Glycolysis And Glucose Oxidation Flashcards
(136 cards)
1
Q
What type of sugar is glucose
A
Heroes
2
Q
What is hypoglycaemia
A
Too little glucose in blood
3
Q
What is hyperglycaemia
A
Too much glucose in blood
4
Q
How can glucose be stored in liver and muscle
A
Glycogen
5
Q
What is the most glucose dependent organ in the body
A
Brain
6
Q
How much of the glucose in the body is used by the brain
A
60%
7
Q
What traps glucose in a cell
A
Phosphorylation
8
Q
Why does phosphorylation trap glucose in cells
A
Negative charge on phosphate group
9
Q
What are specialised glucose transporters called
A
GLUTs
10
Q
How many isoforms of GLUTs are there
A
14
11
Q
what kind of transport do GLUTs do
A
Facilitated diffusion
12
Q
Do GLUTs do active or passive transport
A
Passive
13
Q
What are the 3 most important GLUTs
A
GLUT 1,
GLUT 2,
GLUT 4
14
Q
Where is GLUT 1 expressed
A
All cells
15
Q
Where is GLUT 2 expressed
A
Liver,
Pancreas
16
Q
Where is GLUT 4 expressed
A
Muscle,
Adipose cells
17
Q
Which GLUT acts as a glucose sensor
A
GLUT 2
18
Q
Do GLUT 1 and 4 have high or low Km
A
Low
19
Q
Does GLUT 2 have high or low Km
A
High
20
Q
Which GLUT is controlled by insulin
A
GLUT 4
21
Q
How do GLUTs facilitate glucose transport
A
Glucose binds to GLUT -> conformational change transports glucose to interior -> glucose released inside of cell
22
Q
What does low Km mean in GLUTs
A
Work fast regardless of glucose concentration
23
Q
What does high Km mean in GLUTs
A
Work faster the higher the glucose concentration is
24
Q
Where are most GLUT 4s in skeletal muscle
A
Bound to vesicles in cells
25
What happens to GLUTs when insulin signals skeletal muscle cells
Vesicles containing GLUT 4 merge with cell membrane
26
How many steps in glycolysis
10
27
Which steps of glycolysis require energy
First 5
28
What is the first step of glycolysis
Phosphorylation of glucose to glucose 6 phosphate by hexokinase
29
How many ATP are used up by phosphorylation of glucose
1
30
What does hexokinase do
Phosphorylate 6 ringed carbohydrates
31
Which cells express hexokinase
Almost all cells
32
How does glucose 6 phosphate concentration self regulate
Negative feedback - hexokinase inhibited by glucose 6 phosphate product
33
Where is glucokinase expressed
Liver,
| Pancreas
34
Which enzyme catalyses the phosphorylated only glucose
Glucokinase
35
Why does glucokinase only catalyse phosphorylation of glucose
To respond faster to changes in glucose level
36
Does glucokinase have a high or low Km
High
37
Does glucokinase have feedback inhibition
No
38
Does hexokinase have feedback inhibition
Yes
39
What does glucokinase act as in pancreas B cells
Glucose level sensor,
40
What does glucokinase do in pancreatic b cells
Regulates production/secretion of insulin and glucagon
41
How is activity of glucokinase regulated
Localisation by binding to glucokinase-regulatory protein
42
What is the second step of glycolysis after phosphorylation of glucose
Isomerisation
43
What is the happens in the 2nd step of glycolysis, isomerization
Glucose 6 phosphate converted to fructose 6 phosphate
44
Why is the isomerization step of glycolysis important
Makes later reactions more energetically favourable
45
What is the 3rd step of glycolysis after isomerization
Phosphorylation of glucose 6 phosphate
46
Which step of glycolysis is rate limiting
Phosphorylation of fructose 6 phosphate
47
How does phosphorylation of fructose 6 phosphate limit glycolysis rate
Regulating function of phosphofructokinase 1
48
How many ATP are used up in step 3 of glycolysis, phosphorylation of fructose 6 phosphate
1
49
Which steps of glycolysis require ATP
1 and 3
50
What is the first irreversible reaction in glycolysis
Step 3- phosphorylation of fructose 6 phosphate
51
Why is phosphorylation of fructose 6 phosphate irreversible
Large negative free energy value
52
How is phosphofructokinase regulated
Allosteric activation,
| Inhibition
53
What allosterically activates PFK1
High AMP level,
| Fructose 2 6 bisphosphate
54
