1. Human Inheritance

2. The sex chromosome As we stated before the human has 46 chromosomes
Chromosome set
#23 determines the
sex of the human.

3. Boy or Girl?
If chromosome set #23 is…..
XX- girl
XY- boy
Demo

4. Predicting the sex of the offspring.
Mom’s Genotype XX
Dad’s Genotype XY
Draw the Punnett Square.

5. Review
What is the male sex chromosome? X M Y T

6. Karyotype A karyotype is an x-ray picture of the chromosomes.
Scientist use this as a tool to study the chromosomes.

7. Human Karyotype
Looking at the picture what is the sex of this offspring?
Male (XY)

8. Single Alleles Some traits are controlled by a single pair of alleles.
One will be dominant and one will be recessive.
EX: hitch-hikers thumb, dimples….

9. Multiple Alleles Some genes are controlled by many different alleles.
They may have three or more forms (think of flavors of pudding!)
EX: Height & Blood types exist in many gene forms

10. Codominance
Often times genes have equal effects and both traits will show.
EX: a breed of chicken
will have both black and
white feathers.

11. Review Co-dominance is when… Neither trait is dominant
Both traits are dominant
Both traits show
Both B & C

12. Blood Types Blood Type is controlled by multiple alleles
It also expresses co-dominance
Type A – co-dominant
Type B – co-dominant
Type AB
Type O – recessive
Food Coloring Demo

13. Incomplete dominance
Some times genes are in similar forms and the two traits will blend together.
EX: Red flowers will be crossed with white flowers and make Pink flowers.

14. Sex Linked Genes
Genes on the X and Y chromosomes are called sex linked genes.
These traits appear more often in one sex than the other

15. Color Blindness
The color blindness is a sex-linked trait found on the X chromosome.
Color-blindness is most common in males
Why?

16. Color-blindness
There is no gene for colorblindness on the Y chromosome!
It only takes one recessive allele for men to be colorblind

17. Mutations Mutations happen when there is a mistake in the DNA
Can be harmful or beneficial

18. Review What is a mutation? a mistake in the DNA
an error in the cell’s membrane
a mistake in the mitochondria

19. Pedigree Charts
Scientist use Pedigree Charts to trace the inheritance of traits in humans.
The chart or family tree will track which member of the family have a particular trait.

20. Pedigree Chart