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MRCOG - Part 1 > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

Which cell adhesion molecule binds lymphocytes?

A

L-selectin

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2
Q

Which cell adhesion molecule binds platelets?

A

P-selectin

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3
Q

Which cell adhesion molecule binds endothelial cells?

A

E-selectin

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4
Q

When is B-hCG detectable in blood?

A

8 days post-fertilisation

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5
Q

When is B-hCG detectable in urine?

A

10 days post-fertilisation

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6
Q

Whether a miscarriage is managed expectantly or medically, when should a repeat urinary pregnancy test be performed?

A

Urinary pregnancy test 3 weeks later

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7
Q

What factors shift the oxygen dissociation curve for fetal haemoglobin to the right?

A

1) Increased temp
2) Increased H+
3) Increased 2,3 DPG
4) Increased pCO2

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8
Q

What factors shift the oxygen dissociation curve for fetal haemoglobin to the left?

A

1) Increasing pCO
2) Decreased temp
3) Decreased H+
4) Decreased 2,3 DPG

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9
Q

What are the major biochemical buffers in intracellular fluid?

A

1) Protein; 2) Phosphate

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10
Q

What is the major biochemical buffer in blood and interstitial fluid?

A

Bicarbonate

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11
Q

How much ATP does anaerobic respiration yield?

A

2 ATP

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12
Q

How much ATP does aerobic respiration yield?

A

30-32 ATP (traditionally thought to be 38 ATP)

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13
Q

What pathway converts glucose to pyruvate?

A

Glycolysis

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14
Q

Where does gluconeogenesis occur?

A

Liver and kidneys

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15
Q

What is the name of the process that produces glycogen?

A

Glycogenesis

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16
Q

What is the name of the process that produces glucose?

A

Gluconeogenesis

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17
Q

What is Northern Blotting?

A

Molecular genetic technique to detect RNA

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18
Q

What is Southern Blotting?

A

Molecular genetic technique to detect DNA

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19
Q

What is Southwestern Blotting measuring?

A

DNA binding proteins

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20
Q

What is Western Blotting?

A

Used in protein analysis

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21
Q

What is Eastern Blotting?

A

Used to measure protein modifications, e.g. lipids or carbohydrates

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22
Q

In the extracellular fluids and plasma, what is a) the main cation, b) the main anion

A

a) sodium; b) chloride

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23
Q

In the intracellular fluid, what is a) the main cation, b) the main anion

A

a) potassium; b) phosphate

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24
Q

What happens in prophase?

A

Chromatin condenses to chromosomes (paired as chromatids). Mitotic spindle form.

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25
Q

What happens in metaphase?

A

Chromatids align at the equatorial plane

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26
Q

What happens in anaphase?

A

Chromatids pulled apart into 2 constituent daughter chromosomes

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27
Q

What happens in telophase?

A

New nuclear envelop forms around each daughter chromosome

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28
Q

What happens in cytokinesis?

A

Cells divide

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29
Q

What are the DNA bases?

A

Adenine; guanine; thymine; cytosine

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30
Q

What are the RNA bases?

A

Adenine, guanine; uracil; cytosine

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31
Q

Which DNA/RNA bases pair off?

A

Adenine with thymine or uracil

Guanine with cytosine

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32
Q

Where is AFP produced in a fetus?

A

Principally liver, also GI tract and yolk sac

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33
Q

What are the subphases of mitosis?

A

Prophase, metaphase, anaphase, telophase, cytokinesis

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34
Q

What state proceeds mitosis?

A

Interphase

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35
Q

What happens in interphase, prior to mitosis?

A 
G1 = cells increase in size
S = DNA replication
G2 = cells increase in size
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36
Q

What are the 3 types of ketone bodies?

A

1) Acetone
2) Acetoacetic acid
3) Beta-hydroxybutyric acid

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37
Q

Which of the ketone bodies can be used for energy?

A

Acetoacetic acid and beta-hydroxybtyric acid

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38
Q

When are ketone bodies produced?

A

In times of carbohydrate restriction. They are produced in the liver from fatty acids

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39
Q

What is vitamin K used for?

A

Synthesis of proteins C, S and Z, and clotting factors X, IX, VII and II

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40
Q

What is fibrinogen activated by?

A

Thrombin

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41
Q

What is the normal rate of increase of b-HCG every 48 hours?

A

66%

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42
Q

What are the causes of prolonged PT and INR?

A

Factor V deficiency; warfarin therapy; liver failure; DIC

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43
Q

What are the Ca/phosphate/ALP/PTH levels in osteoporosis?

