meiosis lesson

REVIEW

GIVE THE STAGES OF EACH ILLUSTRATION

Producing Haploid

Daughter cells

MEIOSIS

OBJECTIVES

1. Define Meiosis.

2. Enumerate the stages of Meiosis.

3. Give the significance of Meiosis in

Sexual Reproduction.

Meiosis- Consists of two successive divisions of the nucleus called meiosis I and meiosis II

- Results in four haploid daughter cells

- Only happens in the sex gonads ( testes and ovary)

Stages of MeiosisFirst Meiotic Division• Prophase I• Metaphase I• Anaphase I• Telophase ISecond Meiotic Division• Prophase II• Metaphase II• Anaphase II• Telophase II

Events for First Meiotic Division

• Prophase I- chromosome becomes visible and the nuclear membrane disappears; homologous chromosome appears and share fragments called crossing over

Metaphase I- complete disappearance of nuclear membrane and appearance of spindle fiber; centromeres attached to the spindle fiber and lies on the metaphase plate or central plate

Anaphase I- homologous chromosome separates from each other but centromere do not divide; chromosome continues to consists of two chromatids

Telophase I- chromosomes are still doubled; nuclear membrane is formed and disappearance of spindle fiber

Second Meiotic Division

Prophase II- cells have one chromosome

Metaphase II- chromosomes align at the metaphase plate; centromeres divide thus separating the chromatids

Anaphase II- each new daughter cell move towards opposite poles

Telophase II- spindle disappears; nuclear membrane is formed; nuclei are formed and cytokinesis happens

Gametogenesis - a process of producing sex cells

• Spermatogenesis- sperm production; occurs during puberty stage and continues throughout life

• Oogenesis- production of female gametes or ova

Oogenesis

SeatworkAnswer Activity Sheet on “ Inferring Difference”

E:\Seatwork #3 in meiosis.docx

Assignment #4• Answer activity sheet on Sexual reproduction in lower forms of life and animals