Genetics Flashcards
CYP2A6
Related to metabolism of nicotine
Higher expression related to nicotine addiction
CYP2C8
Related to metabolism of Cerivastatin
CYP2C9
Related to metabolism of drugs like warfarin, phenytoin
Makes up 20% of hepatic CYP and metabolises 10% of drugs
Inhibited by oral contraceptives
CYP2C19
Related to metabolism of antidepressants and PPI’s
CYP3A’s
Metabolises 50% of all drugs and endogenous substances
3A4-adult endogenous metabolism
3A7- Embryonic enzyme
3A5- present in both foetus and adult
CYP2D6
V important Responsible for the metabolism of 25% of all drugs and significantly affects them including: anti emetics anti-cancer anti-depressants neuroleptics anti-arrythmics analgesics
P-gp (P glycoprotein)
Acts as efflux pump stopping xenotoxins/biotics from entering circulation from GI and entering CNS (part of the BBB)
Expression on lumen side results in:
less drug abosrbed from GI
increased excretion into bile/urine
less entry into CNS
TPMT -Thiopurine Methyltransferase
Catalyses thiopurine drugs
90% of people are rapid metabolisers
10% intermediate
0.3% are poor metabolisers- these guys are at high risk of toxicity due to accumulation of drug as it isn’t being inactivated
Host for insulin production
E.coli
Yeast
For diabetes
Host for factor VIII production
Mammalian cells
Used for haemophilia
Antithrombin (A tryn)
Goat
For antithrombin deficiency
The difference between the template and the coding strand
The mRNA is made off of the the template strand and is essence a copy of the coding strand
In which direction is DNA synthesised?
DNA is read and synthesised 5’ to 3’
Poly/monocistronic
Polycistronic is where a single strand of mRNA can code for more than one polypeptide. Can be organised in an operon (not
Monocistronic is where a mRNA strand can code for only one polypeptide. The majority of human mRNA is of this type
DNA processes: Transformation
Uptake of free DNA
Transfection in animal cells
DNA processes: Conjugation
DNA transfer in cell to cell contact
DNA processes: Transduction
DNA transfer via virus
The three steps in molecular cloning
- isolate source DNA
- insert source DNA into cloning vector
- introduce cloned DNA into host organism
Describe the process
Source DNA inserted into a plasmid that has the gene for ampicillin resistance
Mix the plasmids with E.coli and CaCl2 and a pulse of heat
Culture the E.coli on ampicillin plates
Bacteria that take up the plasmids survive, the others don’t
The plasmids will then replicate within the bacteria
PCR- polymerase chain reaction
- Denature the DNA strands (~30secs at 94degrees)
- Anneal with primers (~30 secs @55-65 degrees)
The primers will bind upstream and downstream of the desired gene and will elongate from there - Elongate with thermostable DNA polymerase (1 min per kb @ 72 degrees)
Do this n times and the number of copies of DNA gained is 2^n
MCS and LacZ
Can tell which bacteria have taken up plasmids as those that don’t die but cannot tell whether plasmid has taken up source DNA. This can be done through the use of the lacZ gene.
Explain the LacZ identification
LacZ gene codes for Beta galactosidase which degrades lactose and contains the MCS (site where the source DNA goes)
If the source DNA is taken up then the LacZ gene becomes inactive, if not it remains active
To test whether source DNA was taken up X-gal is added. If LacZ is active then X-gal turns blue
Hence the bacteria will do the following:
If the bacteria has taken up the plasmid and the plasmid contains the source DNA= white cultures
If the bacteria has taken up the plasmid but the source DNA is not in the plasmid= Blue cultures
If the bacteria has not taken up the culture=it dies, due to it not having ampicillin resistance
Why are proteins such as antithrombin/factor VIII not produced in bacteria?
Bacteria generally cannot take glycosylated proteins
The genes usually have large numbers of introns
