Week 5 - Metabolism Flashcards Preview

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Flashcards in Week 5 - Metabolism Deck (68):
1

A 32-year old male comes to see you in a GP surgery. He is concerned that his father died at the age of 50 from a heart attack and wants his blood cholesterol checked. You arrange for a fasting blood sample to be taken. The lab reports the following results:
• total serum cholesterol = 12 mmol/L (reference range = 3.5 – 6.5 mmol/L)
• serum triacylglycerol = 1.0 mmol/L (reference range 0.7 – 2.0 mmol/L)
• serum lipoprotein profile = increased amounts of LDL particles
What other analysis should you request and why?

Blood glucose to check for diabetes

2

What is the link between diabetes and cholesterol?

Diabetes raises LDL cholesterol

3

What is hyperlipoproteinemia?

Any condition resulting in raised blood cholesterol or triglycerides after a 12-hour fast

4

What class of lipoprotein would not be present in a normal fasting blood sample?

Chylomicrons

5

What classes of lipoprotein would be present in a normal fasting blood sample?

LDL, VLDL, and HDL

6

Outline 2 pathways by which tissues obtain the cholesterol they need.

1. Direct synthesis via acetyl CoA within the tissues
2. Indirect synthesis via LDLs the liver

7

Name 3 treatment options for a patient presenting with high cholesterol.

1. Reduce dietary cholesterol intake
2. Statins to reduce synthesis of LDL in the liver
3. Bile salt sequestrants to increase disposal of cholesterol in the liver

8

What are the two main symptoms treated by Paracetamol?

1. Pain
2. Fever

9

Describe how paracetamol overdose damages the liver.

Saturation of phase II pathway of drug metabolism ->
Switch to phase I pathway ->
Production of NAPQI ->
Conjugation of NAPQI with glutathione (GSH) ->
Hepatocytes deprived of an important anti-oxidant defence

10

Compare necrosis and apoptosis.

Necrosis = unprogrammed cell death
Apoptosis = programmed cell death

11

Define homeostasis.

The control of the internal environment to maintain a DYNAMIC EQUILIBRIUM

12

Define the basal metabolic rate.

Energy required to maintain basic functions of life at rest

13

Explain the mechanism of penicillin.

Prevents cross-linking of peptidoglycan (the main component of cells walls), leaving cells unable to grow and divide
Note: only affects gram-positive bacteria.

14

Compare gram-positive and gram-negative bacterial cell walls.

Gram-positive: thick, weaker (analogy: puffy winter coat)
Gram-negative: thin, stronger (analogy: bulletproof vest)

15

List 4 mechanisms by which bacteria become resistant to penicillin.

1. Degradation of penicillin by enzymes (such as β-lactamase)
2. Mutation of target sites (such as penicillin binding proteins)
3. Increased efflux (due to rise in efflux pumps)
4. Decreased penetration (due to altered porins)

16

Describe how uncoupling proteins (UCPs) generate heat.

Let protons leak across the mitochondrial membrane ->
Dissipation of proton motive force ->
ATP production halts ->
Excess energy released as heat

17

The presence of ___ in brown adipose tissue triggers thermogenesis.

UCPs (uncoupling proteins)

18

Lactate is produced by tissues carrying out ___ respiration.

Anaerobic

19

Anaerobic respiration is carried out by tissues low in ___.

Oxygen

20

List 4 areas where lactate is produced.

1. Red blood cells
2. White blood cells
3. Skeletal muscle
4. Kidney

21

How is lactate produced?

LDH (lactate dehydrogenase) reduces pyruvate

22

Pyruvate is reduced to lactate. How does this process allow glycolysis to resume?

Pyruvate accepts electrons from NADH ->
NADH is oxidised back to NAD+ ->
Glycolysis (where NAD+ -> NADH) can resume

23

Oxidation involves ___ electrons.

Losing

24

Which 3 parts of the body contain high concentrations of LDH (lactate dehydrogenase)?

1. Heart muscle
2. Liver
3. Kidney

25

How is LDH (lactate dehydrogenase) circulated through the body?

Via blood

26

List 5 molecular forces involved in maintaining protein structure.

1. Hydrogen bonds
2. Covalent bonds
3. Ionic forces
4. Hydrophobic forces
5. Van der Waals forces

27

List the 3 components of a protein’s structure that determine its ionisation state.

1. Carboxyl group
2. Amine group
3. R group

28

Compare the histological appearance of skeletal and cardiac muscle.

Skeletal: multi-nucleated, nuclei located peripherally, tissue organized into fascicles
Cardiac: single nucleus, nucleus located centrally, tissue organized into branches, presence of intercalated discs

29

A 57-year old man with a predisposition to coronary heart disease complains of intense muscle cramps following rigorous exercise. You discover he has elevated levels of lactate in his blood. Describe why this patient is particularly prone to muscle cramps during exercise.

Heart disease ->
Poor circulation of blood (and thus oxygen) ->
Body relying on anaerobic respiration ->
Lactic acidosis ->
Muscle cramps

30

Excess of molecules containing acidic groups can cause metabolic ___.

Acidosis

31

List 6 molecules that can cause metabolic acidosis.

