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bio component 2 > applications of reproduction and genetics > Flashcards

applications of reproduction and genetics Flashcards

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1
Q

what is genomics?

A

study of structure, function, evolution and mapping genomes

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2
Q

what are the aims of the human genome project?

A

determine order of bases in human genome
identification of all genes
sequencing genes and mapping position one each chromosome
store information on data base
consider ethical, social and legal issues

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3
Q

what are the applications of the human genome project?

A

scan patients DNA sample for mutations
carrier screening
pre-natal testing
PGD
new born baby screening
screening for adult onset disorders
forensic/identity testing

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4
Q

what are the ethical concerns of the human genome project?

A

risk of discrimination
lab errors
anxiety
who should have access to the information
who owns the information
human cloning

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5
Q

what is genetic counseling?

A

individuals allowed to carefully think through consequences of finding out results

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6
Q

what are the sanger sequencing steps?

A

denature dsDNA using heat
make multiple copies of segment
attach a primer
add to 4 polymerase solutions
grow complementary chains until termination dye
denature grown chains
electrophorese the four solutions

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7
Q

what is NGS?

A

can sequence entire genome in a few hours
enables us to study variation within human genome amongst 100,000 in the uk

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8
Q

what is tissue engineering?

A

cells are induced to grow a framework of synthetic material to produce a tissue

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9
Q

what are the advantages of using stem cells?

A

speed of production
large scale production
production of genetically identical cells

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10
Q

what are the disadvantages of using stem cells?

A

expensive and unreliable
inadvertent selection of disadvantageous alleles
long term/unforeseen effect
ethical concerns

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11
Q

what are the benefits of genetically modified plants?

A

higher yield
superior keeping qualities and flavour
reduction of pesticide use
reduces use of fertiliser

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12
Q

what are the concerns of genetically modified plants?

A

dispersal of pollen from herbicide resistant to wild species
unknown effects of eating new proteins produced by crop
antibiotic resistant genes transferred to bacteria in intestine of consumer
reduction in biodiversity
organic farm produce may be compromised

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13
Q

what is genetically modified soya?

A

transgenic GM soya is made by addition of gene into soybean that allows bean plant resistance to cytotoxic effects of roundup
allows farmers to spray fields and only kill weeds

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14
Q

what are the problems of genetically modified soya?

A

land used to plant soya so have to import basic foods
abnormalities appearing in new borns
severe reduction in fertility
gylphosate (in roundup) found to be carcinogenic
deforestation and reduction in biodiversity

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15
Q

what are genetically modified tomatoes?

A

gene introduced into tomato plant that has base sequence complementary to gene that produces enzyme that break down pectin in their cell wall
two mRNA combine and prevents translation of original mRNA so prevents production of enzyme
tomatoes have longer shell life and better taste

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16
Q

what are the applications of genetic engineering?

A

transfer of genes into bacteria to make useful proteins
genes into plants and animals so they can acquire new characteristics
genes into humans so they can no longer suffer from genetic diseases

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17
Q

what is recombinant DNA?

A

when DNA of an organism is formed from combining DNA from 2 different species

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18
Q

what is a transgenic organism?

A

organism that has been genetically modified by the addition of a gene or gene from another species

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19
Q

what is a transformed organism?

A

a cell has incorporated a plasmid containing a foreign gene

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20
Q

what are the steps of genetic engineering?

A

isolation of required gene in DNA fragment
insertion of DNA fragment into vector
transfer - the vector carries the gene into suitable host cell (bacteria)
recipient expresses gene through protein synthesis
identification of host cells that have taken up gene by use of gene markers
cloning of transformed host cells

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21
Q

what are restriction endonucleases?

A

bacterial enzyme that cut the sugar-phosphate backbone of DNA at short, specific palindromic sequences

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22
Q

what are restriction enzymes?

A

cut DNA at specific base sequences
hydrolyses sugar phosphate backbone of DNA
gives a staggered cut
leaves some bases exposed

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23
Q

what are sticky ends?

A

short sequence of unpaired DNA bases on a double stranded DNA molecule that readily base pairs wit complementary sequences

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24
Q

what does DNA ligase do?