A

Ca - normal
Phosphate - normal
ALP - normal
PTH - normal

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44
Q

What are the Ca/phosphate/ALP/PTH levels in osteopetrosis?

A

Ca - normal
Phosphate - normal
ALP - normal
PTH - normal

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45
Q

What are the Ca/phosphate/ALP/PTH levels in osteomalacia?

A

Ca - reduced
Phosphate - reduced
ALP - increased
PTH - increased

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46
Q

What are the Ca/phosphate/ALP/PTH levels in osteitis fibrosa?

A

Ca - increased
Phosphate - reduced
ALP - increased
PTH - increased

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47
Q

What are the Ca/phosphate/ALP/PTH levels in Paget’s?

A

Ca - normal
Phosphate - normal
ALP - increased
PTH - normal

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48
Q

What is the product of glycolysis?

A

x2 pyruvate + x2 ATP + x2 NADH

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49
Q

What is the rate limiting step of glycolysis?

A

Conversion of fructose 6-phosphate to fructose 1,6-biphosphate by phosphofructokinase

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50
Q

What are essential amino acids?

A

Amino acids that cannot be synthesised directly, and so must be obtained by diet

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51
Q

What are some examples of essential amino acids?

A

Arginine; isoleucine; leucine; lysine; trypotophan; valine

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52
Q

What are non-essential amino acids?

A

Amino acids that can be synthesised

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53
Q

What are some examples of non-essential amino acids?

A

Alanine; cysteine; glutamine; glycine; proline; serine; tyrosine

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54
Q

What is another name for the citric acid cycle?

A

The Krebs cycle

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55
Q

What is the start product of the Krebs cycle?

A

Acetyl-CoA

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56
Q

How is Acetyl CoA formed?

A

Formed from pyruvate, from glycolysis, that is then converted to Acetyl-CoA in the process of pyruvate decarboxylation by action of pyruvate dehydrogenase

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57
Q

What are LDLs?

A

Cholesterol or cholesterol esters

Transport cholesterol from liver to tissues

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58
Q

What are HDLs?

A

Collect cholesterol from cells and carried to the liver

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59
Q

How does insulin cause hypokalaemia?

A

Intracellular shifts

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60
Q

How does vomiting and diarrhoea cause hypokalaemia?

A

Loss of K+ from the body

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61
Q

What is the action of cytochrome P450 enzymes?

A

Catalyses hydroxylations

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62
Q

Which cell in the body are dependant on anaerobic respiration?

A

RBCs

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63
Q

Where is the chloride shift phenomenon seen?

A

RBCs

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64
Q

What is the major hydrogen ion buffer in the blood?

A

Haemoglobin

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65
Q

What food has a high vit D2 content?

A

Oily fish

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66
Q

What proportion of plasma Ca2+ is in ionised form?

A

45%

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67
Q

What is the major carrier of plasma Ca2+?

A

Plasma protein

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68
Q

What is the major production method of 2,3-DPG?

A

Glycolysis

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69
Q

What is the Hb concentration in a newborn?

A

17g/dL

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70
Q

What is the coagulation factor number for fibrinogen?

A

Factor I

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71
Q

What is the primary source of negatively charged ions in the blood?

A

Bicarbonate and Cl-

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72
Q

HbA1c is a marker of DM control over what period?

A

8-12 weeks

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73
Q

What are the biochemical findings in Paget’s disease?

A

Normal Ca2+
Normal phosphate
Raised ALP

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74
Q

How is pyruvate produced?

A

Glycolysis

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75
Q

What molecule has a major role in gene transcription?

A

Fatty acids

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76
Q

Where is AFP produced in the fetus?

A

Gut, liver, yolk sac

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77
Q

Which ketone body can be used as an energy supply for brain in starvation?

A

Acetoacetate

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78
Q

What levels of progesterone indicate a non-viable pregnancy?

A

15-25

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79
Q

What levels of progesterone indicate a non-viable pregnancy will spontaneously resolve?

80
Q

What levels of progesterone indicate development of a normal pregnancy in the future?

81
Q

What are the biochemical findings in Conns syndrome?

A

Hypernatraemia
Hypokalaemia
Alkalosis

82
Q

Ammonia is made from what amino acid in the kidney?

83
Q

Where is bicarbonate reabsorbed in the kidney?

A

Proximal convoluted tubules

84
Q

What is the main buffer in urine?

