Science 9 Non-Mendelian Genetics Presentation

Non-Mendelian Genetics

1. Non-Mendelian Genetics

2. Non-Mendelian Genetics
•Some traits don’t follow the simple
dominant/recessive rules that Mendel first
applied to genetics.
•Traits can be controlled by more than one
gene.
•Some alleles are neither dominant nor
recessive.

3. Incomplete Dominance
•One allele is not completely dominant over
another.
•The heterozygous phenotype is a
blending of the two homozygous
phenotypes.
Example: four o’clock flowers
•rr=red
•ww=white
•rw=pink (blending of the two alleles)

4. Codominance
•Two alleles are both
expressed as a
dominant phenotype
•Coat color in cows
–RR: Red
–WW: White
–RW: Roan, white with
red spots (NOT pink!)

5. Multiple-Allele Series
•Codominance
•More than two choices of alleles are present for a
trait
•ABO blood type has three alleles
•ABO Blood types:
–If both A and B are present, type is AB
–Neither is recessive
•Individuals can be type A, B, AB, or O (recessive)

6. What is blood made up of?
•The red blood cells
–contain hemoglobin.
–Red blood cells transport O
2 and CO
2
to and from body tissues.
•The white blood cells
– fight infection.
•The platelets
– help the blood to clot
•The plasma
–Fluid which contains salts and
various kinds of proteins.

7. Determining Blood Type
•Protein molecules found on the surface
of RBC’s and in the blood plasma
determine the blood type of an individual.
–Antigens are located on the surface of the
red blood cells
–Antibodies are in the blood plasma.


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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8. What are the different blood
groups?
•Blood group A (I
A
, I
A
), (I
A
, i)

have A antigens on the surface of
red blood cells and B antibodies in
blood plasma.
•Blood group B (I
B
, I
B
), (I
B
, i)

have B antigens on the surface of
red blood cells and A antibodies in
blood plasma.

9. What are the different blood
groups?
•Blood group AB (I
A
, I
B
)

have both A and B antigens on the
surface of red blood cells and no A or B
antibodies in blood plasma.
•Blood group O (i, i)
have neither A or B antigens on the
surface of red blood cells but have both A
and B antibodies in blood plasma.

10. Blood transfusions – who can
receive blood from whom?
•The transfusion will work if a person who
is going to receive blood has a blood
group that doesn't have any antibodies
against the donor blood's antigens.

11. • People with blood group 0 are called
"universal donors" and people with
blood group AB are called "universal
receivers."

12. Rh Factor
•Refers to another antigen on red blood
cells
•Dominant trait is to have the antigen
–Rh
+

•Recessive trait is not to have it
–Rh
-

•A person with Rh
-
blood will produce
antibodies to Rh
+
blood
•Can be a problem in pregnancy

13. Sex-Linked Inheritance

14. Review
•Males have an X and a Y
chromosome
•Females have two X
chromosomes
•These chromosomes determine
sex, so genes located on these
chromosomes are known as
sex-linked genes.

15. •The X chromosome is
much larger than the Y, so
it carries more genes than
the Y chromosome.
•Disorders that are sex-linked are much
more common in males, because they
would only need 1 recessive allele to have
the trait; rather than the two recessive
alleles the females need.

16. Hemophilia
•Recessive trait
•Disorder where individuals are missing the
normal blood clotting protein.
•Uncontrolled bleeds from minor cuts or
bruises.
•Female genotype:
•Male genotype:

17. Colorblindness
•Recessive
•Inability to see certain colors
•Female genotype:
•Male genotype:

18. Duchenne Muscular Dystrophy
•Recessive
•Progressive weakening and loss of
skeletal muscle.
•Defective version of gene that codes for
muscle protein
•Female genotype:
•Male genotype:

19. •EXAMPLES!!
•A woman who is heterozygous for normal
vision marries a man who is colorblind.
What are the chances of them having a
son or daughter who is colorblind?
**NOTE: You have to use X’s and Y’s, and
read the punnett square separately for
boys and girls!**

20. •A woman who is homozygous for normal
blood clotting marries a man who has
hemophilia. What are the chances of
them having a son or daughter with
hemophilia?