Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

SFM > carbohydrates > Flashcards

carbohydrates Flashcards

1
Q

Are carbohydrates more likely to be oxidised or reduced and why?

A

Oxidised as the have high energy H atom-associated electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In what form are carbohydrates stored as potential energy in animals?

A

Glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are monosaccharides?

A

hexoses - 6 carbon sugars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Name the three important monosaccharides in human biochemistry

A

Glucose
Galactose
Fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are disaccharides?

A

Two monosaccharides linked by a glycosidic bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a glycosidic bond?

A

a covalent bond formed when hydroxyl group of one monosaccharide reacts with anomeric carbon of another monosaccharide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name the three important disaccharides in human biochemistry

A

Maltose
Lactose
Sucrose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Of the three disaccharides, which is a non-reducing sugar and why?

A

Sucrose as it does not have a free anomeric C-1 so there is no oxidation site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What kind of polysaccharide has a single monomeric species?

A

Homopolysaccharides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What kind of polysaccharide has two or more monomer species?

A

Heteropolysaccharides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Name the two polysaccharides you need to know

A

Starch

Glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the two types of glucose polymer in starch?

A

Amylose

Amylopectin (more branched)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where is 90% of glycogen in the body and why? (2 places)

A
  • Liver: to replenish blood glucose when fasting

- Skeletal muscle: catabolism produces ATP for contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give three reasons for storing glucose in polymers

A
  1. compactness
  2. many non-reducing ends so synthesised and degraded o and from monomers, speeding up formation/degradation
  3. they form hydrated gels so are osmotically inactive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why may a carbohydrate be covalently bonded to a protein?(glycoprotein)

A
  • increases solubility
  • influence protein folding/conformation
  • protect from degradation
  • communication between cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where are glycosaminoglycans (GAGs) found?

A

in mucus and also synovial fluid around the joints

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What protein/carbohydrate component forms part of many connective tissues in the body?

A

proteoglycans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which genetic disease is caused by the absence/malfunction of enzymes required to break down glycosaminoglycans?

A

Hurler Syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What carbohydrates are in our diet?

A

starch, glycogen, cellulose, hemicellulose, oligosaccharides containing linked galactose, lactose, sucrose, maltose, glucose, fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the main products from the digestion of carbohydrates?

A

Glucose, galactose and fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What transports glucose from the intestinal lumen into the epithelial cell and what transports it from the cell into the blood?

A

In - Na+ - glucose symporter (driven by high extracellular Na+)
Out - Glucose uniporter GLUT2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the use of cellulose and hemicellulose in the body as they can’t be digested?

A

increase faecal bulk and decrease transit time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the most common disaccharide deficiency?

A

Lactose intolerance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is glucose phosphorylated to by hepatocytes once it has gone through the small intestine, into the blood and arrived at the liver (or other tissue)?

A

glucose-6-phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What enzyme catalyses the phosphorylation of glucose to glucose-6-phosphate at the liver and in other tissues?

A

liver - glucokinase

other tissues - hexokinase

26
Q

What are the three main fates of glucose-6-phosphate?

A

Glycolysis
Stored as glycogen
Pentose-phosphate pathway

27
Q

Which enzyme begins the process of the synthesis of glycogen?

A

Glycogenin

28
Q

Describe the stages of glycogen synthesis

A
  1. glucose from UDP is taken by glycogenin and made into chains (usually 8 Glc)
  2. Glycogen synthase extends the chains
  3. chains are broken and glycogen-branching enzymes reattach them at the alpha 1-6 points so they are branched
  4. Glycogen formed
29
Q

What does glycogen phosphorylase do?

A

Catalyses the removal of terminal Glc residues to release G-1-P

30
Q

What are the steps of the degradation (mobilisation) of glycogen after G-1-P has been released?