85
Q

Which 2nd messenger signalling molecule is generated by oxytocin and stimulates Ca2+ release?

86
Q

What percentage of women with a malignancy also have hypercalcaemia?

87
Q

Which condition is caused by a failure to mineralise newly formed osteoid?

A

Osteomalacia

88
Q

How does pregnancy affect PTH?

A

Increase in PTH, calcium and calcitriol in pregnancy

89
Q

Which enzyme is involved int he rate limiting step of the glycolysis pathway?

A

Phosphofructokinase

90
Q

What hormone deficiency is characteristic of congenital adrenal hyperplasia?

91
Q

What are the features of a salt-wasting crisis?

A

Vomiting, dehydration and appearing shocked

92
Q

What are the hormonal imbalances that account for the salt-wasting crisis seen in 21-hydroxylase deficiency CAH?

A

Aldosterone and cortisol deficiency

93
Q

What electrolyte imbalances may be seen in CAH?

A

Hyperkalaemia and hyponatraemia

94
Q

Which form of CAH results in ambiguous genitalia of a genetic female due to excessive androgen exposure in the fetus?

A

The 21-hydroxylase deficiency form

95
Q

What are the different types of CAH?

A

21-hydroxylase deficiency - ambiguous genitalia
11-beta-hydroxylase deficiency - hypertension (due to EXCESSIVE aldosterone)
17-hydroxylase deficiency - oligomenorrhoea and infertility

96
Q

How does glucose cross the placenta?

A

Facilitated diffusion

97
Q

Where is ALP produced?

A

Bone
Liver
PLACENTA

98
Q

How are substances transported across the placenta?

A

Passive diffusion - O2, CO2, free fatty acids, urea
Active transport - amino acids
Facilitated diffusion - glucose
Endocytosis - IgG

99
Q

What is the structure of fetal Hb?

A

x2 alpha, x2 gamma

100
Q

What are the 3 types of extracellular signalling?

A

Endocrine - acts on distant cells via bloodstream
Paracrine - acts locally on neighbouring cells
Autocrine - acts on the cell producing the hormone

101
Q

What are the 3 main classes of cell surface receptor?

A
  1. Ion-channel-linked receptors - either voltage gated or ligand gated
  2. Enzyme-linked receptors
  3. G protein-coupled receptors
102
Q

What is an example of a G protein-coupled receptor?

A

cAMP receptors

Muscarinic receptors

103
Q

What is an example of an enzyme-linked receptor?

A

Tyrosine kinase receptor

104
Q

What are examples of ion-channel-linked receptors?

A

GABA receptors
Nicotinic acetylcholine receptors
5-HT receptors

105
Q

What is the mechanism and action of alpha-1 receptors?

A

Activation of phospholipase C

Causes smooth muscle contraction, smooth muscle relaxation of the GIT and vasoconstriction of arteries and veins

106
Q

What are examples of alpha-1 agonists?

A

Phenylephrine

Noradrenaline

107
Q

What is the mechanism of alpha-2 receptors?

A

Inactivation of adenylate cyclase leading to decreased intracellular cAMP

108
Q

What are examples of alpha-2 agonists?

109
Q

What is the action of beta-1 receptors?

A

Positive chronotropic and inotropic effect on the heart, stimulates renin release

110
Q

What are examples of beta-1 agonists?

A

Noradrenaline

Dobutamine

111
Q

What is the action of beta-2 receptors?

A

Smooth muscel relaxation, stimulates renin release

112
Q

What are examples of beta-2 agonists?

A

Salbutamol
Salmeterol
Terbutaline

113
Q

What is the only neurotransmitter to be used at the neuromuscular junction?

A

Acetylcholine

114
Q

What are the receptor sites of acetylcholine?

A

Nicotinic receptors

Muscarinic receptors

115
Q

What are some examples of nicotinic agonists?

A

Acetylcholine
Nicotine
Suxamethonium

116
Q

What are some examples of nicotinic antagonists?

A

Atracurium

117
Q

What are some examples of muscarinic agonists?

A

Acetylcholine

Pilocarpine

118
Q

What are some examples of muscarinic antagonists?

A

Atropine
Oxybutinin
Ipratropium

119
Q

Where are M1 receptors found?

A

Exocrine glands

CNS

120
Q

Where are M2 receptors found?

121
Q

Where are M3 receptors found?

A

Blood vessels
Lungs
Salivary glands

122
Q

Where are M4 receptors found?

123
Q

What receptors are exclusively intracellular?