A

joins sugar-phosphate backbone of DNA sections together in a condensation reaction

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25
what does reverse transcriptase do?
used to catalyse synthesis of single stranded DNA
26
what is the first way to obtain a required gene choice for genetic engineering?
gene can be synthesised by an automated polynucleotide sequencer use a DNA probe to identify gene on DNA fragment use restriction enzymes to cut gene out
27
what is a DNA probe?
single stranded piece of DNA complementary to part of the desired gene
28
what are the problems with cutting gene from DNA?
difficult to locate required gene recognition sequence for restriction enzyme could be within the gene so would cut gene in half recognition sequence is too far from start of gene
29
what is the second way to obtain a required gene choice for genetic engineering?
obtain mRNA copies of gene from cells convert to single stranded copy of DNA using reverse transcriptase DNA polymerase then converts into double stranded DNA called copy DNA (cDNA) for putting into plasmid
30
what does the plasmid method of obtaining a require gene allow for?
location of gene introns being present no post-transcriptional processing needed stops restriction enzyme from cutting gene into non-functional fragments
31
how do you insert a gene into a vector plasmid?
treat cells containing plasmids with chemicals to dissolve cell walls use ultracentrifugation to separate plasmids from cell debris produce recombinant DNA
32
how do you produce recombinant DNA?
use restriction endonucleases to cut required gene and cut plasmid DNA staggered cuts and sticky ends that are complementary use DNA ligase to join donor DNA and vector DNA together
33
how do bacteria take up plasmids (in host cell)?
mix plasmids with bacterial cells (only 1% take up plasmids) induced by heat shocking (4 degrees to 42 degrees and calcium salts) bacteria are transformed
34
what are the problems with bacteria taking up plasmids?
can now potentially have 3 types of bacteria: bacteria with no plasmids bacteria with plasmids without donor DNA bacteria with plasmids that have recombinant DNA
35
what are the problems with inserting genes into vector plasmids?
can seal plasmids that have been cut up without the insertion of isolated gene
36
how do you identify which bacteria have taken up recombinant plasmid?
genetic markers were used plasmids have 2 genes - resistance to ampicillin, resistance to tetracycline when plasmids cut, enzyme used that cuts plasmid in middle of gene for tetracycline resistance this causes tetracycline resistant gene to not work if a gene is inserted there
37
what happens on the replica plates?
ampicillin plate bacteria that did not take up any plasmids die tetracycline plate bacteria that took up plasmid with recombinant plasmids die
38
what happens once you have found the bacteria with the recombinant DNA?
scale up return to master plate and collect recombinant bacteria and multiply in small culture vessel inoculate in large fermenter
39
what are the advantages of recombinant DNA technology?
no limit to amount of protein that can be synthesised complicated structure of proteins cannot by synthesised unless by living cells no need to extra proteins from mammals (organs)
40
what are the disadvantages of recombinant DNA technology?
complicated (require experienced staff and equipment) expensive on industrial scale difficult to identify genes from entire human genome some proteins require more than one gene for synthesis
41
what are the potential hazards of recombinant DNA technology?
using antibiotic resistant genes to identify transformed cells could accidentally introduce genes from E.coli that liv in human gut into human pathogens
42
what is genetic screening used for?
confirm diagnosis indicate appropriate treatment allows families to avoid having children with disease identify people at high risk for condition that may be presentable carrier screening pre-natal diagnosis testing new born baby screening pre-symptomatic testing for predicting adult onset disorders forensic and identity testing pre-implantation genetic diagnosis of embryos generated from IVF
43
what are the concerns with genetic screening?
invasion of privacy defective allele identified in tests may increase number of abortions individuals with defects may be placed in high risk group for insurance who owns data potential discrimination misuse of data
44
what are the concerns of embryo screening?
possibility of choosing alleles to ensure specific characteristics
45
what is the aim of gene therapy?
to treat a genetic disorder by inserting functional DNA sequences into cells to counteract the effect of a defective gene new DNA sequence replaces faulty alleles new working gene will now be able to correctly code for the protein that had previously not been produced relieves symptoms associated with genetic disorder
46
what are the 2 methods of replacing defective genes?
somatic cell gene therapy germ-line gene therapy
47
what happens in somatic cell gene therapy?
replacing faulty genes with correct copies in affected tissues of the body these new genes cannot be inherited as only placed in somatic cells
48
what happens in germ-line gene therapy?
gene is inserted into an embryo or gamete all new cells formed contain new gene genetic correction is inherited
49
what are the advantages of somatic cell gene therapy?
relief of symptoms no need to take medication prevents development of cancer does not permanently change genome so any negative effects will not be inherited
