Module 1 Part 2 Flashcards
what is the most common base pairing
C and G, A and T
Why can pairing occur between A and C , G and T
Because of tautomeric shifts
what is a tautomer
a transient isomeric form of a nitrogenous base
how do single base pair substitutions happen?
incorporation of a rare tautomer during DNA replication
what is sickle cell anemia
inherited disorder of red blood cells
what gene is included with sickle cell anemia and what does it code for
HBB gene which codes for B-globin protein
what is hemoglobin
a tetramer formed of 2 a-globin and 2 b-globin subunits
what does hemoglobin do
carries oxygen throughout body
what happens to the HBB gene during point mutation
undergoes point mutation
-glutamic acid to valine at position 6
what is a frameshift mutation
insertion or deletion of one or several bases that may change all or part of the open reading frame
- changes polypeptide sequence of protein
how do small indels happen?
replication slippage (slipped strand mispairing) results in addition or deletion of nucleotides
how long are large indels
hundreds to thousands of nucleotides
what are some examples of large indels
- mobile DNA elements
- unequal crossing over of chromosomes
- expanded trinucleotide repeats
define trinucleotide repeats
3 nucleotides that are repeated several times in succession
- repeated a few to 50 times
- prone to mutations
what are trinucleotide repeats also called
mutation hot spots
