REPRODUCTION STRATEGIES

Genetics UnitNovember 9 , 2015

Asexual Reproduction■ Definition: the production of genetically

identical offspring from a single parent.

■ Single-celled Organisms– Cell division is the only form of

reproduction binary fission.– Simple, efficient, and effective.– Populations increase in size very

quickly.

■ Think about it. Why do bacterial infections spread so quickly through school?

Binary Fission in E.coli

Interphase- including DNA Replication

Mitosis- division of nucleus

Cytokinesis

Two identical E.coli cells

Budding ■ Definition: type of asexual reproduction where a parent organism replicates to produce a clone that eventually splits off from the parent body.

■ Example: Hydra– Small bud grows off of adult

hydra.– Small bud will eventually break off

and become independent organism.

– Asexual reproduction in an animal.

■ Example: Yeast

Hydra bud- eventually bud will become an individual organism. https://www

.youtube.com/watch?v=iOvrq6ssy2Y

Yeast bud- eventually bud will become an individual organism.

Fragmentation and Regeneration■ Definition: types of asexual reproduction

that enable some invertebrates to reproduce new individuals or new body parts from incomplete fragments of the parent body.

■ Example: Planaria– Section of planaria tissue removed

from an adult.– Tissue fragment grows and

differentiates into an adult through the process of mitosis.

■ Example: Starfish can grow a new arm by mitosis to replace one lost by injury.

Regeneration of starfish.

Fragmentation of Planaria.

Sexual Reproduction

■ Definition: involves the fusion of two separate parent cells.

■ Offspring produced by sexual reproduction inherit some of their genetic information from each parent.– One gamete is donated from each parent.– When two gametes fuse, a zygote is

formed.

■ Offspring is genetically different from parents.

Zygote

Gamete from dad

Gamete from mom

Think-Pair-ShareCompare and contrast the two reproductive strategies.Asexual Reproduction Sexual Reproduction

Think-Pair-Share

Sexual Reproduction Asexual Reproduction

Advantages

Disadvantages

MEIOSIS OVERVIEW

Genetics UnitNovember 9, 2015

Chromosome NumberDiploid Cells

■ Cell that contains two sets of chromosomes (one from mom, one from dad).

■ Chromosomes are said to be homologous.

■ Chromosomes have different genetic information.

■ 2N■ Example: Humans

– 23 different chromosomes.

– Our cells have 46 chromosomes (23 from mom, 23 from dad).

Haploid Cells■ Cell that contains

only one set of chromosomes.

■ N■ Example: Gametes

– Male sperm cells.– Female egg cells.

Q: How are haploid gamete cells produced from diploid cells?A: Meiosis■ Definition: a process in which the

number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cells.

■ Two Divisions– Meiosis I– Meiosis II