1. Warm-up
What do you already know about chromosomes? Tell me at least one thing!

2. Chapter 12

3. Human Genetics Learning Intention:
Understand how the patterns of genetic inheritance can used to identify and predict the occurrence of a genetic trait.

4. Success Criteria:
I can … both read and construct a pedigree to study a genetic trait
I can… predict the likelihood that a particular trait will be passed from parent to offspring based on different inheritance patterns
I can… explain how non-disjunction can cause human genetic disorders

5. Pedigrees
What are you reminded of when you see or hear the word pedigree?

6. Pedigrees
What are you reminded of when you see or hear the word pedigree?
What does the term mean in reference to genetics?

7. Pedigrees
A family record that shows how a trait is inherited over several generation
By studying pedigrees, scientists can see patterns of inheritance.
Females are represented by
Males are represented by
People who have the trait are colored in completely
People who are carriers of the trait are colored in halfway

9. Dd DD
d d

10. Pedigree Practice 1 2 3 4
The pedigree shown traces Sudden Arrhythmia syndrome a recessive trait. Normal allele is: N Recessive arrhythmia allele is: n Carriers are not indicated in the graph!!! What are the genotypes of the following individuals? 5

11. Pedigree Practice 1 2 3 4
The pedigree shown traces Sudden Arrhythmia syndrome a recessive trait. Normal allele is: N Recessive arrhythmia allele is: n Carriers are not indicated in the graph!!! What are the genotypes of the following individuals? 1 Nn 2 Nn 3 Nn 4 nn 5 nn 5

12. Genetic Traits Single Allele Traits Recessive Single Allele Traits
Examples:
Phenylketonuria (PKU)
Albinism
Cystic Fibrosis
You must inherit both recessive alleles from your parents…. to get the trait!!!

13. Genetic Traits Single Allele Traits Dominant Single Allele Traits
Examples:
Huntington’s disease:
Polydactyly
Cataracts
If you inherit only one dominant allele…. You will get the trait!!!

14. Genetic Traits Mutiple Allele Traits Polygenic Traits
Controlled by 3 or more alleles
Example: Human blood type (3 alleles A, B, O)
Polygenic Traits
Characteristic controlled by several genes
Examples:
Skin Color
Height

15. Example Polygenic Trait: Eye Color

16. X-linked Traits
A trait which is controlled by a gene
found on the X chromosome
Examples:
Colorblindness
Hemophelia

17. Question: Why are males more likely to have an x-linked trait?
Because males only have one X chromosome they are more likely to have X-linked traits.

18. Practice Problem
Cross a female carrier for Color Blindess (an X- linked trait) with a normal color vision male.
Xb – allele for color blindness
X – normal allele
Y – normal allele

19. Are there any color blind females?
Yes, If the mother was at least a carrier and the dad was color blind

20. Sex Influenced Traits
The presence of specific male and female hormones affect the expression of proteins for particular traits
Males and Females that have the same genotype, will have a different phenotype!!!
Example: Pattern baldness

21. Nondisjunction

22. Chromosomal non-disjunction disorders
Monosomy – missing a chromosome
e.g. Turner’s syndrome – missing a sex chromosome, only have an X
Trisomy – have an extra chromosome
e.g. Down syndrome – extra 21st chrom.
Klinefelter syndrome – extra X chrom. XXY

23. Trisomy Monosomy

24. Journal: What are the possible modes of inheritance?
Autosomal or X-linked
Dominant or Recessive

25. Pedigree Practice!