Chapter 11 Reproduction of Organisms Sexual Reproduction and

Chapter 11 Reproduction of Organisms

Sexual Reproduction and Meiosis Lesson 1

Sexual Reproduction Sexual reproduction: when genetic materials from 2 different cells combine, producing offspring Female Male sex cell: egg sex cell: sperm

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Fertilization During fertilization, an egg cell and a sperm cell join together The new cell that forms is called a zygote

Diploid Cells Diploid cells have pairs of chromosomes Pairs of chromosomes that have genes for the same traits arranged in the same order are called homologous chromosomes

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Mitosis In mitosis, one diploid cell divides and makes two diploid cells The instructions for cell division are found in the chromosomes in the nucleus

Haploid Cells Haploid cells are cells that only have one chromosome from each pair

Meiosis In meiosis, one diploid cell divides and makes four haploid sex cells

Reduction Division

Mitosis Vs. Meiosis Mitosis Meiosis One set of cell division Two sets of cell division 2 diploid daughter cells produced 4 haploid daughter cells produced Body parent cells Reproductive parent cell

Advantages of Sexual Reproduction Genetic variation Selective breeding

Disadvantages of Sexual Reproduction Takes time and energy Limiting by factors such as pregnancy

Complications A zygote with the wrong number of chromosomes could not develop properly Example: Down Syndrome (3 copies of chromosome 21)

Lesson 2 Asexual Reproduction

Asexual Reproduction Asexual reproduction results from one parent and offspring genetically identical to the parent One parent organism produces offspring without meiosis and fertilization

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Prokaryotes Do NOT undergo mitosis because prokaryote’s DNA is not contained in a nucleus

Types of Asexual Reproduction Cloning: produces identical individuals from a cell taken from a multicellular organism

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Types of Asexual Reproduction Fission: cell division in prokaryotes that forms two genetically identical cells Mitotic cell division: two offspring formed through mitosis and cell division

Types of Asexual Reproduction Animal regeneration: when offspring grows from a piece of its parent animal Vegetative reproduction: offspring grow from a part of a parent plant Tissue culture: Cells extracted from a plant or animal are grown in a laboratory

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Advantages of Asexual Reproduction Cloning could save an endangered species Some organisms can rapidly produce a large number of offspring

Disadvantages of Asexual Reproduction Little genetic variation within a population which limits the chances of survival in the case of environmental changes Passing on of harmful mutations