A

Steroid hormone receptors
Thyroid hormone receptors
Vitamin D3 receptors

124
Q

What are the different types of carbohydrate?

A

Monosaccharides - glucose/fructose/galactose
Disaccharides - sucrose/lactose
Oligosaccharides - ABO blood group classification
Polysaccharides - glycogen

125
Q

What is the obligatory glucose requirement?

126
Q

How much energy does glucose provide?

A

4.2kcal/day

127
Q

What is the brains requirement for glucose during normal food intake?

128
Q

What is the brains requirement for glucose during starvation?

129
Q

Where is glycogen stored?

A

Liver - stores for 24 hours

130
Q

Where does anaerobic metabolism take place?

131
Q

Where does aerobic metabolism take place?

A

Mitochondria

132
Q

What is the process of aerobic respiration?

A

Glucose —> pyruvate, via glycolysis
Pyruvate —> acetyl CoA, via pyruvate oxidation
Acetyl CoA —> 36-38 ATP per molecule of glucose, via TCA pathway

133
Q

What is another name for the TCA pathway?

A

Krebs cycle

Citric Acid cycle

134
Q

What tissues can undergo anaerobic respiration?

A

RBC
Retinal cells
Kidney medulla
Skeletal muscle

135
Q

What is the Cori cycle?

A

Converts lactate back to glucose

Its acts to produce glucose and prevent a build up of lactic acid

136
Q

Where does the Cori cycle take place?

137
Q

What is the structure of triglycerides?

A

1 molecule + 3 molecules of free fatty acids (FFA)

138
Q

Where are triglycerides stored?

139
Q

How are triglycerides transported?

A

Via chylomicrons

140
Q

What are the essential fatty acids?

A
  1. Linoleic acid

2. Linolenic acid

141
Q

Where are ketone bodies produced?

A

Liver

Kidney

142
Q

What are ketone bodies?

A

By-products of fatty acid metabolism
Fatty acid –> acetyl CoA —> ketone bodies
They are fuel for intermediate/prolonged starvation

143
Q

What are the types of adipose tissues, and which type stores energy?

A

White and brown adipose

White adipose stores energy

144
Q

What are the limitations of fats?

A

Not metabolised by brain (except ketone bodies)
Not metabolised anaerobically
Cannot synthesise glucose

145
Q

What are the 2 functional groups of amino acid?

A

Amine

Carboxyl

146
Q

What are the 3 classes of protein?

A

Globular proteins - soluble and form enzyme
Fibrous proteins - structural
Membrane proteins - receptors

147
Q

What is the structure of protein?

A

Primary structure - the amino acid sequence held by peptide bonds
Secondary structure - 3D form, held by hydrogen bonds
Tertiary structure - overall shape, held by disulphide bonds

148
Q

What is the structure of haemoglobin?

A

1 haem ring + 4 globulin rings

149
Q

Where is haemoglobin produced?

A

Mitochondria

Cytsol of immature RBCs

150
Q

What is haemoglobin metabolised into, and where?

A

Into bilurubin and carbon monoxide, by the liver

151
Q

Which non-erythroid cells are haemoglobin found in?

A

Dopaminergic neurons in substantia nigra
Macrophages
Alveolar cells
Kidney mesangial cells

152
Q

What is collagen secreted by?

A

Fibroblasts and osteoblasts

153
Q

What are the different types of collagen?

A

Type 1 - bone/dermis/tendon
Type 2 - cartilage
Type 3 - fetal/cardiac/scar
Type 4 - basement membrane

154
Q

How is cholesterol synthesised?

A

In the ER via HMG-CoA reductase pathway

155
Q

What are the structure of steroids?

A

4 rings - 3 rings that have 6C, 1 ring that has 5C

156
Q

What type of receptors are prostaglandin receptors?

A

G-protein couples receptors

157
Q

What type of hormone are steroid hormones?

A

Lipid hormones

158
Q

From what are all steroid hormone derived?

A

Cholesterol

159
Q

What is the rate limiting step of steroid hormone synthesis?

A

Removal of the 6-carbon side chain from cholesterol (27C) to generate pregnenolone (21C)

160
Q

What catalyses the reaction generating pregnenolone from cholesterol?

A

CYP11A1, found in the inner mitochondrial membrane

161
Q

What are the mechanisms for the intracellular trafficking of cholesterol to CYP11A1?

A

1) StAR - steroidogenic acute regulator protein

2) Mitochondrial peripheral benzodiazepine receptors

162
Q

What enzyme types are required for steroid biosynthesis?

