DNA and genes Flashcards
(160 cards)
1
Q
3 components of a nucleotide
A
- phosphate
- sugar
- nitrogenous base
2
Q
2 types of base
A
- pyramidine
- purine
3
Q
purine bases
A
A G
4
Q
pyramidine bases
A
C, T, U
5
Q
how many double bonds between G and C
A
3
6
Q
how many double bonds between A and T
A
2
7
Q
Protein in chromatin which compacts DNA
A
Histone
8
Q
components of the histone core
A
2 x H2a
2x H2b
2 x H3
2 x H4
9
Q
Name of top arm of chromatid
A
p
10
Q
name of bottom arm of chromatid
A
q
11
Q
in which phase of the cell cycle does DNA replication occur?
A
S phase
12
Q
DNA replication - which enzyme breaks H bonds between bases
A
DNA helicase
13
Q
DNA replication - where do proteins bind to stop the strands from joining back up?
A
replication fork
14
Q
In the leading strand which direction does DNA replication occur?
A
5’ to 3’
15
Q
DNA replication - what binds to the 3’ parent strand?
A
RNA primer
16
Q
what produces the RNA primer?
A
DNA primase
17
Q
DNA replication - which enzyme attaches to the RNA primer to add base pairs on the leading strand?
A
DNA polymerase alpha
18
Q
DNA replication - What degrades RNA primer ?
A
RNAse H
19
Q
DNA replication - which enzyme joins the strands together at the end?
A
DNA ligase
20
Q
what is epigenetics?
A
heritable changes which are expressed - but not caused by a change in the DNA sequence
21
Q
2 applications of DNA replication
A
1) PCR
2) Sanger method
22
Q
Which RNA polymerase produces rRNA?
A
RNA P 1
23
Q
what does RNA P 2 form?
A
mRNA
24
Q
what does RNA 3 form?
A
tRNA + small ribosome RNA molecules
25
3 stages where gene expression is regulated?
1. transcription
2. splicing
3. translation
26
Transcription - what binds with promoters in DNA
RNA polymerase
27
Transcription - which enzyme breaks H bonds between strands?
RNA polymerase
28
Transcription - what RNA is formed?
mRNA
29
how does mRNA leave the nucleus?
nuclear pores
30
what 2 things occur during mRNA processing?
1) capped 5'
| 2) cleaved 3'
31
what occurs during capping?
- P
| + methylated guanine molecule
32
what occurs during cleaving?
+ 200 nucleotide tail via poly-A-polymerase
33
which 2 things attach to the intron during splicing?
splicesosome + SnRNPs
34
how do transcription factors affect gene expression?
increase it
35
where do transcription factors bind to on the gene?
promoter region
36
2 mechanisms of transcriptional control
1) switching on a gene
| 2) switching off a gene
37
2 ways genes can be switched off
1) repressor binds next to transcription activator
| 2) repressor binds in the transcription activators place - inhibition
38
in which organ is the WTP transcription factor present?
Kidney
39
which gene does the WTP join to?
EGR-1 gene
40
effect of WTP and EGR-1 joining?
switches of EGR-1 expression
41
when WTP is mutated what can it cause and why?
kidney tumours - due to uncontrolled EGR-1 expression
42
what are the stop codons?
AGA, UAA, UAG
43
what is the start codon?
AUG - met
44
how is translation controlled?
mRNA degradation
45
how are isoforms formed?
alternative gene splicing
46
what proteins do tertiary structures form? (2)
1. fibrous
| 2. globular
47
what are proproteins?
proteins which are inactive until activated by post-translational modifications (PTM)
48
example of proprotein activation
insulin
49
what enzyme removes signal recognition peptide?
signal peptidase
50
SCALP
```
s - addition of small groups
c - proteolytic cleavage
a - AA change chemical structure
l - addition of long groups
p - proline isomerisation
```
51
in proteolytic cleavage, at which bond is it cleaved?
peptide
52
where can the proteolytic cleavage occur?