1. Ketones
2. Fatty acids
3. Amino acid
4. Pyruvate
5. Lactate
6. ATP (releases H+ when hydrolyzed)

32

Compare anabolism to catabolism.

Anabolism: building larger molecules from smaller ones, requires energy
Catabolism: breaking larger molecules into smaller ones, releases energy

33

In a(n) ___ reaction, energy is required.

Reduction
Remember: energy follows electrons

34

In a(n) ___ reaction, energy is released.

Oxidation
Remember: energy follows electrons

35

Gaining electrons ___ energy.

Requires
Remember: energy follows electrons

36

Losing electrons ___ energy.

Releases
Remember: energy follows electrons

37

List examples of anabolic and catabolic pathways.

Anabolic: gluconeogenesis, glycogenesis, ketogenesis, fatty acid synthesis, cholesterol synthesis
Catabolic: glycolysis, glycogenolysis, lipolysis, fatty acid oxidation, pentose phosphate pathway

38

List 4 high energy signals.

1. ATP
2. NADH
3. NADPH
4. FAD2H

39

What do low energy signals indicate?

Cell needs more energy for its immediate needs

40

Why is catabolism generally activated by low energy signals?

Catabolism would provide energy release from fuel molecules

41

Describe how skeletal muscle increases in mass as a result of exercise or steroid use.

Satellite cells divide and fuse with myofibres, leading to hypertrophy

42

Why are there no known genetic defects causing a complete deletion of an enzyme in the TCA cycle?

Crucial cycle for sustaining life; enzyme deletion would be lethal

43

List 4 signs of very high blood cholesterol.

1. Corneal arcus
2. Xanthelasma near eyes
3. Xanthoma
4. Raised blood pressure

44

What is corneal arcus?

Blue, grey, or white ring around the cornea

45

What is xanthelasma?

Yellowish deposit of cholesterol around the eye

46

What is xanthoma?

Yellowish deposit of cholesterol under the skin

47

Glycogen is stored in small ___ in the cytoplasm.

Granules

48

List two tissues where glycogen is stored.

1. Liver
2. Skeletal muscle

49

What is the function of glycogen in the liver?

Regulate blood glucose

50

What is the function of glycogen in skeletal muscle?

Provide glucose 6-phosphate to be metabolized for energy via glycolysis

51

What is the first step for both aerobic and anaerobic respiration?

Glycolysis

52

Which enzyme controls the synthesis of glycogen from glucose subunits?

Glycogen synthase

53

Which hormone activates glycogen synthase? (Hint: glycogen synthase converts glucose subunits to glycogen.)

Insulin

54

Which enzyme controls the degradation of glycogen to glucose subunits?

Glycogen phosphorylase

55

Which 2 hormones activate glycogen phosphorylase? (Hint: glycogen phosphorylase converts glycogen to glucose subunits.)

1. Glucagon
2. Adrenaline

56

What is the major energy storage molecule in animals?

Triacylglycerol (TAG)

57

Why is triacylglycerol (TAG) a more efficient energy storage than glycogen?

It is more reduced, so it releases more energy when metabolized

58

List 5 non-disease related causes of skeletal muscle atrophy.

1. Lack of use
2. Ageing
3. Malnutrition
4. Long-term steroid use
5. Injury

59

In response to low glucose, TAG in adipose tissue is hydrolyzed to yield which 2 sources of energy?

1. Fatty acids
2. Glycerol

60

Which protein transports fatty acids?

Albumin

61

Glycerol can feed into which pathway to produce energy?

Glycolysis

62

Describe the process of oxidative phosphorylation.

NADH and FADH2 are re-oxidized to NAD+ and FAD ->
Electrons are passed down the electron transport chain to form water with O2 ->
Energy used to pump H+ to the intermembrane space ->
Electrochemical gradient produced -> ->
H+ ions flow back to the mitochondrial matrix through ATP synthase
ATP adds Pi to ADP ->
ATP is produced

63

List the 2 main functions of oxidative phosphorylation.

1. Re-oxidize NADH and FADH2
2. Synthesize ATP

64

Briefly describe the effect dinitrophenol (DNP) has on oxidative phosphorylation

UNCOUPLES oxidative phosphorylation (i.e., allows protons to leak across the mitochondrial membrane -> dissipation of proton motive force -> ATP production halts -> excess energy released as heat)

65

Describe the effect an inhibitor of a key enzyme in the electron transport chain (e.g., cyanide) would have on oxidative phosphorylation.

Electrons unable to pass down the chain to form water with O2 ->
No energy to pump H+ to the intermembrane space ->
No electrochemical gradient ->
ATP production halts

66

List 2 pathways involving substrate level phosphorylation.

1. Glycolysis
2. Krebs cycle

67

Describe substrate level phosphorylation.

Transfer of a phosphate from a substrate to ADP in a coupled reaction

68

List 3 differences between oxidative phosphorylation and substrate level phosphorylation.

1. Location: electron transport chain vs. Krebs cycle and citric acid cycle
2. Coenzymes: oxidation of NADH and FADH2 vs. reduction of FAD and NAD
3. Method: indirect phosphorylation vs. direct phosphorylation