8.1- Origins of Genetic Variation

Question 1

where do new variations in a genome arise from?

Answer 1

mutations

Question 2

what is a mutation?

Answer 2

permanent change to the DNA of a cell

Question 3

what are the types of mutations?

Answer 3

point/gene mutations; substitution, deletion, insertion
chromosomal mutations; translocation
loss/duplication of entire chromosomes

Question 4

give the two sources of genetic variation

Answer 4

crossing over
independent assortment
random fertilisation

Question 5

what is crossing over?

Answer 5

homologous chromosomes form bivalents
chiasma are formed, where sections of DNA are exchanged between non-sister chromatids
this leads to recombinant chromosomes with new combinations of alleles

Question 6

what is independent assortment?

Answer 6

occurs during metaphase of meiosis I
either a pair of homologous chromosomes, paternal or maternal, can migrate to either pole
this leads to massive numbers of genetically varied gametes

Question 7

what is random fertilisation?

Answer 7

fusing of two gametes between 7.3 billion humans in sexual reproduction to form a zygote is another random process causing variation

Question 8

give the common sampling errors

Answer 8

chance- combinations of alleles is a random process
death- some offspring die before being sampled
inefficient sampling techniques- difficult to sample small organisms