N - terminus or internally
53
what is proline isomerisation?
Cis and trans transformation of proline
54
where is phosphate donated from in phosphorylation?
ATP
55
what enzyme adds phosphates?
protein kinase
56
what enzyme removes phosphate?
protein phosphotase
57
when is phosphorylatation used? - biological process
- activating pyruvate
- EGF
- CDKs
58
what enzyme adds acetyl groups?
protein acetyltransferase
59
what enzyme removes acetyl groups?
protein deACetylase
60
when is acetylation used?
- histones
| - gene transcription
61
where is methyl groups taken from?
s-adenosyl-methionine
62
which enzyme adds methyl groups?
methyltransferase
63
which enzyme removes methyl groups?
protein demethylase
64
2 processes of addition of large functional groups
1) glycosylation
| 2) mono-poly ubiquitination
65
what is added to a protein to create a glycoprotein?
sugar - poly/monosaccaride
66
what protein is added in ubiquitination?
ubiquitin
67
what amino acid of the ubiquitin is added to the lysine of a protein?
Glycine
68
if one ubiquitin protein is added, what occurs?
change in protein structure
69
if many ubiquitin proteins are added, what occurs?
protein degradation
70
what does the E1 ubiquitin enzyme do?
allows joining of ubiquitin and substrate
71
which enzyme catalyses the functioning of ubiquitin?
E2 - conjugating enzyme
72
which enzyme is involved in deubiquitination of proteins?
proteosome
73
2 uses of polyubiquitinisation
1. removal/degradtion of faulty proteins
| 2. controls protein lifespan
74
what is lipidation?
adding lipids or fatty acids
75
why are lipids added to proteins?
to make them soluble to pass through the plasma membrane
76
4 diseases caused by errors in gene expression
1. cystic fibrosis
2. spinal muscular atropy
3. duchene muscular dystrophy
4. pulmonary arterial hypertension
77
mutated gene in cystic fibrosis?
CFTR
78
mutated gene in spinal muscular atrophy?
SMN1
79
mutated gene in duchene muscular dystrophy
DMD
80
mutated gene in pulmonary arterial hypertension?
BMPR2
81
what can be caused if there is over-expression of transcription factors?
cancer
82
what is haplionsuffiency?
when 1 copy of the gene is not sufficient for protection
83
disease caused by mRNA processing error?
Cystic fibrosis
84
in what specific process does cystic fibrosis gene arror occur?
alternative splicing
85
which exon is skipped in the CFTR gene to cause CF?
7
86
2 techniques to detect DNA, RNA and proteins
1) gel electrophoresis
| 2) western/southern blot
87
what is DNA polymorphism?
DNA variation
88
5 ways mutations arise:
1. strand breakage
2. base loss
3. base change
4. DNA cross-linking
5. DNA replication error
89
which bond is broken in base loss?
glycosidic bond
90
in base changes, what is C changed to?
U
91
which agents cause DNA cross-linking?
- UV light
| - Anti-cancer agents
92
3 types of mutation;
1. point
2. indel
3. chromosomal
93
which type of mutation affects a couple of nucleotides
indel mutation
94
3 types of chromosomal mutations
1. polyploidy
2. aneuploidy
3. chromosome rearrangements
95
which chromosomal mutation involves a few chromosomes
polyploidy
96
what is aneuploidy chromosomal mutations?
abnormal number of extra/missing chromosomes
97
difference between missense and nonsense mutations
```
missense = results in loss/gain of function
nonsense = results in non-functional protein
```
98
what type of codon arises in nonsense mutations
STOP
99
which point mutation results in pulmonary hypertension?
missense - loss of funtion
100
which point mutation results in achondrioplasia?
missense - gain of function
101
what disease is caused by a non-sense mutation?
