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Molecular Biology > Structure, Function and Replication of DNA > Flashcards

Structure, Function and Replication of DNA Flashcards

1
Q

What does DNA contain?

A

genes

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2
Q

What are genes? (2)

A

units of biological information and units of inheritence

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3
Q

Is DNA a polymer or a monomer?

A

polymer

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4
Q

What is a polymer?

A

a long strand (compound made up of a long chain of identical or similar units)

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5
Q

what are the monomers of DNA called?

A

nucleotides

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6
Q

What is a bacteriophage?

A

a virus that infects bacteria and reproduces inside of it using its viral DNA to hijack the host bacterial DNA

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7
Q

What is phage T2?

A

A bacteriophage

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8
Q

What is the genetic material of phage T2?

A

DNA

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9
Q

Describe the method of Hershey and Chase’s 1952 experiment? (3)

A

1) they infected bacteria with phage T2 labelled with 32P in DNA and 35S in protein
2) they separated the phage (protein) coat and the infected bacteria
3) they isolated progeny phage

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10
Q

What did Hershey and Chase find in 1952? (2)

A 
The phage contained mostly 35S label and the infected bacteria mostly 32P. 
When progeny (offspring) of phage was isolated, they found 30% 32P and less than 1% of 35S (basically none)
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11
Q

What do Hershey and Chase’s 1952 findings show?

A
  • The DNA, not the viral protein enter the bacteria

- the DNA of the parent phages becomes part of the progeny phage

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12
Q

How many parts does each DNA nucleotide have?

A

3

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13
Q

What are the 3 parts of each DNA nucleotide?

A
  • A sugar
  • base
  • phosphate group
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14
Q

Why is the sugar 2’ deoxyribose (2 prime)?

A

the 2nd carbon of the sugar ring doesn’t have an oxygen attached (deoxy-)

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15
Q

How does the deoxygenation of the 2nd carbon in the sugar affect stability?

A

It increases it

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16
Q

How many phosphates in the phosphate group of DNA?

A

3

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17
Q

what are the names of the 3 phosphate groups of DNA?

A

alpha (a), Beta (B) and Gamma (y)

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18
Q

Where is the alpha phosphate positioned on the nucleotide?

A

closest to the sugar

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19
Q

Where is the beta phosphate positioned on the nucleotide?

A

between the alpha and gamma phosphates

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20
Q

where is the gamma phosphate positioned on the nucleotide?

A

furthest from the sugar

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21
Q

How many bases are in DNA?

A

4

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22
Q

What are the four bases?

A

Adenine, Guanine, Cytosine and Thymine

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23
Q

What are the 2 types of DNA bases?

A

Purines and pyrimidines

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24
Q

Which bases are purines?

A

Adenine and Guanine

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25
Q

Which bases are pyrimidines?

A

cytosine and thymine

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26
Q

What makes a base a purine?

A

They’re made up of 2 carbon (2C) rings

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27
Q

What makes a base a pyrimidine?

A

They’re made up of 1 carbon (1C) ring

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28
Q

Which part of the base attaches to the sugar in DNA?

A

the nitrogen

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29
Q

What type of bond joins the base and the sugar in a DNA nucleotide?

A

A B-N-glycosidic bond

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30
Q

What’s the full name of the nucleotide with an A base?

A

2’-deoxyadenosine 5’-triphosphate (dATP)

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31
Q

What’s the full name of the nucleotide with a G base?

A

2’-deoxyguanosine 5’-triphosphate (dGTP)

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32
Q

What’s the full name of the nucleotide with a C base?

A

2’-deoxycytidine 5’-triphosphate (dCTP)

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33
Q

What’s the full name of the nucleotide with a T base?

A

2’- deoxythymidine 5’-triphosphate (dTTP)

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34
Q

What happens to the phosphate group of a nucleotide when DNA is polymerising?

A

the alpha phosphate joins to the base of the other nucleotide and the B and Y phosphates are lost

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35
Q

What sort of bond joins 2 nucleotides together in DNA?

A

phosphodiester bond

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36
Q

Is DNA double or single stranded?

A

double

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37
Q

what shape does the double stranded DNA make?

A

A helix

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38
Q

Who discovered the double helix structure of DNA?

A

Watson, Crick and Franklin

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39
Q

Are the ends of DNA the same or different?

A

different

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40
Q

Does DNA have directionality?

A

yes

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41
Q

can DNA be read in 1 or 2 directions?

A

1

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42
Q

How is the directionality of the 2 strands in a DNA molecule described? what does this mean?

