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Foundations in Medicine 1 > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

What are examples of macromolecules?

A

carbohydrates, proteins, nucleic acids, lipids

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2
Q

what are heteropolysaccharides?

A

composted of two or more different polysaccharides

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3
Q

What is an example of a heteropolysaccharide?

A

hyaluronic acid

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4
Q

Name a few functions of carbohydrates

A

selectins
molecular tags (PAMPs)
blood group antigens
cell adhesion molecules

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5
Q

Where can you find hyaluronic acid in the body?

A

surrounding an oocyte (part of the ZP)
major component of extracellular matrix and synovial fluid

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6
Q

What are carbohydrates?

A

organic molecules composed of carbon hydrogen and oxygen

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7
Q

what are lipids?

A

molecules that have key biological functions

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8
Q

What are saturated fatty acids

A

fatty acids without a double bond that compact tightly because there is a bend in the molecule

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9
Q

what are unsaturated fatty acids

A

does not pack because of the presence of a double bond and so created more fluid substances

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10
Q

What are essential nutrients

A

molecules (vitamins and fatty acids etc) that the body cannot obtain itself so requires this from the diet

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11
Q

What is a phospholipid

A

resembles a triglyceride but one fatty acid is replaced by a phosphate

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12
Q

are phospholipids hydrophilic?

A

They are ambivalent, hydrophobic tail and hydrophilic head

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13
Q

what does the hydrophobic tail consist of in a phospholipid

A

saturated fatty acid and unsaturated fatty acid on one of the tails

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14
Q

what does the hydrophilic head consist of?

A

a phosphate and glycerol

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15
Q

What are sphingolipids?

A

a class of lipids that play an important role in cellular structure and function, abundant in the myelin sheath

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16
Q

What is the role of sphingolipids?

A

essential for nerve function and signalling

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17
Q

what are steroids

A

molecules that have a carbon consisting of four fused rings

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18
Q

What are examples of steroids

A

sex hormones (testosterone, progesterone etc) cortisol, vitamin D , cholesterol

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19
Q

What is a polar bond

A

the covalent bond between hydrogen and a more electronegative atom

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20
Q

what is a hydrogen bond

A

the bond between hydrogen and an electronegative atom that is already in a covalent bond with an electronegative atom

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21
Q

Non-polar substances are soluble in water, true or false?

A

false, they are hydrophobic so insoluble

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22
Q

examples of amphipathic molecules

A

sodium palmitate
micelle formation

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23
Q

what are proteins

A

a chain made out of a chain of amino acids

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24
Q

What chemical groups makes up an amino acid

A

amino group NH2
carboxyl group COOH
hydrogen H
side chain -R (determines/varies in each the amino acid)

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25
Q

what are stereoisomers

A

omers non-superimposable mirror images

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26
Q

Acids are molecules which can accept a proton, true or false?

A

false, acids donate protons

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27
Q

Bases are proton acceptors, true or false?

A

true

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28
Q

what is pH

A

measurement of the amount of protons in a solution

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29
Q

a change of one pH changes the proton concentration how?

A

tenfold

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30
Q

what molecules can span both polar and non-polar environments?

A

amphipathic molecules

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31
Q

what is a zwitterionic amino acid

A

one which is overall neutral but contains a positively charged amine group and a negatively charged carboxyl

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32
Q

what are the benefits of a zwitterionic amino acid

A

increased solubility
can act as a buffer so maintains pH
influences the structure and folding abilities

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33
Q

What is the secondary stucture of the protein

A

the polypeptide chain conformation

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34
Q

what is the quaternary structure of the protein

A

in the spatial arrangement of polypeptide chain with its subunits

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35
Q

The tertiary structure of a protein is the sequence of amino acids

A

false, that’s the primary structure the tertiary structure is the three-dimensional structure of the entire polypeptide

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36
Q

where are the two rotational angles on a polypeptide chain

A

the alpha carbon of the amino group and the carboxyl group

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37
Q

Name three types of secondary structure of a protein

A

alpha helix, beta sheet or triple helix

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38
Q

what is the alpha heix

A

the carboxyl group of one amino acid shares a hydrogen bond with the amino group on another amino acid and forms a rod-like shape

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39
Q

beta sheets can only run in a parallel direction, true or false

A

false they can run both parallel and antiparallel

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40
Q

what is a collagen triple helix

A

where three left handed helical chains twist round each other to form a right handed supehelix

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41
Q

where can you find the triple helix

A

in bone and connective tissue

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42
Q

what are fibrous proteins

A

polypeptide chains that are organised parallel along a single axis

properties
long fibres or large sheets
mechanically strong
insoluble in water
structural importance

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43
Q

what are examples of fibrous proteins

A

keratin
collagen of connective tissues (cartilage bone skin blood vessels etc etc)

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44
Q

What are globular proteins?

