Studying genomes, DNA replication and Genetic Engineering Definitions

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Genomics refers to
The study of the whole set of genetic information in the form of the DNA base sequences that occur in the cells of organisms of a particular species, the sequenced genomes of organisms are placed on public access databases
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Outline the steps involved in sequencing the genome of an organism: 1) the genomes are mapped 2) samples of the genomes are sheered into smaller sections (shotgun approach) 3) sections placed into BACs, transferred to E.coli for replication
4) BACs taken and cultured, DNA extracted, restriction enzymes cut into smaller fragments 5) fragments sent through electrophoresis 5) sequenced using automated process 6) computers compare overlapping regions to reassemble whole BAC sequence
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If a gene is found in all organisms, this means that
It is likely that the protein it codes for is essential for a fundamental life process
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The basic prodedure for electrophoresis is 1) DNA samples treated with restriction enzymes to split into fragments 2) placed in wells cut into the negative electrode end of gel
3) gel immersed in a buffer solution and electric current passed through for 2 hours 4) short lengths move faster than long lengths therefore move further 5) position of fragments can be shown with a dye or radioactive marker
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Electrophoresis is
Used to separate DNA fragments based on their size, as the negatively charged fragments are attracted to the positive electrode
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A DNA probe is
A single short stranded piece of DNA that is complimentary to a section of the DNA being investigated, it is labelled either using a radioactive marker, or using a fluorescent marker
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Primers are
Short, single stranded sequences of DNA around 10-20 bases in length, they are needed in sequencing reactions and polymerase chain reactions to bind to a section of DNA as DNA polymerase can't bind directly to single stranded DNA fragments
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The polymerase chain reaction is basically artificial DNA replication, it can be used to generate
Multiple copies of a tiny sample of DNA, useful in forensics etc
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The polymerase chain reaction relys on the the fact that DNA
1) is made of antiparallel backbone strands 2) is made of strands that have 5' prime and 3'prime ends 3) grows from 3' end 4) base pairs use complimentary rule
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PCR is different to natural replication as
PCR can only replicate short sections of DNA, primer molecules must be added, heating and cooling is required
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Outline PCR
1) DNA and DNA polymerase added 2) 95C 3) hydrogen bonds break 4) primer added 5) 55C 6) DNA polymerase binds 7) 72C 8) polymerase extends section with free nucleotides
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Outline automated DNA sequencing, the reaction mixture contains DNA polymerase, single stranded template, free DNA nucleotides, primers
1) pimer joins at 3' end 2) DNA polymerase attatches and adds free nucleotides 3) if a modified nucleotide added, polymerase thrown off 4) as reaction proceeds many molecules are made varying in size in each case the final nucleotide is marked
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Recombinant DNA
A section of DNA, often in the form of a plasmid, which is formed by joining DNA sections from two different sources
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In genetic engineering the following steps are necessary
1) the required gene is obtained 2) a copy of the gene is placed (packed and stabalised) in a vector 3) the vector carries the gene to the recipient cell 4) the recipient expresses the gene through protein synthesis
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Sections of DNA containing desired genes can be extracted from a donor organism using restriction enzymes:
1) particular r enzyme will cut (hydrolyse) DNA at a specific base sequence called a restriction site 2) sticky end 3) DNA ligase used to condense fragments together (same restriction enzyme must be used in order for complimentary sticky ends)
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A sticky end is
Formed when DNA is cut using restriction enzymes, it is a short run of unpaired exposed bases seen at the end of the cut section, complimentary bases can anneal together as part of the process of recombining DNA fragments
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A vector can be
Bacterial plasmid, virus, yeast cell chromosomes
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An organism is described as transgenic when
It contains DNA that has been added to its cells as a result of genetic engineering
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Why do people want to genetically engineer organisms
1) improving a feature of the recipient cell eg resistant crops, growth controlling gene in farms 2) engineering organisms to synthesise useful products eg insulin, golden rice
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Explain how plasmids may be taken up by bacterial cells in order to produce a transgenic microorganism that expresses a desired gene
1) isolated gene and plasmid cut with same restric-enzyme 2) gene and plasmid mixed with ligase 3) some plasmids combine forming recombinant plasmid 4) plasmid mixed with bacteria, calcium salt and heat shock 5) some transgenic bacteria
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Bacteria are capable of performing conjugation, what is an advantage of this
It contributes to genetic variation, gives survival when in the presence of some chemicals (antibiotic resistance)
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Outline the process involved in genetic engineering of bacteria to produce insulin
1) mRNA found (centrifuge), reverse transcriptase 2) DNA polymerase and DNA nucleotides added 3) copied DNA built on 4) unpaired nucleotides added at each end (complimentary sticky) 5) plasmid, DNA, ligase mixed, recombinant plasmid 6) bacteria, agar
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Replica plating is
The process of growing bacteria on agar, then transferring a replica of that growth to plates containing growth inhibitors or promoters, analysis of growth patterns gives information about genetic properties of growing bacteria
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Outline the process involved in genetically engineering golden rice
1) phytoene synthase (from daffodil) and Crt 1 enzyme (soil bacteria) are inserted into the rice, near the specific promoter sequence that switches on the genes associated with endosperm development - genes expressed as endosperm (bit you eat) grows
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What is gene therapy
Any theraputic technique where the functioning allele of a particular gene is placed in the cells of an individual lacking functioning alleles, it can be used to treat some recessive conditions but not dominant conditions eg huntingtons
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Germ line gene therapy involves
Placing the gene into embryonic cell, this technique is not currently legal and is deemed unethical
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Somatic cell gene therapy involves
Placing of the gene in adult differentiated cells, examples include the placing of CFTR genes into the respiratory system cells of individuals with cystic fibrosis
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Pigs have been engineered to lack the enzyme alpha-1,3-transferase, which means
That immune rejection through xenotransplantation was reduced
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Other cards in this set

Card 2

Front

Outline the steps involved in sequencing the genome of an organism: 1) the genomes are mapped 2) samples of the genomes are sheered into smaller sections (shotgun approach) 3) sections placed into BACs, transferred to E.coli for replication

Back

4) BACs taken and cultured, DNA extracted, restriction enzymes cut into smaller fragments 5) fragments sent through electrophoresis 5) sequenced using automated process 6) computers compare overlapping regions to reassemble whole BAC sequence

Card 3

Front

If a gene is found in all organisms, this means that

Back

Preview of the front of card 3

Card 4

Front

The basic prodedure for electrophoresis is 1) DNA samples treated with restriction enzymes to split into fragments 2) placed in wells cut into the negative electrode end of gel

Back

Preview of the front of card 4

Card 5

Front

Electrophoresis is

Back

Preview of the front of card 5
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