Nutrition and Metabolism Flashcards
1
Q
Proteins should comprise of what proportion of our diet?
A
15 - 20%
2
Q
What name is given to the bonds between phosphate groups in ATP?
A
Phosphoanhydride
3
Q
Which enzyme catalyses formation of pyruvate from phosphoenolpyruvate?
A
Pyruvate kinase
4
Q
How many protein complexes make up the ETC?
excluding ATP syhthase
A
4
5
Q
Deficiency of which vitamin causes Wernicke- Korsakoff syndrome?
A
Thiamin (B1)
6
Q
For a 12 carbon fatty acid how many beta oxidation cycles are undergone and how many acetyl CoA molecules are formed?
A
5 + 6
7
Q
McArdle’s disease is caused by a deficiency of which enzyme?
A
Glycogen phosphorylase
8
Q
A child is 65% of average weight and has oedema; which of these conditions do they suffer from:
a) Marasmus
b) Pellagra
c) Kwashiorkor
d) Marasmic-Kwashiorkor
A
Kwashiorkor
9
Q
A deficiency in lipoprotein lipase will lead to?
A
Increase in chylomicrons in blood
10
Q
Subject consumes 500 g of glucose every day for a few days then stopped eating all together. When would urea production be at its highest? After 24-hours, 4 days, 1 week, 40 days?
A
24 hours
11
Q
Why is lipoprotein (a) risk factor for CVD?
A
Inhibits breakdown of fibrin clots
12
Q
Why does muscle protein breakdown slow after a few days of starvation?
A
Brain uses ketone bodies
13
Q
Which vitamin is needed as a coenzyme for transamination and deamination reactions?
A
Thiamin (B1)
14
Q
Which type of glc transporter is found on pancreatic beta cells?
A
GLUT 2
15
Q
What is not a risk factor for obesity?
A
Smoking
16
Q
Which hormone is secreted from stomach parietal cells and signals hunger?
A
Ghrelin
17
Q
Which hormone inhibits secretion of insulin?
A
Adrenaline
18
Q
Which change in blood profile would be caused by deficiency/mutation of a protein C-II?
A
Increase in triacylglycerol
19
Q
Which apoprotein is necessary for lipoprotein remnant uptake by liver?
A
Apo E
20
Q
Which apoprotein activates lipoprotein lipase?
A
Apo C-II
21
Q
What property do vitamins A, C and E have in common?
A
Antioxidants
22
Q
What percentage of energy content of British diet is fat?
A
40%
23
Q
What is energy content of alcohol in kcal/g?
A
7
4 in carbs, 5.4 in proteins
24
Q
What is important criterion of normality for a glucose tolerance test?
A
Blood glucose returns to normal fasting levels by 2 hours
25
What do DoH recommendations actually recommend?
EAR + 2 S.D
26
Pernicious anaemia results from deficiency of?
Intrinsic factor
27
Long-term antibiotic therapy can lead to deficiency of which vitamin?
Vitamin K
28
Insulin inhibits activity of this enzyme involved in fat metabolism?
Hormone sensitive lipase
29
How many people in a society would get sufficient amount of a nutrient if they consumed EAR?
50%
30
How does Akt/PKB inhibit hormone-sensitive lipase in adipocytes?
It phosphorylates and activates phosphodiesterase
31
How does B12 deficiency create a functional folate deficiency?
Doesn't allow removal of methyl group from MeTHF
32
Hemorrhagic disease of newborn is due to deficiency of which vitamin?
Vitamin K
33
For food to be called light/lite it must have?
Less of energy than a food it is compared to
Less of fat than food it is compared to
1/2 salt of a food it is compared to
34
Familial hypercholesterolaemia is caused by a mutation in which receptor?
B100 receptor
35
British group of which origin has highest incidence of stroke, diabetes and hypertension?
South Asia
36
What pH range is ATP chemically stable at?
pH 6-9
37
What is the free energy of the reaction when 1 bond in ATP is cleaved?
30.5 kJ/mol
38
How many different forms does D-glucose have in solution?
5 forms
39
What are the 4 stages of glycolysis?