A
  1. G-1-P
  2. Glc near branch removed in 2. step process by debranching enzyme
  3. 3 Glc residues are removed and attached to the nearest non-reducing end by transferase
  4. the final Glc is removed by breaking an alpha 1-6 linkage. Enzyme involved is glucosidase
  5. left with an unbranched chain
31
Q

What does substrate level phosphorylation of glucose-6-phosphate produce?

A

lactate

32
Q

What is ATP produced from substrate level phosphorylation of G-6-P used for?

A

Muscle contraction

33
Q

What are the symptoms of von Gierke’s disease?

A
  • high liver glycogen
  • low blood glucose
  • high blood lactate
34
Q

What is the treatment of von Gierke’s disease?

A

regular carbohydrate feeding

35
Q

What is McArdle’s disease?

A

Skeletal muscle phosphorylase deficiency

36
Q

Name the two phases of glycolysis

A

1 - preparatory

2 - payoff

37
Q

How many steps does glycolysis have?

A

10

38
Q

How many ATP does glycolysis produce?

A

produces 4, 2 are needed to net gain of 2

39
Q

What is the first step of glycolysis and what enzyme does it requrie?

A

Phosphorylation of glucose

hexokinase

40
Q

Which stages require ATP and which stages produce it?

A

Require: 1 and 3
Produce: 7 and 10 (x2)

41
Q

What is the product after the preparatory phase of glycolysis?

A

G-3-P

42
Q

Why is step 3 known as the first ‘committed’ step of glycolysis?

A

G-6-P and F-6-P can be used in other pathways but F-1,6-bisP is solely designed for glycolysis

43
Q

Which stage in glycolysis produces NADH?

A

6

44
Q

Which two stages form an energy coupled process and why?

A

6 and 7

6 requires energy whereas 7 gives off energy so the two reactions together are spontaneous

45
Q

What’s the difference between ‘substrate-level’ and ‘respiration linked’ reactions?

A

‘substrate-level’ required soluble enzymes and chemical intermediates whereas ‘respiration-linked’ involved membrane bound enzymes and gradients of protons

46
Q

Which essential vitamin does NAD+ come from?

A

niacin

47
Q

The fates of pyruvate will produce NAD+ to replenish the NAD+ required for reduction of various metabolites to NADH in glycolysis. What is this termed as?

A

redox balance

48
Q

What three products may be formed from pyruvate?

A

Ethanol
Lactate
CO2

49
Q

In which two circumstances may pyruvate be converted to lactate in humans?

A

in vigorously exercising muscle

in red blood cells lacking mitochondria

50
Q

Which process reduces pyruvate to lactate?

A

fermentation

51
Q

How is ATP made when our muscles are working vigorously and there’s not oxygen for oxidative phosphorylation?

A

substrate-level phosphorylation

52
Q

What is the Cori cycle?

A

the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose (gluconeogenesis), which then returns to the muscles and is metabolized back to lactate

53
Q

Where does the conversion of pyruvate to acetyl CoA take place? and which enzyme catalyses it?

A

mitochondria

pyruvate dehydrogenase

54
Q

How many reactions are there in gluconeogenesis?

A

4

55
Q

Where do reactions A, B, C and D of gluconeogenesis occur?

A

A and B in mitochondria and C and D in cytosol

56
Q

What is the final step to make free Glc?

A

G-6-P must be shuttled into the lumen of the cell in the ER and Glc is shuttled back out into the cytoplasm

57
Q

What does the pentose phosphate pathway produce?

A

NADPH, pentoses

58
Q

What are the two phases of the pentose phosphate pathway?

A
  • oxidative, irreversible part

- reversible, non-oxidative part

59
Q

What are NAD+ and NADP+ both?

A

electron carriers

60
Q

What is the difference between NAD+ and NADP+

A

NAD+ is used in the metabolism of dietary sugars in the redox reactions of glycolysis and the citric acid cycle
NADP+ is used in anabolism to convert simple precursors into things like fatty acids (also antioxidant)

61
Q

Why does drinking alcohol lead to reduced gluconeogenesis?

A

Liver requires NAD+ for metabolising ethanol so less available for gluconeogenesis

SFM (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions