8.3.3 Meiosis: Prophase I

Question 1

note

Answer 1

• Review: In order for sexual reproduction to occur, haploid cells (also called gametes) must be produced from diploid cells in a process called meiosis. Diploid cells have two sets of each chromosome, while haploid cells have only one set of each chromosome. Two haploid cells can fuse during fertilization to produce a diploid cell with two sets of each chromosome (one set from each haploid cell).
  • Review: Homologous chromosomes are the two chromosomes within a chromosome pair that have the same genetic composition.
  • The process of meiosis involves two divisions with phases in each division similar to the phases in mitosis. The first division (meiosis I) involves splitting the homologous chromosomes from each other into two different cells. The second division (meiosis II) involves separating sister chromatids of a replicated chromosome into two different cells.

Question 2

prophase I

Answer 2

• In prophase I, the chromosomes become highly condensed. The homologous chromosomes synapse or pair up with each other and become tightly joined (the pairing up is called synapsis). When in synapsis, the joined chromosomes can be called tetrads (emphasizing the four chromatids).

Question 3

chiasmata

Answer 3

• Chiasmata (singular: chiasma) form within regions of the synapsed chromosomes. Chiasmata are areas where crossing over between the two homologous chromosomes occurs. At the location of the chiasma, genetic material is exchanged between homologous chromosomes.

Question 4

All of the following are functions of meiosis except:

Answer 4

• Production of identical daughter cells

Question 5

The centromere is the location where

Answer 5

• chromatids are attached to one another

Question 6

Which of the following statements regarding homologous chromosomes is true?

Answer 6

• They have genes for the same traits

Question 7

The chiasma connects a pair of:

Answer 7

• homologous chromosomes during meiosis I

Question 8

Crossing over can contribute to genetic variation by exchanging genetic material between

Answer 8

• nonsister chromatids of homologues

Question 9

True or false?
A synapsis is the X-like formation that represents an exchange of genetic material between chromatids on homologous chromosomes.

Answer 9

• false