Chap 19 Genetic Technology
W17/41
4a) Suggest the advantages of using, in Bt cotton, the gene coding for Cry1Ac, rather than one of the genes coding
for other types of the Cry-protein. (2)
- (only) kills / targets / acts on, specific / some, insects / pests ;
- does not kill, beneficial / useful, insects ;
- (such as) pollinators / bees / predators of pests ;
- to conserve / protect, biodiversity / food web ; ora
- idea that other Cry proteins might not kill, right pests / bollworm
Explain why a promoter is included in the genetic package. (2) / Role of promoter
- (so, new / foreign / inserted) gene(s) are, expressed / switched on / transcribed (and translated) / allow
transcription
- RNA polymerase binds (at promoter) ;
- ref. to correct / template, strand ;
- to control quantity of Cry(1Ac / protein) made ;
- to control, where / which part(s) of plant, make Cry(1Ac / protein)
Suggest how the herbicide resistance gene can be used as a genetic marker. (3)
- insert, herbicide resistance gene / it, next to, Bt / Cry(1Ac), gene ;
- spray / add, herbicide on (transformed) plants / protoplasts / cells ;
- survivors have, Bt / Cry(1Ac), gene ;
- to identify, successful / GM / insect-resistant, plants ;
7c) Explain how the presence of galactosaemia in a foetus may be determined. (2)
- genetic screening ;
- obtain fetal, cells / DNA ;
- by, amniocentesis / chorionic villus sampling ;
- electrophoresis + probe ;
W17/42
5a) With reference to the information given, explain why Huntington’s disease cannot be treated with gene therapy.
(4)
- allele is dominant ;
- so will still be expressed even when, normal / recessive, allele is present ; ora
- (gene therapy only) used to treat recessive (allele) disorders ;
- cannot, remove dominant allele / replace an allele ;
- dominant allele affects tissues in many parts of the body
S17/42
5b) Suggest a type of cell from a blood sample that is suitable for testing for the presence of this allele and explain
your choice. (1)
- white cell, because it contains a nucleus ;
Outline how a microarray enables the detection of particular alleles. (4)
- ref. to probes are (short) lengths of ssDNA ;
- complementary to the, alleles / DNA, being tested for ;
- many copies of one type of probe placed in each cell (of the microarray) ;
- (target), alleles / DNA, made single-stranded or single-stranded DNA made from mRNA ;
, - (target), alleles / DNA, labelled, (with fluorescent 'tags') ;
- (target), alleles / DNA, hybridises / binds, with, probes / ssDNA ;
- unbound (target), alleles / DNA, washed off or bound (target), alleles / DNA, will not be washed off ;
- laser / UV light, used to detect presence of, fluorescence / hybridised probes / alleles / DNA ;
W16/41
3a) Explain why the DNA sample is heated to 95°C in step 1. (2)
- to, separate the two strands /denature DNA ; A make single-stranded DNA
- by breaking hydrogen bonds (between bases) ;
- so that bases are exposed ;
- to produce template strands for (complementary) copying
Explain why primers are added in step 2. (2)
- (primer) binds /anneals, to DNA by complementary base pairing ;
- idea of attaching close to the specific section of DNA ;
- (DNA) polymerase only attaches to double-stranded DNA ;
- (primers) reduce re-annealing of separated strands ;
Explain why the enzyme Taq polymerase is used in step 3 (2)
- synthesises complementary DNA strands ;
- (Taq polymerase), is heat stable/works at high temperature ;
