Mendelian and non-mendelian genetics
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Transcript Mendelian and non-mendelian genetics
Mendel’s Laws of
Heredity
Why we look the way we
look...
Mendel used peas...
They reproduce sexually
They have two distinct, male
and female, sex cells called
gametes
Their traits are easy to
isolate
Mendel crossed them
Fertilization - the uniting of
male and female gametes
Cross - combining gametes
from parents with different
traits
What Did Mendel
Find?
He discovered different laws
and rules that explain
factors affecting heredity.
1. Rule of Dominance
The trait that is observed in
the offspring is the
dominant trait (uppercase)
The trait that is masked in
the offspring is the recessive
trait (lowercase)
2. Law of Segregation
Genes appear in pairs on
homologous chromosomes
SEPARATED when gametes are
formed
Recombine during fertilization
3. Law of Independent
Assortment
The genes for different traits are
inherited independently of each
other.
Homologous chromosomes move
randomly to gametes
Explains why siblings look different
Genetics Continued
Dihybrid crosses
Exceptions to Mendelian Genetics
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Incomplete vs. Complete Dominance
Codominance
Sex-Linked Genetics
Blood Types (Multiple Alleles)
Monohybrid Vs Dihybrid
Monohybrid
Cross - crossing
parents who differ in only
one trait (AA with aa)
Dihybrid
Cross - crossing
parents who differ in two
traits (AAEE with aaee)
S= yellow
s= green
Y= round
y= wrinkled
How many round yellow?
How many round green?
How many wrinkled yellow?
How many wrinkled green?
Dihybrid Cross - 2 traits
Bozeman Tutorial
http://www.youtube.com/watch?v=Y1P
CwxUDTl8
Incomplete Dominance - Blend
Heterozygous genotype=
blend of two phenotypes
RR= Red
RW= pink
WW= white
Codominance – Both show
Both alleles of the trait show in the
heterozygote
Codominance: Both traits show
in heterozygotes
Try these: what are the phenotype ratios?
Cows
R= Brown
W= white
Calico Cat Coats
B: Black
Y: Yellow
Sex-Linked
Sex-Linked
Sex-linked Punnett
C= color-blindness
XX= Female
XY= Male
Is mom colorblind?
Is dad colorblind?
What is the chance that they have:
1)
2)
3)
4)
a colorblind girl?
a female carrier?
an unaffected male?
an affected male?
Polygenic: controlled by many genes
Polygenic inheritance
is a fancy term for
those genetic traits that
are controlled by more
than 1 gene
-
Height, Skin Color
Because there are
MANY genes that
influence polygenic
inheritance, you
see a spectrum of
phenotypes
Blood Types: Multiple Alleles
- What is multiple allele inheritance?
- Non-Mendelian Inheritance Pattern
- involves more than just 2 alleles
- that means there is more than two
phenotypes
Blood Types:
Multiple Alleles
- Example: Blood Type (Red Blood Cells)
- There are markers on the surface of RBCs
- Our immune system has antibodies:
ATTACK foreign invaders (germs, viruses)
- YOU DO NOT WANT ANTIBODY for your
BLOOD TYPE
- What would be the result? Your immune
system attacks your body!!
Multiple Alleles - Blood Type
Universal Donor (can give to everyone): 0 Blood…. why?
Universal Recipient (can accept from anyone): AB Blood…..why?