Meiosis and Sexual Life Cycles

Page
8

Fig. 13-9

MITOSIS

MEIOSIS

MEIOSIS I

Prophase I

Chiasma

Homologous

chromosome

pair

Chromosome

replication

Parent cell

2n = 6

Chromosome

replication

Replicated chromosome

Prophase

Metaphase

Metaphase I

Anaphase I

Telophase I

Haploid

n = 3

Daughter

cells of

meiosis I

Anaphase

Telophase

2n

2n

Daughter cells

of mitosis

n

n

n

n

MEIOSIS II

Daughter cells of meiosis II

SUMMARY

Meiosis

Occurs during interphase before meiosis I begins

Two, each including prophase, metaphase, anaphase, and

telophase

Occurs during prophase I along with crossing over

between nonsister chromatids; resulting chiasmata

hold pairs together due to sister chromatid cohesion

Four, each haploid (n), containing half as many chromosomes

as the parent cell; genetically different from the parent

cell and from each other

Produces gametes; reduces number of chromosomes by half

and introduces genetic variability amoung the gametes

Mitosis

Occurs during interphase before

mitosis begins

One, including prophase, metaphase,

anahase, and telophase

Does not occur

Two, each diploid (2n) and genetically

identical to the parent cell

Enables multicellular adult to arise from

zygote; produces cells for growth, repair,

and, in some species, asexual reproduction

Property

DNA

replication

Number of

divisions

Synapsis of

homologous

chromosomes

Number of

daughter cells

and genetic

composition

Role in the

animal body

Slide 60

Fig. 13-9a

MITOSIS

MEIOSIS

MEIOSIS I

Prophase I

Chiasma

Chromosome

replication

Homologous

chromosome

pair

Chromosome

replication

2n = 6

Parent cell

Prophase

Replicated chromosome

Metaphase

Metaphase I

Anaphase I

Telophase I

Haploid

n = 3

Daughter

cells of

meiosis I

MEIOSIS II

Daughter cells of meiosis II

n

n

n

n

2n

2n

Daughter cells

of mitosis

Anaphase

Telophase

Slide 61

Fig. 13-9b

SUMMARY

Meiosis

Mitosis

Property

DNA

replication

Number of

divisions

Occurs during interphase before

mitosis begins

One, including prophase, metaphase,

anaphase, and telophase

Synapsis of

homologous

chromosomes

Does not occur

Number of

daughter cells

and genetic

composition

Two, each diploid (2n) and genetically

identical to the parent cell

Role in the

animal body

Enables multicellular adult to arise from

zygote; produces cells for growth, repair,

and, in some species, asexual reproduction