end] 6. [blank_start]Oxidation[blank_end] 7. [blank_start]Hydration[blank_end] 8. [blank_start]Oxidation[blank_end]

Fill in the blanks below to describe the reactions of the TCA cycle. 1. First, acetyl CoA and [blank_start]oxaloacetate[blank_end] combine to form the 6-carbon compound [blank_start]citrate[blank_end]. This is catalysed by citrate synthase. 2. Then, [blank_start]citrate[blank_end] is isomerised to [blank_start]isocitrate[blank_end]. This is catalysed by [blank_start]aconitase[blank_end]. 3. [blank_start]Isocitrate[blank_end] is decarboxylated to [blank_start]a-ketoglutarate[blank_end]. This is catalysed by [blank_start]isocitrate dehydrogenase[blank_end] and forms NADH and H+ from [blank_start]NAD+[blank_end]. 4. [blank_start]a-ketoglutarate[blank_end] is decarboxylated to [blank_start]succinyl CoA[blank_end]. This involves addition of [blank_start]coenzyme A[blank_end] and is catalysed by [blank_start]ketoglutarate dehydrogenase[blank_end]. This also forms [blank_start]NADH[blank_end]. 5. [blank_start]Succinyl CoA[blank_end] is cleaved into s[blank_start]uccinate[blank_end] and coenzyme A by [blank_start]succinate thiolase[blank_end]. This forms [blank_start]GTP[blank_end] from [blank_start]GDP[blank_end] and inorganic phosphate. 6. [blank_start]Succinate[blank_end] is decarboxylated into [blank_start]fumarate[blank_end]. This is catalysed by [blank_start]succinate dehydrogenase[blank_end] and forms [blank_start]FADH2[blank_end]. 7. [blank_start]Fumarate[blank_end] is hydrated to form [blank_start]malate[blank_end]. This is catalysed by [blank_start]fumarase[blank_end]. 8. [blank_start]Malate[blank_end] is decarboxylated into [blank_start]oxaloacetate[blank_end]. This is catalysed by [blank_start]malate dehydrogenase[blank_end] and forms [blank_start]NADH[blank_end]. 9. The cycle repeats.

How many molecules of ATP are yielded from 1 molecule of NADH?

How many molecules of ATP are yielded from 1 molecule of FADH2?

How many molecules of ATP are yielded from one molecule of GTP?

Which minerals are the carrier protein complexes in the electron transfer chain dependent on? Select all that apply.

Fill in the blanks below to describe oxidative phosphorylation. 1. The proton pump on the [blank_start]inner[blank_end] mitochondrial membrane moves [blank_start]protons[blank_end] into the [blank_start]intermembranal space[blank_end]. This id driven by [blank_start]NADH[blank_end]. 2. The [blank_start]pH[blank_end] of the intermembranal space [blank_start]decreases[blank_end]. 3. A gradient of [blank_start]H+[blank_end] ions is produced. 4. Protons move back into the [blank_start]matrix[blank_end] via [blank_start]ATP synthase[blank_end] causing it to [blank_start]rotate[blank_end]. 5. [blank_start]Rotational[blank_end] energy is used to synthesise [blank_start]ATP[blank_end] from ADP and Pi.

Fill in the blanks below to describe the yield from the TCA cycle. Each TCA cycle yields [blank_start]3[blank_end] NADH molecules. [blank_start]3[blank_end] x [blank_start]2.5[blank_end] = [blank_start]7.5[blank_end] ATP from NADH. Each TCA cycle yields [blank_start]1[blank_end] FADH2 molecule. [blank_start]1[blank_end] x [blank_start]1.5[blank_end] = [blank_start]1.5[blank_end] ATP from FADH2. Each TCA cycle yields [blank_start]1[blank_end] GTP molecule. [blank_start]1[blank_end] x [blank_start]1[blank_end] = [blank_start]1[blank_end] ATP from GTP. This totals to [blank_start]10[blank_end] ATP per TCA cycle.

Which enzymes are involved in irreversible steps of the TCA cycle that regulate it by feedback inhibition?

Fill in the blanks below to describe the feedback inhibition of the 3 irreversible enzyme steps of the TCA cycle. Isocitrate dehydrogenase is inhibited by [blank_start]NADH[blank_end] and activated by [blank_start]ADP[blank_end]. Ketoglutarate dehydrogenase is inhibited by [blank_start]NADH[blank_end] and s[blank_start]uccinyl CoA[blank_end]. Citrate synthase is inhibited by N[blank_start]ADH[blank_end] and [blank_start]succinyl CoA[blank_end].

Label this image to show the other fates of some of the intermediates in the TCA cycle.

Fill in the blanks below to describe the links between the TCA cycle and biosynthesis. Pyruvate can be converted to [blank_start]oxaloacetate[blank_end] by [blank_start]pyruvate carboxylase[blank_end]. [blank_start]Citrate[blank_end] can be used to form fatty acids and sterols. [blank_start]A-ketoglutarate[blank_end] can be involved in transamination reactions to form g[blank_start]lutamate[blank_end]. [blank_start]Malate[blank_end] can form pyruvate in a reaction catalysed by [blank_start]malic enzyme[blank_end]. Oxaloacetate can be converted to [blank_start]phosphoenol pyruvate[blank_end] by [blank_start]phosphoenol pyruvate carboxylase[blank_end] and then into [blank_start]glucose[blank_end]. Oxaloacetate can be involved in [blank_start]transamination[blank_end] reactions to form a[blank_start]spartate[blank_end].