A

proteins folded into a spherical shape somewhat

properties
soluble in water and salt solution
polar side chains interact with aqueous environment by hydrogen bonding
non-polar chains are internal
sections of both alpha helix AND beta sheets

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45
Q

What are examples of globular proteins

A

myoglobin and haemoglobin

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46
Q

What bonds are involved in tertiary structures

A

covalent disulphide
hydrophobic
hydrogen bonds (backbone and side chain)
electrostatic interactions

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47
Q

What is the mutation in sickle cell anaemia

A

single nucleotide sequence change that results in the alteration of valine instead of glutamic acid, glutamic acid is responsible for the folding of the haemoglobin so because of the lack the RBCs become sickle-shaped and can block blood flow through capillaries

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48
Q

In what diseases does the protein fold incorrectly

A

alzhiemers, parkisons, CJD

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49
Q

What are prions?

A

misfolded proteins that encourage other proteins to do the same tend to be preen tin the brain and affect this area

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50
Q

What is a nucleoside

A

nitrogenous base and pentose sugar

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51
Q

a nucleotide is a nucleoside and phosphate group, true or false?

A

True

52
Q

What is the difference between purines and pyrimidines

A

purines are six-membered ringed molecules fused with a five-membered ring and pyrimidines are a singular six-membered ring

53
Q

What are examples of pyrimidines

A

uracil thymine and cytosine

54
Q

examples of purines are adenine uracil and guanine, true or false?

A

false, uracil is a pyrimidine

55
Q

what bond holds the bases together

A

van der waals

56
Q

why is it important to have weak bonds between the bases

A

to allow for bond breakage during DNA replication

57
Q

where is the phosphodiester bond used

A

between nucleotides

58
Q

give an example of a drug that is an analogue of thymidine

A

retrovir (anti-retroviral for HIV)

59
Q

what enzyme catalyses DNA replication

A

DNA polymerase

60
Q

what are the small individual strands created during replication called

A

Okazaki fragments

61
Q

okazaki fragments are present on which strand

A

lagging strand

62
Q

which enzyme stitches up the lagging strand after replication

A

DNA ligase

63
Q

How are nucleotides added to the leading strand

A

5’ to 3’ direction continuously

64
Q

what does the promoter consist of

A

TATA box, initiation site

65
Q

Enzymes alter the equilibrium of a reaction, true or false

A

False, they do not alter the position of the equilibirum

66
Q

Enzymes reduce the time for a chemical reaction to reach equilibrium, true or false?

A

True

67
Q

Enzymes stabilise the intermediates that are formed as substrates are converted into products

A

True

68
Q

Enzymes catalyse reactions to avoid the loss of free energy when substrates are converted to products

A

True (enzymes lower the activation energy)

69
Q

Give three examples of a cofactor

A

zinc iron and copper

70
Q

give three examples of a coenzyme

A

CoA NAD+ ATP

71
Q

What is an apoenzyme

A

enzyme without a cofactor

72
Q

A prosthetic group determines the chain of amino acids in the protein

A

false, it is part of an enzyme that determines its function

73
Q

What is a zymogen?

A

precursor of an enzyme, irreversibly changed when it becomes an enzyme

74
Q

What two form a holoenzyme?

A

zymogen and cofactor

75
Q

What are the five characteristics of all enzymes?

A

specific, potent, mostly proteins, biological catalysts and increase rate of reaction

76
Q

Enzymes reduce the activation energy of a reaction

A

true

77
Q

What is an example of glycogen storage disease?

A

von-dierkes disease

78
Q

what is von dierkes disease/glycogen storage disease?

A

mutation in glucose-6-phosphate, in these patients they cannot break glycogen down therefore resulting in a high level of glucose-6-phosphate

79
Q

coenzymes are permanently bound to the enzymes, true or false

A

false, they are transiently bound they only associate for a short period of time

80
Q

what is an example of a prosthetic group

A

haem in haemaglobin

81
Q

what is meant by induced fit

A

where the binding of the substrate induces a confirmational change in the enzyme

82
Q

What are isozymes

A

form of enzyme that catalyses the same reaction but may differ in structure and mechanisms

83
Q

Give an example of isozymes used in hypoxia

A

lactate dehydrogenase has five isozymes and depending on the quaternary structure they will engage in lactate to pyruvate reaction or pyruvate to lactate (the latter in the presence of low oxygen)

84
Q

How can isozymes be used in a clinical setting

A

examine the blood for specific forms - creatine kinase is a dimeric protein which can be found in muscle, brain and heart which has both types as a heterodimer (MB) but if say the brain form is found in circulation could suggest a stroke or tumour

