Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Uni year 1 > FLS - DNA > Flashcards

FLS - DNA Flashcards

1
Q

Which bases are purines?

A

guanine and adenine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which bases are pyrimidines?

A

cytosine and thymine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Which direction does DNA polymerase work?

A

5’ to 3’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is at the 5’ end?

A

A phosphate group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is at the 3’ end?

A

A hydroxyl group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which direction does the coding strand run in?

A

5’ to 3’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What direction does the template strand run in?

A

3’ to 5’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What causes major and minor grooves?

A

The binding between purines and pyrimidines is at a slight offset - glycosidic binds are at an angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do the minor and major grooves do?

A

Allow transcription factors to bind

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which enzyme unzips the double helix?

A

Helicase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What keeps the DNA strands open?

A

single strand binding proteins which bind to the parent strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the junctions between the separated strands during replication called?

A

The replication fork

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does the enzyme primase do? Which end of DNA does it bind to?

A

Adds ribonuclease triphosphates to synthesise an RNA primer

It binds to the 3’ end because it runs in a 5’ to 3’ direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does DNA polymerase do?

A

Extends DNA in a 5’ to 3’ direction. Requires all 4 dNTPs, a primer and a template

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What occurs after laying down of nucleotides?

A

Proof reading to prevent mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does exonuclease do?

A

Removes nucleotides from the end of the DNA strand which is needed because DNA polymerase will overshoot slightly so some will need to be removed. It works in both directions, 5’ to 3’ and 3’ to 5’.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does ligase do?

A

Joins ends of DNA strands by making new phosphate binds. It also connects Okazaki fragments.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the 3 main parts of DNA replication

A

Initiation:

  • helicase unwinds, hydrogen bonds broken
  • primase lays down primers

Elongation:

  • DNA polymerase in 5’ to 3’ direction
  • leading strand synthesised faster than lagging strand

Putting it together:

  • exonuclease removes RNA primer (because wrong bases)
  • DNA polymerase fills gaps
  • ligase joins nucleotides together
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why is the lagging strand synthesised discontinuously?

A

Because DNA polymerase works 5’ to 3’ and the lagging strand runs 3’ to 5’ so it needs to wait for more of the DNA strand to be unzipped by helicase before DNA polymerase can start adding nucleotides.`

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does gyrase do?

A

It is a topoisomerase that relaxes the supercoils produced when DNA is twisted during replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does telomerase do?

A

uses short RNA templates to add short DNA repeats at the end of linear chromosomes once the primer has been removed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Transcription

A
  • DNA double helix is unwound
  • RNA polymerase lays down complementary sequence of pre mRNA
  • RNA processing turns pre mRNA to into mRNA
  • mRNA is transported through nuclear pores to the ribosome where it is translated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does small nuclear RNA do?

A

Turns pre mRNA into mature mRNA, only required in eukaryotes

24
Q

What is the promoter region for within a gene?

A

Usually contain a CAT or TATA box to allow transcription factors to bind to allow RNA polymerase to bind so transcription can occur.

25
Q

What is the terminator region for?

A

So that transcription stops happening so the correct protein is made

26
Q

Which strand is the 5’ to 3’ strand

A

coding strand

27
Q

Which strand is the 3’ to 5’ strand

A

template

28
Q

How is the pre mRNA modified

A

GTP cap at 5’ end used as recognition signal as a recognition signal for ribosomes to bind to mRNA
Poly A tail at 3’ end so that when it starts to be degraded by proteases, it will start degrading the poly As
The GTP cap prevents the 5’ end from being degraded

29
Q

What are small nuclea RNAs for?

A

Splicing introns out of pre mRNA, snRNAs bind to either end of the intron causing it to loop out.

30
Q

Why does RNA not need an RNA primer?

A

It uses a transcription factor instead

31
Q

Which codon forms the first amino acid?

A

AUG = methionine

32
Q

What is a reading frame?

A

the different ways the code can be read in threes, the reading frame that will be chosen is the one that contains an AUG. If multiple reading frames contain AUG then the one that produces the largest protein will be chosen.