- (so) does not need to be added again for each cycle /needs replacing only after a number of cycles ; or other
polymerases need replacing regularly ;
- process is, more efficient / faster (than normal DNA polymerase)
3b) Explain why there are usually more than 100 copies of mtDNA in a cell, but only two copies of nuclear DNA. (2)
- many mitochondria per cell but only one nucleus ;
- cell, is diploid / has two copies of each chromosome (in nucleus)
W16/43
3a) Describe the properties of plasmids that make them suitable for their roles in the production of Golden Rice. (3)
- small ;
- circles (of DNA) ;
- contain genes (for enzymes) to enable DNA transfer to plant cells ;
- contain, restriction sites /polylinkers ;
- own origin of replication / can multiply independently ;
- ref. to marker genes
3b) Explain why the original Golden Rice had to be developed by genetic engineering, but locally-adapted varieties of
Golden Rice could be developed by selective breeding. (3)
- β-carotene, gene(s) come from a different species ;
- ora β-carotene / new/ inserted, gene(s) not in rice cannot breed two different species together ;
- local varieties have, desired / adaptive, genes /alleles / characteristics ;
- crossing them with Golden Rice combines (good / best) features
3c) Explain why the Golden Rice was grown using water containing deuterium. (2)
- idea of, label / marker ;
- to, identify /measure, vitamin A (in body) from Golden Rice
Suggest why it took several hours after the Golden Rice had been eaten for the maximum concentration of
vitamin A containing deuterium to be reached. (1)
, - β-carotene must be converted to vitamin A ;
- absorbing β-carotene takes time
S16/41
3a) Define the term bioinformatics. (2)
- database(s) ;
- computer (programs) / software ;
- analysis of, data/ biological information/ sequences ;
Outline how sequencing the genome of Plasmodium and the use of bioinformatics can suggest new targets for
anti-malarial drugs. (3)
- identify /recognise, gene(s) ; A find where genes are
- predict, primary structure/ amino acid sequences, of proteins ;
- predict 3D structure of proteins ; A tertiary
- identify / predict, functions of proteins (from 3D structure) ;
- ref. to drug to, bind with/ block activity of/ disrupt structure of, protein/ enzyme ; A drug specific to protein I
denature, protein/ enzyme
- drug prevents, transcription/ expression, (of gene) ; I gene editing
3b) Suggest advantages of using theoretical models in this research, rather than testing possible drugs in the
laboratory. (3)
- cheaper ; A more economic(al)
- faster/ can try many different drugs in a short period of time ; A time-saving
- can try out changes to, model/ drug structure, to see if more effective ;
- no need for, laboratories / equipment ; I uses less labour (initially)
- no need for tests on, animals / humans ; A fewer ethical issues
Suggest why theoretical modelling cannot completely replace laboratory trials in the search for new drugs (2)
- functionality / to test that drug, actually works / is effective ; A cannot assume predictions are correct
- A ref. to clinical trials / side effects dosage ;
- A theoretical modelling will not give information on doses
S16/42
3a) In order to produce the GM males, the researchers inserted the gene coding for a restriction endonuclease called
I-PpoI. This restriction endonuclease was known to destroy the X chromosome of A. gambiae.
