DNA to Proteins Flashcards
(115 cards)
1
Q
how is DNA to converted to RNA?
A
by transcription
2
Q
how is RNA converted to protein?
A
by translation
3
Q
what sugar is found in RNA?
A
ribose
4
Q
what sugar is found in DNA?
A
deoxyribose
5
Q
what makes up a nucleoside?
A
base + sugar
6
Q
what makes up a nucleotide?
A
nucleoside (base + sugar) + phosphate group
7
Q
what are the four bases in DNA?
A
Adenine Cytosine Guanine Thymine
8
Q
what are the four bases in RNA?
A
A C G Uracil
9
Q
what is the nucleoside containing adenine called?
A
adenosine
10
Q
what is the nucleoside containing cytosine called?
A
cytidine
11
Q
what is the nucleoside containing guanine?
A
guanosine
12
Q
what is the nucleoside containing thymine called?
A
thymidine
13
Q
what is the nucleoside containing uracil called?
A
uridine
14
Q
what are the four building blocks of DNA?
A
dATP
dCTP
dGTP
dTTP
15
Q
what are the four building blocks of RNA?
A
ATP
CTP
GTP
UTP
16
Q
where does a phosphodiester bond form in DNA?
A
between a free 3’ OH group and a 5’ triphosphate
17
Q
what does polymerisation of two nucleotides in DNA require?
A
two high energy bonds
18
Q
where are new nucleotides added in a growing strand of DNA?
A
the free 3’ end
19
Q
name a drug that is a nucleotide analogue
A
retrovir
20
Q
which nucleotide is retrovir an analogue of?
A
thymidine
21
Q
where is retrovir incorporated into when taken?
A
growing viral DNA
22
Q
how does retrovir inhibit viral growth?
A
it lacks a 3’ OH growth so terminates chain elongation of the viral DNA
23
Q
how does retrovir target only viral DNA and not human?
A
retrovir has a higher affinity for viral reverse transcriptase than it does for human DNA polymerases
24
Q
what connects nucleotides in the same strand along the outside?
A
the sugar phosphate backbone
25
what bond forms between base pairs on complementary DNA strands?
hydrogen bonds
26
what are the complementary DNA base pairs?
A to T
| C to G
27
how many hydrogen bonds form between A and T nucleotides?
two
28
how many hydrogen bonds form between C and G nucleotides?
three
29
how can the replication of DNA be described?
semi conservative
30
what unwinds DNA?
helicase
31
what enzyme catalyses DNA replication?
DNA polymerase
32
why does DNA have to be replicated before cell division?
to ensure daughter cells have a complete copy of the genome
33
what is required for DNA polymerase to begin replication and why?
an RNA primer as it can only add nucleotides to existing nucleotides
34
how is eukaryotic DNA replication bidirectional?
genomes have many origins of replication allowing it to begin simultaneously at several points
35
which strand of DNA is replicated continuously and why?
the leading strand
| it always has a free 3' strand
36
which strand of DNA is replicated discontinuously?
the lagging strand
37
what are the short segments replicated in the lagging strand called?
okazaki fragments
38
what enzyme synthesises the RNA primer needed for DNA synthesis?
primase
39
what enzyme looks for DNA damage and repairs it following replication?
DNA polymerase
40
what type of activity does DNA polymerase have that allows it to detect and repair DNA damage?
3' to 5' exonuclease activity
41
what is RNA?
ribonucleic acid
42
how many strands does RNA have?
one
43
what is a stem loop in RNA?
a local stretch of intramolecular base pairing
44
what are the three main classes of RNA?
rRNA
tRNA
mRNA
45
what is rRNA?
ribosomal RNA
46
what is tRNA?
transfer RNA
47
what is mRNA?
messenger RNA
48
what is the function of rRNA?
combines with proteins to form ribosomes where protein synthesis takes place
49
what is the function of tRNA?
carries amino acids to be incorporated into the protein
50
what is the function of mRNA?
carries the genetic information for protein synthesis
51
what base is different in RNA compared to DNA?
contains U instead of T
52
what enzyme makes RNA?
RNA polymerases
53
how many types of RNA polymerase does a prokaryotic cell have?
one
54
how many types of RNA polymerase does a eukaryotic cell have?
three
55
what are the three types of RNA polymerase called in eukaryotic cells?
Pol I
Pol II
Pol III
56
what RNA polymerase synthesises all mRNA?
