Biology Lab 9 Meiosis: Sexual Reproduction

Front 1

Meiosis

Back 1

Nuclear division which reduces the chromosome number so that the gametes have half the species number of chromosomes

- Two divisions

- Introduces variation because the chromosomes are shuffled and the genetic material is recombined

Front 2

Sperm

Egg

Back 2

Gametes (Sex Cells) for men and women

Front 3

Zygote

Back 3

Fusion of sperm and egg results in a ____________ that develops into a new individual

Front 4

Start of meiosis

Back 4

The parent cells have the full number of chromosomes and each is duplicated

Front 5

Following the two divisions of meiosis I and II

Back 5

Four daughter cells have only one copy of each type chromosome, and these chromosomes consist of only one chromatid

Front 6

Diploid (2n)

Back 6

containing two complete sets of chromosomes (called homologues), one from each parent

Front 7

Homologues

Back 7

Pair of chromosomes (2 chromatids)

Front 8

Tetrad

Back 8

Pair of homologues (Contains 2 pairs of sister chromatids or 4 chromatids altogether)

Front 9

Haploid (n)

Back 9

One from each pair of homologues, single set of unpaired chromosomes

Front 10

Synapsis

Back 10

Pairing up of homologues

Front 11

Prophase I

Back 11

Homologues pair up to tetrads, nuclear envelopes disintegrate

Front 12

Metaphase I

Back 12

Tetrads (Homologue pairs) are at the plate in the middle of the cell

Front 13

Anaphase I

Back 13

Homologues separate and move toward opposite poles

Front 14

Telophase I

Back 14

Poles have one chromosome from each tetrad (pair of homologues), nuclear envelope reappears

Front 15

Interkinesis

Back 15

Chromosomes still consist of two sister chromatids, cell plate divides the middle of the cell

Front 16

Prophase II

Back 16

Cells have one chromosome from each tetrad (pair of homologues), nuclear envelope disintegrates

- Diploid 2n

Front 17

Metaphase II

Back 17

Chromosomes bunch at metaphase plate with spindles

- Diploid 2n

Front 18

Anaphase II

Back 18

Daughter chromosomes move toward poles

- Haploid n

Front 19

Telophase II

Back 19

Daughter nuclei re-form: cytokineses takes place, cell plate forms to divide cells

- Haploid n

Front 20

Result of Meiosis

Back 20

Four haploid daughter cells

Front 21

Because when the sex cells (gametes) combine, they form a diploid (2n) to maintain the same number of chromosomes as the parent

Back 21

Why do sperm and egg have to be haploid?

Front 22

Diversity of genetic material in the gametes

Back 22

During meiosis, crossing over and independent separation of homologues leads to?

Front 23

Genetic material on a chromosome in a gamete can be different from that in the parent cell

Back 23

What is the result of crossing over during meiosis?

Front 24

All possible combinations of the haploid number of chromosomes can occur among the gametes

Back 24

What is the result of independent homologue separation?

Front 25

Life Cycle

Back 25

In sexually reproducing organisms refers to all the reproductive events that occur from one generation to the next (Involves both mitosis and meiosis)

Front 26

Mitosis

Back 26

- During development and after birth, involved in the continued growth of the child and the repair of tissues at any time

- Results in cells with the diploid number of chromosomes (2n = 46)

Front 27

Meiosis

Back 27

- During gamete formation, reduces chromosome number from diploid to haploid (n = 23) so that gametes (sperm and egg) have one chromosome derived from each tetrad (pair of homologues)

Front 28

Spermatogenesis

Back 28

Meiosis in males, occurs in the testes and produces sperm

Front 29

Oogenesis

Back 29

Meiosis in females, occurs in the ovaries and produces eggs

Front 30

Zygote

Back 30

After sperm and egg join during fertilization, the resulting haploid (2n)

Front 31

Keeps number of chromosomes constant between generations, and to be different from one another, resulting in variations

Back 31

Purpose of Meiosis

Front 32

Mitosis

Back 32

Number of Divisions 1

Chromosome number in daughter cells 46

Number of daughter cells 2

Front 33

Meiosis

Back 33

Number of Divisions 2

Chromosome number in daughter cells 23

Number of daughter cells 4

Front 34

Mitosis

Back 34

Prophase: No pairing of chromosomes

Metaphase: Duplicated chromosomes at metaphase plate

Anaphase: Sister chromatids separate

Telophase: Chromosomes have one chromatid

Front 35

Meiosis I

Back 35

Prophase I: Synapsis (homologues pair) and crossing over occur

Metaphase I: Homologues align at cell plate

Anaphase I: Homologues separate

Telophase: Daughter cells have 2 chromosomes, 1 from each tetrad

Front 36

Meiosis II

Back 36

Which metaphase where the haploid number of chromosomes alight at the metaphase plate of the spindle? (Mitosis, meiosis I, or meiosis II?)

Front 37

- Number of divisions: 1, 2

- Chromosome number in daughter cells: 46, 23

- Number of daughter cells: 2, 4

- Daughter Cells Identical and not identical

Back 37

Differences between mitosis and meiosis

Front 38

12

Back 38

If the cells of an organism have 12 chromosomes, what is the number of chromosomes at the metaphase plate during metaphase of mitosis?

Front 39

6

Back 39

If the cells of an organism have 12 chromosomes, what is the number of chromosomes at the metaphase plate during metaphase of meiosis II?

Front 40

Cell containing 2 nuclei each with 46 chromosomes

Back 40

Appearance of a cell that completes mitosis but not cytokinesis

Front 41

Cell containing 4 nuclei each with 23 chromosomes

Back 41

Appearance of a cell that completes meiosis but not cytokinesis

Front 42

Regeneration, growth

Back 42

In the life cycle of humans, when does mitosis occur?