Manipulating Genomes 2 Flashcards
Human genome
All of genetic material one contains that is dna in nucleus and mitochondria
Dna that codes for proteins
20-25000 regions of dna code for proteins
Only 2% - extrons
Introns
Large non coding regions of DNA
Removed from mRNA before translation
Satellite dna
Short sequences of dna that are repeated many times
Minisatellites
Sequence of 20-50 base pairs will be repeated from 50 to several hundred times
Occur at more than 1000 locations in genome
Known as variable number tandem repeats
Micro satellites
2-4 bases repeated only 5-15 times
Known as short tandem repeats
Patterns of dna satellites
Appear in same positions on chromosomes however the number of repeats vary (inherited mix)
Closer relation more similar the patterns
Producing dna profile
Extracting dna
Digesting the sample
Hybridisation
Seeing evidence
Extracting dna
Dna extracted from a tissue sample and use pcr in order to produce enough dna to develop a profile
Digesting the sample
Strands of dna cut into fragments using restriction endonucleases
Separating the dna fragments
Cut fragments of dna separated to form a clear pattern using electrophoresis
Hybridisation
Fluorescent dna probes are added in excess to fragments which are complementary to known dna sequence
Probes identify the micro satellites which are more varied than the minisattelites
Seeing the evidence
Sample placed under uv light so fluorescence glows - gives a pattern of bars which is unique to every individual apart from mz twins -THE DNA PROFILE
Restriction endonucleases
Enzymes which split dna into small fragments at specific sequences known as restriction site( complements active site)
Cut both dna strand
Allows scientist ability to cut at known and defined points in introns
Electrophoresis
Dna fragments put into well in gel strips ( one well contains known dna fragments)
Current passed through fragments move towards cathode due to -ve phosphate groups in dna - smaller frag closer to anode
Placed in alkali to denature
Southern blotting
Strands of dna transferred to nitrocellulose paper
Identical positions to the gel (alkali removed using absorbent paper)
Then hybridised
Pcr
Form of artificial dna replication
Semi conservative multiple complies
Amplifies sample
Pcr components
Pcr vial contains dna sample nucleotides 2x primers Taq DNA polymerase
Denature dna - heat 95 give single strands
Primers - cool mixture to 55 allows primers to anneal to dna
Synthesis - at 72 taq DNA polymerase strat synthesising new dna comp to og strand next to primer
Uses of dna profiling
Forensic science - evidence at scene
Paternity of a child
Identifying those at risk of particular disease
Dna sequencing
Process of determining the precise order of nucleotides within a dna molecule