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Y1 - Principles > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

What is a glycosidic bond?

A

The bonds that form between monosaccharides to form a disaccharide

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2
Q

What type of reactions form and break glycosidic bonds?

A

Formed by condensation

Broken by hydrolysis

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3
Q

What are sugars broken down into?

A

Monosaccharides

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4
Q

What is entropy?

A

Free energy tends towards an unusable state after multiple transformations - entropy is the degree of this

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5
Q

What is free energy?

A

The energy available to do work

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6
Q

How is ∆G calculated?

A

Energy of products - energy reactants

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7
Q

What does exergonic mean?

A

Free energy of products is less than reactants, ∆G is negative, reaction occurs spontaneously

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8
Q

What does endergonic mean?

A

Free energy of products is greater than reactants, ∆G is positive, reaction therefore requires input of energy (e.g. from ATP breakdown)

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9
Q

What does amphipathic mean?

A

Can be polar or non-polar

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10
Q

Do acids and bases donate or accept protons?

A

Acids donate

Bases accept

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11
Q

What is meant by the strength of an acid or base?

A

How readily it donates or accepts electrons - the dissociation constant

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12
Q

What is pH?

A

The number of protons in a solution

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13
Q

What is the equation for pH?

A

pH = -log10[Ka]

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14
Q

What does the Henderson Hasselbach equation determine?

A

pH of weak acids in a solution

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15
Q

What is the Henderson Hasselbach equation?

A

pH = pKa + log(base]/[acid]

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16
Q

What is a buffer?

A

A substance that resists change in pH upon moderate addition of acid/base

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17
Q

What is primary protein structure?

A

The sequence of amino acids

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18
Q

What is secondary protein structure?

A

The shape of the backbone

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19
Q

What are examples of secondary protein structures?

A

Alpha helix
Beta pleated sheet
Triple helix

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20
Q

What is tertiary protein structure?

A

3D structure including side chains

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21
Q

What are examples of tertiary protein structure?

A

Covalent disulphide bridge
Hydrophobic interaction
Hydrogen bonds

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22
Q

What level of protein structure determines if a protein is fibrous or globular?

A

Tertiary

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23
Q

What is quaternary protein structure?

A

The spacial arrangement of a chain in a protein with multiple subunits

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24
Q

Why does vitamin C deficiency cause scurvy?

A

Vitamin C is needed to hydrate proline
Hydroxyproline is needed for hydrogen bond formation
Vit C deficiency therefore causes weakened collagen

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25
Q

What can disrupt protein structure, and how do they do it?

A

Heat - increases vibrations
pH -interrupt electrostatic interactions
Detergents/urea.guanine hydrochloride - disrupt hydrophobic interactions
Thiols/reducing agents -disrupt disulphide bonds

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26
Q

In which direction does DNA replicate?

A

5’ to 3’

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27
Q

What does the lagging strand of DNA use to replicate?

A

Okazaki fragments

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28
Q

Which enzyme unwinds DNA?

A

Helicase

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29
Q

What is the term for the backbone of DNA?

A

Phosphodiester

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30
Q

Which enzyme replicated DNA?

A

DNA polymerase

31
Q

What is a nucleotide made of?

A

Nitrogenous base + sugar + phosphate

32
Q

What is a nucleoside made of?

A

Nitrogenous base + sugar (without phosphate)

33
Q

What is an anti-retroviral?

A

Thymidine analogue which incorporates into viral DNA with more affinity than human DNA
It lacks 3’OH so terminates elongation

34
Q

What is the function of rRNA?

A

Combines with proteins to form ribosomes

35
Q

What is the function of tRNA?

A

Carries amino acids to incorporate into protiens

36
Q

What is the function mRNA?

A

Encodes genetic information

Identical to the coding DNA and complementary to template DNA

37
Q

Where does transcription take place?

A

Nucleus

38
Q

What is the function of a TATA box?

A

A TATA box is present 25 nucleotides behind, to introduce a kink into DNA to determine start and direction of transcription

39
Q

How does premature mRNA become mature mRNA?

A

Splices out introns, keeps exons
Adds poly-adenosine tail
Adds 5’ cap to prevent the transcript from being broken down

40
Q

Where does translation take place?

A

Cytoplasm

41
Q

What is the start codon?

A

Methionide

42
Q

What is an example of a stop codon?