Explain the meaning of the term restriction endonuclease and suggest why I-PpoI destroys the X chromosome, but
not the Y chromosome. (4)
explain (max 3)
- cuts DNA at specific, site /base sequence ;
- detail of cut ; e.g. palindromic or blunt/ sticky, ends or staggered cut
- enzyme derived from, bacteria/ prokaryotes ;
- ref. to destroys viral DNA in bacteria ;
suggest
- only X chromosome has the I-Ppol, restriction/recognition, site ; ora
- X and Y chromosomes are different in, size/ shape/ base sequence
3b) Explain why the researchers introduced the gene for GFP, as well as the gene for I-Ppol. (2)
- as a marker ; to identify the GM mosquitoes
, S18/43
5a) Suggest what steps will be needed to make identical genetically modified AD mice. (4)
- obtain (dominant APP) allele ;
- detail ; any one from: e.g. synthesise gene make cDNA from mRNA use probe select and amplify with PCR gel
electrophoresis
- restriction enzyme ;
- use, vector / plasmid / virus ; A gene gun / direct (micro)injection
- (on) zygote / secondary oocyte / egg (cell) / early embryo ; I sperm
- AVP ; e.g. cloning / embryo splitting add promoter marker gene / tag gene
Suggest why it is useful to have an animal model of a human disease. (1)
- to test treatments without harming humans ; to investigate, cause / progress, of disease ;
5b) Explain the principles of this type of DNA microarray analysis (4)
- identifies, active / switched on / expressed / transcribed, genes ;
- transcription of a gene produces mRNA ;
- ssDNA act as, probes / reporters ;
- (ssDNA) bound at known positions to a, solid surface / slide / chip ;
- cDNA, binds to / hybridises with, complementary (probe) ssDNA ;
- show up / identified as, fluorescent spots / named colour ;
- positions / intensity, recorded by, laser / scanner ;
- positions identified as named genes ;
- intensity proportional to gene expression
S18/41
5c) Describe two advantages of the gene-editing technique compared to the traditional genetic modification
technique used to make transgenic pigs in 1985. (2)
- success rate (in altering gene) is, greater / 100% (instead of 1%) ;
- (only) specific gene is altered / targets gene more precisely ;
- (unwanted) gene is, removed / deleted / disabled / knocked out ;
S18/42
5a) Explain what is meant by gene therapy (2)
- to treat disease caused by, faulty / recessive, allele ; A cure
- deliver, gene / allele / DNA (into target cells of individuals) ; named example ; e.g. SCID / cystic fibrosis
Describe the roles of reverse transcriptase and DNA polymerase in making cDNA (2)
- (reverse transcriptase) uses mRNA to make (ss)DNA ; (DNA polymerase) makes DNA double-stranded
Suggest why the researchers chose a vector that could not replicate (2)
- to prevent virus spreading (throughout the body) ;
- to limit, side effects / immune response / cancer / illness / infection / cell destruction ;
W15/41
2
Gold ions (Au3+) are toxic to most microorganisms. However, the bacterium Delftia acidovorans is frequently found
in sticky layers, called biofilms, that form on the surface of gold deposits.
W17/41
4a) Suggest the advantages of using, in Bt cotton, the gene coding for Cry1Ac, rather than one of the genes coding
for other types of the Cry-protein. (2)
- (only) kills / targets / acts on, specific / some, insects / pests ;
- does not kill, beneficial / useful, insects ;
- (such as) pollinators / bees / predators of pests ;
- to conserve / protect, biodiversity / food web ; ora
- idea that other Cry proteins might not kill, right pests / bollworm
Explain why a promoter is included in the genetic package. (2) / Role of promoter
- (so, new / foreign / inserted) gene(s) are, expressed / switched on / transcribed (and translated) / allow
transcription
- RNA polymerase binds (at promoter) ;
- ref. to correct / template, strand ;
- to control quantity of Cry(1Ac / protein) made ;
- to control, where / which part(s) of plant, make Cry(1Ac / protein)
Suggest how the herbicide resistance gene can be used as a genetic marker. (3)
- insert, herbicide resistance gene / it, next to, Bt / Cry(1Ac), gene ;
- spray / add, herbicide on (transformed) plants / protoplasts / cells ;
- survivors have, Bt / Cry(1Ac), gene ;
- to identify, successful / GM / insect-resistant, plants ;
7c) Explain how the presence of galactosaemia in a foetus may be determined. (2)
- genetic screening ;
- obtain fetal, cells / DNA ;
- by, amniocentesis / chorionic villus sampling ;
- electrophoresis + probe ;
W17/42
5a) With reference to the information given, explain why Huntington’s disease cannot be treated with gene therapy.