Activation
Splitting
Oxidation
Synthesis of ATP
40
What are the reactions and their enzymes in the activation stage of glycolysis?
(Stages that use ATP/NADH etc)
Glucose ==> Glucose-6-phosphate (Hexokinase/Glucokinase)
Glucose-6-phosphate <==> Fructose-6-phosphate (Phosphoglucose isomerase)
Fructose-6-phosphate ==> Fructose-1,6-biphosphate
(Phosphofructo kinase)
41
What are the reactions and their enzymes in the splitting stage of glycolysis?
Fructose 1,6-biphosphate <==> Glyceraldehyse 3-phosphate/Dihydroxyacetone phosphate (Aldolase A)
Glyceraldehyde 3-phosphate <==> Dihydroxyacetone phosphate (Triose phosphate isomerase)
42
What are the reactions and their enzymes in the oxidation stage of glycolysis?
(Stages that use ATP/NADH etc)
Glyceraldehyde 3-phosphate <==> 1,3-biphosphoglycerate
| glyceraldehyde 3-phosphate dehydrogenase
43
What are the reactions and their enzymes in the synthesis stage of glycolysis?
(Stages that use ATP/NADH etc)
1,3-biphosphoglycerate <==> 3-phosphoglycerate
(Phosphoglycerate kinase)
3-phosphoglycerate <==> 2-phosphoglycerate
(Phosphoglycerate mutase)
2-phosphoglycerate <==> Phosphoenolpyruvate
(Enolase)
Phosphoenolpyruvate <==> Pyruvate
(Pyruvate Kinase)
44
What is the net yield of ATP from glycolysis?
2 ATP
45
What enzyme catalyses pyruvate to lactate in muscles and what coenzyme is used?
Lactate dehydrogenase
| NADH + H+ ==> NAD+
46
What are the 3 metabolic fates of pyruvate?
Lactate
Acetyl CoA ==> TCA Cycle ==> CO2
Ethanol
47
How many reaction are there in the TCA cycle?
| Name all and enzymes
8
48
How many protein complexes are there in the mitochondrial membrane?
5
49
What metal is needed as a micronutrient for the elecron transport proteins in the mitochondrial membrane?
And what is the main metal they require?
Cu (micronutrient)
| Fe (main)
50
What 3 enzyme reactions in the TCA cycle are irreversible and why?
Oxaloacetate (+acetyl CoA) ==> Aconitase
Isocitrate ==> Alpha-ketoglutarate
Alpha-ketoglutarate ==> Succinyl-CoA
Highly exergonic
51
What type of bond is formed between CoA and carboxylic acids?
Thioester bonds
52
What is the CPT enzyme?
Carnitine Palmitoyl Transferase
53
What is the CACT enzyme?
Carnitine Acelcarnitine Translocase
54
What is the 1st reaction of beta oxidation and the enzyme?
| Any coenzymes etc
Fatty acyl CoA ==> Enoyl-CoA
| Acyl-CoA dehydrogenase
55
What is the 2nd reaction of beta oxidation and the enzyme?
| Any coenzymes etc
Enoyl-CoA ==> 3-L-hydroxyacyl-CoA
| Enoyl-CoA hydratase
56
What is the 3rd reaction of beta oxidation and the enzyme?
| Any coenzymes etc
3-L-hydroxyacyl-CoA ==> beta-ketoacyl-CoA
| 3-L-hydroxyacyl-CoA dehydrogenase
57
What is the 4th reaction of beta oxidation and the enzyme?
| Any coenzymes etc
beta-ketoacyl-CoA ==> fatty acyl CoA + Acetyl CoA
| beta-keto-acyl-CoA thiolase
58
What is the fate of odd-chained FA?
Left with a 3C compound that enters TCA cycle
59
What is the transition metal in vitamin B12?
Cobalt
60
What hormone(s) activate lipase enzyme?
Adrenaline, glucagon
61
Can muscle glycogen contribute to blood glucose levels?
No
62
What are the 2 types of links in glycogen?
Alpha-1,6 glycosidic links
| Alpha-1,4 glycosidic links
63
How is UDP glucose made from glucose (and enzymes)?
