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A2 BIOLOGY > 4.5 Application of reproduction and genetics > Flashcards

4.5 Application of reproduction and genetics Flashcards

things to focus on: recombinant DNA, why different primers are used, enzymes used to add genes to plasmid, QER (103 cards)

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1
Q

what is a genome

A

reders to all the DNA, including its genes, in an organism

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2
Q

intended purpose of the human genome project and the 100k project

A

to improve knowledge and understanding of genetic disorders and improve their diagnosis and treatment

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3
Q

what process did the human genome project use

A

‘Sanger Sequencing’

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4
Q

what is ‘sanger sequencing’

A

which sequences relatively small sections of DNA at a time

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5
Q

problem with sanger sequencing

A

process takes a long time

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6
Q

Aims of the project

A

-determine the sequence of A,T,C and G in all human DNA
-identify all the genes formed by the bases
-find the locus of all genes on all 23 chromosomes
-stores this information on a database
-consider the ethical, social, legal issues which arise from obtaining and storing this information

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7
Q

what did the 100k genome project contain

A

-used next generation sequencers (NGS) : much faster
- study variation amongst 100,000 people in the UK
-used NHS patients with rare disorders

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8
Q

main aims of the 100k genome project

A

-study variation within the human genome
-create a new genomic medicine service of the NHS
-enable new medical research to study the potential of new research (more effective)
-kick-start a UK genomics industry
-concerns regarding the storage of genetic information and its missuse

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9
Q

what has happened in terms of DNA sequencing as technology has developed

A

DNA sequencing has become faster and cheaper
become more accessible

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10
Q

what is genetics

A

a study of the functions of single genes

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11
Q

what is genomics

A

can be defined as a study of the complete genetic material of an organism; their genome

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12
Q

ethical issues surrounding use of knowledge from genome projects

A

-ownership of genetic information, potential discrimination, social stigmatisation and misuse of the data
-compare a patient’s gene to a normal version of the gene
-screening embryo’s
-concerns regarding routine screening to diagnose Alzheimer’s disease and some cancers

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13
Q

what does the identification of allele sequences enable

A

scientists to scan a patients DNA sample for mutated sequences and also to compare the sequence of DNA bases in a patient’s gene to a normal version of the gene

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14
Q

how can you use the genome project to screen embryos

A

to detect the presence of disorders such as cystic fibrosis, huntington’s disease

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15
Q

what has screening of embryos led to

A

to concerns over choosing alleles to ensure specific characteristics

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16
Q

what does genome sequencing of other organisms allowed scientist to

A

-look at evolutionary relationships
-consider how to conserve species in the future

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17
Q

how can human genome sequencing allow us to look at evolutionary relationships

A

provides true phylogenetic classification and can be used to correct mistakes made using classification based on phenotypic characteristics

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18
Q

how can human genome sequencing allow us to look at how to conserve species in the future

A

by targeting which species need particular protection

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19
Q

example of sequencing the genome of other organisms

A

malaria

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20
Q

purpose of sequencing in non-human genomes

A

-to study evolutionary relationships
-to study disease transmitting and causing organisms e.g. malaria
-to conseves species in the future

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21
Q

what is malaria caused by

A

plasmodium

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22
Q

how is the plasmodium parasite mainly spread

A

by female mosquitos (Anopheles gambiae)

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23
Q

what is malaria caused by

A

plasmodium parasite (sp)

