1. Pedigrees & Karyotypes
How do pedigrees show inheritance of traits?
What can we learn from karyotypes?

2. Geneticists can predict the future!
(kind of)
Geneticists analyze family history to predict the future appearance of traits.

3. Pedigrees Show relationships within a family
Explain family history of a trait or disease
Used to find the probability of a child having a trait

4. Pedigree symbols

5. Roman Numerals represent generations

6. How to interpret a Pedigree
We can determine if a trait is:
Autosomal or sex-linked
Autosomal disorders- HC1-HC22
Affects males and females equally
X-linked disorders - X chromosomes
Males are affected more frequently
Dominant or recessive
Dominant
If a parent has it, a child usually does too
Does NOT skip generations
Recessive
Can show up in a child whose parents did not have it
Skips a generation

7. Example of a Pedigree
Does this show a dominant or a recessive trait?

8. Example of a Pedigree
Does this show a dominant or a recessive trait?

9. Example of a Pedigree What is the genotype of the circled individual?
Homozygous Recessive
What are the genotypes of the individual’s parents?
Heterozygous

10. Pedigree Practice
Autosomal or sex-linked?
Recessive or dominant?

11. Pedigree Practice
Autosomal or sex-linked?
Recessive or dominant?

12. Karyotypes

13. Karyotypes
Karyotypes show us all the chromosomes in the cells of a person
Autosomal = Chromosomes 1-22
Sex chromosomes = X/Y
The chromosomes are arranged in number order based on:
Size
Location of the centromere
Banding pattern
Karyotypes tell us 2 things:
If the person is male (XY) or female (XX)
If the person has chromosomal abnormalities
Normal number of chromosomes (46)
Trisomy-Extra chromosomes (47)
Monosomy-Too few chromosomes (45)

14. Down Syndrome
Result of an extra chromosome 21
Trisomy 21

15. Sex-linked chromosomal abnormalities
When there are too few or too many “X” Chromosomes
Examples
Monosomy X (Turner Syndrome)
Trisomy X
XXY