Mitosis and MeiosisSexual and Asexual Reproduction

BiologyFall 2012

Objectives

•Differentiate between asexual and sexual reproduction

•Identify three types of asexual reproduction

•Evaluate the relative genetic and evolutionary advantages and disadvantages of asexual and sexual reproduction

Sexual and Asexual Reproduction•Reproduction: the process of producing

offspring, can be asexual or sexual

Sexual and Asexual Reproduction•Asexual reproduction: single parent

passes copies of all of its genes to each of its offspring ▫No fusion of haploid cells such as gametes

•Clone: individual produced by asexual reproduction, genetically identical to its parents

•Example: prokaryotes, binary fission ▫Do eukaryotes reproduce asexually?

Asexual Reproduction

Prokaryotes Eukaryotes

Sexual and Asexual Reproduction•Sexual reproduction: two parents each

form reproductive cells that have one-half the number of chromsomes ▫Haploid gametes form diploid offspring▫“2 halves make a whole”

•Offspring have traits of both parents•Occurs in eukaryotes

Sexual Reproduction

Types of Asexual Reproduction•Fission:

separation of a parent into two or more individuals of about equal size ▫Prokaryotes

Types of Asexual Reproduction

•Fragmentation: body breaks into several pieces, fragments develop into complete adults▫Eukaryotes

Types of Asexual Reproduction

•Budding: new individuals split off from existing ones ▫Eukaryotes

Genetic Diversity

•Asexual reproduction •Advantages:

▫Simplest and most primitive method of reproduction

▫Allows organism to produce many offspring with less energy

•Disadvantages:▫DNA varies little between individuals ▫Less adaptation abilities

Genetic Diversity

•Sexual Reproduction:•Advantages:

▫Genetic variation •Disadvantages:

▫Takes more time and energy

Sexual Life Cycle in Eukaryotes

•Life cycle: entire span in the life cycle of an organism from one generation to the next

•Eukaryotes that undergo sexual reproduction can have one of three types of sexual life cycles:▫Haploid ▫Diploid (humans)▫Alternation of generations

Review

•True or False:1.Only prokaryotes undergo asexual

reproduction2.A benefit of asexual reproduction is that

it can produce many offspring quickly3.A disadvantage of sexual reproduction is

that it provides genetic variation4.Humans undergo a diploid life cycle

Answers

1. Only prokaryotes undergo asexual reproduction False

2. A benefit of asexual reproduction is that it can produce many offspring quickly True

3. A disadvantage of sexual reproduction is that it provides genetic variation False

4. Humans undergo a diploid life cycleTrue