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Things To Remember > Metabolism > Flashcards

Metabolism Flashcards

1
Q

Define catabolism and anabolism.

A

catabolism- breaks down molecules releasing energy

anabolism- creates molecules, using energy

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2
Q

exergonic reactions use energy, true or false.

A

false, exergonic reactions release energy, while endergonic reactions use energy.

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3
Q

What are the fat soluble vitamins?

A

A,D,E,K

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4
Q

What’s the calculation used to calculate BMI?

A

Weight(Kg)/Height^2 (m^2)

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5
Q

hypoglycaemia is defined as?

A

a blood glucose level of below 3mmol/L

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6
Q

what are the common symptoms of hypoglycaemia?

A

Trembling, weakness, tiredness, headache, sweating, sickness, tingling around the lips, palpitations, changes in mood, slurred speech and staggered walking.

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7
Q

hyperglycaemia is defined as?

A

a blood glucose level above 7mmol/L

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8
Q

what are the common symptoms of hyperglycaemia?

A

polydipsia and polyuria.

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9
Q

What are the general effects of feeding? (1-4)

A

Increased concentration of aa, glucose and lipids in the blood, which stimulates the release of insulin, which promotes:

  • increased glucose uptake and utilisation in adipose and muscle
  • storage of glucose
  • aa uptake and protein synthesis in the liver and muscle
  • lipogenesis and storage of fatty acids as triacylglycerols in adipose tissue
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10
Q

What are the general effects of fasting? (1-3)

A

As glucose levels fall, insulin secretion is suppressed and glucagon secretion is stimulates, which promotes:

  • glycogenolysis in the liver to maintain blood glucose levels
  • lipolysis in adipose tissue to provide fatty acids.
  • gluconeogenesis to maintain glucose levels to the brain.
  • if fasting passes 10hrs starvation processes begin.
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11
Q

What are the changes experienced during starvation? (4)

A
  • ACTH is released due to the prolonged reduction in glucose levels—–> increased cortisol
  • increased cortisol stimulates gluconeogenesis, and breaks down protein and fat.
  • high level of lipolysis
  • fatty acids are oxidised in the liver producing ketones
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12
Q

What general things can energy be used for? (5)

A
  • Biosynthetic work
  • transport work
  • mechanical work
  • electrical work
  • osmotic work
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13
Q

What molecule can tissues use as a source of energy when metabolic activity is high e.g. skeletal muscle?

A

Creatine Phosphate

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14
Q

What’s the reversible reaction which phosphocreatine can be formed by?

A

Creatine phosphocreatine
catalysed by creatine kinase
ATP ADP

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15
Q

What’s the clinical significance of creatine kinase levels in the blood?

A

CK is made up of two subunits, one isoform is specific to cardiac myocytes, and is released when damage is done to the myocardium. It’s diagnostic of an MI.

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16
Q

What can be formed spontaneously by both creatine and phosphocreatine?

A

Creatinine

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17
Q

What is the creatinine level in the urine proportional to?

A

Muscle mass, so can be used as a marker of urine dilution.

18
Q

Which isomers are found naturally in humans, D or L?

A

D

19
Q

What monosaccharides is sucrose formed from?

A

glucose and fructose

20
Q

What monosaccharides is lactose formed from?

A

galactose and glucose

21
Q

What monosaccharides is maltose formed from?

A

glucose and glucose

22
Q

What bonds link monosaccharides?

A

Glycosidic bonds

23
Q

What type of glycosidic bonds link glucose in glycogen?(1)

A

alpha-1,6 and alpha-1,4 glycosidic

24
Q

what are the two types of starch which can be found in plants and their types of glycosidic bonds/

A
  • Amylose-alpha1,4

- Amylopectin-a mix of alpha 1,4 and alpha 1,6

25
Q

Why can’t humans digest cellulose?

A

It contains beta-1,4 glycosidic bonds, which humans don’t have the enzymes to digest.

26
Q

Describe how lactose intolerance comes about.

A

lactase levels decrease after infancy, if levels become too low the lactose remains in the GI tract. it’s then broken down by bacteria, and disrupts the osmotic pressure of the contents and draws water into the lumen causing diarrhoea. The bacteria produce gas leading to bloating.

27
Q

What are the different types of glucose transporter and where can they be found? (6)

A

GLUT1-high levels in fatal tissues, but mainly in erythrocytes and the blood-brain-barrier in adults.(UNIPORTER)
GLUT2- renal tubular cells, small intestinal epithelial cells, liver cells and pancreatic beta cells, basolateral membrane of the small intestine epithelium. (BIDIRECTIONAL)
GLUT3-in neurones and the placenta
GLUT4- adipose tissues and striated muscle (skeletal muscle and cardiac muscle). More are expressed in the presence of insulin.
GLUT5-a fructose transporter
GLUT7- transporting glucose out of the endoplasmic reticulum.

28
Q

What is the overall reaction for glycolysis?

A

Glucose+2Pi+2ATP+2NAD+–>2pyruvate+2ATP+2NADH+2H++2H20.

29
Q

What is step 1 of glycolysis and what is it catalysed by?

A

GlucoseGlucose-6-phosphate

1=glucokinase in the liver and hexokinase in skeletal muscle

30
Q

What’s the benefit of phosphorylating glucose? (3)

A
  • it makes it anionic (-ve) which prevents it from crossing plasma membranes.
  • increases reactivity
  • allows the formation of compounds with a high phosphoryl-group transfer potential that can transfer their phosphate group to ADP to form ADP (substrate level phosphorylation)
31
Q

What is step 3 of glycolysis and what is it catalysed by?

A

Fructose-6-phosphate—3—->fructose-1,6-bisphosphate

3=phosphofruktokinase (PFK)

32
Q

why is step 3 of glycolysis important?

A

It’s known as the committing step as it commits glucose to metabolism via glycolysis as it’s irreversible.

33
Q

What is step 10 of glycolysis and what is it catalysed by?

A

phosphoenolpyruvate—10—>pyruvate+ATP

10=pyruvate kinase

34
Q

During what steps is ATP formed in glycolysis?

A

7 and 10

35
Q

what’s the net production of ATP from glycolysis?

A

2 moles of ATP are used, 4 are produced, so a net production of 2 moles of ATP.

36
Q

what are the two types of regulation for phosphofructokinase?

A
  • allosteric regulation (muscle)-inhibited by ATP, stimulated by AMP/ADP
  • hormonal regulation (liver)- insulin stimulates and glucagon inhibits
37
Q

What happens to glycolysis in anaerobic conditions?

A

Pyruvate is reduced to lactate by lactate dehydrogenase

38
Q

What are the steps in galactose metabolism and the enzymes at each step?

A

Galactose—1—>Galactose-1-phosphate—2—>glucose-1-phosphate glucose-6-phosphate

  1. Glucokinase
  2. Galactose-1-phosphate uridyl transferase (epimerase)
39
Q

Which enzyme is worse if it’s absent in glactosaemia?

A

Galactose 1-phosphate uridyl transferase, as galactose-1-phosphate accumulates in the tissues and is toxic.

40
Q

In galactosaemia, what is galactose-1-phosphate reduced to and what by?

A
  • Galactitol by aldose reductase.

- uses NADPH

41
Q

How can galactosaemia lead to cataracts?

A

-The reduction of galactitol used up NADPH so they can’t maintain disulphide bonds leading to cataracts.

42
Q

How does glaucoma occur?

A

accumulation of galactose and galactidol in the eye.

Things To Remember (17 decks)

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