Topic 7 - Modern Genetics: Using gene sequencing Flashcards
number of genes in a human genome
20000
number of base pairs in human genome
3100000000
What is a genome?
all the genes in a cell or organism
bases only account for ____ % of the genome?
1.5%
if bases only account for 1.5 % of the genome, then what makes up the other 89.5% ?
non-coding DNA
what does non-coding DNA not do?
and what does it do?
- doesn’t code for amino acids
- makes DNA work properly
- can be used by scientists
what does Vitro mean?
outside of a living organism
- fertilisation in culture dish, outide of female body
What does Vivo mean?
inside of a living organism
example of In Vitro
IVF
In Vitro Fertilisation
- fertilisation in culture dish, outide of female body
what does IVF stand for?
In Vitro Fertilisation
what does PCR stand for
Polymerase Chain Reaction
Whatis PCR
its in in vitro method used to amplify (make more of) DNA fragments
PCR
what does DNA polymerase do?
- assembles the DNA nucleotides to form newly synthesised DNA
What does the PCR method involve? and what does this try and replicate?
cyclical cooling and heating to a series of temps
- tries to mimic the events of DNA replication in Interphase cell cycle
what are the 3 key temperatures for PCR testing?
- 72°C
- 95°C
- 50°C -65°C
what is thermophilus aquaticus?
(it has TAQ Polymerase)
its a type of bacteria that has TAQ polymerase, an enzyme that’s stable at high temperatures such as 95°C
- its magnesium dependant, which is why it needs magnesium ions
how many pcr stages are there?
6
PCR stages:
Stage1
- reaction mixture set up, containing DNA sample, mg ions, primers, free nucleotides, and DNA polymerase
PCR stages:
Stage 2
- mixture heated to 95°C
- this breaks hydrogen bonds btwn the 2 \dna strands, resulting in single strands
why can we heat the mixture to 95°C without denaturing anything?
dependant on anything, how do we compromise
- TAQ polymerase is an enzynme stable at high temperatures and so doesnt denature at 95°C.
- but its mg dependant wich is why we use mg ions
PCR stages:
Stage 3
annealing (to join) - refers to the pairing of complementary DNA (or RNA) sequences by hydrogen bonding
- mixtue is cooled to btwn 50°C and 65°C
- at this temp, the primers will anneal to their complementary base sequence at 3’ end of each single strand of DNA
PCR stages
what are primers?
short pieces of single-stranded DNA that are complementary to the target sequence
PCR stages:
Stage 4
- TAQ polymerase binds to the small section of DNA and the temp is increased to 72°C (optimum for this enzyme)
PCR stages:
Stage 5
- The enxyme moves along in the 5’ to 3’ direction, catalysing condensation reactions to join free DNA nucleotides by phosphodiester bonds.
