LM10 Flashcards

1
Q

Which molecules act as stores of energy and reducing power during catabolism?

Enzyme inhibitors

Protein kinases

Coenzymes such as NADH

Enzymes such as glyceraldehyde 3-phosphate dehydrogenase

A

c

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2
Q

When oxygen is present, which of the following metabolic reactions occurs first after glycolysis?

Conversion of pyruvate into lactate

Synthesis of Acetyl-CoA

Synthesis of glucose from pyruvate

Synthesis of ATP by oxidative phosphorylation

A

b

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3
Q

Glucagon binds to the glucagon recepton on the cell surface. The resulting downstream signalling ultimately inhibits glycolysis by

preventing the phosphorylation of glucose

blocking the GLUT4 transporter

stimulating the formation of fructose 2,6 bisphosphate

phosphorylation of phosphofructokinase 2

A

d

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4
Q

Which of the following statements is false?

More ATP is produced following the citric acid cycle than during glycolysis

NADH and QH2 are directly converted to ATP in the mitochondrion

The citric acid cycle produces reduced coenzymes for the electron transport chain

The pyruvate dehydrogenase complex is regulated by phosphorylation

A

b

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5
Q

Which statement about glucose metabolism is incorrect?

In animals, triglycerides can be converted to glucose after formation of acetyl coA

Blood glucose levels can be maintained by formation of glucose from pyruvate

Glucose can be converted into triglycerides to be stored in adipose tissue

Amino acids can be utilised to maintain the levels of blood glucose

A

a

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6
Q

Following a meal and fasting, in which order are the different sources of glucose used to maintain blood glucose levels?

Dietary glucose first, then fats, then glycogen

Dietary glucose first, then glycogen, then proteins

Glycogen first, then proteins, then fats

Fats first, then glycogen, then proteins

A

b

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7
Q

Which metabolite represents the convergence of carbohydrate, fat and protein catabolisms and directly enters the citric acid cycle?

Pyruvate

Citrate

Acetyl CoA

α-Ketoglutarate

A

c

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8
Q

Which of the following metabolic pathways both take place within the mitochondrial matrix?

Citric acid cycle, β-oxidation of fatty acids

Citric acid cycle, fatty acid synthesis

Gluconeogenesis, glycolysis

Glycolysis, β-oxidation of fatty acids

A

a

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9
Q

The conversion from fumarate to malate generates no ATP, GTP nor NADH, nor any redox potential. It is energetically neutral. Why is it present in the TCA cycle?

It allows the cycle to turn in the opposite direction.

It removes a toxic double bond from the cycle.

It has not yet been eliminated by selective pressure (evolution).

It is useful when no energy is required during resting.

It reorganises atoms so that the oxidation of malate to oxaloacetate can occur in the next step.

A

b

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10
Q

In the electron transport chain, the cofactor that transfers electrons between complexes III and IV is

Coenzyme Q

Cytochrome C

FADH2

NADH

A

b

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11
Q

The chemiosmotic theory of energy conversions suggests that

osmosis of water across a membrane provides the driving force for ATP formation.

a proton concentration gradient causes a flow of electrons to ATP.

a proton concentration gradient causes the protonation of ATP.

a proton concentration gradient and electrical potential across a membrane provides the driving force for ATP formation.

oxygen consumption is coupled to ADP phosphorylation to make ATP.

an electrical potential across the membrane attracts phosphate ions to the surface and drives ATP formation.

A

4

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12
Q

The so-called dark reactions of photosynthesis occur in which region of the chloroplast?

Thylakoid membrane

Lumen

Stroma

Intermembrane space

A

c

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13
Q

Photosystem II complexes that oxidise water using light energy are found whereabouts in the chloroplast?

Stroma

Granal lamellae

Inner membrane

Outer membrane

Stromal lamellae

Lumen

A

b

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14
Q

During illumination, the pH of the stroma is

alkaline

acidic

neutral

A

a

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15
Q

During ATP generation,

protons accumulated in the lumen pass into the stroma through the H+-ATPase complexes in the stromal lamellae.

protons accumulated in the intermembrane space pass into the stroma through the H+-ATPase complexes in the stromal lamellae.

protons accumulated in the lumen pass into the intermembrane space through the H+-ATPase complexes in the stromal lamellae.

protons accumulated in the stroma pass into the lumen through the H+-ATPase complexes in the stromal lamellae.

A

a

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