Reproduction of OrganismsWhy do living things reproduce?

Why does an offspring not receive all traits of each parent?

How are organisms that do not reproduce by sexual reproduction still able to reproduce?

Sexual Reproduction and Meiosis

• Distinguish between the cell cycle ( asexual reproduction) and meiosis (sexual reproduction) a reduction division

• What kind of cells does the cell cycle produce?

• What kind of cells do you think meiosis produces---diploid or haploid?

• What are other terms for sex cells---egg or sperm cells ( germ cells or gametes)?

Analyze the Vocabulary

• Asexual reproduction, sexual reproduction, the cell cycle, meiosis, gametes, diploid, haploid, mutation, binary fission, (2n) chromosome number, (n) chromosome number,

• Zygote, fertilization, homologous chromosomes, egg, sperm

Lesson 1: Sexual Reproduction

&MeiosisDIPLOID CELLS REDUCTION OF

HOMOLOGOUS CHROMOSOME PAIRS TO HAPLOID SET OF CHROMOSOMES

MEIOSIS OCCURS IN FORMATION OF GAMETES

• How does the meaning of single relate to haploid?

• What are the two phases of meiosis called?

• If there are two divisions of the nucleus, why aren’t there four times as many chromosomes in the sex cells?

• Identify the phases of meiosis I and meiosis II

Meiosis I

• Reproductive cell goes through interphase before beginning meiosis I.

• Prophase I—

• Metaphase I—

• Anaphase I—

• Telophase I—

Meiosis II

• After meiosis I , the two cells formed during this stage go through a second division of the nucleus and the cytoplasm.

• Prophase II—

• Metaphase II—

• Anaphase II—

• Telophase II—

Understand that Meiosis II involves the same phases but no duplication of chromosomes

•Compare telophase I and telophase II

•What happens to the haploid cells that are produced by the process of meiosis?

•How does meiosis produce genetic variation?

How do mitosis and meiosis differ?

• Table 2: Comparison of types of Cell Division

• P. 123

•How many cells are produced during mitosis? During meiosis?

Advantages of Sexual Reproduction

•Genetic variation—

• Selective Breeding –

Disadvantages of Sexual Reproduction

• Sexual reproduction takes time and energy

•Maturation of organisms to produce sex cells

• Limited by time to find a mate—predation, diseases, or harsh environmental conditions.

HOMEWORK FRIDAY

• 1. questions on pp.126, # 1—10.

• 2. Quiz on Friday– study Lesson 1 and your power-point notes.