  • therefore useful for diagnostics
85
Q

What are examples of zymogens

A

in the pancreas - trypsinogen and chymotrypsinogen
small intestine - enteropeptidase cleaves trypsinogen to active trypsin which cleaves chymotrypsinogen to chymotrypsin

86
Q

What carbon of the nucleoside does the free hydroxyl sit on

A

3’

87
Q

which carbon of the nucleoside does the phosphate group sit on

A

5’

88
Q

nucleotides are always added to the 5’ end of the DNA chain, true or false

A

false, they are added to the 3’ end where the hydroxyl group sits

89
Q

Which direction does the DNA strand get synthesised?

A

5’ to 3’

90
Q

Name the steps of translation

A

initiation, elongation, translocation and termination

91
Q

What is a polysome

A

multiple ribosomes engaging in translation at the same time

92
Q

What is glycolysis?

A

the process by which one molecule of glucose produces two molecules of pyruvate

93
Q

what are post translational modifications?

A

the addition of functional/chemical groups

94
Q

What four fates can glucose have in the body?

A

stored as glycogen
lactic acid fermentation
pentose phosphate pathway
glycolysis

95
Q

What is the role of hexokinase in glycolysis?

A

controls substrate entry of glucose

96
Q

what is the function of the pentose phosphate pathway?

A

uses glucose to form nucelotides

97
Q

what happens in the absence of oxygen during glycolysis?

A

pyruvate accepts electrons from NADH to produce lactic acid (lactate) from glucose

98
Q

What two glucose transporters have a low Km and are present in the brain?

A

GLUT 1 and 3

99
Q

Where can you find glucose transporters with a high Km?

A

in the liver and beta cells (GLUT2)

100
Q

What glucose transporters are found in the adipose tissue and muscle?

A

GLUT 4

101
Q

where are GLUT 5 transporters found?

A

the gut

102
Q

What regulates PFK-1 and why?

A

AMP because it is more sensitive to fluctuating ATP

103
Q

What is the function of phosphofructokinase?

A

rate of substrate (glucose) flow through glycolysis

104
Q

what are the different allosteric effectors for PFK-1

A

ATP
citrate
H+

105
Q

how does citrate modify PFK-1

A

slows downstream pyruvate entry

106
Q

How does H+ modify PFK-1

A

slows down glycolysis if lactic acid is increased

107
Q

What enzyme controls the production of pyruvate at the end of glycolysis?

A

pyruvate kinase

108
Q

What are the products of glycolysis?

A

4ATP and 2NADH and H+

109
Q

What is the mechanisms of action dichloroacetate?

A

promotes the conversion of lactic acid to pyruvate

110
Q

What drug blocks further metabolism of glucose 6-phosphate

A

2 deoxy-glucose

111
Q

how do cancer cells exploit lactate?

A

excess production to damage NK and T cells and activate suppressor cells

112
Q

Why would the body produce lactate in the absence of oxygen?

A

during muscle exercise, hypoxemia and septic shock

113
Q

Is the conversion of pyruvate to acetyl-CoA reversible?

A

No

114
Q

What happens to the TCA if pyruvate supply is limited

A

acetyl-CoA diverts to ketones

115
Q

Where does glycolysis take place?

A

cytosol

116
Q

where does the TCA cycle take place?

A

in the mitochondrial matrix (predominantly)

117
Q

What type of inheritance is PDC deficiency?

A

X-linked

118
Q

How many ATP, NADH H+, FADH2 and CO2 are produced after the TCA cycle (including all previous steps - net accumulation)?

A

ATP - 4
NADH H+ - 10
FADH2 - 2
CO2 - 6

119
Q

What molecule combines with acetyl CoA to form citrate?

A

oxaloacetate

120
Q

What are the symptoms of PDC deficiency?

A

poor muscle tone and lack of coordination
retardation and seizures
persistent lactic acidosis
respiratory problems

121
Q

What is the Warburg effect?

A

Cancer cells produce energy by high rate of glucose metabolism to lactate

122
Q

Why is NADH needed for oxidative phosphorylation?

A

it provides the electrons to facilitate the production of ATP

123
Q

What provides energy to pump protons across the membrane in oxidative phosphorylation?

A

electrons

124
Q

What is E0

A

how likely a substance is going to gain or lose electrons
positive - it’ll gain electrons and be reduced
negative - it’ll lose electrons and be oxidised

125
Q

Can NADH cross the membrane as itself?

A

No
donates its electrons to oxaloacetate forming malate which can cross the membrane into the matrix

126
Q
A

Foundations in Medicine 1 (11 decks)

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