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24
Q

what is plasmodium parasite killed by

A

anti-malarial drugs

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25
problem with anti-malarial drugs
evolved to be resistant to the drugs
26
what does the resistance to anti malarial drugs lead to the genome being sequenced to
create effective drugs. restore susceptibility
27
what is malaria transmitted by
anupheles gambia mosquito (vector)
28
what is the vector
anupheles gamvia mosquito
29
what is the vector killed by
insecticdes
30
what does the vector rapidly evolving lead to
insector resistance
31
after the vector rapidly evolved, what does this lead to
insecticide resistance
32
what is the genome sequenced to (vector)
to restore insecticide susceptibility
33
explain what non-invasive screening can be used to do
to scan a patient's DNA for mutated sequences and compare the sequence to a normal version
34
why have embryos been screened
to detect the presence of: -cystic fibrosis -huntington's disease -thalassaemia
35
what's DNA probes
short sequences of DNA bases which are complementary to the mutated sequence
36
use of DNA probes
can be added to the patients blood, if the mutated sequence is present, the probe will bind to and label the mutation
37
what can genetic testing be used for
-carrier screening -pre-symptomatic testing for onset disorders e.g. Hungtintons -estimating the risk of developing onset concerns/illnesses (breast cancers,Alzheimers)
38
what's the role of the polymerase chain reaction
Amplify DNA (make lots of copies)
39
method of PCR step 1
1. double-stranded DNA sample, heat to 95oc (strands separated) by breaking the hydrogen bonds
40
method of PCR- what happens after DNA strands are separated by being heating step 2
cool to 50-60 to allow primers to anneal (stick/join)
41
what is a primer
single stranded DNA which is complementary to the start of the sequence
42
method of PCR step 3 what happens after primers anneal
heat to 70-77 (optimum temp) to allow DNA polymerase (Taq-Thermus aquaticus) to add complementary nucleotides by farming phosphodiester bonds (in the sugar phosphate backbone)
43
uses of PCR
-forensic investigations( (samples of DNA from crime scenes can be amplified to generate enough material for genetic profiling) -rare genetic disorder (don't want to keep asking for more DNA from people) -DNA found in archaeological structures (might not have a lot of the DNA)
44
limitations of PCR
-PCR is not identical to natural DNA replication (not 1) - if it gets contaminated, if not using aseptic techniques might amplify something else -certain chemicals may break down DNA so won't be able to amplify DNA (denim, humic acid) -error rate (1 in 9000 nucleotides) cannot amplify DNA idefinitely
45
what is the role of electrophoresis
separates DNA by size
46
how does electropheresis work
DNA has a negative charge so it moves towards the positive electrode when electricity is passed through the buffer solution. small DNA fragments travel further
47
what are exons
code for proteins (can see mutation)
48
what are introns
non-coding DNA blocks of repeated nucleotides called short tandem repeats (STR) can also be called variable number tandem repeats (VNTR) used to check for relatedness
49
method of electropheresis step 1
1. the DNA is extracted from the sample and cut into small fragments using restriction endonucleases
50
method of electropheresis step 2 after DNA cut into small fragments
2. fragments of DNA are loaded into wells at one end of a trough containing gel
51
method of electropheresis step 3 after fragments of DNA loaded into a trough
3. gel is exposed to an electric current
52
method of electropheresis step 4 after gel is exposed to an electric current
4. since the fragments are negatively charged they move towards the positive terminal
53
method of electropheresis step 5 after the negative fragments move towards positive terminal
smaller fragments find it easier to migrate through the pore in the gel and so travel further than large fragments in the same time
54
method of electropheresis step 6 after fragments migrate
the DNA becomes separated into bands according to the size of the fragments
55
what is a restriction endonuclease
a bacterial enzyme that cuts DNA at specific nucleotide sequence
56
method of electropheresis step 7 after DNA separate according to size
fragment size can be estimated by running a DNA ladder (which contains fragments of known size) alongside
57
uses of electropheresis
-used for genetic profiling (genetic fingerprinting) -if you wanted to check whether someone had a mutated gene (you would separate fragments of DNA) e.g. used to check a deletion mutation -used to see how related people are (paternity test) look at the introns -forensic studies -phylogenetic studies-in classification of organisms -doesn't involve an invasive procedure (swabs,urine, hair)
58
limitations of electropheresis
-only separates DNA by size (probability, not absolute) -results offer probabilities not absolutes, doesn't sequence the DNA (only size) -ethical issues with accessing the information (it is held on a data base) who can access it?
59
what is genetic engineering/recombinant DNA
is a technique used to extract and transfer genes from one organism (donor) to another organism (recipient) to produce a genetically modified organism (GMO) with a new genotype
60
example of recombinant DNA
insulin production using bacteria
61
what are the steps of recombinant DNA
1-identifying the gene 2-isolating the gene 3-inserting the gene into a vector 4- insert the vector into the host 5-identifying the host
62
explain step 1 of recombinant DNA
-identifying the gene use a gene probe. it is labelled with either -a radioactive marker which is identified using photographic film -fluorescent marker which is identified when it emits colour under UV light
63
explain step 2 of recombinant DNA method 1
(making DNA for mRNA) mRNA is isolated, using the enzyme reverse transcriptase, single stranded copies of DNA are made, they are called cDNA this is made double stranded using the enzyme DNA polymerase
64
explain step 2 of recombinant DNA method 2
