Modern Genetics Flashcards
(39 cards)
What is a genome?
Complete set of genes or genetic material present in a cell of an organism
What does the genome include?
DNA in the nucleus
DNA in mitochondria and chloroplast
What is needed for the polymerise chain reaction (PCR)?
The DNA fragment to be copied
Primers
Nucleotides
DNA polymerase from thermophilic bacteria
What is the machine used for PCR called?
Thermocycler
4 stages of PCR:
1) heat to 95* o break the hydrogen bonds and separate the 2 stands of DNA
2) cool to 55* so primers will join with the complementary base pairs at the end of each DNA strand. DNA polymerase will attach
3) heat to 72* which is the optimum temp for DNA polymerase which adds complementary nucleotides along each DNA strand
4) As the process is repeated the number of DNA strands increases exponentially
The danger method of DNA sequencing using PCR: what materials are needed in each of the 4 samples?
All materials for PCR (including 4 normal nucleotides) and a different dideoxynucleotide
The danger method of DNA sequencing using PCR: what will happen to the primer?
It will be marked eg fluorescent
The danger method of DNA sequencing using PCR: what is the effect of the dideoxynucleotide?
As each one is put through PCR the addition of a dideoxynucleotide to the sequence means no more nucleotides can bind due to the missing oxygen and added phosphate groups- the sequence will end
The danger method of DNA sequencing using PCR: what do you do after completion of PCR?
A sample from each tube is taken to be separated with gel- DNA is neg so moves to pos- shortest will move furthest and a sequence will be read
Uses of DNA sequencing
- predicting the protein in an organism for uses in medicine
- disease management
What is full genome sequencing?
Sequencing mitochondrial or chloroplast DNA as well as nuclear DNA
Uses of full genome sequencing
Comparisons that can determine evolutionary relationships and differing responses to medical treatments
Where are minisatelites found and what do they contain?
Found within introns and contain core nucleotide sequences
How do minisatelites vary between individuals? What are they used for?
Vary in number of repeats used for genetic fingerprinting
How do you avoid getting 2 individuals with the same minisatelites when genetic fingerprinting?
Choose minisatelites with the most variation
Stages of genetic fingerprinting: collection
Same of tissue containing DNA to be analysed
Stages of genetic fingerprinting: extraction
Sample mixed with phenol and chloroform then centrifuged so proteins precipitate out. DNA is precipitated out of water later using ethanol
Stages of genetic fingerprinting: digestion
Restriction enzymes cut DNA close to minisatelites regions so they keep original length
Stages of genetic fingerprinting: separation (and process of denaturation and southern blotting)
Fragments are separated by size by gel electrophoresis- denaturation= gel soaked in alkaline solution to separate DNA into single strands .
DNA is transferred to a nylon membrane using blotting paper to draw it up out of the gel by capillary action
Stages of genetic fingerprinting: hybridisation
The membrane is immersed in a solution of labelled DNA probes that hybridise with chosen core sequences the unbound probes are washed off and the membrane is dried
Stages of genetic fingerprinting: development
X Ray film placed over membrane- membrane is dogged in areas where radiation is present producing an autoradiograph. Bands are the DNA fingerprint to be compared
Stages of genetic fingerprinting: order of the stages
Collection Extraction Digestion Separation Hybridisation Development
When is a gene expressed?
When a gene is switched on it is transcribed into an mRNA strand then translated into a protein- if a gene is present on DNA but not mRNA then the gene is not expressed in that cell
How can you determine which genes are expressed
A gene probe can be used to determine the presence of a gene in dna and mRNA
If the gene is present on dna but not mRNA then the gene is not expressed in that cell