A

Antiparrallel organisation

This means they go in opposite directions- 1 going 5’ -> 3’ on one and 3’ –> 5’ on the other

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43
Q

Is DNA a regular helix?

A

no

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44
Q

What are the 2 grooves in DNA?

A

Major and Minor

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45
Q

What’s the advantage of having a major DNA groove?

A

enzymes can go in and read the DNA

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46
Q

What bonds hold the 2 strands of DNA together?

A

Hydrogen bonds

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47
Q

What’s the hydrogen bonding between the 2 strands of DNA called?

A

complementary base pairing

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48
Q

What bases pair?

A

A to T

C to G

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49
Q

How many hydrogen bonds between A and T?

A

2

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50
Q

How many hydrogen bonds between G and C?

A

3

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51
Q

Which is a stronger bond, that between A and T or that between G and C and why?

A

G and C has they have more hydrogen bonds

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52
Q

What do you call the amount of G + C nucleotides in an organism’s DNA?

A

GC content

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53
Q

What’s the GC content of human DNA?

A

40.3%- medium amount

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54
Q

can the DNA helix exist in different forms?

A

yes

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55
Q

What are the 3 forms of DNA helix?

A

A, B and Z

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56
Q

What’s the main difference between A and B helix DNA?

A

A DNA has a narrow major groove but B DNA has a wide major groove

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57
Q

Which is the best known DNA helix?

A

B

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58
Q

In what conditions does A-DNA form?

A

When there;s not enough water (dehydrated conditions)

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59
Q

What’s the structure of Z-DNA?

A

It’s wound into a left handed helix

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60
Q

Where’s Z-DNA found?

A

Found with B-DNA naturally in regions of human and other organism’s DNA

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61
Q

Is Z-DNA biologically active?

A

yes

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62
Q

What’s a Hydrogen bond?

A

A weak electrostatic attraction between an electronegative atom and a hydrogen atom attached to a second electronegative atom

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63
Q

What’s the 3’-OH terminus?

A

The end of a polynucleotide that terminates with a hydroxyl group attached to the 3’-carbon of the sugar

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64
Q

What’s the 5’- P terminus?

A

The end of a polynucleotide that terminates with a mono-, di- or tri- phosphate attached to the 5’- carbon of the sugar

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65
Q

What are the 2 roles of the genes in a cell?

A
  • units of biological information

- genes are units of inheritance

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66
Q

what’s intergenic DNA?

A

part of DNA which aren’t genes

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67
Q

what’s the purpose of intergenic DNA?

A

mostly unknown, however believed to be involved in DNA replication

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68
Q

How long is a gene?

A

varies greatly

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69
Q

what’s the unit of length of a DNA molecule?

A

Base Pair (number of base pairs) (BP)

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70
Q

How many BPs in 1 kilobase pair (kb)?

A

1000000 (million) BP

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71
Q

How many BPs in 1 megabase pair (mb)?

A

1000 BP (1 million)

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72
Q

How long are the shortest genes?

A

around 100 bps

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73
Q

How long are the longest genes?

A

around 2,400,00 bp

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74
Q

Do the longest genes contain 24000 times more information than the shortest?

A

no

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75
Q

What are genes split into (to make them discontinuous)?

A

introns and exons

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76
Q

what are exons?

A

parts of the gene which contain the information needed to make protein

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77
Q

what are introns?

A

information not needed to make a protein

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78
Q

How many introns does the average human gene have?

A

8

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79
Q

How many exons does the average human gene have?

A

9

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80
Q

What’s the mean intron length?

A

3365 bp

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81
Q

what’s the mean exon length?

A

145 bp

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82
Q

are genes directional?

A

yes

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83
Q

which direction are genes read in?

A

5’–> 3’

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84
Q

What’s the process of reading gene information called?

A

gene expression

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85
Q

by which process do genes become RNA?

A

transcription

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86
Q

By which process does RNA become a protein?

A

translation

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87
Q

what are RNA and proteins?

A

functional end products of gene expression (sometimes RNA is the end product)

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88
Q

do proteins play many roles in the cell?

A

yes

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89
Q

name 3 types of protein..