A

1) CYP enzymes - catalyse the hydroxylation reactions

2) HSD enzymes - catalyse the oxidation reactions

163
Q

What is the enzyme sequence required to synthesise testosterone in Leydig cells?

A

CYP11A1 —> CYP17A —> 3B-HSD —> 17B-HSD

164
Q

What is the enzyme sequence required to synthesise androstenedione in the theca cells?

A

CYP11A1 —> CYP17A —> 3B-HSD

165
Q

What enzyme can convert estrone to estradiol?

166
Q

What are the enzymes required to synthesis progesterone and estradiol in the corpus luteum?

A 
CYP11A1 
3B-HSD
CYP17A
CYP19
17B-HSD
167
Q

Which form of oestrogen, and indeed which steroid hormone is uniquely produced by the placenta?

168
Q

What is aromatised to form estriol in the placenta?

A

16a-hydroxyandrostenedione

169
Q

What is required for virilisation of the external genitals?

A

Conversion of testosterone to 5a-dihydrotestosterone by 5a-reductase

170
Q

How are steroid hormones made hydrophillic so that they can be eliminated by the body?

A

1) CYP or HSD enzymes create a polar hydroxyl (alcohol) groups
2) Conjugating enzymes add a polar or charged chemical groups to the polar hydroxyl (alcohol) groups

171
Q

What are the 4 common functional domains to steroid hormone receptors?

A
  1. Lignad-binding domain
  2. DNA-binding domain
  3. Dimerisation domain (within the ligand-binding domain)
  4. Transactivating factor domain
172
Q

From what are all prostaglandins synthesised?

A

Arachidonic acid, a polyunsaturated fat

173
Q

How are is arachidonic acid liberated from membranes for prostaglandin synthesis?

A

Action of phospholipase A2

174
Q

How are prostaglandins formed from arachidionic acid?

A

Action of COX enzymes

175
Q

What is the difference between COX1 and COX2?

A

COX1 is constitutively active, whereas COX2 is hormone responsive

176
Q

What are the contractants of myometrial contraction?

A

Oxytocin and prostaglandin, by action of activating phospholipase C, leading to an increase in intracellular Ca2+

177
Q

What are the relaxants of myometrial contraction?

A

NO, relaxin and progesterone by action cAMP and cGMP

178
Q

How much weight gain during pregnancy is accounted for by a rise in intracellular fluid volume?

179
Q

What is the acid-base disturbance that is physiological in pregnancy?

A

Slight respiratory alkalosis - the low pCO2 being required to maintain a diffusion gradient of CO2 across the placenta. There is a partial compensation of a HCO3- fall

180
Q

When does the respiratory alkalosis in pregnancy become more pronounced?

A

During labour, due to maternal hyperventilation

181
Q

What proportion of total body calcium is extracellular?

182
Q

What channels transport Ca2+ a) out of the gut lumen and b) out of the glomerulus filtrate?

A

a) TRPV6

b) TRPV5

183
Q

What are the types of cells present in the parathyroid glands?

A

Oxyphil cells

Chief cells

184
Q

What triggers the secretion of PTH?

A

The Ca2+-sensing receptor CaSR in response to low Ca2+

185
Q

What type of receptor is CaSR?

A

G-protein coupled receptors

186
Q

What is the major circulating form of vitamin D?

187
Q

What is the main action of vitamin D?

A

Increasing serum levels of Ca2+ and phosphate, mainly by increasing intestinal absorption

188
Q

What is the 1st step in vitamin D synthesis?

A

Modification of 7-dehydrocholesterol to vitamin D3 (cholecalciferol), a reaction mediated by UV light in the keratinocytes

189
Q

What type of receptor is the vitamin D receptor?

A

Nuclear receptor

190
Q

What does vitamin D deficiency cause?

A

Children - rickets

Adults - osteomalacia

191
Q

What is osteomalacia?

A

Failure to mineralise newly formed osteoid

192
Q

How many g of Ca2+ does the fetus require?

193
Q

How much Ca2+ is required for lactation?

A

280-400mg/day

194
Q

What is the biochemistry of primary hyperparathyroidism?

A

High PTH, high Ca2+, low phosphate

195
Q

What are the causes of primary hyperparathyroidism?

A

1) Parathyroid gland adenoma(s)

2) Parathyroid hyperplasia

196
Q

What is the biochemistry of secondary hyperparathyroidism?

A

High PTH, but low Ca2+

MRCOG - Part 1 (13 decks)

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