1. Mutations
Dr. Evil: I have one simple request. And that is to have sharks with frickin' laser beams attached to their frickin’ heads! What do we have?
Number Two: Sea bass.
Dr. Evil: Rrrriiight.
Number Two: They're mutated sea bass.

2. Mutations Changes in the DNA occasionally occur.
Almost always harmful, but VERY occasionally code for a new, good, protein/trait.
Methods to protect DNA from changes are constantly active.

3. Types of Mutations
A point or substitution mutation is a change in a single base pair in DNA.
mRNA
Normal
Protein
Stop
Replace G with A
Point mutation
mRNA
Protein
Stop

4. The effects of point mutations
CAN change the amino acid that the codon codes for. Sometimes not. (Why not?)
A single wrong amino acid can affect the shape of the protein.

5. Frameshift mutations Deletion A single base lost in DNA.
mRNA would be out of position by one base.
Every codon after the deleted base would be different and thus different amino acids.
Deletion of U
Frameshift mutation
mRNA
Protein

6. Frameshift mutations Insertion
Same thing as deletion - every amino acid after insertion would be different.
Frameshift mutation because it shifts the reading of codons by one base.

7. Causes of Mutations Just happen, spontaneous mistake.
Caused by something else.
Mutagens cause changes in DNA.
Radiation
X rays, cosmic rays, ultraviolet light, nuclear radiation
Cause deletions
Chemicals
Dioxins, asbestos, benzene, formaldehyde (gasoline, old insulation, refrigerants, preservatives)
Cause Point or Substitution mutations
High temperatures.

8. Repairing DNA Enzymes proofread DNA, replace incorrect nucleotides.
Not perfect.
Greater the exposure to a mutagen the more likely a mistake will not be corrected.

9. Mutations in body cells
Damage not passed on to offspring.
May cause problems for the individual.
Impair the function of the cell
Cell divides, new cells also will have mutation
Could affect genes that control cell division = cancer.

10. Mutations in reproductive cells
Mutation in a sperm or an egg cell.
Offspring affected.
New beneficial protein/trait (VERY rare)
Defective protein
Nonfunctional protein - embryo death

11. Chromosomal Alterations
Changes may occur in chromosomes too.
Called chromosomal mutations.
Common in plants.
Few passed on, zygote usually dies.

12. Chromosomal Alterations
Part of a chromosome is left out.
A B C D E F G H
A B C E F G H
Deletion
Part of a chromatid breaks off and attaches to its sister chromatid.
A B C D E F G H
A B C B C D E F G H
Insertion

13. Chromosomal Alterations
Part of one chromosome breaks off and is added to a different chromosome, a translocation occurs. A B C D E F G H W X A B C D E F G H W X Y Z Y Z
Translocation

14. Question 1 Any change in DNA sequences is called a _______.
A. replication
B. mutation
C. transcription
D. translation
The answer is B.

15. Question 2
Which is more serious, a point mutation or a frameshift mutation? Why?
Answer
A frameshift mutation is more serious than a point mutation because it disrupts more codons than a point mutation.

16. Question 3
Why are chromosomal mutations rarely passed on to the next generation?
Answer
Few chromosomal changes are passed on to the next generation because the zygote usually dies. If the zygote survives, it is often sterile and incapable of producing offspring.

17. Question 10 The DNA sequences of a parrot _________.
A. are more similar to those of a clam than a robin
B. are more similar to a fern than a dog
C. are exactly the same as those of a human
D. contain exactly the same nucleotides as those of a beetle
The answer is D.