Download Genetics Terms - Kent City School District

Exploring Mendelian
Genetics
11-3
Independent Assortment
Inheritance Patterns Beyond
Simple Dominance
Quick Review
Allele: each letter (R or r)
 Dominant
masks Recessive
(Rr or rr)
Law of Dominance?
Homozygous RR/rr
Heterozygous Rr
Law of Independent
Assortment
 States that genes for different traits can
segregate independently during meiosis
 Gives many more genetic variations
 MEANING: If a pea plant is yellow and
wrinkled < RrYy>, both sets of alleles will
separate independently (they work
alone!)
 An offspring can receive any
combination of r’s and y’s
Dihybrid Crosses Used For
Proof (pg 270/271)
Incomplete Dominance
Dominant and Recessive Blend
in a heterozygous genotype
Ex: Flower Color
Red (RR) Flower X White (rr)
Flower =PINK (Rr)
Can you think of other
examples?
Co dominance
 No recessive,
Both traits
expressed
 Ex:coat color
 Heterozygous
will both be capital
letters because
both dominant!
RR=Black, WW=White,
RW=Black and White Bunny
Other Ways To Show
Genotypes
 Use 2 different letters (all caps)
 Ex: BW=black and white bunny
 Use apostrophes to show the other allele
 Ex: RR = red R’R’ = white RR’=Roan
 (Roan= both)
 Found in cows, horses, dogs, etc
Examples of Roan Animals
(co-dominant coat color)
Multiple Alleles
 Genes with 3 or more alleles
 Ex: Blood Typing
 3 alleles = IA, IB, i
 Give 4 possible phenotypes:




A (IAIA, IAi)
B (IBIB, IBi)
AB (IAIB)
O (ii)
Here’s How…
AA= A
Ai = A
BB = B
Bi = B
AB= AB
ii = O
Polygenic Trait
 Several Genes Influence a Trait
 Ex: Skin, Weight, Eye Color, Height
 Most genes scattered along the same
chromosome
 What causes so many variations?
Traits Influenced by
Environment
 Phenotypes can change based on
environment
 Ex: Hydrangea Color
 Fur in mammals (color and thickness)
 Height and weight in humans based
nutrition