Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology > Control of gene expression > Flashcards

Control of gene expression Flashcards

(61 cards)

Start Studying
1
Q

gene mutation

A

the alteration of a bas in the sequence of bases for one gene

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

when are gene mutations likely to occur

A

during DNA replication during interphase of the cell cycle

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

mutagenic agents

A

factors which increase the frequency of gene mutationsradiation like UV light/x-rays/gamma rayshigh energy particles like alpha/beta particlescarcinogens like tar in tobacco smoke/mustard gas/peroxides

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

what impact do gene mutations have

A

they alter the gene
resulting in a different amino acid sequence in the encoded polypeptide
when protein is modified to its tertiary structure, it will form hydrogen ad ionic bonds in different places and fold differently
this results in a different 3D shape and therefore can impact protein function

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

types of gene mutation

A

additiondeletion substitution inversionduplication translocation

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

addition mutation

A

an extra base is added
all subsequent codons are altered - frame shift

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

deletion mutation

A

one base is deleted from the sequence
causes frameshift to the left

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

substitution

A

base is changed for a different base
no. bases remains the same so no frameshift
since genetic code is degenerate, it may still code for the same amino acid and have no impact

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

inversion mutation

A

a series of bases detach and rejoin but inverted
this results in different amino acids being coded for but no frameshift

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

duplication

A

one base is duplicated
causes frameshift

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

translocation

A

section of bases on one chromosome detaches and attaches to a different chromosome
has significant impacts on gene expression and the resulting phenotype

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

how does cancer arise

A

mutations in genes that regulate mitosis
can lead to rapid uncontrolled division of cells and the creation of a tumour

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

benign tumour

A

can grow to be large but at a slow rate
non-cancerous as they produce adhesive molecules which stick tumour cells together and to a particular tissue
often surrounded by a capsule and have clean borders
can be removed by surgery and have low chance of recurrence
impact is localised and often not life-threatening

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

malignant tumour

A

grow large rapidly
cell nucleus becomes large and cells can become unspecialised
don’t produce adhesive molecules so can metastasise
tumour is not encapsulated and can grow projections into surrounding tissues and develop its own blood supply
it can be life threatening and removal often also includes another treatment like radiotherapy or chemotherapy
recurrence is more likely

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

what causes the development of a tumour

A

gene mutation in tumour suppressor gene and/or oncogene
abnormal methylation of TSG or OG
increased oestrogen concentrations

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

oncogenes

A

mutated version of protons-oncogene which creates a protein that stimulates the initiation of DNA replication and mitotic cell division
oncogene mutations can result in this process being permanently activated

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

tumour suppressor genes

A

produce proteins to slow down cell division and cause cell death if DNA copying errors are detected
if a mutation results in the tumour suppressor gene not producing the proteins to carry out this function, cell division continues and mutated cells are not identified and destroyed
BRCA1 and BRCA2 are two known mutated tumour suppressor genes that are linked to breast cancer

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

methylation of tumour suppressor genes to cause cancer

A

hypermethylation - increased no. methyl groups added resulting in the gene being inactivated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

methylation of protons-oncogenes leading to cancer

A

hypomethylation - reduces no. methyl groups attached, gene becomes permanently activated

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

how does increased oestrogen concentration lead to cancer

A

fat cells in breast tissues can produce oestrogen
oestrogen can activate a gene by binding to a gene that initiates transcription - if this is a porto-oncogene then this gene is permanently turned on and activates rapid uncontrolled cell division
tumours in breast tissue can lead to even more oestrogen production which increases the size of the tumour

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

stem cells

A

undifferentiated cells that continually divide (self renew) and become specialised

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

totipotent

A

stem cells that can divide to produce any body cell
occur for a limited time in early mammalian embryos

