Topic 2

Question 1

describe synapsis

Answer 1

• occurs during early prophase 1
• the homologous chromosomes become closely associated with one another and are attached to each other by a structure called synaptonemal complex
• the paired homologues can physically exchange their parts by crossing over or re-combination

Question 2

describe the crossing over process

Answer 2

• genetic recombination that occurs between non sister chromatids
• allows homologues to exchange chromosomal material
• the alleles of genes that were formerly found on separate homologues can now be found on the same homologue
• chiasmata is the site where the chromosomes cross over, the contact is maintained until anaphase 1

Question 3

evolutionary change is quickened my genetic recombination resulting from sexual reproduction and meiosis, what are the 3 major ways?

Answer 3

• independent assortment
• crossing over
• random fertilization

Question 4

what is independent assortment

Answer 4

random assortment of maternal and paternal chromosome into gametes during meiosis 1

Question 5

what is crossing over

Answer 5

DNA exchange between arms of non sister chromatids during prophase 1 of meiosis

Question 6

what is random fertilization

Answer 6

zygote forms a new individual due to the random fusion of two gametes

Question 7

describe the random orientation of each cell on the metaphase plate

Answer 7

• the number of possible different chromosome orientation on the metaphase plate would be 2 to the power of the number of chromosome pairs
• each orientation produces gametes with different combinations parental chromosomes