Pol II
57
what acts as an adapter between the nucleic acid code and the amino acid code?
tRNA
58
what does an anticodon consist of?
three tRNA nucleotides
59
what is attached to the 3' end of a tRNA anticodon?
a specific amino acid, depending on the anticodon sequence
60
what are the five steps of transcription?
```
RNA polymerase binding
DNA chain separation
transcription initiation
elongation
termination
```
61
what is required for RNA polymerase binding?
transcription factors
62
what are initiation sites for transcription called on DNA?
promotors
63
what happens during transcription initiation of RNA?
selection of the first nucleotide of the growing RNA
64
what happens during elongation of RNA?
addition of further nucleotides to the RNA chain
65
what happens during termination of RNA?
release of the finished RNA
66
where does transcription start?
initiation nucleotide + 1
67
where is the TATA box found?
around 25 nucleotides before the transcriptional start (-25)
68
what is TBP?
TATA box binding protein
69
what does TBP do?
recognises the TATA box
70
what is TBP part of?
TFIID
71
what is TFIID?
a general transcription factor required for all Pol II transcribed genes
72
what direction is the RNA chain synthesised in?
5' to 3' direction
73
what does a newly synthesised RNA make when finished?
a stem loop structure followed by a stretch of U's
74
what happens when finished RNA is cleaved off of the DNA template?
RNA is released
| polymerase dissociates
75
what is a coding section of a gene called?
an exon
76
what is a non coding section of a gene called?
an intron
77
what needs to be removed before mRNA is translated into a protein and what is this process called?
introns by splicing
78
what are steroid receptors?
a family of transcription factors that are a subset of a family of nuclear hormone receptors
79
where are steroid receptors found and what state are they in?
the cell cytoplasm where they are inactive
80
what happens when a steroid binds to a steroid receptor?
the steroid moves to the nucleus and binds to DNA at a steroid response element (SRE)
81
what is an SRE?
steroid response elements
82
what happens to tRNA in translation?
the anticodons on tRNA molecules form base pairs with codons on mRNA
83
how many nucleotides are found in codons and anticodons?
three
84
how many amino acids are there?
20
85
what does each possible codon code for?
one amino acid or a stop
86
how many possible reading frames are there for translation of each RNA molecules?
three, depending on where translation starts
87
what is the function of an aminoacyl-tRNA synthetase?
bind amino acids specifically to their corresponding tRNA molecule
88
what is an If?
initiation factor
89
what provides energy for initiation?
hydrolysis of GTP
90
what initiates RNA translation?
a small ribosomal subunit binds to the 5' end of the mRNA and moves until it finds the start codon
91
what is the start codon?
AUG
92
what amino acid does the start codon code for?
methionine
93
what is the tRNA sequence complementary to the start codon?
UAC
94
where is the initiator tRNA located at the end of initiation?
the P site
95
what brings the second aminoacyl-tRNA into a ribosome during translation?
Ef-1a, an elongation factor
96
what site does the second amino-acyl tRNA enter during translation?
the A site
97
what is EFBy?
a second elongation factor in translation
98
what is the function of EFBy?
regenerates Ef-1a to bring the next aminoacyl-tRNA for translation
99
what moves the ribosome along by one triplet during translation?
elongation factor EF-2
100
when does termination of translation occur?
when the A site of the ribosome encounters a stop codon
101
what are the three stop codons?
UAA
UAG
UGA
102
what binds to stop codons and what does this cause?
```
release factor (RF)
causes GTP hydrolysis
```
103
how many rRNA molecules does a ribosome contain?
four
104
what are the three tRNA binding sites in a ribosome?
```
E = exit
P = peptidyl
A = aminoacyl
```
105
what are the two types of ribosomes?
free and bound
106
where is a free ribosome found?
in the cytosol
107
where is a bound ribosome found?
on the rough endoplasmic reticulum
108
what is a point mutation?
a change in a single base in DNA
109
what does a missense mutation cause?
a change of the amino acid sequence
110
what can a missense mutation change?
protein function
111
what is an example of a disease caused by a missense mutation?
sickle cell anaemia causing akterer haemoglobin
112
what is a silent mutation?
a mutation causes by degeneracy of the egentic code that has no effect on amino acid sequence
113
what are the two types of frameshift mutation?
addition or deletion of a base
114
what effect does a frameshift mutation have?
changes the reading frame of translation into a protein
115
name four types of chromosomal mutation
deletions
duplications
inversions
translocations