What is the effect of a decreased ATP:AMP ratio in cells
Glycolysis stimulated
55
What is PFK1 inhibited by
High ATP level,
| Citrate
56
How does ATP inhibit PFK1
ATP binds to allosteric site on PFK1
57
What molecules reverses ATP inhibition of PFK1
AMP
58
How does PFK2 activate PFK1
Increases PFK1s affinity for G6P
59
Why is PFK2 bifunctional
Has kinase and phosphatase activities
60
What stimulates kinase activity in PFK2
Insulin
61
What stimulates phosphatase activity in PFK2
Glucagon
62
What does kinase activity in PFK2 lead to
Stimulation of PFK1 -> fructose 2 6 bisphosphate formation
63
What does phosphatase activity in PFK2 lead to
Gluconeogenesis
64
What molecule is Fructose 2 6 bisphosphate produced from
Fructose 6 phosphate
65
Why does increased phosphatase activity in PFK2 cause a decrease in PFK1 activity
Increased phosphatase activity -> less fructose 2 6 bisphosphate present -> PFK1 activity decr
66
What is the 4th step of glycolysis after phosphorylation of fructose 6 phosphate
Breakdown of 6 carbon ring to 2 3 carbon chains
67
What happens in step 4 of glycolysis - Breakdown of 6 carbon ring to 2 3 carbon chains
Fructose 1 6 bisphosphate broken down the middle to form 2 carbon chains
68
Which enzyme catalyses step 4 of glycolysis - Breakdown of 6 carbon ring to 2 3 carbon chains
Aldolase
69
Which 2 molecules are formed in step 4 of glycolysis - Breakdown of 6 carbon ring to 2 3 carbon chains
Glyceraldehyde 3 phosphate,
| Dihydroxyacetone phosphate
70
What happens to dihydroxyacetone phosphate produced in step 4 of glycolysis
Converted to glyceraldehyde 3 phosphate
71
What happens in step 5 of glycolysis after Breakdown of 6 carbon ring to 2 3 carbon chains
dihydroxyacetone phosphate Converted to glyceraldehyde 3 phosphate
72
Which enzyme catalyses conversion of dihydroxyacetone phosphate to glyceraldehyde 3 phosphate in step 5 of glycolysis
Triose phosphate isomerase
73
Why is dihydroxyacetone phosphate Converted to glyceraldehyde 3 phosphate
Dihydroxyacetone phosphate can’t be used for glycolysis
74
What happens in step 6 of glycolysis after dihydroxyacetone phosphate Converted to glyceraldehyde 3 phosphate
Inorganic phosphate added to glyceraldehyde 3 phosphate
75
Where is the phosphate added to glyceraldehyde 3 phosphate in step 6 of glycolysis from
Cytosol
76
Which enzyme catalyses step 6 of glycolysis
Dehydrogenase
77
What happens to NAD+ in step 6 of glycolysis
Reduced to NADH and H+
78
How can NAD+ regenerated
Krebs cycle,
Electron transport chain,
Lactic acid from anaerobic glucose breakdown
79
Why does NAD+ regenerated from NADH
To keep glycolysis going
80
What happens in step 7 of glycolysis after inorganic phosphate added to glyceraldehyde 3 phosphate
First ATP produced
81
What is produced in step 6 of glycolysis
1 3 bisphosphoglycerate,
NADH,
H+
82
What is 1,3 bisphosphoglycerate
3 carbon chain with 2 phosphate groups,
83
How is ATP produced in step 7 of glycolysis
Substrate level phosphorylation, phosphate moved from 1 3 bisphosphoglycerate to ADP to produce ATP
84
Which enzyme catalyses step 7 of glycolysis
Phosphogkycerate kinase
85
How many ATP are generated in step 7 of glycolysis
2 -
| 1 for each 1 3 bisphosphate molecule
86
What happens in step 8 of glycolysis after the first ATP is produced by substrate level phosphorylation
Phosphate group moved from carbon 1 to middle carbon of 3 carbon chain,
3 phosphoglycerate converted to 2 phosphoglycerate
87
What type of reaction is step 8 in glycolysis
Isomerisation
88
Which enzyme catalyses step 8 of glycolysis
Phosphoglyceromutase
89
What happens in step 9 of glycolysis after Isomerisation of 3 phosphoglycerate
Dehydration
90
What happens in step 9 of hydrolysis
Water molecule removed from 2 phosphoglycerate to produce PEP
91
Which enzyme catalyses step 9 of glycolysis
Enolase
92
When can PEP be produced
Step 9 of glycolysis or Gluconeogenesis
93
What can enolase be inhibited by
Fluoride ions
94
How does step 9 of glycolysis cause an increase in the potential energy in the remaining phosphate group
