Chapter 13

Question 1

Meiosis

Answer 1

Important for gametes. Produces haploid cells (n), and no 2 gametes are the same. Important for variation.

Involves Interphase, Meiosis I and Meiosis II. Results in 4 daughter cells. Half as many chromosome as parent cell.

Question 2

Locus

Answer 2

A gene’s specific location along the length of a chromosome. Plural: loci, from Latin, meaning “place.”

Question 3

Genetics

Answer 3

The study of both heredity and inherited variation.

Question 4

Gametes

Answer 4

Reproductive cells in plants and animals that are the vehicles that transmit genes from one generation to the next. Haploids in all 3 sex cycles.

Question 5

Somatic Cells

Answer 5

2n. Any cell of a living organism other than the reproductive cells. Also known as autosomal cells.

Question 6

Karyotype

Answer 6

1-22 chromosomes. Sex chromosomes are either X X, or X Y.

Question 7

Homologous Chromosomes (Homologs)

Answer 7

2 chromosomes of a pair have the same length, centromere position, and staining pattern. Both chromosomes of each pair carry genes controlling the same inherited characters. TETRSADS

Same length, centromere position, and staining pattern.

Question 8

Diploid cells

Answer 8

Diploid number of chromosomes, abbreviated 2n. Differ per species.

Question 9

Haploid cells

Answer 9

Haploid number of chromosomes, or n. n = 23 in humans, 22 autosomes plus a single sex cell. Gametes are haploid.

Question 10

Autosomes

Answer 10

Any chromosome that is not a sex chromosomes.

Question 11

Zygote

Answer 11

Fertilized egg. Is diploid, since it contains 2 haploid sets of chromosomes.

Question 12

Tetrads

Answer 12

Specifically when there is four chromosomes together. Homologs can refer to the double ones, but tetrads are specifically the 4. Tetra.

Question 13

Prophase I

Answer 13

When synapsis and crossing over occur.

Question 14

Metaphase I

Answer 14

No prometaphase, since there is no nuclear envelope. Alignment of homologs at the metaphase plate.

Question 15

Anaphase I

Answer 15

Separation of homologs. Sister chromatids of each duplicated chromosome remain attached.

Question 16

Second division

Answer 16

Cells divide twice in meiosis unlike mitosis, where they only divide once. Results in 4 daughter (haploid) cells instead of 2 (diploid) cells.

Meiosis 2 = mitosis without pro-metaphase and prophase.

Question 17

Synaptonemal complex

Answer 17

A zipper-like protein that forms during crossing over. Attaches one homolog to the other. Once the synaptonemal complex is fully formed; the two homologs are said to be in synapsis.

Question 18

Synapsis

Answer 18

During synapsis, the DNA breaks, which are precise corresponding points on 2 sister chromatids, are closed up when each broken end is joined to the corresponding segment of the non-sister chromatid, producing crossovers.

Question 19

Crossing over

Answer 19

How DNA and variation exists. The sharing of precise sections of the homologs. Happens at the chiasma.
2 non sister chromatids.

Question 20

Chiasma (chiasmata for plural)

Answer 20

Point/points where crossing over has just occurred after the synaptonemal complex dissembles and the homologs move slightly apart from each other.

Question 21

Mitosis vs. Meiosis.

Answer 21

Mitosis: 2 identical daughter cells.

Meiosis: 4 haploid daughter cells. Has 2 phases of meiosis. No second S phase.

Question 22

Recombinant chromosmes

Answer 22

Individual chromosomes that carry genes (DNA) from 2 different parents.