Post on 26-Mar-2015
• 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
2
•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.
2
33
MitosisSomatic Cell Division
5
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.
6
Science of InheritanceGenes
• Genotype: • The Allele combination, heterozygous (hybrid)
or homozygous (gg, GG, or Gg).
• Phenotype: • The physical characteristic displayed (green
or yellow).
6
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-