Transcript nonmendelian genetics and pedigrees

Right now!
Show a cross between a heterozygous
Purple flower and a pink flower.
•What are the odds of these flowers
producing a pink flower?
•What are the genoytypic and phenotypic
ratios?
Read and explain this problem
involving one of Mr. Selent’s hundreds
of cats
• Carbon is a white male cat who successfully
courts and mates with Flourine, a black cat.
• Every one of their kittens is grey!
How is this
possible? Explain.
Is every trait dominant and recessive
• Nope!
• Not every trait is determined by completely
dominant and completely recessive alleles!
• You may have incomplete dominance!
=The blending of traits
Incomplete dominance
class practice
• If the alleles for color of Lilly flower color are
incompletely dominant… R=codes for red, B =
blue
• What is the color of a Lilly homozygous for
Red?
• What color is a Lilly with R and B allele?
Wait there is another one!
• Co dominance!
• What does cooperate mean? Co exist? Co
worker?
Codominance
Phenotype
(Blood Type
Genotype
Antigen on
Red Blood Cell
Safe
Transfusions
To
From
Blood type shows codominance and has multiple alleles
Multiple Alleles
• Many genes have multiple alleles for
each gene.
• Coat color in rabbits is determined
by 4 alleles on a single gene.
Codominance
• When both alleles show up in the phenotype
• Example: Black Zebra plus a White Zebra =
Which one is co Dominant
How to we show heredity over
generations?
• Pedigrees!
Pedigree Chart
• A pedigree chart shows relationships
within a family
• Define carrier!
A circle
represents a
female.
A horizontal line
connecting a male and
female represents a
marriage.
A half-shaded
circle or square
indicates that a
person is a carrier
of the trait.
A completely
shaded circle
or square
indicates that a
person
expresses the
trait.
A square
represents a male.
A vertical line and a
bracket connect the
parents to their
children.
A circle or square
that is not shaded
indicates that a
person neither
expresses the
trait nor is a
carrier of the trait.
Hemophilia
• Sex linked trait
• Cannot clot blood
• Called the Royal Disease
Platelets
Factor VIII: antihaemophilic globulin
Queen Victoria
How to read pedigrees
• Squares = males
Circles = females
• Horizontal lines to square and circle = mating
• Vertical lines shows parenthood and offspring
• Colored squares/circles = individual exhibits
trait in question
What is this about??
Last one
Practice!
• Make 3 practice pedigrees with at least 10
individuals - 7 minutes
• Involving autosomal dominant, recessive or X
linked (Sex linked) traits
• Give to someone in classroom and see if they
can determine type of disease and carriers (if
applicable)
Poly genetic traits
• Traits controlled by more than one gene
Polygenic Traits
• Most of your traits are controlled by the
interaction of many genes.
• At least 4 different genes control skin color.
• Multiple genes working together produce a
continuous distribution in a “Bell Shape” curve
of degrees of light to dark.
The MC1R gene is located on the
long (q) arm of chromosome 16 at
position 24.3.
Examples of Polygenic Traits
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Body Type
Height
Skin Color
Intelligence
We often see the
famous “Bell Curve”
• Individual genes of a
polygenic trait follow
Mendel's laws
• but together do not
produce Mendelian
ratios.
Polygenic Traits
Height in humans is controlled by ~700 genes in the body
Recent studies show …
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Hypertension &Diabetes
Cancers & Allergies
Cardiovascular diseases
Behavioral traits (alcoholism and phobias)
Have some genetic link but also
environmental explanation…