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Y1 PRINCIPLES > BioChem > Flashcards

BioChem Flashcards

1
Q

The most strong type of bond is…

A

Covalent

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2
Q

The five main types of bonds are…

A 
Covalent
Ionic
Hydrogen
Hydrophobic PD-PD interaction
LDFs/ Van der Waals - interaction of electrons in non-polar substances
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3
Q

Electronegativity is…

A

The attractive force that an atomic nucleus exerts on electrons

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4
Q

EN carbon is greater than EN hydrogen. Which is reduced?

A

Carbon has a greater attractive force for electrons, so it gains electrons, therefore it is reduced and hydrogen is oxidised

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5
Q

Reducing agents are themselves oxidised. True/False?

A

True`

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6
Q

First law of thermodynamics?

A

Energy is neither created or destroyed

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7
Q

Second law of thermodynamics?

A

When energy is converted to another form, some of it is lost (never 100% efficient)

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8
Q

∆G = the change in free energy = ?

A

∆H - T∆S ∆G°’ + RTln([C][D]/[A][B])

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9
Q

Exergonic reactions are where…

A

Products have less free energy than the reactants ∆G is -ve

Reaction can occur spontaneously

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10
Q

Endergonic reactions are where…

A

Products have greater free energy than the reactants ∆G is +ve
Reaction cannot occur spontaneously

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11
Q

The difference between normal standard conditions and biochemical standard conditions is…

A

pH = 7

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12
Q

At equilibrium ∆G = 0. This is characteristic of readily reversible reactions. True/False?

A

True

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13
Q

Reaction spontaneity can be achieved by…

A

Changing concn of reactants/products
Coupling with highly favourable processes (e.g. with hydrolysis of ATP)
Both of the above help ∆G become -ve (EXERGONIC IS FAVOURABLE)

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14
Q

Distinguish between catabolism and anabolism

A

Breaking down complex molecules into smaller ones to give out energy (favourable)
Synthesise complex molecules out of smaller ones, requires energy

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15
Q

What is the hydrophobic effect?

A

Tendency of non-polar substances to aggregate in aqueous solutions (in centre) and exclude water molecules

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16
Q

Amino acids are subdivided into 4 groups, which are?

A

Non-polar hydrophobic
Polar uncharged
Acidic (-COOH)
Basic (-NH)

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17
Q

The N-terminal of a peptide chain is -ve. True/False?

A

False It is +ve due to NH3

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18
Q

The C-terminal of a peptide chain is -ve. True/False?

A

True due to COO-

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19
Q

A zwitterion has which type of charge?

A

None! No net charge - AA with charged side groups in neutral solutions

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20
Q

Ka = acid dissociation constant = ?

A

[H+][A-]/[HA]

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21
Q

pH = measurement of how many H+ in a solution = ?

A

-log10[H+]

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22
Q

Henderson Hasselbach Equation connects Ka of a weak acid with the pH of a solution containing this acid. The equation is…

A

pH = pKa + log[A-]/[HA] pKa - pH = log[HA]/[A-]

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23
Q

Primary protein structure describes…

A

The specific sequence of amino acids in a chain

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24
Q

Secondary protein structure describes…

A

The hydrogen-bonded 3D arrangement of the chain α-helix (one peptide chain spiralled; right-handed) B-stranded-sheet or B-pleated-sheet

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25
Q

Tertiary protein structure describes…

A

The arrangement of the chain in space and forces stabilising the structure - H bonds, salt bridges, covalent disulphide bonds

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26
Q

Quaternary protein structure describes…

A

Association of non-protein groups to the chain e.g. haemoglobin, myoglobin with multiple subunits

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27
Q

Give the number of bonds between bases A?T and C?G…

A

A-T = 2, C-G = 3

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28
Q

What is the central dogma?

A

DNA is transcribed to RNA, which is translated into protein

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29
Q

A nucleoside has…

A

5C sugar + organic base

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30
Q

A nucleotide has…

A

5C sugar + organic base + phosphate group(s)

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31
Q

Pol II synthesises only stable RNA. True/False?

A

False Pol II (specific promotor - binds to TATA box creating a kink in DNA — transcription) synthesises all RNA. Pol I and III synthesise only stable RNA

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32
Q

DNA polymerase has 3 important characteristics

A

Can only add to existing nucleic acids
Cannot start synthesis on its own
Requires an RNA primer to start replication

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33
Q

Differentiate between leading and lagging strands of DNA

A 
Leading = 3-5, free 3 end for next nucleotide
Lagging = 5-3, uses short okazaki fragments
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34
Q

Nucleotides only add to the free 3’ end of a strand? True/False

A

True

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35
Q

Describe the structure of ribosomes

A

4 rRNA molecules - EXIT, PEPTIDYL (peptides held), AMINOACYL (where tRNA goes to bind) area

36
Q

Enzymes can affect the equilibrium position of a reaction. True/False?

A

False

37
Q

How do enzymes lower the activation energy of a reaction?

A

Bind to and stablise the transition state and provide alternative reaction pathways

38
Q

Enzyme without a cofactor is called a…

A

Apoenzyme

39
Q

What is a cofactor?

A

Inorganic metal ions e.g. Zn, Fe, Cu that stabilise transition states

40
Q

Enzyme with a cofactor is called a…

A

Holoenzyme

41
Q

What are coenzymes?

A

Organic molecules derived from vitamins

42
Q

Induced fit model describes enzyme-substrate interaction by…

A

Binding of substrate induces a conformational change in the enzyme, resulting in complementary fit

43
Q

Trypsin and chymotrypsin work in the ____ and have an optimum pH of _

A

Small intestine, 7

44
Q

What are isozymes?