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

pluripotent

A

can become almost any type of cell
found in embryos
used to treat disorders like replace burnt skin cells or beta cells for type 1 diabetics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

multipotent

A

can divide to form a limited number of different cell types
found in mature mammals
e.g. bone marrow cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
unipotent
can only differentiate into one type of cell found in mature mammals
26
sources of stem cells
embryos up to 16 days after fertilisation have pluripotent umbilical cord blood and placenta have multipotent bone marrow has adult stem cells
27
induced pluripotent stem cells
produced form adults somatic cells genes that were switched off to make the cell specialised are switched back on using transcriptional factors
28
how is transcription initiated
transcription factor enters the nucleus from the cytoplasm and binds to the DNA each TF can bind to different base sequences on DNA and initiate transcription of that gene
29
how does oestrogen aid transcription
it is a steroid hormone it binds to a receptor site on the TF this causes it to change shape and make it complementary and able to bind to the DNA to initiate transcription
30
epigenetics
heritable change in gene function without changing the DNA base sequence changes are caused by changes in the environment and can inhibit transcription
31
what can add epigenetic chemical tags to DNA
diet, stress, toxins
32
epigenome
a single layer of chemical tags on the DNA
33
increased methylation
more methyl groups are added to DNA by attaching to cytosine this prevents TF from binding and attracts proteins that condense the DNA-histone complex reduces transcription
34
decreased methylation
less methyl groups so more TF can bind and DNA-histone complex unwinds increased transcription
35
decreased acetylation
acetyl groups are removed from DNA histones become more positive and are attracted to negative phosphate group on DNA makes DNA and histones more strongly associated harder for TF to bind inhibits transcription
36
increased acetylation
less attraction between DNA and histones easier for TF to bind increased transcription
37
RNA interference (RNAi)
translation of mRNA can be inhibited by RNAi the mRNA molecule is transcribed but destroyed before it is translated this is done by siRNA
38
how does siRNA carry out RNAi
an enzyme cuts mRNA into siRNA one strand of the siRNA combines with another enzyme this siRNA-enzyme complex binds via complementary base pairing to another mRNA molecule once bound, the enzyme will cut up mRNA so it cannot be translated
39
proteome
all the proteins a cel can produce
40
recombinant DNA technology
combining of different organisms' DNA to enable scientists to manipulate and alter genes to improve industrial processes and medical treatment
41
why is transferring DNA fragments between species possible
the genetic code is universal transcription and translation methods are the same in all organisms
42
methods of creating DNA fragments
conversion of mRNA to complementary DNA using reverse transcriptase using restriction enzymes to cut a fragment from DNA creating the gene in a 'gene machine'
43
conversion of mRNA to cDNA using reverse transcriptase
enzyme naturally occurs in viruses and it makes DNA copies from mRNA a cell that naturally produces the protein of interest is selected these cells should have large amounts of mRNA for the proteinreverse transcriptase joins DNA nucleotides with complementary bases to the mRNA sequencecDNA (single stranded) is madeto make this double stranded, DNA polymerase is usedthe cDNA is intron free as it is based on the mRNA template
44
why can a DNA fragment produced using reverse transcriptase be inserted into a prokaryotic cell
it doesn't have introns as it is based on the spliced mRNA template
45
use of restriction enzymes to cut a fragment containing the desired gene from DNA
restriction endonucleases are enzymes that cut up DNA - they naturally occur in bacteria as a defence mechanism there are many restriction endonucleases that have an active site complementary to a range of DNA base sequences - recognition sequences each enzyme cuts the DNA at a specific locationsome enzymes cut at the same location in the double strand to create a blunt end, whereas others cut to create staggered ends with exposed DNA bases - sticky endsstaggered ends are often palindromic and have the ability to hound DNA with complementary base pairs
46
creation of a gene in a gene machine
DNA fragments created in a lab using a computerised machinescientists first examine the protein of interest to identify the amino acid sequence, and then from that work out what the mRNA and DNA sequence would be the DNA sequence is entered into the computer which checks for biosafety and biosecurity to ensure the DNA being created is safe and ethical to produceshort fragments are synthesised and joined together to create longer sequences
