Transcript ppt

GENETICS
SINCE MENDEL
THE STUDENTS
WILL:
• Explain how traits are inherited
by incomplete dominance.
• Compare Multiple Alleles and
Polygenic Inheritance.
• Describe 2 human genetic
disorders and how they are
inherited.
• Explain how sex-linked traits are
passed to the offspring.
TERMS WE SHOULD KNOW:
• Incomplete
dominance
• Polygenic
inheritance
• Sex-linked gene
• Multiple alleles
Incomplete
dominance
• Offspring of two homozygous
parents that show an intermediate
phenotype is called incomplete
dominance.
Example. Flower color, coat color of
horses
Multiple Alleles
• A trait controlled by more than two alleles is
said to be controlled by multiple alleles.
- Produced more than 3 phenotypes
Example: Blood Type
Phenotypes: A, B, AB, O
Genotypes: AA,AO,AB,BB,BO,OO
Polygenic Inheritance
• Happens when a group of gene
pairs acts together to produce a
trait.
Example. Height, eye and skin
color , grain color, milk
production in cows, egg in
chickens
Human Genes and Mutations
- changes/ errors that occurs
that may result in trait
expressed differently.
- Caused by radioactive
substances, chemicals, X
rays
Chromosome Disorders
- Incorrect number of chromosomes in a
cell.
Example: Down’s Syndrome
RECESSIVE GENETIC
DISORDER
Cystic Fibrosis- caused by recessive
genes
-Homozygous recessive disorder
-Caucasian American
-Affects Respiratory System
SEX DETERMINATION
• -Chromosomes
that
determines the sex of an
organism are :
XX- GIRLS
XY-BOYS
• Females- eggs with X
chromosomes
• Males- sperm with X or Y
chromosomes
SEX-LINKED DISORDER
• An allele inherited on a sex
chromosome is called sexlinked chromosome.
Example: color blindness
Pedigrees Trace Traits
• A visual tool for following a trait through
generations of a family.
• Can predict if the baby will be born with a specific
trait.
• Important in breeding of animals or plants.