Download - Human genetic inheritance patterns
Human Genetics
I. 5 Human Patterns of Inheritance:
a. Complete Dominance (Basic Mendelian Genetics)
b. Incomplete Dominancec. Co-dominanced. Sex-Linkede. Polygenic
a. Complete Dominance
• Traits inherited are either DOMINANT or RECESSIVE
• Ex. BB, Bb, bb
b. Incomplete Dominance
• Traits inherited show a new phenotype that is a BLENDING or MIXING of parental alleles–HETEROZYGOUS results in a blending
of two alleles–Use 2 different CAPITAL letters to
represent (neither allele is dominant or recessive)
Incomplete Dominance cont.Ex: 4 o’clock flowers, snapdragons, Tay Sach’s Disease
Incomplete Dominance cont.Ex: 4 o’clock flowers, snapdragons, Tay Sach’s Disease
Incomplete Dominance cont.Ex: 4 o’clock flowers, snapdragons, Tay Sach’s Disease
c. Co-dominance
• Trait inherited shows a new phenotype that EXPRESSES BOTH parental alleles
–HETEROZYGOUS condition results in the expression of both alleles
– Use 2 different capital letters to represent
Co-dominance continuedEx: Roan Horse
X
Co-dominance continuedEx: Roan Horse, Dalmatian
d. Sex Linked Traits• Traits are controlled by genes on
the X or Y chromosomes
a. _X linked traits can be passed on to males and females
b. _Y linked traits can only be passed to males
X-Linked Traits
1. Affect the X chromosome
2. _FEMALES tend to be CARRIERS and pass on the trait to their sons - XtY
3. Females can be affected but BOTH X chromosomes must have the gene for the trait - XtXt
Examples:
Hypertrichosis – Human Werewolf Syndrome:
Congenital generalized hypertrichosis (CGH) Rare, X-linked dominant trait
Found in a single multigenerational Mexican family
Colorblindness Self Test:
NUMBERS: 5 | 8 | 9 | 5 | 3 | 5 | 9 | 10 |
Hemophilia
Male Pattern Baldness
Genotypes of Male Pattern Baldness
e. Polygenic Traits
• Traits are controlled by MULTIPLE gene pairs
1.Genes may be on same or different chromosomes
2.Expressed trait varies greatly
Ex. Hair color, eye and skin colors, height, weight
II. How to study patterns of inheritance in families
Two Methods:1. _KARYOTYPE: Photograph of an individual’s
chromosomes arranged in homologous pairs and can be viewed underneath a microscope
a. Used to identify problems with chromosomes
• _ABNORMAL NUMBERS• _DAMAGED OR BROKEN• _TO DETECT GENETIC DISEASES
Typical Karyotype: Normal Individual
Pattern of Inheritance:Normal Chromosome Pattern
Abnormality:None
Notation:46, XY, Male
2. _PEDIGREE CHART: Diagram to show genetic traits and used to map genetic traits through generations
a. Shows SEX, PHENOTYPES, and GENOTYPES of family members
b. Can predict patterns of inheritance
c. Uses symbols