33
Q

What is the UTR?

A

The UnTranslated Region is the leader sequence of a gene which is untranslated. It is the sequence of bases before methionine.

34
Q

What is the trailer sequence?

A

The sequence at the end that is not translated after the stop codon

35
Q

What are the two subunits of a ribosome?

A

60S subunit and a 40S unit that join together to make 80S

36
Q

What is the large ribosomal subunit made up of?

A

28S rRNA
5.8S rRNA
5S rRNA

37
Q

How many subunits does the large subunit have and what are they?

A

2
The P site is the peptidyl-tRNA binding site
The A site is the amino tRNA binding site
The amino acid will bind to one of the two docking sites

38
Q

Why is the acceptor stem on tRNA uncharged?

A

So that the the tRNA can be charged with the appropriate amino acid

39
Q

Which enzyme adds the correct amino acid to tRNA?

A

aminoacyl-tRNA synthease

40
Q

How is an amino acid added to tRNA?

A

The amino acid binds to a specific docking site on the enzyme (aminoacyl-tRNA synthease). This requires ATP and the structure of the enzyme is changed slightly. ATP loses 2 phosphate groups and binds form between the amino acid and AMP. This signals the tRNA to move towards the enzyme and it binds to a different docking site when AMP is released. tRNA binds to the amino acid and becomes charged.

41
Q

What binds to the small subunit and what binds to the large subunit?

A

The small subunit binds to mRNA

The large subunit binds to the large subunit

42
Q

What binds to the P site and what binds to the A site?

A

Methionine binds to the P site so the A site is still free. The next tRNA molecule will bind to the A site.

43
Q

What is a polysome?

A

When several ribosomes translate a single mRNA strand

44
Q

Why are the leader and trailer sequences required?

A

mRNA is very unstable so when it starts to be degraded, it will be degraded from the untranslated regions first

45
Q

What are the 4 core histones?

A

H2A, H2B, H3, H4

46
Q

What is needed to package DNA?

A

2 of the core histones and one H1 (linker hisotne)

47
Q

What is the linker histone for?

A

Prevents the nucleosome moving as the DNA is wound around it?

48
Q

What is the first level of DNA packaging?

A

The nucleosome, 2 of each of the core hisotnes is required.
one molecule of H3 and one molecule of H4 bind in a horeshoe shape, the other two molecule make the same shape and bind to the first horseshoe.
H2A and H2B bind and make a dimer above and below the tetramer

49
Q

Which direction is the DNA wrapped around the nucleosome and why?

A

In a left handed helix so that the major and minor grooves form pockets for transcription factors to bind which will cause DNA to unravel away from the nucleosome

50
Q

What is the second level of DNA packaging?

A

The 10nm fibre:

  • transcriptional activity allowed
  • packing ratio is 6-7
51
Q

What is the third level of DNA packaging?

A

The 30nm solenoid:

  • 10nm fibre wraps with 6 nucleosomes per turn to form a solenoid
  • transcription is partially permissable
  • H1 is essential, it is at the centre and gives rigidity to the solenoid so it can form
  • packing ratio is 40
52
Q

What is the fourth level of DNA packaging?

A

The 300nm solenoid:

- protein scaffold gives more structure so it will be unravelled in an ordered way

53
Q

What is the 5th level of DNA packaging?

A

The 700nm fibre:
- the coiled coil
- 10 to 4 ratio
transcription cant occur

54
Q

What is the sixth level of DNA packaging>

A

The 1400nm meptahase chromosome

- telomeres and centromeres are made up of heterochromatin, the arms carry euchromatin

55
Q

What is constitutive heterochromatin?

A
  • found in chromosomes of all eukaryotes
  • concentrates euchromatic DNA towards the nucleus to be transcribed
  • necessary for separation of sister chromatids and centromeres
56
Q

What is facultative heterochromatin?

A
  • amount differs between cells
  • often associated with morphogenesis or differentiation
  • X-inactivation
  • less condensed and less stable than constitutive

Uni year 1 (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions