Its all about sex

What happens during meiosis I?

Homologous chromosomes separate

What happens during meiosis II?

sister chromatids separate

When does crossing over occur?

Prophase I of meiosis

What is crossing over and what does it produce?

the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring. - recombinant chromosomes

Reductional division

in meiosis I, homologous chromosomes are separated generating haploid daughter cells

Differences between meiosis I and II

No DNA synthesis is meiosis II

Haploid cells in meiosis II

Meiosis II is the same as mitosis except there are haploid cells

Nondisjunction

results in missing and extra chromosomes

Why reproduce sexually?

-recombination of genetic material

-maintenance of genetic variation

-evolutionary flexibility in a population

Sexual reproduction disadvantages

Two individuals

Costs of seeking, choosing and competing for mates

Destroys adaptive combinations of alleles

Production of males that can't bear offspring so reduces reproductive success

How do prokaryotes benefit from gene exchange?

conjugation - donor plasmid copies plasmid into another bacteria

transformation - takes bacteria form surroundings

transduction - Bacterial viruses carry DNA from one bacteria to another

hermaphrodite

an organism that has both male and female reproductive organs

Parthenogenesis

Asexual reproduction in which females produce offspring from unfertilized eggs.

Isogamy

gametes are equal in size

Anisogamy

difference in gamete size

Heterogametic

sex chromosomes are of different types

Sequential hermaphroditism

an individual reverses its sex during its lifetime