A

AUG, AGU, UAG

43
Q

Which enzyme binds amino acid to the corresponding tRNA, and with what type of bond?

A

Aminoacyl-tRNA

Covalent bond

44
Q

What do free ribosomes produce and for what purpose?

A

Proteins that are translocated post-translationally for cytosol, nucleus and mitochondria

45
Q

What do bound ribosomes produce and for what purpose?

A

Proteins that are translocated co-translationally for membrane, endoplasmic reticulum, Golgi and secretion

46
Q

What is the function of enzymes?

A

Increase the speed a reaction reaches equilibrium by reducing the energy needed for substrates to reach transition state

47
Q

What is a co-factor?

A

metal ion that forms metalloprotein complex, involved in redox reactions to stabilise transition state

48
Q

What is a co-enzyme?

A

Organic molecule that transiently alters charge and structure of enzyme, which is regenerated after

49
Q

What is the difference between apoenzymes and holoenzymes?

A

Apoenzyme - enzyme that is inactive without co-factor

Holoenzyme - enzyme with a co-fector, therefore complete and catalytically active

50
Q

What is a zymogen?

A

Inactive precursor

51
Q

What is V max?

A

The maximum possible rate of reaciton

52
Q

What is Km?

A

The concentration of substrate at which the reaction occurs at 50% of its maximum possible rate

53
Q

In a Lineweaver Burke plot, what is represented by the x and y axis?

A

1/[V] is y

1/[S] is x

54
Q

In a Lineweaver Burke plot, what is represented by the intersections of the x and y axis?

A

Vmax - intersection with y-axis

Km - intersection with x-axis

55
Q

How does competitive inhibition affect a Lineweaver burke plot?

A

Vmax doesn’t change but Km is reduced

56
Q

How does non-competitive inhibition affect a Lineweaver burke plot?

A

Vmax is reduced but Km doesn’t change

57
Q

What are the possible functions of glucose?

A

Stored as glycogen, starch, sucrose of converted into lipids
Oxidosed to precursor for nucleotide synthesis (ribose-5-phosphate)
Fermented by anaerobic glycolysis to lactic acid
Oxidised by aerobic glycolysis to pyruvate

58
Q

How does glucose enter cells?

A

Na+/glucose symporters

59
Q

What is the equation for glycolysis?

A

Glucose + 2ADP + 2Pi + 2NAD+ –> 2 pyruvate + 4ATP + 2H2O + 2NADH + 2H+

60
Q

What is the rate limiting enzyme for glycolysis?

A

Phosphofructokinase

61
Q

What is the enzyme that limits substrates in glycolysis, and which reaction does it catalyse?

A

Hexokinase

Glucose to G-6-P

62
Q

What are the activators and inhibitors for glycolysis?

A

Activators: AMP and fructose-2,6-biphosphate
Inhibitors: ATP/citrate and H+

63
Q

What happens instead go glycolysis in anaerobic conditions?

A

NADH ferments 2 pyruvate to lactic acid and 2ATP

64
Q

Where does the TCA cycle occur?

A

Mitochondrial matrix

65
Q

What are the products of the TCA cycle?

A

2CO2
3NADH + 3H+
FADH2
GDP + Pi (converted to GTP, converted to ATP)

66
Q

How many ATP does 1 glucose molecule produce?

A

2

67
Q

How does NADH enter?

A

Malate-aspartate shuttle

68
Q

What is the TCA cycle activated and inhibited by?

A

Activated by: ADP, NAD+ (lack of energy)

Inhibited by: ATP, NADH, acetyl-CoA (excess energy)

69
Q

What happens to the products of the TCA cycle NADH and FADH2?

A

Electron transport chain

70
Q

What is the electron transport chain?

A

NADH and FADH2 donate electrons which are passed along the chain which produces energy
The energy is used to pump H+ across the inner mitochrondrial matrix.
The flow of H+ back into the mitochrondria through ATP synthase produces ATP

71
Q

Which stage of glycolysis produces the most ATP, and how much does it produce per glucose molecule?

A

Electron transport chain - 30-32 ATP

72
Q

What is the electron transport chain inhibited by?

A

Cyanide, azide and CO

73
Q

What is the function of UCP?

A

Uncoupling Protin

Short-circuit mitochondrial battery that pumps out H+ without the electron transport chin

74
Q

Where is UCP found int he body?

A

Brown fat in newborns

Y1 - Principles (11 decks)

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