Biotechnology (evidence of evolution)

chp 10

polymerase chain reaction (PCR)

technique to produce multiple copies of DNA from a sample for testing. steps: denaturation, annealing, extension

denaturation (PCR)

heating of double stranded DNA to 95C, breaking the hydrogen bonds holding the strands together

annealing (PCR)

temp lowered to 50-60C, so primers can bind to a specific part of the single DNA strand they are complementary to

primer

short strand of DNA that serves as a starting point for DNA replication

extension (PCR)

around 70C, Taq polymerase used to join new complementary nucleotides to single strand DNA (5’ to 3’ direction). results in an additional strand of DNA

Taq polymerase

heat resistant enzyme originating from a bacterium

restriction enzyme

cuts DNA at specific nucleotide sequences

gel electrophoresis

process used to separate DNA strands based on length

gel electrophoresis process

restriction enzymes cut DNA, pieces placed in wells in gel. negatively charged DNA will move to positive electrode on the other end

small vs larger DNA pieces in gel electrophoresis

smaller DNA pieces can travel faster through the gel, will be furthest away from the well

DNA profile

the banding patterns of DNA fragments as a unique identification

micropipette

used to accurately place DNA into wells

DNA ladders

segments of DNA with known lengths to compare with the sample

visualising DNA

• fluorescent added to agar, DNA picks up, UV light shone over gel

• dye added to gel which binds to DNA

• DNA probes with florescent molecule

DNA sequencing

determination of the precise order of nucleotides in a DNA sample

dideoxyribonucleotides (ddNTPs)

synthetic nucleotides that lack the OH groups, disrupt elongation as the next nucleotide cannot attach

Sanger’s method

ddNTPs with dye based on nucleotide added to DNA strand during PCR, stops elongation. creates segments of different lengths. dye helps determine order of nucleotides

DNA sequencing uses

• identify mutation + inherited disorders

• compare with different organisms

• maternity/paternity tests

• track evolutionary changes

ethical considerations

• autonomy- choose to be tested, share info

• confidentiality- authorised access

• equity- fair and equal treatment

• privacy- right to make own decisions

genome

complete set of DNA in each cell of an organism

comparative genomics

comparison of genomes of different species

non-coding DNA

no function or purpose. closely related species have more in common

endogenous retroviruses (ERVs)

viral sequence that has become part of the genome, non-coding DNA

process of endogenous retrovirus

retrovirus enters cell, copies RNA into DNA by reverse transcription, which is inserted into host cell. becomes endogenous if inserted into gametes to be inherited

evidence from ERVs

ERVs will be passed on to next generations in the same chromosome location. provides evidence of common ancestry if two organisms have the same ERVs

mitochondria

organelle where aerobic phase of respiration occurs to produce energy

mitochondrial dna (mtDNA)

small circular DNA found in mitochondria. codes for its functioning, making tRNA, enzymes for cellular respiration

mtDNA inheritance

sperm have just enough mitochondria to reach egg, so is destroyed at fertilisation. is only inherited by mothers

evidence from mtDNA

amount of mutation roughly proportional to amount of time passed. comparing similarities provides evidence of common maternal ancestor

protein sequences

comparing amino acid sequences in similar proteins. fewer differences indicate closer evolutionary relationship

ubiquitous proteins

proteins found in all species, carry out same essential functions

cytochrome C

ubiquitous protein, essential in cellular respiration. more similarity in protein sequence = more recent common ancestor

bioinformatics

use of computers to describe the molecular components of living things

annotation

identifying genes in DNA sequence. is computerised for easy comparison

applications of bioinformatics

identify mutation and inherited disorders, personalised medicine