meiosis

Question 1

what are the 2 classes of cells in a human

Answer 1

somatic cells- skin cells, liver cells, ect.
gametes- sperm cells and egg cells

Question 2

describe homologous chromosomes

Answer 2

Pairs of chromosomes that have the same structure- same size and the same genes (not identical), one chromosome from each parent

Question 3

When would a tetrad be able to form? with duplicated or unduplicated homologous pairs.

Answer 3

Tetrads form with duplicated homologous pairs

Question 4

Describe the similarities and differences of the chromosomes that make up a homologous pair.

Answer 4

Homologous pairs have around the same size, shape, and arrangement of genes, a pair consists of 1 chromosome from each parent, info of genes(alleles) may vary making the homologous chromosome pairs NOT identical

Question 5

What is the difference between a diploid and haploid cell? Give examples of diploid and haploid cells.

Answer 5

diploid= 2 sets of every chromosome, ex- somatic cells, product of mitosis
haploid= 1 set of every chromosome, ex- gametes/sex cells, product of meiosis

Question 6

What is the n number of a cell? How can you determine the value of that number in different species cells? Does the value of n in a species change if the cell is diploid or haploid?

Answer 6

n= the number of chromosomes in one set or the number of chromosomes in a haploid cell, diploid= 2n, haploid=n

Question 7

How are haploid cells formed?

Answer 7

Meiosis- when the homologous pairs are split in half in Anaphase 1 and telophase 1, the 2 newly created cells now has 1 type of each homologous pair, making haploid cells. And after the 2nd stage of meiosis, 4 new haploid cells are made.

Question 8

What is the main purpose of meiosis?

Answer 8

to create genetically unique gametes (sex cells)

Question 9

What types of cells undergo meiosis?

Answer 9

germ cells

Question 10

prophase I

Answer 10

Chromosomes condense, nuclear membrane breaks down, duplicated homologous chromosomes pair up forming a tetrad, crossing over occurs

Question 11

metaphase I

Answer 11

homologous chromosomes line up along equator- 1 duplicated chromosome on either side, mix of chromosomes from each parent on each side

Question 12

anaphase I

Answer 12

homologous chromosome pairs are separated, sister chromatids still together

Question 13

telophase I

Answer 13

nuclear membrane forms, cytokinesis occurs resulting in 2 haploid daughter cells with sister chromatids attached

Question 14

prophase II

Answer 14

chromosomes condense, nuclear membrane breaks down

Question 15

metaphase II

Answer 15

chromosomes line up along the equator- 1 sister chromatid on each side

Question 16

anaphase II

Answer 16

sister chromatids are separated

Question 17

telophase II

Answer 17

nuclear membrane forms, cytokinesis occurs which results in 4 unique haploid daughter cells w/ unduplicated chromosomes

Question 18

describe the number of daughter cells after meiosis I

Answer 18

2 daughter cells

Question 19

compare their genetic make-up of the cells after meiosis I

Answer 19

pairs of homologous cells separate, the homologous chromosomes are similar not identical (not genetically identical) due to not being the same at first+crossing over that occurred in prophase 1

Question 20

diploid or haploid cells after meiosis I

Answer 20

haploid

Question 21

in a human cell - describe the number of autosomes and sex chromosomes

Answer 21

22 pairs individual autosomes, 1pair sex chromosome (xx or xy)

Question 22

describe the # of cells after meiosis II

Answer 22

4 daughter cells

Question 23

genetic make-up of the cells after meiosis II

Answer 23

all are genetically unique to each other (due to the crossing over that occurred and independent assortment in meiosis 1)

Question 24

number of autosomes and sex chromosomes after meiosis 2

Answer 24

23 total chromosomes- 22 autosomes, 1 sex chromosome

Question 25

end result of mitosis vs meiosis

Answer 25

mitosis- 2 genetically identical diploid cells, meiosis- 4 genetically unique haploid cells

Question 26

differences of processes in mitosis and meiosis

Answer 26

mitosis- 1 stage of division, asexual reproduction, 2 daughter cells produced, diploid, no genetic variation Meiosis- 2 stages of division, sexual reproduction, 4 daughter cells produced, haploid, lots a genetic variation, homologous pairs initially but then separated, crossing over occurs in prophase 1

Question 27

overall purpose of mitosis

Answer 27

growth and repair, make identical body cells

Question 28

overall purpose of meiosis

Answer 28

contributes to genetic variation, makes gametes

Question 29

When does independent assortment happen - what process and what phase. What is necessary for it to happen.

Answer 29

Metaphase and anaphase 1- when the homologous pairs line up in the middle during metaphase, they have a 50/50 chance of moving to either pole during anaphase, making the variation of genes completely random which contributes to genetic variation

Question 30

What happens and why can it only happen in meiosis and not mitosis for independent assortment

Answer 30

independent assortment requires homologous pairs to randomly separate, and this pairing up only occurs in meiosis (during prophase 1 and metaphase 1) and not in mitosis

Question 31

how does independent assortment contribute to genetic variation

Answer 31

leads to random combinations of maternal and paternal chromosomes in the resulting gametes

Question 32

When does it happen - what process and what phase. What is necessary for it to happen for crossing over

Answer 32

Occurs during prophase 1, is the exchanging of genetic material between homologous chromosomes, is necessary for genetic variation (genetic diversity)

Question 33

What happens and why can it only happen in meiosis and not mitosis for crossing over

Answer 33

happens in meiosis because its whole purpose is to produce genetically diverse gametes, while mitosis has the purpose of producing genetically identical cells for growth and repair

Question 34

how does crossing over contribute to genetic variation

Answer 34

when the pieces of chromosomes are swapped, the alleles are swapped which creates new combinations of genotypes= new phenotypes

Question 35

What processes lead to chromosomal abnormalities within a single chromosome?

Answer 35

A mistake in DNA replication, Deletion: removes a segment of chromosome Duplication: repeats a segment Inversion: reverses a segment within a chromosome Translocation: piece is broken off and added to another chromosome

Question 36

What process leads to additional chromosomes in a gamete and thus offspring?

Answer 36

Nondisjunction- pairs of homologous chromosomes/sister chromatids don’t separate normally during meiosis, resulting in gametes having extra copies of chromosomes while others receive no copies of chromosomes