fundamental molecular lecture 1 mutations 1

Question 1

what is a mutation?

Answer 1

mutations are changes in the genetic material of a cell and any heritable alteration in the genetic material.

Question 2

what is does genetics focus on?

Answer 2

traditionally any heritable mutations in genes

Question 3

what is the definition of a gene?

Answer 3

a gene is a genomic sequence such as DNA directly encoding functional product molecules, either RNA or protein

Question 4

what does natural selection require?

Answer 4

genetic differences, generated by sex (recombination) and by spontaneous mutation

Question 5

what is the rate of spontaneous mutation?

Answer 5

3 new mutations per 108 base pairs per generation (in 6 billion bps, diploid)
~ 200 new mutations in each human child, including YOU

Question 6

how do you find the net mutation?

Answer 6

DNA damage - repair

Question 6

how do you increase the net mutation rates?

Answer 6

-increasing the rate of DNA damage such as sunbathing and holidaying in Chernobyl
-reducing repair efficiency such as bright sunlight

Question 7

what are the features of a germ line cell?

Answer 7

• 1 cell
• passed on to the next generation as it reproduces the organism
• can differentiate into somatic cells
• low mutation rates ( around 200/ generation)

Question 8

what are the features of a somatic cell?

Answer 8

• genetic dead end
• disposable to natural selection
  -cant reproduce the organism but its essential for germline cells
• higher mutation rate (10X, 100X..)

Question 9

Why do most mutations not have an effect?

Answer 9

most random mutations affect unimportant regions such as between exons or between genes. most mutations do not change phenotype.

Question 10

when do mutations affect phenotype?

Answer 10

when they affect important parts (1-2% of genome) such as regulatory regions or key functional residues

Question 11

what is a silent mutation?

Answer 11

when a letter changes but it doesn’t result in a different protein being produced

Question 12

what is a nonsense mutation?

Answer 12

when a letter changes to create a stop codon

Question 13

what is a missense mutation?

Answer 13

when a letter changes resulting in a different protein being expressed

Question 14

why are do most mutations not have an affect?

Answer 14

most are recessive and can only affect phenotype when homozygous

Question 15

when do recessive mutations show?

Answer 15

when they are homozygous. if a mutation b is dominant then Bb shows mutant and if its recessive then its the wild type phenotype

Question 16

what does 2 recessive mutations require?

Answer 16

inbreeding. this is because the only way for recessive b mutation to affect phenotype is if two carriers (b/B) fall in love BUT this means they are inbreeding

Question 17

what is scientifically wrong with inbreeding?

Answer 17

on average we each carry 1-2 lethal mutations hence avoid incest as 2 copies could create a mutant phenotype