BIOCHEMISTRY - i hate it too its ok but you need to know it :( Flashcards

1
Q

What are enzymes?

A

Biological catalysts which speed up the rate at which a reaction reaches equilibrium but does not affect the position of equilibrium, by lowering the activation energy and stabilising the transition state

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2
Q

Enzymes without a cofactor

A

apoenzymes

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3
Q

Enzymes with a cofactor

A

holoenzymes

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4
Q

What does a substrate bind to?

A

Enzyme’s active site

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5
Q

Induced fit

A

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

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6
Q

What are phosphorylation reactions carried out by?

A

Protein kinases

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7
Q

Vmax

A

maximal rate of reaction at unlimited substrate concentration
intersection of the straight line with the Y axis

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8
Q

Km

A

Michaelis constant = 50% Vmax
intersection of the straight line with the X axis

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9
Q

Competitive enzyme inhabition

A

Binds to active site
Vmax remains the same
Km varies

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10
Q

Non-competitive enzyme inhabition

A

Bind to site other than active site
Km stays the same
Vmax varies

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11
Q

Cholesterol

A

Present in cell membranes
Component of myelin sheath
Precursor molecule for steroid hormones, vitamin D and bile acids

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12
Q

Triglycerides

A

Present in all cell membranes - lipid bilayer
Highly concentrated energy stores

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13
Q

Nucleoside

A

base + sugar

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14
Q

Nucleotide

A

nucleoside + phosphate

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15
Q

Purines

A

Adenine and guanine

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16
Q

Pyrimidines

A

Uracil, thymine and cytosine

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17
Q

Where does phosphodiester bond?

A

3’ OH group and 5’ triphosphate

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18
Q

Base pairing

A

A-T
C-G

19
Q

What direction does DNA replication occur in?

A

always 5’-3’

20
Q

What is DNA replication catalysed by?

A

DNA polymerases

21
Q

What is required for DNA replication?

A

RNA primer

22
Q

Leading strand

A

always has 3’ end free

23
Q

Lagging strand

A

replicated in short fragments called Okazaki fragments

24
Q

What unwinds DNA?

A

helicase

25
Q

RNA

A

single stranded, contains a stem loop

26
Q

3 main classes of RNA

A

rRNA, tRNA, mRNA

27
Q

rRNA

A

ribosomal
combines with proteins to form ribosomes where protein synthesis takes place

28
Q

tRNA

A

transfer
carries amino acids to be incorporated into protein
anticodons consist of 3 nucleotides

29
Q

mRNA

A

messenger - stable RNAs
carries genetic information for protein synthesis

30
Q

What are RNA polymerases?

A

multi-subunit complexes

31
Q

How many types of RNA polymerases do prokaryotic cells have?

A

1

32
Q

How many types of RNA polymerases do eukaryotic cells have?

A

3
Pol I, II, III
Pol II synthesises all mRNA

33
Q

Transcription order

A
  1. RNA polymerase binding
  2. DNA chain separation
  3. Transcription initiation
  4. Elongation
  5. Termination
34
Q

RNA polymerase binding

A

Detects initiation sites on DNA (promoters)
Requires transcription factors

35
Q

DNA chain separation

A

Unwinding of DNA

36
Q

Transcription initiation

A

Selection of first nucleotide of growing RNA
Requires addition general transcription factors

37
Q

Elongation

A

Addition of further nucleotides to RNA chain
RNA synthesised in a 5’-3’ direction

38
Q

Termination

A

release of finished RNA

39
Q

TFIID

A

general transcription factor required for all Pol II transcribed genes

40
Q

Why are specific transcription factors required?

A

for specific regulation of transcription

41
Q

Exons

A

coding regions

42
Q

Introns

A

non-coding regions

43
Q

How are introns removed after transcription?

A

By splicing before translation into the protein