A

any 3 from:

  • structural proteins
  • motor proteins
  • catalytic proteins (enzymes)
  • transport proteins
  • storage proteins
  • protective proteins
  • regulatory proteins
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90
Q

Give an example of a structural protein

A

either collagen or keratin

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91
Q

give an example of a motor protein

A

myosin or dynein

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92
Q

give an example of an enzyme

A

hexokinase or DNA polymerase

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93
Q

give an example of a transport protein

A

hemoglobin or serum albumin

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94
Q

give an example of a storage protein

A

ovalbumin or ferritin

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95
Q

give an example of a protective protein

A

immunoglobulins or thrombin

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96
Q

give an example of a regulatory protein

A

insulin or somatostatin or somatotrophin

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97
Q

what’s the structure of collagen?

A

long and thin

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98
Q

what does hemoglobin do?

A

transports O2 in RBCs

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99
Q

what does insulin do?

A

regulates sugar levels

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100
Q

do RNAs that do not translate play important roles in cells?

A

yes

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101
Q

what percent of RNA is coding RNA?

A

4%

102
Q

what’s the coding RNA?

A

mRNA (messenger)

103
Q

what percent of RNA is noncoding?

A

96%

104
Q

give 3 types of noncoding RNA

A

any 3 from

  • rRNA
  • tRNA
  • snRNA
  • snoRNA
  • scRNA
  • miRNA
  • siRNA
105
Q

What’s rRNA?

A

ribosomal RNA

106
Q

what’s snRNA?

A

small nuclear RNA

107
Q

What’s tRNA?

A

transfer RNA

108
Q

where are noncoding RNAs often found?

A

in intergenic regions

109
Q

what does it mean if a gene is unique?

A

there’s only one copy of this gene

110
Q

what’s a gene family?

A

a group of the same/similar genes

111
Q

when do simple multi-gene families occur?

A

when genes are needed in large quantities

112
Q

what’s a complex multi-gene family?

A

where the genes aren’t identical but have similar sequences- they code for similar but non- identical proteins

113
Q

what’s a tandem array?

A

a set of identical or very similar genes that are arranged one after the other in a group

114
Q

do human globin genes form complex or simple multigene families?

A

complex

115
Q

how many complex multigene families do globin genes form?

A

2

116
Q

what are the 2 complex multigene families and where are they found?

A

the alpha-globin are on chromosome 16

the beta-globin are on chromosome 11

117
Q

when are hemoglobin genes expressed in humans?

A

at different stages in human development

118
Q

By what process do genes in a multigene family arise?

A

gene duplication

119
Q

what happens after gene duplication?

A

the sequences of the genes gradually change so the members of the gene family have slightly different sequences

120
Q

the greater the time that has passed since the duplication….

A

… the more differences we see between the pair of genes

121
Q

why do we see more differences between gene pairs after a longer time has passed?

A

more mutations to the base code have occured

122
Q

what’s a molecular clock?

A

a measure of the rate at which the sequence of a gene changes

123
Q

what can molecular clocks show?

A

when a pair of genes were formed by duplication, allowing estimation of how long ago genes duplicated and diverted from each other (can study evolution)

124
Q

what do you call genes that have lost their function?

A

pseudogenes

125
Q

can pseudogenes become functional genes again?

A

yes, by mutation

126
Q

How many pseudogenes are there in the alpha-globin family?

A

3

127
Q

how many pseudogenes are there in the beta-globin familiy?

A

1

128
Q

how does DNA replicate?

A

by semi-conservative replication

129
Q

what is semi-conservative replication?

A

replication whereby half of the old information is included in the new molecule and the other half is new (gives 2 exact copies)

130
Q

what were the other 2 possibilities of a mechanism for replication?

A

conservative and dispersive

131
Q

How might conservative replication work?

A
  • the parent molecule separates in to 2 strands
  • semi-conservative replication occurs
  • when strands rejoin the 2 old join together and the 2 new join together
132
Q

what’s dispersive replication?

A

where old and new DNA are mixed up in both strands

133
Q

How might dispersive replication happen?

A

the parent molecule opens up into 2 strands

  • a bit of new DNA is made
  • the template switches repeatedly and old and new segments join
134
Q

why was semi- conservative replication first thought impossible?

A

DNA is plectonemic- strands can’t be separated without unwinding
many DNA molecules are circular making unwinding more difficult

135
Q

what would happen if you made a double stranded cut to unwind circular DNA?

A

it would tighten up the helix
trying to unwind the DNA from one end would cause DNA at such a fast speed that the energy produced would destroy the DNA

136
Q

which was the most popular theory of replication in the 1950s?

A

dispersive (due to the issue of unwinding)

137
Q

What was the purpose of the meselson-stahl experiment?

A

to dsitinguish between the 3 modes of DNA replication and work out which occurs in E.coli bacteria

138
Q

What was the method of the Meselson-Stahl experiment?