47
process of in vivo cloning
isolation of fragmentrestriction endonucleases used to cut out the gene at recognition sites, leaving sticky endspreparation of fragmentpromoter region added to the start of the DNA fragmentterminator region added to the end of the fragment so only one gene at a time is copied into mRNA insertion into vectorisolated DNA is joined to a vector to transport it to a host cell - plasmids are commonly usedthe same restriction endonucleases are used to cut open the plasmid - this ensures they have complementary sticky endsDNA ligase is used to stick the DNA fragment in - recombinant DNA is createdtransformation of host cellplasmids and bacterial cells are mixed in a solution of calcium ions sudden changes in the temperature of the solution make the bacterial membrane more permeable and the plasmid enters
48
promoter region
sequence of DNA that is the binding site for RNA polymerase to enable transcription
49
terminator region
causes RNA polymerase to detach and stop transcription
50
how do you identify which host cells contain the gene of interest
marker genes on the plasmid can be used to identify which bacteria successfully took up the recombinant plasmid e.g. antibiotic resistant genes or genes coding for fluorescent proteins or for enzymes once these host cells are identified, the bacteria are grown and the DNA fragment is amplified
51
what does PCR stand for
polymerase chain reaction
52
process of in vitro cloning - PCR
temperature is increased to 95oC to break the hydrogen bonds and separate the DNA into single strands (denaturing)temperature decreased to 55oC so primers can attach (annealing)temperature increased to 72oC and free nucleotides associate with their complementary base pairs enzyme taq DNA polymerase forms phosphodiester bonds between adjacent nucleotides, synthesising a new strand of DNA
53
what are primers
short sequences of DNA that have base sequences complementary to the 3' end of the DNA/RNA being copied
54
what is the advantage of PCR
it is automated and therefore efficient its is rapid, making 100 billion copies within hours it doesn't require living cells so is quicker and less complex
55
what are VNTRs
variable number tandem repeats non-coding DNA which makes up 95% of human DNA unlikely to have the same VNTRs as anyone else
56
genetic fingerprinting
analysis of VNTR DNA fragments that have been cloned by PCR is determines the genetic relationships and variability within a population
57
what can genetic fingerprinting be used for
forensic science - finding suspects from DNA at crime scenes medical diagnosis ensure animals/plants aren't closely related before being bred
58
process of gel electrophoresis
collection + extractionsmallest sample of DNA can be collected for genetic fingerprintingthe DNA is extracted by cell fractionation and ultracentrifugationif the sample is small, then PCR is used to amplify the amountdigestionrestriction endonucleases are added to cute DNA into smaller fragments - they are selected so they cut close to the target VNTRsseparation - gel electrophoresisDNA samples loaded into small wells in agar gelgel placed in a buffer liquid with an electrical voltage appliedthe DNA is negative charged so move through the gel towards the positive end gel creates resistance so smaller pieces of DNA move faster and further along the gel - different VNTRs are separatedheat/alkali is applied to separate the double stranded DNA so a probe can bind hybridisationDNA probes are radioactively/fluorescently labelled and mixed with the VNTRs to allow them to bind development VNTRs and props are transferred to a nylon sheet which can be exposed to x-rays/UV light to visualise the position of radioactive gene probesanalysisposition of DNA bands compared to identify genetic relationships/presence of disease-causing gene/match samples from a crime scene
59
what are DNA probes
short, single stranded pieces of DNA which have complementary base sequences to the VNTRs
60
how can DNA probes be used to identify alleles
they are complementary to sequences of DNA that are known to cause heritable conditions, drug responses, or health risks they are radioactively/fluorescently labelled sample of patient DNA is removed and heated to make it single stranded it is mixed with the DNA probes if the patient has the allele of interest their DNA will bind to the prob which can then be identified using UV/x-rays
61
how can medicine be personalised by screening for the presence of certain alleles
doctors can select medicines and personalise health advice based on your genotype some drugs are more/less effective depending on your allele - more effective and cost-effective treatment genetic counselling can give people advice based on screening of disease

Biology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions