Practical Stuff Flashcards
Which organism has the most base pairs of DNA?
Frog - 2.8 x 10^13
Roughly how many base pairs are found in a human gene?
10^4 bases
How is animal DNA arranged?
DNA arranged in chromosomes in nucleus
What occurs when bacterial DNA is packaged for use in a lab?
Two different conformations of DNA arise, one supercoiled (helix) one coiled (circular)
How will a supercoiled and coiled DNA vary on an electrophoresis trace?
Supercoiled is more compact so will travel further than the equivalent coiled DNA
What is used to cut DNA into smaller pieces?
Restriction endonucleases, made naturally by bacteria
What are restriction endonucleases used for by bacteria?
Used to protect from pathogenic invasion (e.g. virus), breaks down DNA
How does a bacterial cell protect it’s own DNA from breakdown by restriction endonucleases?
Methylates the target sequence so the RE cannot bind
What is an important feature of all restriction sites?
They are palindromic
What does EcoR1 cut between?
G/AATTC and CTTAA/G
What does Taq1 cut between?
T/CGA and AGC/T
How would you work out the probability of a specific sequence n bases long occurring?
1/(4^n) e.g 6 bases = 1/(4^6)
Are shorter or longer sequences more likely to occur in DNA?
Shorter sequences, higher probability, you fucking dick
After DNA is cut with restriction enzymes, how are they separated?
Use agarose gel electrophoresis and compare to fragments of known size
Which part of the DNA chain has a negative charge?
The phosphate in the DNA phosphate backbone (at pH of above 1)
What type of molecule is agarose?
A polysaccharide, which forms open gels
Which way will DNA strands travel through electrophoresis plate?
Travel from anode to cathode
What is Ethidium Bromide used for in electrophoresis?
Used to visualise DNA, intercalates between bases and fluoresces at 300nm (UV light)
Why does an uncut plasmid and a plasmid cut at one point run at different positions on the gel?
Even though they have the same no. of bases, the uncut plasmid would be more compact so travel further along gel
When drawing a calibration curve what should you plot?
log10 number of base pairs (x) against distance migrated (y)
Do animals store amino acids?
No you fucking cretin, excess AA are deaminated, carbon skeletons used as fuel
What are amino acids interconverted between to remove nitrogen?
Interconverted between amino acids and ketoacids (oxo acids)
What enzyme moves amino groups between alpha-amino acids and 2-oxoacids?
Transaminases/Aminotransferases, transfer from an alpha-amino acid to an alpha-keto acid (2-oxoacid)
What catalyses the oxidative deamination of glutamate?
Glutamate Dehydrogenase