A
  • A culture of bacteria were grown in a medium containing heavy Nitrogen (N15, instead of the normal N14)
  • The bacteria colony was transferred to a growth medium containing normal Nitrogen (N14)
  • Samples from this colony were removed after 20 minutes (1 cell division) and 40 minutes (2 cell division)
  • The colonies were centrifuged
139
Q

What were the findings of the Meselson-Stahl experiment?

A
  • When grown in the heavy Nitrogen and centrifuged all bacteria appeared in the same band (15N), bacteria grown in normal Nitrogen (14) medium showed a higher up band (lighter)
  • After one replication in lighter the medium, the bacteria band appeared in between where the 14 and 15 were
  • after 2 replications, there was a band where N14 was and a band where the N14/15 was
140
Q

Which method of replication did the meselson- stahl’s findings support?

A

semi-conservative

141
Q

what would meselson- stahl have seen if they had been conservative replication after 1 division?

A

2 bands- one for N14, one for N15

142
Q

what would meselson and stahl have seen after one replication in dispersive replication?

A

what they did see- a band in between N14 and N15

143
Q

what would meselson- stahl have seen after two divisions in dispersive replication?

A

one band- between N14 and N15 (same as first division)

144
Q

which type of enzyme is reponsible for DNA strand separation/ unwinding?

A

DNA topoisomerases

145
Q

What’s the mode of action of a Type I DNA topoisomerase?

A

It makes a nick in 1 strand and passes the other through that nick to allow unwinding by releasing tension

146
Q

What’s the mode of action of a Type II DNA topoisomerase?

A
  • it makes a double strand nick and one segment of DNA passes through the gap, unwinding this section, then the 2 cut strands are rejoined and the process repeats further down the strand
147
Q

Which enzyme breaks the bonds between the base-pairs?

A

DNA helicase

148
Q

what’s the replication fork?

A

the open part of the DNA where the new strands of DNA are being synthesised

149
Q

What’s the process of DNA synthesis called? (2 names)

A

template-dependent DNA synthesis
and
DNA-dependent DNA synthesis

150
Q

What enzyme carries out DNA-dependent DNA synthesis?

A

DN-dependent DNA polymerase

151
Q

What direction is DNA synthesis always in?

A

5’–>3’

152
Q

what’s required to initiate the synthesis of a new DNA strand?

A

a primer

153
Q

why is a primer needed to initiate the synthesis of a new DNA strand?

A

unknown

154
Q

as well as synthesising DNA, what other function does DNA polymerase serve?

A

It can degrade DNA- exonuclease activity

155
Q

How many types of exonuclease activity are there?

A

2

156
Q

what are the names of the 2 types of exonuclease activity?

A

3’–>5’
and
5’–>3’

157
Q

What happens during 3’–>5’ exonuclease activity?

A

the polymerase can remove nucleotides it has just just inserted
this is called proofreading, allowing errors to be corrected

158
Q

What happens during 5’–>3’ exonuclease activity?

A

the polymerase can remove DNA already attached to the template

159
Q

what are the 2 bacterial DNA polymerases?

A

I and III

160
Q

what are the 2 eukaryotic DNA polymerases?

A

alpha (a) and delta

161
Q

what’s the function of DNA polymerase I?

A

DNA repair and replication

162
Q

What’s the function of DNA polymerase III?

A

main replicating enzyme- in bacteria

163
Q

what’s the function of DNA polymerase alpha?

A

priming during replication

164
Q

what’s the function of DNA polymerase delta?

A

main replicative enzyme- in eukaryotes

165
Q

does DNA polymerase I have 3’–>5’ activity?

A

yes

166
Q

does DNA polymerase I have 5’–>3’ activity?

A

yes

167
Q

does DNA polymerase III have 3’–>5’ activity?

A

yes

168
Q

does DNA polymerase III have 5’–>3’ activity?

A

no

169
Q

does DNA polymerase alpha have 3’–>5’ activity?

A

no

170
Q

does DNA polymerase alpha have 5’–>3’ activity?

A

no

171
Q

does DNA polymerase delta have 3’–>5’ activity?

A

yes

172
Q

does DNA polymerase delta have 5’–>3- activity?

A

no

173
Q

what must first happen at the replication fork?

A

the separated single strands must be protected

174
Q

why must the the separated single strands be protected? (2)

A

they may just reattach to each other
or
be attacked by nucleases

175
Q

what protects the separated single strands at the replication fork?

A

single-strand binding proteins (SSBs)

176
Q

What’s the leading strand?

