1. Mutations, Sex-linked traits, Disorders, Pedigrees
Human Genetics

2. What’s a Mutation? A change in DNA sequence Two types:
Changes in a single gene
(called gene mutation)
Changes in a whole chromosome
(called chromosomal mutation)

3. What’s a Mutation? TTA-GTA-CCG becomes TAA-GTA-CCG
Gene Mutations: Two types…
1. Point Mutation
One nucleotide is affected …
that is…
ONE LETTER IS WRONG!
TTA-GTA-CCG becomes
TAA-GTA-CCG
(usually changes one amino acid in a protein)

4. What’s a Mutation? TTA-GTA-CCG becomes Gene Mutations: Two types…
2. Frameshift Mutation
Addition or deletion of one letter (nucleotide)
Sequence is “read” one letter off from correct way
TTA-GTA-CCG becomes
TTT-AGT-ACC-G
thesunwashotbuttheoldmandidnotgethishat

5. What’s a Mutation? Chromosomal Mutations 1. Deletion
Part of chromosome is missing

7. What’s a Mutation? Chromosomal Mutations 1. Deletion 2. Duplication
Part of chromosome is missing
2. Duplication
Part of chrom. is included twice

9. What’s a Mutation? Chromosomal Mutations 1. Deletion 2. Duplication
Part of chromosome is missing
2. Duplication
Part of chrom. is included twice
3. Inversion
Part of chrom. is reversed from usual direction

11. What’s a Mutation? Chromosomal Mutations 1. Deletion 2. Duplication
Part of chromosome is missing
2. Duplication
Part of chrom. is included twice
3. Inversion
Part of chrom. is reversed from usual direction
4. Translocation
Two non-homologous chrom. exchange portions

13. Mutagens Can alter DNA’s ability to be edited (corrected)
Affects gamete and somatic cell formation
Sources
Ultraviolet radiation
Radioactive substances
X - rays
Chemical exposure

14. What’s a Mutation?
Some mutations are significant and severe, some are less so, some are never noticed…
Consider the car…

15. Sex-Linked Traits Sex-linked diseases are X linked…
The sex chrom. are the X and y
Consider Hemophilia
(the inability for blood to clot properly)
Also Colorblindness
(the inability to distinguish certain colors)
Gene that can cause it found on X chrom.

16. Sex-Linked Traits XH XH Female, clots XH Xh Female, clots (carrier)
Hemophilia (sex-linked recessive)
Females/Males:
XH XH Female, clots
XH Xh Female, clots (carrier)
Xh Xh Female, can’t clot
XHy Male, clots
Xhy Male, can’t clot

18. Other Disorders
While mutations are generally gene related and inherited from one or both parents, sometimes OTHER reasons cause problems…
NONDISJUNCTION
The parent’s genes can be fine. But during MEIOSIS of the gametes, too many or too few chromosomes were pulled into the new gamete cell…

22. Normal Male Karyotype:
22 sets of autosomes, 1 set of sex chromosomes

23. Inheritance Patterns AUTOSOMAL DOMINANT AUTOSOMAL RECESSIVE
Only one mutated gene on one chrom. is needed to display the disorder
AUTOSOMAL RECESSIVE
Two copies of mutated gene must be present to display the disorder
X-Linked DOMINANT
Mutations on the X chrom. that are dom.
X-Linked RECESSIVE (like hemophilia)

24. Pedigrees
A pedigree chart is a tool used to show all the known phenotypes of an organism and its ancestors…
Used in human genealogy study