Mr Dewhurst- manipulating genomes Flashcards
what is a genome
all genetic information of an individual, population or species
what is genomics
study of genomes
what is gene technology
manipulation of DNA
what are autosomes
chromosomes that aren’t sex related
what is DNA profiling
producing an image of patterns in non-coding DNA in individuals
what is the method of DNA profiling known as
Sanger method
what is the first stage of DNA profiling
extract DNA from tissue sample and then using a technique called PCR can produce enough DNA to profile
what is the second stage of DNA profiling
digesting sample- strands of DNA are cut into smaller fragments using enzymes called restriction endonucleases - each enzyme makes one cut through each strand of DNA on helix
different enzymes cut a specific nucleotide sequence
what is in the test tube with DNA fragments
primers, terminator bases ( stop DNA synthesis)
what is the third stage of DNA profiling
separating DNA fragments using electrophoresis which uses an electric current to separate fragments as phosphate on fragment ( nucleotide) is negatively charged so attracted to cathode at bottom.
what is the fourth stage of DNA profiling
hybridisation - fluorescent DNA probes or radioactive labels added to join to complementary sequence so fragments are visible
what is the last stage of DNA profiling
seeing evidence- if radioactive labels added first then x-ray images produced, if fluorescent dies added then it is viewed under UV rays
the shorter fragments will be at the bottom
what is the purpose of Polymerase chain reaction
to amplify millions of copies of DNA - can be used for paternal testing, crime scenes, identifying new species
what is the first stage of PCR
denature DNA by heating machine up to 95* which breaks hydrogen bonds between DNA strands so they separate
what is the second stage of PCR
annealing of primers- machine cooled to 55* to allow primers to join which prevents strands joining back together and signals DNA polymerase where to begin replication
what is the third stage of PCR
synthesis of DNA- temperature increased to 72* to allow taq polymerase to catalyse the formation of sugar phosphate backbone
why is PCR good for crime scenes
often little traces of DNA found so not enough to provide evidence for analysis but can be copies and amplified for analysis
what are the 2 principles of genetic engineering
genetically modifying DNA by combining DNA from different organisms to produce recombinant DNA
genes are isolated from one organism and inserted into another organism using a vector
what is the summarised process of genetic engineering
1- gene isolated
2- copy of gene placed in vector
3- vector carries gene into recipient cell
4- recipient expresses novel gene ( new gene)
what is one way of isolating genes
extract mRNA from cells to show what gene is expressed, reverse transcriptase then copies mRNA back to DNA called cDNA (complementary DNA) so it can be copied into double stranded DNA which codes for original protein
what is another way of isolating genes
restriction endonuclease - cut gene staggered leaving some bases unpaired called sticky ends
what is it called when sticky ends join together
ligation
outline the process of inserting gene into a cell using a plasmid
1- chromosomal DNA of organism A is extracted
2- gene of interest is amplified using PCR A
3- multiple copies of gene is made from organism A
4- gene is inserted into bacterial plasmid using ligase enzyme
5- plasmid now contains gene from organism A
6- the plasmid is then inserted into organism B
what is one way of getting the vector (plasmid) into recipient cell
heat shock- heats host cell from 0-42* in the presence of calcium ions to allow the membrane to become more porous
the CA2+ surrounds DNA to allow it to enter through phospholipid bilayer and foreign DNA enters cell
