Meiosis

Question 1

What are the 4 phases of meiosis 1?

Answer 1

• prophase 1
• metaphase 1
• anaphase 1
• telophase1/cytokinesis

Question 2

Describe prophase 1

Answer 2

• typically occupies more than 90% of time
• chromosomes begin to condense
• homologous chromosomes loosely pair up aligned gene by gene

Question 3

What is a homologous pair lined up called?

Answer 3

Tetrad (4 chromatids)

Question 4

What’s the main difference between meiosis and mitosis

Answer 4

Mitosis conserves the number of chromosome sets, producing cells that are genetically identical to parent cell whereas meiosis reduces number of chromosomes from diploid to haploid that are different genetically from parent cells and each other

Question 5

Describe Metaphase 1

Answer 5

• retreads Line up in metaphase plate with one pair facing each pole
• microtubules are attached to the keneticore of the homologous pair closest to their pole

Question 6

Describe anaphase 1

Answer 6

• pairs of homologous chromosomes separate
• migrate to poles by spindle apparatus
• sister chromatids remain attached and move as one toward pole

Question 7

Describe telophase 1 and cytokenisis

Answer 7

• each half of a cell has a haploid set of chromosomes sill consisting of 2 sister chromatids
• cytokinesis usually occurs simultaneously forming two haploid daughter cells
• chromosomes to not replicate because already replicated

Question 8

What are the 4 phases of meiosis 2

Answer 8

• prophase2
• metaphase2
• anaphase2
• telophase2/cytokinesis

Question 9

Describe prophase 2

Answer 9

• spindle apparatus forms

- in late prophase 2 chromosomes move toward metaphase plate

Question 10

Describe metaphase 2

Answer 10

• sister chromatids are arranged at metaphase plate
• sister chromatids are no longer the same because of crossing over
• keneticore of sister chromatids attach to spindle apparatus

Question 11

Describe anaphase 2

Answer 11

• sister chromatids separate

- migrate to poles from spindle apparatus

Question 12

Describe telophase 2 and cytokinesis

Answer 12

• chromosomes arrive at poles
• nuclei begin to form
• cytokinesis desperate cytoplasm
• 4 daughter cells created, each with haploid set of Unreplicated chromosomes
• genetically distinct from parent cell

Question 13

What do mutations create?

Answer 13

Different versions of genes called Alleles

Question 14

What produces genetic variation?

Answer 14

Reshuffling of Alleles during reproduction

Question 15

What is responsible for most variation that arrises in each generation?

Answer 15

The behaviour of chromosomes during meiosis and fertilization

Question 16

What are the three mechanisms that contribute to genetic variation?

Answer 16

• Independent assortment of chromosomes
• crossing over
• random fertilization

Question 17

When does crossing over begin?

Answer 17

Very early in in prophase 1 when homologous chromosomes are lining up gene by gene

Question 18

What is crossing over

Answer 18

When homologous portions of 2 non sister chromatids Thrace places

Question 19

How does crossing over contribute to genetic variation?

Answer 19

By combining DNA from 2 parties into a single chromosome

Question 20

What does each zygote have?

Answer 20

A unique genetic identity