• Types of Chromosomes

•a. Autosomes

• Any chromosome that is not a sex chromosome. 1 to 22

•b. Sex Chromosomes

• A chromosome involved with determining the sex of an organism. X and Y chromosomes

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•Types of Cells

•a. Somatic cells

• Any cell of a living organism other than the reproductive cells. 

•b. Gametes (sex cells)

• A reproductive cell having the haploid number of chromosomes.

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MitosisSomatic Cell Division

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Science of InheritanceGenes• Alleles:

•Different forms of a gene.

•Dominant: •If the dominant allele (gene) is present, the organism will show that trait.

•Recessive: •Trait will be exhibited only if organism does not have dominant allele or is pure for recessive trait.

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Science of InheritanceGenes

• Genotype: • The Allele combination, heterozygous (hybrid)

or homozygous (gg, GG, or Gg).

• Phenotype: • The physical characteristic displayed (green

or yellow).

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Trait Dominant Allele

Recessive Allele

PossibleGenotype

PossiblePhenotypes

Seed Color G (green) g (yellow) GGHomozygous

GgHeterozygous

gg

Green

Green

Yellow

Flower Color

P (purple) p (white) PPHomozygous

PpHeterozygous

pp

Purple

Purple

white

Science of InheritanceGenes

Science of InheritanceGenes

Homozygous: 2 copies of the same alleles (ex. TT and tt)

homozygous dominant- TT

homozygous recessive- tt

Heterozygous: different copies of alleles (ex. Tt)

Sex Linked Genes Traits located on the X chromosome

Genotype Phenotype

XCXC Normal Female

XCXc Carrier Female

XcXc Colorblind Female

XCY Normal Male

XcY Colorblind Male

Cross: A normal male with a carrier female. XCY x XCXc XC XC

Normal Female

XCYNormal Male

XCXc

Carrier Female

XcYColorblind Male

XC Y

XC

Xc

Sex Linked Genes Traits located on the X chromosome

Genotype Phenotype

XCXC Normal Female

XCXc Carrier Female

XcXc Colorblind Female

XCY Normal Male

XcY Colorblind Male

Xc Y

XC

Xc

Cross: A colorblind male with a carrier female. XCY x XCXc Xc Xc

Colorblind Female

Xc YNormal male

XC Xc

Carrier Female

XC YColorblind

Male

Sex Linked Genes Traits located on the X chromosome

Genotype Phenotype

XCXC Normal Female

XCXc Carrier Female

XcXc Colorblind Female

XCY Normal Male

XcY Colorblind Male

Cross: A normal male with a carrier female. XCY x XCXc

XC XC

Normal Female

XCYNormal Male

XCXc

Carrier Female

XcYColorblind Male

XC Y

XC

Xc

Cross: A colorblind male with a carrier female. XCY x XCXc

Xc Xc

Colorblind Female

Xc YNormal male

XC Xc

Carrier Female

XC YColorblind

Male

Xc Y

XC

Xc

II. Practice with Punnett Squares- Mendelian Genetics (autosomes!)

A.homozygous recessive x homozygous dominant

B. heterozygous x heterozygous

C.homozygous recessive x heterozygous

D.homozygous dominant x heterozygous

III. Crosses that involve sex-linked (X-linked) genes

“Carrier”-

Examples of X-linked diseases-