GametogenesisFertilization

2B: creating sperm and egg2D: fertilization creates new genetic combinations2E: each parent contributes half of their DNA2F: sex chromosomes determine sex

Objectives:

I will be able to differentiate between gametogenesis and fertilization

I will be able to ___that half of my genes come from my ___; the other half come from my ___.

I will be able to ___that I am a new combination of my ___ and ___.

I will be able to ___that girls have ____chromosomes and boys have ___chromosome

DefinitionsChromosome - linear DNA molecule

Centromere - special region of spindle attachment

Homologous Chromosomes• Have the same kind of

genes in the same order• 1 from father, 1 from

mother

Sister chromatids (Blue, orange)

DNA Replication

Definitions

Chromatids Chromatids

Homologous Chromosomes

A chromatid pair has an identical sequence of DNA

Grand SchemeMitosis

2N

2N 2N

2N

2N 2N

N N N N

Meiosis

ReplicateDivision

ReplicateDivision

Division

Meiosis Produce 4 haploid gametes through

- Interphase – replication of DNA- Meiosis I – separation of

homologous chromosomes

- Meiosis II – separation of sister chromatids

Only occurs in ovary/testis

Gametogenesis

Differences between male and female MeiosisIn Humans

Fertilization Half of the

chromosomes from each parent.

Haploid-> Diploid

Genetic combination-> Variation

Zygote has a new combination ( new genes-> mutation)

Bb

BB

bB

bb

bb

sperm ovum 4 Possible combinations

BB, Bb and bB= brown eyesbb gives rise to blue eyes

4 possible combinations of genes:

B B

fertilization

X and Y chromosomes

XX= female

XY = Male

Sperms determine the sex of the zygote

If the egg is fertilized by a sperm with an X chromosome, what will be the sex of the zygote?

A human male gets his X chromosome from _?

Mutation

XXYY

XXYY O

XY XY O O

XXYY

XX YY

XX O Y Y

X XXY XXY XO XO XXX XO XY XY

Klinefelter’sSyndrome

Turner’sSyndrome

Non-disjunctionXY