1. GENETIC MUTATIONS

2. Sexual Reproduction Results in variations
Variations help organisms adapt
Allow breeders to develop new strains of plants/animals
Most variations come from segregation and crossing over in meiosis

3. Source of Variations Most variations come from: Segregation
Crossing over

4. Mutations
Mutations are sudden changes in the structure or amount of genetic material
Most mutations are harmful; some are beneficial (i.e. ones that allow species to meet needs of environment)
Ehlers-Danlos syndrome is a group of disorders that affect connective tissues, which are tissues that support the skin, bones, blood vessels, and other organs. Defects in connective tissues cause the signs and symptoms of Ehlers-Danlos syndrome, which vary from mildly loose joints to life-threatening complications.

5. Types of Mutations 2 Main Types:
Chromosome Mutation = changes structure of all/part of chromosome
Gene Mutation = affects a gene on a chromosome
Mutation must be in DNA of sex cells in order for it to be passed on.
Mutations in body cells can’t be passed on.

6. What Causes Mutations Random error in DNA replication
Environmental Factors (called mutagens)
Radiation (X-rays)
UV light
Chemicals (chloroform and mustard gas)

7. Chromosome Mutations Translocation
One part of a chromosome is transferred to a non-homologous chromosome

8. Chromosome Mutations 2) Inversion
One part of a chromosome is rotated (reverses order of genes)

9. Chromosome Mutations 3) Addition
One part of a chromosome breaks off and attaches to a homologous chromosome

10. Chromosome Mutations 4) Deletion
One part of a chromosome breaks off. This results in a loss of some genes
E.g. Angleman’s Syndrome (Chromsome #15)
Angelman syndrome (AS) is a neurological disorder first described in 1965 by an English physician named Dr. Harry Angelman.  Symptoms are usually evident after the age of three, and are characterized by severe congenital mental retardation, unusual facial appearance, and muscular abnormalities.
Who gets it?
Symptoms of Angelman syndrome include a stiff, unstable jerky gait, absent or diminished speech skills, hand flapping, excessive laughter/unusually happy demeanor, developmental delay, and small head size (microcephaly).  Some patients may also develop epilepsy and have problems with balance.

11. Chromosome Mutations 5) Non-disjunction
Addition or loss of a whole chromosome (ones that usually separate during meiosis remain together)

12. Chromosome Mutations 6) Polyploidy
More than normal copy of chromosomes

13. Gene Mutations
Genes tell the cell what order to arrange amino acids (to form proteins)
Changes in the DNA sequence will change the message transcribed into mRNA & likely change the protein
Types of Mutations:
Point Mutation
Base Substitution

14. Point Mutation Single nucleotide in a gene is changed
This is drastic as all triple codons beyond are changed
This makes the gene useless and the organism will lack the protein normally made by the gene

15. Base Substitution One base in a nucleotide is substituted for another.
This changes 1 codon and one amino acid
Results in a protein that doesn’t function normally
E.g. PKU
Substitution of GT to AT