A

The strand which can be synthesised by continuous DNA synthesis

177
Q

Why can the leading strand be copied by continuous DNA synthesis?

A

It goes in the 5’–>3’ direction (with the parent strand being read 3’–>5’)

178
Q

What’s the primer for bacteria synthesis made of?

A

RNA

179
Q

In bacteria, what makes the primer?

A

Primase enzyme

180
Q

how long is the primer in prokaryotes?

A

4-15 nucleotides in length

181
Q

What synthesises the new DNA strand after the primer has been made in prokaryotes?

A

DNA polymerase III

182
Q

what happens after the primer attaches to the template stand in eukaryotic DNA?

A

the primer is extended by DNA polymerase alpha, which adds about 20 nucleotides
then DNA polymerase delta makes the rest of the new strand

183
Q

How is DNA on the lagging strand synthesised?- generally

A

It’s made in segments called Okazaki fragments

184
Q

How are Okazaki fragments joined in bacteria?

A

DNA polymerase III stops when it reaches the RNA primer
DNA polymerase I continues synthesis
DNA ligase links the two DNA fragments

185
Q

How are Okazaki fragments joined in eukaryotes?

A

DNA polymerase delta and helicase push aside the primer
FEN1 cuts the DNA at the branch point
there’s still a missing phosphodiester bond between the okazaki fragments which is joined by DNA ligase

186
Q

What does the enzyme telomerase do in eukaryotes?

A

prevents the ends of chromosomes from getting shorter

187
Q

How does the enzyme telomerase prevent the ends of chromosomes from getting shorter?

A

it extends the parent DNA by adding the sequence TTAGGG several times so the final okazaki fragment can be primed

188
Q

What’s a genome?

A

the complete set of DNA molecules possessed by an organism

189
Q

where does the replication of an E.coli genome begin?

A

the origin of replication (always the same position of the genome)

190
Q

In E.coli, how is the direction of replication described?

A

bidirectional (goes in 2 directions)

191
Q

describe the origin of replciation

A
  • spans approx. 245 bp of DNA

- contains 2 short repeat motifs (one is 9 nucleotides long, the other is 13)

192
Q

what are origins of replication like in human DNA?

A

there are many on each chromosomal DNA molecule

usually around 300kb apart from eachother

193
Q

where do DNaA proteins bind?

A

close to the origin of replication

194
Q

what happens to the DNA near the DNaA proteins?

A

it becomes wound around the barrel of these proteins

195
Q

What does the winding of DNA around the DNaA proteins do?

A

causes torsional stress causing the base pairs at the origin of replication to break

196
Q

what type of DNA is typically at the origin of replication? why?

A

A-T rich sequence

because the bonds are weaker (2 H bonds rather than 3)

197
Q

How is the prepriming complex formed and opened into replication forks?

A

by attachment of DNaB proteins to the origin on either end. This starts breaking base-pair bonds, opening up the DNA further, moving the replication forks further away from the origin of replication

198
Q

What is synthesised as the double helix unzips?

A

new polynucleotides

199
Q

what is DNaB?

A

a helicase enzyme

200
Q

How is the primosome formed?

A

by the attachment of 2 primase enzymes

201
Q

What do primase enzymes do at the primosome?

A

make the RNA primers that initiate replication

202
Q

what’s needed before DNA Polymerase III can begin to make DNA?

A

a special type of RNA polymerase that synthesizes the primers

203
Q

describe events at the replication fork in E.coli?

A
  • DNA topoisomerase separates the strands
  • DNA helicase breaks base pairs
  • single strand binding proteins (SSBs) protect the bare single strands
  • primase makes primers on the lagging strand
  • DNA polymerase III synthesizes DNA
  • DNA polymerase I and DNA ligase joins up the okazaki fragment
  • the gamma complex attaches and detaches polymerase III from the lagging strand
204
Q

what’s single binding proteins (SSBs) purpose?(2)

A

prevent attacks by nucleases- if the body treats the exposed single strand as viral genetic material
prevents base pairs from rejoining

205
Q

describe events at the replication fork in humans?

A
  • DNA topoisomerases separates strands
  • helicase breaks base pairs
  • SSBs protect the single bare strands
  • primase/DNA polymerase alpha make primers on the lagging strand
  • DNA polymerase delta synthesizes DNA
  • FEN1 and DNA ligase join up the okazaki fragments
  • the proliferating cell nuclear antigen (PCNA) holds DNA polymerase delta tightly onto the DNA
206
Q

What is required due to the bidirectionality of replication in E.coli?