```
Glucose ==> Glucose-6-phosphate
(Hexokinase/Glucokinase in liver)
Glucose-6-phosphate ==> Glucose-1-phosphate
(Phosphoglucomutase)
Glucose-1-phosphate ==> UDP Glucose
(UDP-glucose phosphorylase 2)
```
64
What enzyme is used to remove glucose units from glycogen - which 2 from which links?
Debranching enzymes hydrolyse 1,6 glycosidic link
| Glycogen phosphorylase hydrolyse straight chain regions with 1,4 glycosidic links
65
Where does calcium bind to on glycogen phosphorylase kinase and what is the response?
Calmodulin domain
| Activates enzyme
66
What is an allosteric activator of glycogen phosphorylase?
AMP
67
What is an allosteric inhibitor of glycogen phosphorylase?
ATP
68
What is von Gierke's disease?
Defective glucose-6-phosphatase
69
What is Pompe's disease?
Defective lysosomal glycosidase
70
What is McArdle's disease?
Defective glycogen phosphorylase
71
What is the amount recommended protein for each day?
| In grams
50-70g
72
What 9 amino acids humans cannot synthesise?
Valine, Methionine, Histidine, Lysine, Phenylalanine, Leucine, Isoleucine, Threonine, Tryptophan
73
When does positive nitrogen balance occur?
During normal growth in children
In convalescence after serious illness
After immobilisation after an accident
In pregnancy
74
When does negative nitrogen balance occur?
In starvation
During serious illness
In late stages of some forms of cancer
In injury and trauma
75
By what process are most old/damaged cellular proteins removed by?
Ubiquitin breakdown system
76
What is oxidative deamination?
Removing an AA to generate an alpha keto acid + other oxidised products
Occurs only in liver
77
What is transamination?
Transfer of an amino group from one molecule to another, esp from AA to keto acid
78
What vitamin is aminotransferase derived from?
Vitamin B6
79
What amino acid(s) are classed as only ketogenic?
Leucine
| Lysine
80
What amino acid(s) are classed as glucogenic and ketogenic?
```
Phenylalanine
Tyrosine
Tryptophan
Isoleucine
Threonine
```
81
Why is glutamine important in relation to NH3?
Self carrier of NH3 in blood
NH3 is toxic to brain
Can carry 2 NH3 equivalents to liver for urea formation
82
How is NH4+ used in the Ornithine (urea) cycle?
```
NH4+ + CO2 + 2ATP ==> NH2COP + 2ADP + Pi
Carbamoyl phosphate (NH2COP) is added to cycle
```
83
What are the 4 end products of N2 metabolism?
Urea - protein breakdown
Creatinine - creatine phosphate breakdown
Uric acid - DNA + RNA breakdown
Ammonia (NH4+) - control of body pH
84
What is hyperammonemia?
Impaired conversion of NH3 to urea
85
What is physiological circulating glc concentration?
3.9 - 6.7 mM
86
What is average fasting glc level?
4.4-5 mM
87
What is the Cori cycle?
Lactate produced by anaerobic glycolysis in muscles moves to liver + converted to glc
Returns to muscle and cyclically metabolized to glc
88
Out of insulin and glucagon, which one is anabolic/catabolic?
Insulin - anabolic
| Glucagon - catabolic
89
What does EAR stand for?
Estimated Average Requirement
90
What is RNI and where is it in relation to EAR?
Reference Nutrient Intake
| 2 S.D. above EAR
91
What is LRNI and where is it in relation to EAR?
Lower Reference Nutrient Intake
| 2 S.D below EAR
92
What is the formula for BMI?
wt/(ht) ^2
93
What is bioelectrical impedance measurement?
Electrical signal sent throughout body
| Estimate % of body fat + muscle mass
94
What is basal metabolic rate?
Energy expenditure of doing nothing, 12 hours after eating + exercising
95
What is the satiety signal?
Feeling of fullness
96
What pathway do these hormones stimulate?
a) Leptin + insulin
b) Neuropeptide Y (NPY) + grehlin
a) Satiety pathway
| b) Hunger pathway
97
How much fat in the diet does the UK DoH recommend?
2.5g
98
What sugar is commercially produced for foods for diabetics?
Sorbitol
99
What is Marasmus?
Inadequate energy intake in all forms, incl protein
100
What is Kwashiorkor?
Protein deficiency with adequate energy intake
101
What are the water soluble vitamins?
B group, C
102
What are the fat soluble vitamins?
A, D, E, K
103
What vitamins act as enzymes in metabolic pathways?
B vitamins
104
What is Beriberi disease?
B1 (thiamin) deficiency
105
What is Wernicke's encephalopathy?
Neurological disorder caused by thiamine deficiency, typically from chronic alcoholism/persistent vomiting
106
What is Korsakoff's syndrome?
Late complication of persistent Wernicke encephalopathy
| Chronic memory disorder caused by severe deficiency of thiamine (vitamin B-1)
107
What reaction does thiamine pyrophosphate (TPP) catalyse?
Pyruvate ==> acetyl CoA
108
Why do alcohols suffer many vitamin B deficiencies?
Adequate calorie intake due to 'empty' calories
| So X consume much, lack of nutrients + vitamins
109
What vitamin is riboflavin and what is it's main function?
B2
| As FAD and FMN in redox reactions
110
What vitamin is niacin?
Vitamin B3
| Function as NAD + NADP in redox reactions
111
What is pellagra?
Deficiency in B3/niacin
112
What vitamin is pyridoxine?
Vitamin B6
113
What is cobalamin?
Vitamin B12
| Carrier of methyl groups
114
What is the active form of folate and what enzyme is used to maintain this form?
Tetrahydrofolate
| Dihydrofolate reductase
115
What is pernicious anaemia?
Inability of body to absorb vitamin B12
116
What vitamin is ascorbic acid?
Vitamin C
117
What is the average store of vitamin C in a healthy human body?
6 months
118
Which vitamin D can we synthesise?
D3 (Cholecalciferol)
119
What vitamin D is available commercially?
Vitamin D2 (ergocalciferol)
120
What is deficiency of vitamin D in:
a) Children?
b) Adults?
a) Rickets
| b) Osteomalacia
121
What is the first step in FA synthesis and what is the enzyme that catalyses it?
Acetyl CoA + HCO3 ==> Malonyl-CoA
| Acetyl CoA carboxylase
122
What reactions does Malonyl CoA inhibit?
Carnitine transferase
| Entry of FA ==> mito + subsequent oxidation
123
What are the 4 classes of lipoproteins?
Chylomicrons
VLDL
LDL
HDL
124
When a lipoprotein has more fat, does it have higher or lower density?
Lower density
125
How is cholesterol formed and what is one of the main enzymes?
Acetyl CoA + Acetoacetyl CoA ==> HMG-CoA ==> Mevalonate ==> Cholesterol
2nd step enzyme is HMG-CoA reductase
126
What enzyme do statins inhibit?
HMG-CoA reductase
127
What is familial hypercholesterolaemia?
Deficiency of LDL receptors which leads to v high blood cholesterol levels
Mutated B100 receptor, statins x cope with high levels of LDL
128
What does plasminogen do?
Break down blood clots
129
What transition metal is ATP complexed with (most of the time)?
Mg2+
130
What complex chelates with Fe to treat secondary Fe overload?
Deferoxamine
131
What transition metal is complexed with insulin when it is stored in the pancreas?
Zn
132
What is acrodermatitis enteropathica?
Mutation inf Zip4, Zn uptake low
| Completely curable with Zn
133
What is transient neonatal Zn deficiency?
Mutation in ZnT2-Zn transporter in gut
| Curable with Zn given to child for entire life
134
What is Wilson's disease?
Cu accumulation in liver
| Kayser-Fleischer rings around eyes
135
What is Menkes Disease?
Defective absorption of Cu in intestines
136
What percentage of the pancreas is endocrine?
2%
137
What might be the subsequent metabolic fate of glucose-6-phosphate in the following
tissues:
a) Fast (white/glycolytic) skeletal muscle (with high % of type 2 fibres)
b) Slow (red/oxidative) skeletal muscle (with high % of type 1 fibres)
a) Anaerobic glycolysis to lactate
| b) Glycolysis to pyruvate, then into TCA cycle to give CO2