50
what are the disadvantages of somatic cell gene therapy?
more than 1 treatment required difficult to get gene to integrate into chromosome and function correctly genetic disorder can still pass to offspring long term effects unknown immune response can be caused by viral methods
51
what are the advantages of germ-line gene therapy?
children could be born free of diseases
52
what are the disadvantages of germ-line gene therapy?
fear that gene therapy may be used to modify characteristics of a cild permanent modification raises difficult moral, ethical and social issues could create new disease
53
what are examples of genetic disorders?
Duchenne Muscular Dystrophy (DMD) Cystic Fibrosis (CF)
54
what is cystic fibrosis?
sufferers are homozygous for an autosomal recessive allele autosomal linkage
55
what is duchenne muscular dystrophy?
recessive sex-linked condition caused by 1 or more deletions which introduces a stop codon too soon so protein dystrophin is not produced causes progressive muscle weakness average life expectancy is 27 years
56
how does the DMD treatment work?
drug drisapersen works by 'exon skipping' aims to treat DMD by introducing 'molecular patch' using the drug patch over exon that contains mutation makes gene readable again shorter form of protein is produced but more functional than untreated version
57
what is the drug drisapersen?
50 nucleotide sequence that is complementary to mutated sequence in codon 51
58
what does the 'molecular patch' do?
complementary to and binds to mutated pre-mRNA splices out mutated codon restores reading frame and functional mRNA is formed
59
what is a genetic fingerprint?
a person's DNA profile only represents non-coding portions of DNA
60
what are introns?
usually 20-40 bases long short 3-5 nucleotide sequences repeat e.g. GATAGATAGATA in DNA = short tandem repeats (STRs) in mitochondrial DNA = hypervariable regions (HVRs) acquired from parental chromosomes but number of repeats is different in different individuals
61
what is the example of a short tandem repeat?
'D75280' on chromosome 7 'GATA' repeated 6-15 times
62
what is genetic fingerprinting?
number of times that lengths of non-coding DNA are repeated that is used in genetic fingerprinting to show difference between individuals
63
what are the 2 methods of genetic fingerprinting?
polymerase chain reaction (PCR) gel electrophoresis
64
what does polymerase chain reaction do (basic)?
makes large number of copies of DNA fragments
65
what are the beginning steps of polymerase chain reaction?
DNA sample is dissolved in buffer and mixed with taq polymerase, DNA nucleotides and short single-stranded pieces of DNA called primers that are complementary to the start of the DNA and bind to it
66
what is a primer?
strand of about 10 nucleotides long base pairs with the end of another long strand which makes a double-stranded section
67
what are the main steps of polymerase chain reaction?
denature DNA - at 95 degrees to separate 2 strands into 2 single strands anneal primers - cool to 55 degrees, triggers primers to anneal to complementary base sequences on each single strand of DNA extend DNA chain - heat to 72 degrees, taq polymerase catalyses synthesis of complementary stranded for each single strand of DNA for each initial fragment of double stranded DNA, 2 identical double strands are produced
68
how is PCR different from DNA replication?
only replicates short sequences of DNA requires addition of primers cycle of heating and cooling is used to separate and bind strands (not DNA helicase)
69
what are the uses of PCR?
classification or organisms mutation detection screening cancer research DNA fingerprinting genetic engineering pre-natal diagnosis genetic matching drug discovery
70
what are the limitations of PCR?
contamination error rate DNA fragment size sensitivity to inhibitors limits on amplifications
71
what does gel electrophoresis do (basic)?
separates DNA fragments based on size
72
what are the steps of gel elctrophoresis?
DNA extracted from sample and cut with restriction enzymes cut DNA at specific base sequences either side of STR (different lengths depending on length of STR) DNA fragments separated by electrophoresis on agarose gel in a well negatively charged DNA fragments migrate towards positive electrode smaller fragments move faster through gel
73
what do you do once DNA fragments have travelled through gel?
treat with NaOH to separate DNA strands gel covered with nylon membrane and fragments transferred to membrane radioactive DNA probes attach by base pairing to STRs placed under X-ray film probes expose film reveals pattern of light and dark bands which are unique to an individual
74
what are probes?
short piece of DNA that is labelled with fluorescent or radioactive marker used to detect presence of a specific base sequence
75
what are the uses of gel electrophoresis?
forensic use to identify and rule out suspects proof of siblings immigration, proof of relatedness twins paternity
76
what are the pros of DNA profiling?
non-invasive can be used on small DNA samples can be used to reverse wrongful convictions
77
what are the limitations of DNA profiling?
request for DNA samples could be violation of privacy storage of genetic information on computers can be hacked or misused access regulated carefully (insurance companies) may produce wrongful convictions discrimination for jobs

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