1. SB2. The learner will analyze how biological traits are passed on to successive generations.
d. Describe the relationships between changes in DNA and potential appearance of new traits 1

2. LEQ3: What relationship exists between changes in DNA and the potential appearance of new traits?

3. Mutations
Mutations are changes in DNA that may or may not affect the phenotype of an organism.
Physical appearance
Change in an organisms DNA
Some mutations affect a single gene, while others affect an entire chromosome.

4. MUTATIONS Two main types: Gene
Mutation that causes a change in a single gene
Chromosomal
Mutation that involves the entire chromosome
Both can be caused by nature, random events, or environmental factors 4

5. Gene Mutations
A gene mutation is a change in the DNA of a single gene in an organism.
Many kinds of mutations can occur, especially during replication.
Point mutation
Frameshift mutations

6. Gene Mutations A point mutation substitutes on nucleotide for another.
Mutated Base

7. Gene Mutations
A frameshift mutation inserts or deletes a nucleotide in the DNA sequence.

8. Chromosomal Mutations
A chromosomal mutation affects an entire chromosome.
Affect many genes.
Occurs when chromosomes fail to separate correctly during gamete production ( Meiosis)
Nondisjunction
May lead to abnormalities in offspring

9. Chromosomal Mutations
Types of Chromosomal Mutations:
Gene deletion
Gene duplication
Gene inversion
Gene Translocation 9

10. Chromosomal Mutation Deletion
Occurs when part of a chromosomes breaks off during mitosis/meiosis
Normal
Mutated 10

11. Chromosome Mutation Duplication
Occurs when a section of a chromosomes is repeated
Results from unequal crossing over during Meiosis.
Normal
Mutated 11

12. Chromosomal mutation Inversion
Occurs when a section of a chromosome breaks off, changes direction, and recombines to the same chromosome
Genes are still intact and present on correct chromosome 12

13. Chromosomal Mutation Translocation
Piece of chromosome breaks off one chromosome and combines with a different chromosome. 13

14. Consequences of Mutations
Mutations my or may not affect phenotype.
Chromosomal mutations tend to have a big effect.
Death of the organism
Severe mental or physical disabilities
Genetic Disorders:
Down syndrome 14

15. Consequences of Mutations
Some gene mutations change phenotype.
A mutation may cause a premature stop codon.
A mutation may change protein shape or active site.
A mutation may change gene regulation
Some gene mutation do not affect phenotype.
A mutation may be silent.
A mutation may occur in a noncoding region.
A mutation may not affect protein folding or the active site.

16. Consequences of Mutations
Also, depend on the type of cell the DNA mutation occurs in
Can occur in two types of cells
Somatic (body cell)
Germ line (gametes: sperm/egg)

17. Somatic Mutation Are NOT passed down to offspring Causes:
Random natural causes
Environmental factors: radiation, x-rays, sunlight
Chemical: cigarettes, cleaners
Often lead to cancer 17

18. Germ Line Cells Mutations can be passed down to offspring (inherited)
May be harmful or beneficial to offspring.
Usually occur during Meiosis
Natural selection often removes mutant alleles from a population when they are less adaptive. 18

19. Causes Mutations can be caused by several factors.
Replication errors can cause mutations
Mutagens, such as UV rays and chemicals, can cause mutations.
Some cancer drugs use mutagenic properties to kill cancer cells.

20. Did you know…
Mutations can occur in all types of organisms…even the human race.
One mutation that is very unlikely to be seen is multiple toes and fingers.
Doctors usually remove extra digits at birth. 20