Session 1-Energy Production I Flashcards

(67 cards)

1
Q

What is stage 1 of metabolism of dietary carbs?

A

Breakdown to building blocks

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

Which enzyme is present in saliva to digest carbs and which reaction does it catalyse?

A

Amylase

Starch/glycogen -> dextrins

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

Which enzyme is present in the pancreas to digest carbs?

A

Amylase

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

Which enzymes are present on the brush border membrane of epithelial cells?

A

Lactase
Sucrase
Pancreatic amylase
Isomaltase

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

What causes primary lactase deficiency?

A

Absence of lactase persistence allele

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

True or false: primary lactase deficiency occurs in children and adults

A

FALSE - only adults

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

What causes secondary lactase deficiency?

A
Injury to small intestine: 
Gastroenteritis 
Coeliac disease
Crohn's disease 
Ulcerative colitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

True or false: secondary lactase deficiency occurs in both infants and adults

A

TRUE

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

What is congenital lactase deficiency?

A

Autosomal recessive defect in lactase gene

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

What are the symptoms of lactose intolerance?

A
Bloating/cramps
Flatulence
Diarrhoea
Vomiting 
Rumbling stomach
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does the absorption of monosaccharides occur by active transport?

A

Active transport by sodium-dependent glucose transporter 1 (SGLT1) into intestinal epithelial cells and then, via GLUT2, into blood supply

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

Apart from active transport, in which other way can monosaccharides be absorbed?

A

Uptake into cells from blood via facilitated diffusion using transport proteins (GLUT1-GLUT5)

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

Where is GLUT2 found?

A

Kidney
Liver
Pancreatic beta cells
Small intestine

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

Where is GLUT4 found?

A

Adipose tissue

Striated muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which cells have an absolute requirement for glucose? (4)

A

1) RBCs
2) Neutrophils
3) Innermost cells of kidney medulla
4) Lens of eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why do RBCs have an absolute requirement for glucose?

A

No mitochondria so can only carry out glycolysis

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

Why do the innermost cells of the kidney medulla have an absolute requirement for glucose?

A

Kidney cortex has a very high oxygen demand so the innermost cells need glucose

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

Why do the lens of the eye have an absolute requirement for glucose?

A

They have a poor oxygen supply (absorb directly from the atmosphere) so rely on glycolysis

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

True or false: CNS can use ketone bodies for some energy requirements but it prefers glucose as a fuel

A

TRUE

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

What are the functions of glycolysis? (4)

A

1) oxidation of glucose
2) NADH production (2 per glucose)
3) synthesis of ATP from ADP
4) produces C6 and C3 intermediates

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

What is the net ATP production per glucose?

A

2 ATP

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

True or false: glycolysis only occurs in selected tissues

A

FALSE - occurs in all tissues

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

True or false: there is no loss of CO2 in glycolysis

A

TRUE

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

True or false: glycolysis is the only pathway that can operate anaerobically

A

TRUE - but with additional enzyme (pyruvate dehydrogenase=PDH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the difference between hexokinase and glucokinase?
Hexokinase has a lower affinity for glucose and is inhibited by glucose-6-P whereas glucokinase isn't inhibited by glucose-6-P
26
Where is glucokinase found?
Liver
27
Which are the three key enzymes of glycolysis that we need to know?
1) Hexokinase (glucokinase) 2) Phosphofructokinase-1 3) Pyruvate kinase
28
Why are there so many (10) enzymes/steps in glycolysis? (4)
1) chemistry easier in small steps 2) efficient energy conservation 3) gives versatility 4) allows for fine control
29
What is phase 1 of glycolysis called?
Investment
30
What is phase 2 of glycolysis called?
Payback
31
What does the phosphorylation of glucose to G-6-P do?
Makes glucose negatively charged | Prevents passage back across plasma membrane
32
How many moles of ATP are used per mole glucose in phase 1 of glycolysis?
2
33
What happens in reaction 1 of glycolysis?
Glucose to glucose-6-P
34
What happens in reaction 2 of glycolysis?
Glucose-6-P to fructose-6-P and vice versa
35
What happens in reaction 3 of glycolysis?
Fructose-6-P to fructose 1,6-bis-P
36
Which glycolysis reactions have large negative delta-G and what does this mean?
1, 3 and 10 | Means they are irreversible
37
Which step of phase 1 is the committing step and why?
Step 3 because it commits glucose to metabolism via glycolysis
38
Which reactions are in phase 2 of glycolysis?
4-10
39
What happens in reaction 4 of glycolysis?
Cleavage of C6 into two C3 units
40
What happens in reaction 6 of glycolysis?
Reducing power captured (NADH)
41
What happens in reactions 7 and 10 of glycolysis?
ATP synthesis by substrate level phosphorylation
42
When is the rate of glycolysis up to 200 times greater?
In cancer
43
What is the key regulator of glycolysis?
Phosphofructokinase (PFK)
44
Which reaction does phosphofructokinase (PFK) catalyse?
Fructose-6-P to fructose-1,6-bisphosphate
45
In which two ways can phosphofructokinase be regulated?
1) allosteric regulation (muscle) | 2) hormonal regulation (liver)
46
What inhibits allosteric regulation of PFK?
High ATP
47
What stimulates allosteric regulation of PFK?
High AMP
48
What stimulates hormonal regulation of PFK?
Insulin
49
What inhibits hormonal regulation of PFK?
Glucagon
50
What is BPG?
2,3-bisphosphoglycerate
51
Where is BPG produced?
RBCs
52
What does BPG regulate?
Haemoglobin's affinity for O2
53
Why is glycerol phosphate important?
Important to triglyceride and phospholipid biosyntesis
54
Where is glycerol phosphate produced?
Adipose and liver
55
Why does NAD+ need to be regenerated?
So glycolysis can continue
56
By which other method can NAD+ be regenerated?
Lactate dehydrogenase (LDH)
57
What is the reaction that lactate dehydrogenase catalyses?
NADH + H+ + pyruvate NAD+ + lactate
58
How is plasma lactate concentration determined?
Relative rates of: 1) production 2) utilisation (heart, liver, muscle) 3) disposal (kidney)
59
What is the range of hyperlactaemia and what does this mean?
2-5mM, below renal threshold so no change in blood pH
60
What is the range of lactic acidosis and what does this mean?
Above 5mM, above renal threshold, blood pH lowered and kidneys can no longer excrete it
61
A deficiency in which three enzymes can cause galactosaemia?
Galactokinase Uridyl transferase UDP-galactose epimerase
62
Which enzyme is missing in fructose intolerance and what does this mean clinically?
Aldolase | Fructose-1-P accumulates in liver, leading to liver damage
63
What does glutathione prevent?
Oxidative damage to the cell
64
Where does the pentose phosphate pathway start?
Glucose-6-phosphate
65
What is NADPH from the pentose phosphate pathway needed for? (3)
1) reducing power for biosynthesis 2) maintenance of GSH levels 3) detoxification reactions
66
The pentose phosphate pathway produces a C5-sugar, ribose. What is this required for? (2)
Synthesis of: 1) nucleotides 2) DNA and RNA
67
What is the rate limiting enzyme in the pentose phosphate pathway?
Glucose 6-phosphate dehydrogenase