(4)
- allele is dominant ;
- so will still be expressed even when, normal / recessive, allele is present ; ora
- (gene therapy only) used to treat recessive (allele) disorders ;
- cannot, remove dominant allele / replace an allele ;
- dominant allele affects tissues in many parts of the body
S17/42
5b) Suggest a type of cell from a blood sample that is suitable for testing for the presence of this allele and explain
your choice. (1)
- white cell, because it contains a nucleus ;
Outline how a microarray enables the detection of particular alleles. (4)
- ref. to probes are (short) lengths of ssDNA ;
- complementary to the, alleles / DNA, being tested for ;
- many copies of one type of probe placed in each cell (of the microarray) ;
- (target), alleles / DNA, made single-stranded or single-stranded DNA made from mRNA ;
, - (target), alleles / DNA, labelled, (with fluorescent 'tags') ;
- (target), alleles / DNA, hybridises / binds, with, probes / ssDNA ;
- unbound (target), alleles / DNA, washed off or bound (target), alleles / DNA, will not be washed off ;
- laser / UV light, used to detect presence of, fluorescence / hybridised probes / alleles / DNA ;
W16/41
3a) Explain why the DNA sample is heated to 95°C in step 1. (2)
- to, separate the two strands /denature DNA ; A make single-stranded DNA
- by breaking hydrogen bonds (between bases) ;
- so that bases are exposed ;
- to produce template strands for (complementary) copying
Explain why primers are added in step 2. (2)
- (primer) binds /anneals, to DNA by complementary base pairing ;
- idea of attaching close to the specific section of DNA ;
- (DNA) polymerase only attaches to double-stranded DNA ;
- (primers) reduce re-annealing of separated strands ;
Explain why the enzyme Taq polymerase is used in step 3 (2)
- synthesises complementary DNA strands ;
- (Taq polymerase), is heat stable/works at high temperature ;
- (so) does not need to be added again for each cycle /needs replacing only after a number of cycles ; or other
polymerases need replacing regularly ;
- process is, more efficient / faster (than normal DNA polymerase)
3b) Explain why there are usually more than 100 copies of mtDNA in a cell, but only two copies of nuclear DNA. (2)
- many mitochondria per cell but only one nucleus ;
- cell, is diploid / has two copies of each chromosome (in nucleus)
W16/43
3a) Describe the properties of plasmids that make them suitable for their roles in the production of Golden Rice. (3)
- small ;
- circles (of DNA) ;
- contain genes (for enzymes) to enable DNA transfer to plant cells ;
- contain, restriction sites /polylinkers ;
- own origin of replication / can multiply independently ;
- ref. to marker genes
3b) Explain why the original Golden Rice had to be developed by genetic engineering, but locally-adapted varieties of
Golden Rice could be developed by selective breeding. (3)
- β-carotene, gene(s) come from a different species ;
- ora β-carotene / new/ inserted, gene(s) not in rice cannot breed two different species together ;
- local varieties have, desired / adaptive, genes /alleles / characteristics ;
- crossing them with Golden Rice combines (good / best) features
3c) Explain why the Golden Rice was grown using water containing deuterium. (2)
- idea of, label / marker ;
- to, identify /measure, vitamin A (in body) from Golden Rice
Suggest why it took several hours after the Golden Rice had been eaten for the maximum concentration of
vitamin A containing deuterium to be reached. (1)
, - β-carotene must be converted to vitamin A ;
- absorbing β-carotene takes time
S16/41
3a) Define the term bioinformatics. (2)
- database(s) ;
- computer (programs) / software ;
- analysis of, data/ biological information/ sequences ;
Outline how sequencing the genome of Plasmodium and the use of bioinformatics can suggest new targets for
anti-malarial drugs. (3)
- identify /recognise, gene(s) ; A find where genes are
- predict, primary structure/ amino acid sequences, of proteins ;
- predict 3D structure of proteins ; A tertiary
- identify / predict, functions of proteins (from 3D structure) ;
- ref. to drug to, bind with/ block activity of/ disrupt structure of, protein/ enzyme ; A drug specific to protein I
denature, protein/ enzyme
- drug prevents, transcription/ expression, (of gene) ; I gene editing
3b) Suggest advantages of using theoretical models in this research, rather than testing possible drugs in the
laboratory. (3)
- cheaper ; A more economic(al)
- faster/ can try many different drugs in a short period of time ; A time-saving
- can try out changes to, model/ drug structure, to see if more effective ;
- no need for, laboratories / equipment ; I uses less labour (initially)
- no need for tests on, animals / humans ; A fewer ethical issues
Suggest why theoretical modelling cannot completely replace laboratory trials in the search for new drugs (2)
- functionality / to test that drug, actually works / is effective ; A cannot assume predictions are correct
- A ref. to clinical trials / side effects dosage ;
- A theoretical modelling will not give information on doses
S16/42
3a) In order to produce the GM males, the researchers inserted the gene coding for a restriction endonuclease called
I-PpoI. This restriction endonuclease was known to destroy the X chromosome of A. gambiae.
