Meiosis and Sexual Life Cycles

Page
5

in diploid parent cell

Chromosomes

replicate

Homologous pair of replicated chromosomes

Sister

chromatids

Diploid cell with

replicated

chromosomes

Slide 35

Fig. 13-7-2

Interphase

Homologous pair of chromosomes

in diploid parent cell

Chromosomes

replicate

Homologous pair of replicated chromosomes

Sister

chromatids

Diploid cell with

replicated

chromosomes

Meiosis I

Homologous

chromosomes

separate

1

Haploid cells with

replicated chromosomes

Slide 36

Fig. 13-7-3

Interphase

Homologous pair of chromosomes

in diploid parent cell

Chromosomes

replicate

Homologous pair of replicated chromosomes

Sister

chromatids

Diploid cell with

replicated

chromosomes

Meiosis I

Homologous

chromosomes

separate

1

Haploid cells with

replicated chromosomes

Meiosis II

2

Sister chromatids

separate

Haploid cells with unreplicated chromosomes

Slide 37

Meiosis I is preceded by interphase, in which chromosomes are replicated to form sister chromatids

The sister chromatids are genetically identical and joined at the centromere

The single centrosome replicates, forming two centrosomes

BioFlix: Meiosis

Slide 38

Fig. 13-8

Prophase I

Metaphase I

Anaphase I

Telophase I and

Cytokinesis

Prophase II

Metaphase II

Anaphase II

Telophase II and

Cytokinesis

Centrosome

(with centriole pair)

Sister

chromatids

Chiasmata

Spindle

Homologous

chromosomes

Fragments

of nuclear

envelope

Centromere

(with kinetochore)

Metaphase

plate

Microtubule

attached to

kinetochore

Sister chromatids

remain attached

Homologous

chromosomes

separate

Cleavage

furrow

Sister chromatids

separate

Haploid daughter cells

forming

Slide 39

Division in meiosis I occurs in four phases:

– Prophase I

– Metaphase I

– Anaphase I

– Telophase I and cytokinesis

Slide 40

Metaphase I

Fig. 13-8a

Prophase I

Anaphase I

Telophase I and

Cytokinesis

Centrosome

(with centriole pair)

Sister

chromatids

Chiasmata

Spindle

Homologous

chromosomes

Fragments

of nuclear

envelope

Centromere

(with kinetochore)

Metaphase

plate

Microtubule