Meiosis And Recombination

Question 0

What is the goal of meiosis?

Answer 0

• make four haploid gamete that are not identical to the original
• when they combine you get a diploid

Question 1

What is the goal of mitosis

Answer 1

-end up with two identical cells to the original that are both diploid

Question 2

Interphase of meiosis

Answer 2

• Where cells spend a majority of their time

- where all the genetic material is replicated

Question 3

Prophase I

Answer 3

• centrioles migrate to their poles
• homologous chromosomes pair up and form a tetrad
• crossing over
• longest step in meiosis
• nuclear envelope is disappearing

Question 4

Metaphase I

Answer 4

-tetrads line up across metaphase plate

Question 5

Anaphase I

Answer 5

• pulling apart homologous sets of chromosomes

- pulling apart tetrads

Question 6

Telophase I and cytokenesis

Answer 6

Makes two haploid cells

Question 7

Prophase II

Answer 7

• nuclear envelope disappears

- centromeres migrate to opposite poles

Question 8

Metaphase II

Answer 8

Sister chromatids line up on metaphase plate

Question 9

Anaphase II

Answer 9

Sister chromatids are pulled apart

Question 10

Telephase II and cytokenesis

Answer 10

End up with four haploid gametes

Question 11

What do we pull apart in meisis I? II?

Answer 11

I:Tetrads
II: sister chromatids

Question 12

Problems in meiosis

Answer 12

1. Nondisjunction

2. Translocation

Question 13

Nondisjunction

Answer 13

• failure of tetrads to separate during meiosis i or sister chromatids in meiosis
• can lead to:
  1. Down syndrome (trisomy 21)
  2. Turner syndrome (x)
  3. Kleinfelter syndrome (xxy)

Question 14

Nondisjuction in meiosis I

Answer 14

Creates two trisomies and two monosomies

Question 15

Nondisjunction in meiosis II

Answer 15

Makes one trisomy
One monosomy
Two normal

Question 16

Is nondisjunction in meiosis I or II worse?

Answer 16

Meiosis I because there are no normal cells

Question 17

Translocation

Answer 17

• movement of a segment of one chromosome to another non-homologous chromosome
• ex is down syndrome.. Chromosome 21 -> chromosome 14

Question 18

Recombination

Answer 18

• single crossover

- double crossover

Question 19

Linked genes

Answer 19

• genes on the same chromosome that probably will not undergo independent assortment
• the closer together on the chromosome the greater the linkage between genes
• the liklihood of recombination increases with distance between genes
• –when genes are closer they are less likely to undergo recombination and are more likely linked