Causes formation of a double bond
95
What happens in step 10 of glycolysis
ATP produced
96
How is an ATP produced in step 10 of glycolysis
Substrate level phosphorylation,
| PEP converted to pyruvate
97
Where does pyruvate produced by glycolysis go
Krebs cycle
98
Which enzyme catalyses the conversion of PEP to pyruvate in step 10 of glycolysis
Pyruvate kinase
99
Which steps of glycolysis are energy depleting
1 2 3 4 5
100
Which steps of glycolysis are energy generating
6 7 8 9 10
101
How many ATP are generated in glycolysis
4
102
How many ATP are consumed in glycolysis
2
103
How many pyruvate and NADH molecules are produced per glucose molecule in glycolysis
2 pyruvate,
| 2 NADH
104
What are the net products of glycolysis
```
2 ATP,
2 pyruvate,
H20,
2 NADH
2 H+
```
105
What happens to pyruvate produced by glycolysis in aerobic conditions
Converted to acetyl CoA by pyruvate dehydrogenase then enters Krebs cycle
106
What happens to pyruvate produced by glycolysis in anaerobic conditions
Acts as an electron acceptor and reduced to lactate to oxidise NADH to NAD+
107
Which molecule can glycerol be converted to to feed into glycolysis
Dihydroxyacetone phosphate,
108
Where can glycerol be converted to Dihydroxyacetone phosphate
Liver
109
Can fatty acids go into the glycolysis pathway
No
110
Can glycerol go into the glycolysis pathway
Yes
111
What step can Dihydroxyacetone phosphate enter glycolysis in
Step 4
112
Which enzyme converts glycerol to glycerol 3 phosphate
Glycerol kinase
113
How is glycerol kinase converted to DHAP
oxidation by NAD,
| Releases NADH
114
How can DHAP enter glycolysis
Isomerisation reaction producing glyceraldehyde 3 phosphate
115
What 2 molecules can fructose be converted to to enter glycolysis
Fructose 6 phosphate,
| Fructose 1 phosphate -> Dihydroxyacetone phosphate
116
Which enzyme converts fructose to Fructose 6 phosphate
Hexokinase
117
What step can Fructose 6 phosphate enter glycolysis
Step 3
118
Which enzyme converts fructose to Fructose 1 phosphate
Fructokinase
119
Which enzyme converts fructose 1 phosphate to Dihydroxyacetone phosphate
Aldolase B
120
How can fructose be converted to Dihydroxyacetone phosphate
Fructokinase converts fructose to fructose 1 phosphate -> Aldolase B converts fructose 1 phosphate to glyceraldehyde
121
At what step can glyceraldehyde from fructose enter glycolysis
5
122
Where can fructose be converted F6P by hexokinase
All cells
123
Where can fructose be converted to glyceraldehyde by Fructokinase and Aldolase B
Liver
124
What causes essential hepatic fructosuria
Mutation in ketohexokinase KHK gene
125
What is the inheritance pattern of essential hepatic fructosuria
Autosomal recessive
126
What does essential hepatic fructosuria cause
Deficiency in Fructokinase,
| Inability to proccess fructose
127
How can essential hepatic fructosuria be controlled
Avoiding sugary foods
128
What causes hereditary fructose intolerance
Mutation in Aldolase B gene,
| Deficiency in Aldolase B
129
How can hereditary fructose intolerance kill infants
F1P builds up in and kills liver cells
130
Symptoms of hereditary fructose intolerance
Jaundice,
Haemorrhage,
Kidney failure,
Hepatomegaly
131
What molecules is NADPH needed to synthesise
Fatty acids,
| Steroid hormones
132
What is the pentode phosphate pathway
Alternative pathway for G6P to produce pentose sugars
133
Products of the pentose phosphate pathway
Ribose 5 phosphate,
NADPH,
Glyceraldehyde 3 phosphate,
Fructose 6 phosphate
134
Why is NADPH needed in red blood cells
Keep proteins in a reduced state
135
Which products of the pentose phosphate pathway can feed into glycolysis
Glyceraldehyde 3 phosphate,
| Fructose 6 phosphate
136
What are the 10 steps of glycolysis
```
Phosphorylation of glucose,
Isomerization,
Phosphorylation of fructose 6 phosphate,
Breakdown of 6 carbon ring to two 3 carbon chains,
Adding inorganic phosphate,
First ATP produced,
Shifting phosphate,
Second ATP produced
```