A

Catalyse same reactions as enzymes but have different properties and structure

45
Q

CK is an isozyme. The M form is produced in ____ and the B form is produced in the ___. MB form is produced in the ___

A

Skeletal muscle, brain, heart

46
Q

Which enzymes carry out phosphorylation?

A

Kinases

47
Q

What are zymogens?

A

Inactive precursors of an enzyme

48
Q

Where are trypsinogen and chymotrypsinogen formed? Why is it important they are produced inactive?

A

Pancreas

They would digest the pancreas if active

49
Q

Which enzyme activates trypsinogen? Where does this occur?

A

Enteropeptidase

Small intestine

50
Q

Vmax is?

A

The maximal rate of reaction at unlimited substrate concn

51
Q

Km is?

A

The concn of substrate which gives 50% maximal rate, i.e. 0.5Vmax

52
Q

A low Km means…

A

An enzyme only needs a little substrate to work at 0.5Vmax (it has high affinity)

53
Q

Vmax can be obtained from a Lineweaver-Burk plot by looking at the interesection with the X axis. True/False?

A

False

Intersection with X (horizontal) axis is Km; intersection with Y (vertical) axis is Vmax

54
Q

In competitive inhibition, Vmax is ___ and Km is ___

A

The same, increased

55
Q

In non-competitive inhibition, Vmax is ___ and Km is ___

A

Decreased, the same

56
Q

Orthosteric enzymes follow M-M kinetics and the curve is shaped like a ____

A

Hyperbola

57
Q

Allosteric enzyme do not follow M-M kinetics and the curve is shaped like a ___

A

Sigmoid

58
Q

Hexokinase has a low Km (0.5) for glucose while glucokinase had a Km of 5. What does this tell you about their affinity for glucose?

A

Hexokinase has a higher affinity for glucose than glucokinase - needs less enzyme to work at 50% of Vmax

59
Q

GLUT3 is located in the…

A

Brain

60
Q

GLUT5 is located in the…

A

Gut

61
Q

In glycolysis, glucose (6C) is converted into…

A

2 x pyruvate (3C each)

62
Q

In glycolysis, there is a net gain of how many ATP?

A

2 ATP (4 gained, 2 lost)

63
Q

The _, _ and _ reactions in glycolysis are control points (irreversible as they are very exergonic)

A

1st, 3rd and final

64
Q

3 enzymes involved in the glycolysis control points

A

Hexokinase (GLUCOSE), phosphofructokinase (FRUCTOSE), pyruvate kinase (PYRUVATE)

65
Q

We must reoxidise NADH to form __ in order to continue ATP synthesis after glycolysis

A

NAD+

66
Q

Pyruvate conversion to lactate occurs when?

A

Low oxygen - muscle cells work very hard to allow glycolysis to continue NAD+ is regenerated by oxidation of NADH

67
Q

What is Warburg effect?

A

Upregulation of anaerobic glycolysis in cancer cells

68
Q

What is the substrate for the TCA cycle?

A

Acetyl-CoA

69
Q

Where does TCA cycle occur?

A

Mitochondria (mainly central matrix and then cristae)

70
Q

What is the fate of pyruvate before TCA cycle?

A

Enters mitochondria, where PDC catalyses oxidative decarboxylation of pyruvate to acetyl-CoA 2CO2 released in total

71
Q

Citric acid (6C) is formed by the combination of which 2 molecules?

A

Oxaloacetate (4C) + Acetyl-CoA (2C)

72
Q

How many cofactors are reduced in total in TCA cycle?

A

4 - 3x NAD+ and 1x FAD+

73
Q

How does pyruvate enter the TCA cycle?

A

Via the H+ gradient from the cytosol into the matrix of the mitochondria

74
Q

GDP conversion to GTP is known as…

A

Substrate level phosphorylation

75
Q

Succinate hydrogenase uses FAD+ as a cofactor. It is the one enzyme of TCA cycle that is located in the central matrix. True/False?

A

False It is the only enzyme located in the cristae - all others located in the central matrix

76
Q

Lipids are converted to ______ and then ____ which enters TCA cycle

A

Fatty acids, Acetyl-CoA

77
Q

Each turn of TCA cycle involves the uptake and release of how many carbon atoms, and in what form?

A

C uptake as Acetyl-CoA, 2C released as 2CO2

78
Q

Glycolysis + PDC + TCA cycle reactions = _NADH, _H+, _FADH2

A

10NADH, 10H+, 2FADH2

79
Q

Each NADH and FADH2 molecule contains how many electrons?

A

2

80
Q

A -ve electron transfer potential means…

A

Substance is more likely to donate electrons than hydrogen

81
Q

What is the function of Co-enzyme Q?

A

Pick up electrons from Complex 1 or 2 and donate them to Complex 3

82
Q

Transfer of electrons through the respiratory chain is coupled to transport of _ from the mitochondrial matrix to the intermembrane space

A

H+

83
Q

Key point of oxidative phosphorylation: Electrons from NADH and FADH2 reduce O2 to __ e- energy is used to pump protons from the matrix to the _____, causing matrix pH to ____ Protons follow their concn and flow across the membrane - this energy is used to phosphorylate ___ to ___

A

H2O
Intermembrane space,
pH to increase (and intermembrane space pH to decrease)
ADP to ATP

84
Q

1 glucose molecule yields how many ATP molecules in total?

A

30-32 ATP

85
Q

How does NADH from cytoplasm enter mitochrondia to be oxidised into NAD+?

A

Using shuttles - glycerol 3 phosphate, malate aspartate

86
Q

Electron transport and ATP synthesis happens ______ using ____ pumps

A

Simultaneously

(Seperate) H+

87
Q

Explain the process of uncoupling electron transport and phosphorylation…

A

Brown adipose tissue contains uncoupling protein thermogenin

Y1 PRINCIPLES (10 decks)

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