A

a point to stop (termination point) at (in case the replication in either direction is going at different speeds)

207
Q

How many terminator sequences are there in the E.coli genome?

A

6

208
Q

what binds to each of the terminator sequences in E.coli?

A

Tus protein

209
Q

are the terminator sequences in E.coli directional? why?

A
  • yes
  • because they affect the direction at which the Tus protein binds, one side has protein oriented one way the other the opposite way
210
Q

What do Tus proteins allow and disallow?

A

replication fork can pass in one direction but not the other

211
Q

what’s chromatin?

A

DNA extracted from the nucleus

a DNA-protein complex

212
Q

what structure is shown on the electron microscope image of chromatin?

A

beads-on-a-string structure (proteins are beads on DNA string)

213
Q

How are the proteins distributed along DNA?

A

At regular intervals

214
Q

what are the proteins in chromatin called?

A

histones

215
Q

what do histones contain in high amounts?

A

basic amino acid content

216
Q

what’s a nucleosome?

A

the ‘beads’

an octamer of DNA wrapped around 8 histones

217
Q

Which histones are found in a nucleosome?

A

2x H2A
2x H2B
2x H3
2x H4

218
Q

How long is linker DNA between nucleosomes?

A

50-70 bp

219
Q

What’s Histone H1?

A

a linker histone

220
Q

what does Histone H1 do?

A

attaches to the outside of the nucleosome

221
Q

what is a chromatosome made up of?

A

nucleosome + DNA + linker histone

222
Q

Is DNA static?

A

no (during replication it leaves the nucleosome package and remains in it when not in use)

223
Q

How much does the beads on a string structure reduce the length of DNA?

A

by 1/6

224
Q

What’s the next level of packaging DNA?

A

30nm chromatin fibre

225
Q

How much does the 30nm chromatin fibre reduce DNA length by?

A

another 1/7

226
Q

are higher levels of packaging DNA after 30nm chromatin fibre understood?

A

no

227
Q

what’s the highest level of DNA packaging?

A

the metaphase chromosome

228
Q

where is the metaphase chromosome found?

A

only in dividing cells (when chromosomes condense)

229
Q

How is euchromatin seen under the microscope?

A

light areas

230
Q

what does euchromatin contain?

A

active genes

231
Q

what level of packaging is euchromatin at?

A

probably 30nm fibre

232
Q

How is heterochromatin seen under the microscope?

A

dark areas

233
Q

what does heterochromatin contain?

A

inactive genes

234
Q

Is heterochromatin or euchromatin more densely packed?

A

heterochromatin

235
Q

what’s the difference between constitutive and facultative heterochromatin?

A

constitutive contains DNA that is tightly packed in all cells
facultative contains DNA that is tightly packed in some cells

236
Q

what’s the nuclear matrix?

A

a protein network which gives round structure to nucleus

237
Q

what is euchromatin attached to and why?

A

the nuclear matrix to prevent the DNA from getting tangled up

238
Q

what’s the structure of a metaphase chromosome?

A
  • centromere golds the daughter chromosomes together

telomeres protect the ends

239
Q

what do the centromeres contain?

A

special histones- CENP-A instead of H3

240
Q

what do telomeres protect the ends of chromosomes from?

A

exonuclease attack
and
being mistaken for chromosome breaks and joining together

241
Q

what are chromatids?

A

the arms of chromosomes

242
Q

what forms telomeres?

A

telomerase

243
Q

what’s the karyogram?

A

a complete set of stained chromosomes

244
Q

what does each chromosome show when stained?

A

a specific pattern of staining to that chromosome

245
Q

what are the dark bands seen on chromosomes on the karyogram?

A

constitutive heterochromatin (where DNA/chromosomes are packaged more tightly)

246
Q

define interphase

A

the period between cell divisions

247
Q

what’s a nuclease protection experiment?

A

a technique that uses nuclease digestion to determine the positions of proteins on DNA or RNA molecules

248
Q

What’s the UTR?

A

UnTranslated Region

249
Q

what’s a spacer?

A

an area of non-coding DNA between genes (different to introns which are non-coding within genes)

250
Q

what’s a cistron?

A

a section of DNA or RNA molecule that codes for a specific polypeptide in protein synthesis (a gene)

251
Q

what 3 factors are required for the initiation of DNA replication in E.Coli?

A

Primase
DNA Helicase
DNaA

252
Q

what’s unusual about telomerase?

A

it contains an RNA component

Molecular Biology (4 decks)

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