lecture 5

Question 1

list point mutation types

Answer 1

• Point mutation:
  Pyrimidine to pyrimidine or
  purine to purine (transition)
  Pyrimidine to purine
  (transversion)
  Silent mutations: result in
  the same amino acid.
  Nonsense
  Missense

Question 2

describe silent mutations

Answer 2

Silent mutations: result in the same amino acid

Question 3

describe nonsense and missense mutations

Answer 3

○ Nonsense- can be a truncated protein if the code is changed to a stop codon
○ Missense - the substitution of the base pair results in a different amino acid
§ Conservative: no change in the function
§ Non-conservative: change in the function

Question 4

describe frameshift mutations

Answer 4

• Frameshift mutations:
  ○ Insertions and deletions (indel)
  Causes a shift in the whole reading frame for producing a specific protein

Question 5

describe chromosomal mutations

Answer 5

○ When a whole segment is deleted, translocated, duplicated, or inverted

Question 6

what do mutations lead to? when do they have a direct evolutionary consequence?

Answer 6

• Lead to evolution
  
  • Mutation is the ultimate source of all genetic variations
  • All alleles start as mutations
  • A mutation will have a direct evolutionary consequence only if it occurs in a sex cell (gametes) - the only way a mutation can be passed to the next generation

Question 7

how is a mutation random? why are they evolutionary?

Answer 7

• A mutation is random with respect to its evolutionary significance
  
  • A mutation is an evolutionary force bc it leads to a change in allele frequency over time
  • Mutation is important to produce a change over time, but there are other forces that change allele frequency
  • They are necessary but not sufficient

Question 8

what debate surrounds neutrality of evolution?

Answer 8

• Kimura believed that mutations are neutral - changes in the dna sequence that are neither beneficial nor detrimental to the ability of an organism to survive or reproduce

Question 9

how has mutation in covid 19 been examined

Answer 9

• In looking at the genomes that were coming in from wuhan, we could see that there was very little genetic diversity
  
  • The low number of mutations not only told him the virus is new in humans, it also corrected an early misunderstanding and revealed that the virus was spreading easily between humans
  • From animals to humans sometime around mid nov 2019 - from here followed the mutations

Question 10

who looked at chromosomal inversions? what are transposible elements

Answer 10

obzhansky looked at chromosomes in fruit flies - tried to find the mutations in these chromosomes and how it impacted their behavior etc
* Transposable elements
* Sequences of dna that move/jump from one location of the genome to another
*
* Introduced by Barbra Mclintock In 1940s
* Was assumed to be “junk DNA” without impact - not true