Meiosis

Question 1

What is a homologous pair?

Answer 1

Chromosomes that code for the same trait. They can have different information though. They different versions, or alleles, of the same gene.

Question 2

What do homologous pairs have that sister chromatids dont?

Answer 2

1. One comes from mom, one from dad

2. Have different versions of the same genes

Question 3

What do sister chromatids have that homologous pairs dont?

Answer 3

1. Bound together by centromeres
2. Chromatids are identical
3. Product of DNA replication

Question 4

What is represented by “n”?

Answer 4

The number of pairs or different types of chromosomes(haploids).

Question 5

What is represented by “2n”?

Answer 5

The total number of chromosomes(diploids)

Question 6

What is a haploid?

Answer 6

A cell that has 1 copy of each type of chromosome(Human gametes)

Question 7

What is a diploid?

Answer 7

A cell that has 2 copies of each type of chromosome.(Human somatic cells)

Question 8

What is the result of meiosis?

Answer 8

4 haploid, gamete, daughter cells with half the number of chromosomes that the parent cell has.

Question 9

What are gametes?

Answer 9

Cells with only half the “normal” number of chromosomes.

Question 10

What is fertilization?

Answer 10

The joining of gametes, the result is an individual cell with the same number of chromosomes as the parent.

Question 11

What happens in the interphase of meiosis 1?

Answer 11

• Cell spends 90% of its life in this phase.
• Growth
• Cell carries out life processes
• Chromosome(DNA) replication takes place
• Centrioles replicate

Question 12

What is synapsis?

Answer 12

The process of homologous chromosomes coming together, and “crossing over” occurs. The result ks the formation of tetrads.

Question 13

What happens in prophase 1?

Answer 13

• Homologous chromosomes join together(synapsis)
• Tetrads are formed
• Crossing over occurs
• Centrioles move away from each other
• Nuclear membrane disappears
• Spindles and asters appear

Question 14

What is a tetrad?

Answer 14

A group of 4 chromatids bound together after the homologous pairs have “crossed” over.

Question 15

What happens in metaphase 1?

Answer 15

•Chromosomes that are now grouped as homologous pairs align on the equator

Question 16

What happens in anaphase 1?

Answer 16

• Sister chromatids remain attached at centromeres
• Replicated chromosomes move to opposite poles
• Homologous pairs separate

Question 17

What happens in telophase 1?

Answer 17

• Chromosomes reach poles
• Cells start to cleave
• Two non-identical haploid cells are produced
• Cytokenesis occurs
• New cells may or may not enter a brief interphase

Question 18

What is chiasma?

Answer 18

The point or space where two homologous pairs cross over.

Question 19

What happens in prophase 2?

Answer 19

• Spindle forms
• Replicated chromosomes move towards equator
• Any nuclear membrane that may have formed from meiosis 1 disappears

Question 20

What happens in metaphase 2?

Answer 20

•Replicated chromosomes line up on equator

Question 21

What happens in Anaphase 2?

Answer 21

•Sister chromatids move towards opposite poles

Question 22

What happens in telophase 2?

Answer 22

• Nuclear membranes form at opposite poles
• Cytokinesis occurs(division of cell)
• 4 haploid cells are produced

Question 23

What are the 4 main differences between meiosis and mitosis?

Answer 23

1. In meiosis in prophase 1, homologous chromosomes pair up, unlike in mitosis
2. In meiosis, homolougous pairs align on the equator in metaphase 1
3. In meiosis in anaphase 1, homologous pairs of chromosomes separate, NOT pairs of sister chromatids
4. Meiosis results in 4 haploid daughter cells, and mitosis results in two diploid daughter cells.

Question 24

What is gametogenesis?

Answer 24

The production of gametes.

Question 25

What is spermatogenesis?

Answer 25

The production of sperm cells.

Question 26

What is Oogenesis?

Answer 26

The production of egg cells.

Question 27

What do gametogenesis, spermatogenesis, and oogenesis have in common?

Answer 27

1. All of meiotic divisions | 2. They all result in haploid gametes

Question 28

What are pros and cons of sexual reproduction?

Answer 28

Pro: Genetic variation Con: Requires another individual

Question 29

Why is genetic variation good?

Answer 29

1. Organisms the have variety are less likely to all be invaded by pathogens or parasites 2. Differential reproductive success 3. Able to adapt better

Question 30

What are the sources of varitation?

Answer 30

1. Crossing over-Exchanges more genetic material | 2. Independent assortment-Over 8 million combinations from just two parents for humans

Question 31

What is the result of fertilization?

Answer 31

A zygote, represented by 2n.

Question 32

What is darwin evolution?

Answer 32

* The foundation of adaptation | * "Only the strongest survive", best adapted are most likely to survive.

Question 33

What is artificial insemination?

Answer 33

* Semen is collected from male * Semen is inserted into female by artificial means * Pregnency/birth is natural * The mother is the biological mother and carries her own baby

Question 34

What is invitro fertilization?

Answer 34

* Sperm and ovum are united outside the female * Zygote is allowed to develop until 8 cell stage * "embryo" is implanted into the female, this could be an egg donor or surrogate mother. * Egg donor is usually treated with fertility drugs to "super" ovulate * Multiple "embryos" usually implanted * Extra embryos can be frozen and used later if others arent successful

Question 35

What is the cloning process?

Answer 35

* Egg cell is enucleated * 2n nucleus from individual to be cloned is inserted * "Zygote" clone is incubated until the 8-cell stage * Embryo is implanted into uterus of surrogate mother * Goes through gestation and birth

Question 36

What is a chromosome?

Answer 36

A long strand of genes. Humans have 23 pairs, we get one set from mom, and one from dad.