(isolating the gene) -this is done by using restriction endonucleases (Restriction enzymes) to cut the DNA at a specific sequence
65
what are restriction endonuclease
enzymes used to cut fragments of DNA. a group of enzymes found in bacterial cells, they are used to target viruses (phages) that attack bacteria
66
where can you find restriction endonucleases
can be obtained from bacteria or made in a lab
67
what do restriction endonucleases have
a specific target site of 4-6 bases long. (this is where DNA is always cut)
68
2 ways restriction endonucleases are cut
-sticky ends (better, more S.A) - blunt ends
69
what is the beneficial method of cutting restriction endonuclease (all step 2 of recombinant DNA)
sticky ends are preferable, if the cut gives blunt ends, sticky ends are added by mixing with free nucleotides (e.g. C-C-C-C) and the enzyme terminal transferase
70
what is the role of the vector
used to carry the gene into the cell
71
what is the most commonly used vector (recombinant DNA)
plasmid (circular DNA found in bacteria)
72
explain step 3 of recombinant DNA
inserting the gene into a vector 1-plasmid is removed from the bacteria 2- the plasmid is cut open using the same restriction endonucleases 3-the open plasmids are mixed with the wanted gene 4- DNA ligase anneals (joins) the 2 pieces of DNA together by forming phosphodiester bonds between the sugar phosphate backbone
73
why is it important that the same restriction endonucleases are used
so the ends are complementary
74
explain step 4 of recombinant DNA insert the vector into the host
plasmids are mixed with bacterial cells and calcium chloride, (this is positively charged so it attracts the DNA into the cell the cells are heat shocked (4-42) to make the membrane porous so that the plasmid can enter
75
why must the membrane be porous
so the plasmid can enter
76
explain step 5 of recombinant DNA how do you go about identifying the host
-use marker genes to identify which bacteria has taken up the plasmid -marker genes use usually antibiotic resistance genes that are inserted into plasmids made in the lab
77
what are the 3 options of bacteria (identifying the host)
-bacteria with no plasmid -bacteria with plasmid without wanted gene -bacteria with plasmid and wanted gene
78
how can you see what DNA it is
bacteria with either the recombiant plasmid containing the insulin gene or the original plasmid without the insulin gene will grow on ampicilin agar
79
what type of DNA will grow on a tetracycline agar
only non-recombinant colonies grow
80
examples of GMO
tomatoes soya
81
how are tomatoes modified
- when they ripen they produce pectinase which produce sugar but also softens them. they are modified to produce sugar but not soften. also modified to be toxic to insects
82
how is soya modified
to be resistant to herbicides
83
benefits of GM grops
-higher yield (more ppl fed) -better keeping quality (lasts longer) -less use of pesticides (less bioaccumulation) -less fertilisers (less eutrophication) -less land use, no loss of biodiversity
84
concerns of GM vrops
-production of 'superweeds' -reduction in biodiversity as only few species suitable -unsure of the affects they could have (health)
85
how to superweeds form
dispersal of pollen from GM crops transferring to wild relatives
86
purpose of gene therapy
used to treat genetic disorders by inserting functional DNA sequences into cells to counteract the effect of a defective gene
87
method of treating genetic disorders
can be treated by replacing genes or using drugs to replicate the function of the gene
88
what are the 2 possible methods of replacing defective genes
1- somatic cell therapy (body cells)- temporary 2. germ line therapy (gametes)- permanent/can be passed on
89
gene therapy to treat duchenne muscular dystrophy
drisapersen has been developed by introducing a 'molecular patch' over the exon with the mutation to make it readable again. a shorter form of dystrophin is produced, more functional than the untreated version the patch is an antisence oligonucleotide (sequence of 50 nucleotides complementary to the mutated sequence) process is called exon skipping
90
explain somatic cell therapy
genetic changes are not inherited in daughter cells of the treated cells (not passed on) treatment will need to be repeated regularly as the treated cells become worn out and are replaced by the body with new cells which don't contain a working copy of the gene
91
what is germ-line therapy
introduces corrective genes into germ-line cells. the genetic correction is inherited. controversial
92
what is germ-line therapy controversial
has the potenital to cause unpredicatble effects in future generations
93
how can genomics enable healthcare to be improved
-more accurate diagnosis -better prediction of the effect of drugs - improves design of drugs -introduction of new and improves treatments for disease
94
applications of tissue engineering
blood vessel replacements, bone and cartilage repair, treatment of degenerative nerve disease
95
what is a stem cell
an undifferentiated cell capable of dividing to give rise to cells which can develop into different types of specialised cells.
96
totipotent cells:
ability to differentiate into all possible cell types for that organisms
97
pluripotent cells:
ability to differentiate into many different cell types for the organism. not as versatile
98
advantages of using stem cells
large quantities of genetically identical cells cam be produced quickly
99
disadvantages of using stem cells
in mammals (expensive and unreliable) plants (disease or entry of pathogens may cause problems) inadvertent selection of disadvantageous alleles long term or unforsee effects such as premature aging of cells
100
ethics of using stem cells and cloning human tissues and organs
some argue that it is unethical as it represents a destruction of a potential human life, possibility of cloning humans
101
what enzymes are used in PCR that are also used in interphase
DNA polymerase
102
use of DNA polymerase in interphase
DNA replication
103
why are 2 different PCR's required
increases efficiency DNA has 2 strands that run in opposite directions (one for each)

A2 BIOLOGY (16 decks)

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