7.3 Meiosis

Front 1

Reduces the amount of genetic information

Back 1

Meiosis

Front 2

Involves two successive divisions of a diploid nucleus

Back 2

Meiosis

Front 3

Sperm or egg cell

Back 3

Gametes

Front 4

Number of chromosomes of gametes

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Haploid

Front 5

Occurs only in gonads (testes or ovaries)

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Meiosis

Front 6

Development of sperm cell

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Spermatogenesis

Front 7

Development of egg cell

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Oogenesis

Front 8

Pairing of homologous chromosomes forming a tetrad

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Synapsis

Front 9

2 chromosomes or 4 chromatids

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Tetrad

Front 10

Chromatids of tetrad exchange parts/genetic material; this allows greater variety in the gametes

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Crossing over

Front 11

Site of crossing over

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Chiasmata

Front 12

Pair of chromosomes (maternal and paternal) that are similar in shape and size

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Homologous chromosomes

Front 13

Homologous pairs carry genes controlling the ______ inherited traits

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Same

Front 14

Position of a gene

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Locus

Front 15

Humans have ___ pairs of homologous chromosomes

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23

Front 16

The first 22 pairs of human chromosomes are

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Autosomes

Front 17

The last pair of human chromosomes is

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Sex chromosome (XX or XY)

Front 18

Results in reducing the number of chromosomes (reduction division)

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Meiosis I

Front 19

Tetrads to dyads

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Meiosis I

Front 20

This stage is called reduction division

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Meiosis I

Front 21

Similar to mitotis interphase

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Interphase I

Front 22

Chromosomes (DNA) replicate in the S phase

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Intephase I

Front 23

Each duplicated chromosome consist of two identical sister chromatids attached at their centromeres

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Interphase I

Front 24

Nucleus and nucleolus are visible

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Interphase I

Front 25

Longest and most complex phase

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Prophase I

Front 26

Chromosomes condense

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Phrophase I

Front 27

Synapsis occurs

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Prophase I

Front 28

Tetrads or homologous chromosomes move to the center of the cell

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Metaphase I

Front 29

Homologous chromosomes pulled to opposite poles

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Anaphase I

Front 30

Sister chromatids remain attached at centromere regions

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Anaphase I

Front 31

Dyads complete their migration to opposite poles

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Telophase I

Front 32

Daughter nuclei formed

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Telophase I

Front 33

Results to haploid daughter cells and no additional replication occurs

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Meiosis II

Front 34

Separation of sister chromatids

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Meiosis II

Front 35

Spindle fibers form again

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Prophase II

Front 36

The chromosomes condense again, following a brief interphase in which DNA does not replicate

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Prophase II

Front 37

Dyads contract

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Prophase II

Front 38

Sister chromatid move to the center

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Metaphase II

Front 39

Centromeres are directed to the equatorial plat and then divide

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Metaphase II

Front 40

Kinetochores of the paired chromatids line up across the equator of each cell

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Metaphase II

Front 41

Centromeres split

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Anaphase II

Front 42

Individual chromosomes are pulled to poles

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Anaphase II

Front 43

The chromatids of the chromosomes finally separate, becoming chromosomes in their own right, and are pulled to opposite poles

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Anaphase II

Front 44

Monads are at the poles, forming two groups of chromosomes

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Telophase II

Front 45

The chromosomes gather into nuclei, and the cells divide

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Telophase II

Front 46

Similarities of mitosis and meiosis

Back 46

-nuclear division

-involve replication

-involve disappearance of the nucleus, nucleolus, nuclear membrane

-formation of spindle fiber

Front 47

Differences of meilsis and mitosis

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-meiosis: haploid, mitosis: diploid

-daughter cells in meiosis are not genetically identical

-meisois: cell division twice, replication once

Front 48

The rearrangement of genetic material, especially by crossing over in chromosomes or by the artificial joining of segments of DNA from different organisms

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Recombination

Front 49

Differences between members of a population

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Variation

Front 50

Results in random separation of chromosomes in gametes

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Meiosis

Front 51

Causes diverse population that over time can be stronger for survival

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Recombination and variation