Biochemical Pathways & mutations

mutations are

changes in genetic material

biochemical pathways have

epistatic interactions

one gene makes one

polypeptide

wildtype mole strain

will grow on minimal media since it is capable of

synthesizing Arginine that it needs for growth.

mutant mole strain

requires supplemental Arginine for growth - won’t grow

on minimal media.

mutations cause changes in

protein function

what is an example of a point mutation

sickle cell anemia

point mutations result in the

subsitution of one base for another

transition point mutations

purine to purine or pyrimidine to pyrimidine

transversion

purine to pyrimidine and vice versa

What are the four types of effects the point mutation can have at a protein level?

missense, nonsense, silent, and readthrough

missense mutation

changes the amino acid (may alter protein function)

nonsense

changes codon so that it becomes a stop codon

silent mutation

codes for the same amino acid

read through

stop is changed to a amino acid that results in a protein

What are the three types of spontaneous point mutations

depurination, deamination, and wobble base pairing

depurination

removes the glycosdici bond at either G or A bases

• RESULTS IN APURINC SITE

deaminiation of cytosine

results in uracil and causes a GC to AT transition

Wobble base pairing

mispairing due to flexibility if helix and results in transitions after replication

wobble base pairing causes

replication errors

base abalogs cause

transitions after replication

mutagens can alter

DNA bases

example of a framsehift mutation

cystic fibrosis

strand slippage and unequal crossing over in replication can cause

frameshift mutations

what are the thee main diseases caused by expanding nucleotide repeates

fragile x syndrome, huntingtons, fredreich ataxia

UV light can cause

pyrimidine dimer formation

Xeroderma pigmentosum

a human disorder where a

repair mechanism is defective. Results in tumors on the

skin surface.