Duchene muscular dystrophy
102
what is used to identify mutations?
electropherogram
103
what is a simple tandon repeat?
same part of a sequence repeated many times
104
example of simple tandon repeat disease
Huntingtons
105
in what gene are the repeats in huntingtons disease?
IT15 gene
106
what is a transposon?
a sequence of DNA which can move around the gene
107
transposon which copies and pastes
retroposon
108
What does a DNA transposon do?
cut and paste DNA sequences
109
example of Alu repeats
Cholesterol (LDL)
110
what is a selective pressure?
diseases which have a protective effect
111
which disorder protects against sickle cell anaemia?
Malaria
112
what is the open reading frame?
region between start and stop codon
113
2 types of protein secretion
1) constitutive (non-regulatory)
| 2) regulated
114
what is translocation?
movement of protein to the site of action
115
what are the 2 translocation pathways?
1) direct
| 2) secretory
116
what is the direct translocation pathways?
cytosol, mitochondria, nucleus, perioxsomes
117
where does post translational modifications occur?
Golgi
118
where do the vesciles travel to after the golgi?
Cytoplasm
119
what type of gland is the pancreas?
both endocrine and exocrine
120
what group of cells make up the endocrine pancreas?
islets of langerhans
121
3 cells of islets of langerhans
alpha beta gamma
122
what cells make up the exocrine pancreas?
secretory acini
123
what 2 enzymes are released by the acini cells
- chymotrysinogen
| - trypsinogen
124
what is a zymogen?
inactive substance which is coverted to an enzyme by another enzyme
125
which organ conducts protein synthesis?
Ribsomes on rough ER
126
how do secretory proteins enter the ER lumen to segregate from the cytosolic proteins?
via signal recognition proteins (SRPs)
127
how are proteins processed?
glycosylation
128
when are proteins exocytosed?
when ligands bind to the cell membrane
129
2 causes of disease:
1) genetics
| 2) environment
130
what is multifactorial inheritance?
phenotype determined by multiple genes at multiple loci
131
which has a higher penetrance, monogenic or polygenic diseases?
monogenic
132
which disease type can have gene predisposition and environmental contribution?
polygenic
133
what does it mean if a disease is fully penetrant?
other genes or the environment doesnt affect it
134
In the threshhold model, the frequency of distribution is being measured between who?
relatives vs the general population
135
what are epistatic alleles?
only have an effect if in conjuction with another mutation
136
what disease is strongly influenced by genes?
autism
137
what does SNP stand for?
single nucleotide polymorphism
138
what is a SNP?
point mutation occuring in the same place (gene) in another chromosome
139
chromosomal deletion syndrome?q
DiGeorge syndrome
140
what are autosomal diseases?
not affecting sex chromosomes
141
term that describes, 'different mutations in the same gene cause different diseases'
genetic heterogenecity
142
what is prophylaxis?
treatment given to prevent disease
143
another word for pharmacogenomics?
precision medicine
144
what is pharmacogenomics
correlating gene expression from SNPs with a drugs efficacy/toxicity
145
advantages of precision medicine
- max efficacy
| - minimal ADR
146
what does the process of pharmacogenomics measure?
polymorphisms in cytochrome P450
147
what is a genome
someones complete set of data
148
what is a nonsynomous mutation
a mutation that results in change in protein structure
149
what is gene therapy
replacing bad genes with good genes
150
2 types of gene therapy
1. germline
| 2. somatic
151
which gene therapy only affects the individual?
somatic
152
definition of transgene delivery
genetic material which has been transferred naturally or by genetic engineering techniques from one organism to another
153
what does en vivo mean
outside of the bodyq
154
which type of gene therapy involves a delivery vehicle?
en vivo
155
what is the adenovirus?
common cold
156
what is the herpesvirus?
cold sore
157
what is the retrovirus?
HIV
158
which virus carries the DNA in the virion?
Herpesvirus
159
what virus carries RNA + Reverse transcriptase?
Retrovirus
160
which is the only virus to use its own transcription mechanism?
Retrovirus
