1. Human Genetic Mutations

2. Mutations Mutations are a result in a change in DNA sequence
A protein with a different AA sequence could be produced.
Germ Cell - If mutations occur in sex cells they may be passed on to the next generation.
Somatic- A mutation occurring only in body cells may be a problem for the individual but will not be passed on to the offspring.
Mutations may be classified as chromosomal alterations or gene mutations
Chromosomal alterations are generally more severe because many genes are usually involved.

3. 2 Main Types of Mutations
1.) Chromosomal Mutations
2.) Gene Mutations

4. Chromosomal Mutations
Any change in the structure or number of chromosomes
Large scale: Affect many genes

5. Gene Mutations Small scale: one gene is affected
Any change to the DNA sequence of a gene:
Nucleotides/Bases may be added, missing, or changed

6. Significance of Mutations
Most are neutral
Eye color
Birth marks
Some are harmful
Cystic Fibrosis
Down Syndrome
Some are beneficial
Sickle Cell Anemia to Malaria
Immunity to HIV

7. What Causes Mutations?
There are two ways in which DNA can become mutated:
Mutations can be inherited.
Parent to child
Mutations can be acquired.
Environmental damage
Mistakes when DNA is copied

8. 5 Types Deletion Duplication Inversion Translocation NonDisjunction
Pericentric
Paracentric
Translocation
NonDisjunction

9. One or more genes are removed
Chromosomal Deletion
One or more genes are removed
Causes:
Wolf-Hirschhorn syndrome (severe mental retardation)
cri du chat syndrome (mewing sounds, mental retardation)

10. Chromosomal Duplication
A segment of genes is copied twice and added to the chromosome
Causes:
Charcot–Marie–Tooth disease
(high arched foot, claw feet, confined to a wheelchair)

11. Chromosomal Inversion
a segment of genes flip end-to-end on the chromosome
Causes:
Four-Ring Syndrome
(cleft pallate, club feet, testes don’t descend)

12. Chromosomal Translocation
Material is swapped with another chromosome
Causes:
Burkitt’s Lymphoma
(cancer of the lymph nodes, in children)

13. Nondisjunction Chromosomes FAIL TO SEPARATE during meiosis
Meiosis I Nondisjunction
Meiosis II Nondisjunction

14. Nondisjunction
Produces gametes (and therefore a baby) with one missing chromosome or one extra chromosome

15. Too much or too little DNA is bad!
KEY POINT #1
Too much or too little DNA is bad!

16. Gene Mutations: 2 Types
Point Mutation
Frameshift Mutation

17. Point mutation
Only one nucleotide changes, but it makes a different protein

18. Point Mutation One base (A, T, C, or G) is substituted for another
3 Possible Consequences:
nonsense mutations: code for a stop, which can translate the protein
missense mutations: code for a different amino acid
silent mutations: code for the same amino acid

19. Gene Mutations Point Mutations – changes in one or a few nucleotides
Substitution
THE FAT CAT ATE THE RAT
THE FAT HAT ATE THE RAT
Insertion
THE FAT CAT XLW ATE THE RAT
Deletion
THE FAT ATE THE RAT

20. Frameshift Mutation
One or more bases (A, T, C, or G) are added or deleted
Caused by:
Insertion: adding a base
Deletion: removing a base

21. Frameshift
Causes every codon in the DNA sequence to be changed after the mutation:
Insertion- one or more bases are added
Deletion- one or more bases are removed A

22. Causes of Mutations spontaneous occur during DNA replication
Caused by MUTAGENS
physical, ex: radiation from UV rays, X-rays or extreme heat
or chemical (molecules that misplace base pairs or disrupt the helical shape of DNA).

23. Gene Mutations KEY IDEA: A mutated gene will make a mutated protein
Mutant proteins are trouble!
They do not go where they are supposed to go
They do not do what
they are supposed to do

24. KEY POINT #2 Mutation of a gene = Mutant protein
Dysfunctional proteins cause the symptoms of the disorder

25. Length of Telomeres telomeres
Telomeres are structures at the ends of chromosomes that shorten with each cell division. After 50 divisions, the shortened length of telomeres causes mitosis to stop.