Explain the meaning of the term restriction endonuclease and suggest why I-PpoI destroys the X chromosome, but
not the Y chromosome. (4)
explain (max 3)
- cuts DNA at specific, site /base sequence ;
- detail of cut ; e.g. palindromic or blunt/ sticky, ends or staggered cut
- enzyme derived from, bacteria/ prokaryotes ;
- ref. to destroys viral DNA in bacteria ;
suggest
- only X chromosome has the I-Ppol, restriction/recognition, site ; ora
- X and Y chromosomes are different in, size/ shape/ base sequence
3b) Explain why the researchers introduced the gene for GFP, as well as the gene for I-Ppol. (2)
- as a marker ; to identify the GM mosquitoes
, S18/43
5a) Suggest what steps will be needed to make identical genetically modified AD mice. (4)
- obtain (dominant APP) allele ;
- detail ; any one from: e.g. synthesise gene make cDNA from mRNA use probe select and amplify with PCR gel
electrophoresis
- restriction enzyme ;
- use, vector / plasmid / virus ; A gene gun / direct (micro)injection
- (on) zygote / secondary oocyte / egg (cell) / early embryo ; I sperm
- AVP ; e.g. cloning / embryo splitting add promoter marker gene / tag gene
Suggest why it is useful to have an animal model of a human disease. (1)
- to test treatments without harming humans ; to investigate, cause / progress, of disease ;
5b) Explain the principles of this type of DNA microarray analysis (4)
- identifies, active / switched on / expressed / transcribed, genes ;
- transcription of a gene produces mRNA ;
- ssDNA act as, probes / reporters ;
- (ssDNA) bound at known positions to a, solid surface / slide / chip ;
- cDNA, binds to / hybridises with, complementary (probe) ssDNA ;
- show up / identified as, fluorescent spots / named colour ;
- positions / intensity, recorded by, laser / scanner ;
- positions identified as named genes ;
- intensity proportional to gene expression
S18/41
5c) Describe two advantages of the gene-editing technique compared to the traditional genetic modification
technique used to make transgenic pigs in 1985. (2)
- success rate (in altering gene) is, greater / 100% (instead of 1%) ;
- (only) specific gene is altered / targets gene more precisely ;
- (unwanted) gene is, removed / deleted / disabled / knocked out ;
S18/42
5a) Explain what is meant by gene therapy (2)
- to treat disease caused by, faulty / recessive, allele ; A cure
- deliver, gene / allele / DNA (into target cells of individuals) ; named example ; e.g. SCID / cystic fibrosis
Describe the roles of reverse transcriptase and DNA polymerase in making cDNA (2)
- (reverse transcriptase) uses mRNA to make (ss)DNA ; (DNA polymerase) makes DNA double-stranded
Suggest why the researchers chose a vector that could not replicate (2)
- to prevent virus spreading (throughout the body) ;
- to limit, side effects / immune response / cancer / illness / infection / cell destruction ;
W15/41
2
Gold ions (Au3+) are toxic to most microorganisms. However, the bacterium Delftia acidovorans is frequently found
in sticky layers, called biofilms, that form on the surface of gold deposits.
