Section 6.1 Sexual Reproduction Text Pages 170 - 179

Key Terms Sexual Reproduction Gamete Fertilization Zygote Embryo Diploid Haploid Meiosis Homologous Chromosomes Interkinesis

Section 6.1 Learning Objectives Define sexual reproduction Define gamete, fertilization, zygote, and embryo Define diploid and haploid Describe the role of meiosis in sexual reproduction State and briefly describe the eight phases of meiosis

Sexual Reproduction: Genetic variety Sexual Reproduction: reproduction that combines the genetic information from two different parents to produce offspring that are genetically unique.

Sexual Reproduction: Genetic variety Brothers may look similar, and look something like their parents, but neither one is exactly the same as anyone else in their family. (Unless they are identical twins!! This is a special case)

Sexual Reproduction: Genetic variety Since sexual reproduction creates unique individuals, it increases the genetic variety in a species. It is like shuffling DNA around without ever knowing exactly what the combination will be.

Sexual Reproduction: Genetic variety This can give some individuals a better chance of surviving! Unfortunately, sometimes it makes others less likely to survive! Overall this can help the species to survive in changing environments.

Sexual Reproduction: The Role of Gametes You have 46 chromosomes in each of your body cells: They are found in 23 pairs of similar chromosomes. In each pair, one chromosome came from your father and one came from your mother.

Sexual Reproduction: The Role of Gametes In Section 5.1, you learned that Mitosis is the process of cell division that creates genetically identical cells. Body cells formed by mitosis are known as Diploid cells. Diploid cells: same # of chromosomes as the parent cell (46 in humans)

If humans reproduced through mitosis like Bacteria or Fungi, we would all have exactly the same 46 chromosomes (with the occasional mutation). So what makes us unique?

Sexual Reproduction: The Role of Gametes Sexual reproduction involves combining cells called gametes.

Sexual Reproduction: The Role of Gametes Gametes: cells that combine during sexual reproduction. Sperm in males and eggs in females. They are haploid cells.

Haploid Cells: half the number of chromosomes as normal body cells (23 in human gametes)

Diploid Haploid Formed by mitosis Same # of chromosomes as parent cells Humans = 46 chromosomes Body cells Formed by meiosis Half the # of chromosomes as parent cells Humans = 23 chromosomes Sperm and eggs (gametes)

Fertilization: a sperm cell penetrates an egg cell and the 23 chromosomes in each combine to create a new diploid cell called a zygote

Zygote: The diploid cell formed as a result of fertilization.

Embryo: A zygote that is growing larger Embryo: A zygote that is growing larger. It creates more cells through mitosis.

Salmon Reproduction In Nature Aquaculture

Meiosis: How Gametes are Formed

Meiosis: How Gametes are Formed Meiosis: the process through which gametes are created from diploid cells. It involves two cell divisions (Meiosis I and Meiosis II) Meiosis occurs in the sex organs: - testicles in males (sperm) - ovaries in females (eggs)

Meiosis must create haploid cells Meiosis must create haploid cells. If sperm and eggs were diploid they would combine to create a zygote with twice the number of chromosomes as the parents (92 instead of 46)!

Meiosis occurs in two distinct stages: Meiosis I and Meiosis II Meiosis I Interkinesis Meiosis II i) Prophase I - cell grows and i) Prophase II ii) Metaphase I makes various ii) Metaphase II iii) Anaphase I proteins iii) Anaphase II iv) Telophase I iv) Telophase II

Meiosis: How Gametes are Formed Meiosis Video

Comparing Mitosis and Meiosis Homologous Chromosomes Homologous Chromosomes

  Mitosis Meiosis Type of Cells In body cells In sex organs to produce sex cells (gametes) Number of Daughter Cells Produced Two daughter cells Four daughter cells Genetic Material in each Cell Same # of chromosomes as in parent cell Genetically identical cells Half the # of chromosomes as in the parent cell Genetically different cells. Function Grow new body cells or replace dead/damaged cells. Creating haploid cells for sexual reproduction.