1. Biology
Chapter 12.4

2. What is a mutation?
A change (mistake) in the replication of genetic material.
The daughter cell is different from the parent

3. Gene Mutation
Most replication errors are corrected by the cell’s built in spell check system.
However, some do escape detection

4. Gene Mutation
Deletion – Leaving out one nucleotide in the sequence, shifts the reading of the sequence to the left, creating a totally different set of amino acids

5. DELETION Normal mRNA reads: AUG AAG UUU GGC GCA UUG UAA
Met Lys Phe Gly Ala Leu Stop.
Mutated mRNA reads:
AUG AAG UUG GCG CAU UGU AA…
Met Lys Leu Ala His Cys …

6. Gene Mutation
Insertion – Mutation in which an extra nucleotide is added to the chain during replication, shifts reading to the right, creating a totally different set of amino acids

7. INSERTION Normal mRNA reads: AUG AAG UUU GGC GCA UUG UAA
Met Lys Phe Gly Ala Leu Stop.
Mutated mRNA reads:
AUG AAG UUU GUG CGC AUU GUA A
Met Lys Phe Val Arg Ile Val

8. Gene Mutation
Point Mutation – A base substitution occurs. One nucleotide is replaced with a different one

9. POINT MUTATION Normal mRNA reads: AUG AAG UUU GGC GCA UUG UAA
Met Lys Phe Gly Ala Leu Stop.
Mutated mRNA reads:
AUG AAG UUU AGC GCA UUG UAA
Met Lys Phe Ser Ala Leu Stop.

10. Gene Mutation
These mutations arise spontaneously during DNA replication.
External agents may cause mutations, called mutagens.

11. Chromosome Mutations
Changes may occur in chromosomes as well as in genes.
Chromosome mutations can have serious effects on the distribution of genes to gametes during meiosis.

12. Chromosome Mutations
Deletion:
ABCDE---FGH
ABCE---FGH

13. Chromosome Mutations
Duplication:
ABCDE---FGH
ABCBCDE---FGH

14. Chromosome Mutations
Inversion:
ABCDE---FGH
ADCBE---FGH

15. Chromosome Mutations Attachment to a different chromosome: ABCDE---FGH
WXY---Z
WXABCDE---FGH
Y---Z

16. Other causes of genetic variation
During meiosis, homologous pairs fail to separate.
This would cause the offspring to have an extra chromosome.
During meiosis, part of one chromatid breaks of and joins to the other (see pg 264.)

17. CANCER
Abnormal cells, go through cell cycle very fast, creating new cells like it.
They reproduce in an uncontrolled way, crowding out healthy cells and destroying tissues and possibly organs.
It can spread to other parts of the body

18. Causes of Cancer
Genes that control the cell cycle mutate, called an oncogene.
Mutations may be inherited or caused by a carcinogen, a cancer causing agent in the environment.
Tobacco smoke, radiation and other chemicals.

19. Causes of Cancer Viruses may also cause cancer.
Their presence disrupts normal cell processes.
They can also carry oncogenes into the host cell.

20. Technology
Scientists can transfer a gene artificially from a donor organism to a bacteria.
The DNA of the bacterium is called recombinant DNA.
The bacteria will transcribe and translate the foreign gene and produce the protein it is coding for.

21. Technology
Small, circular pieces of DNA, called plasmids, are where the foreign DNA is placed.

22. Technology
To obtain a foreign gene, mRNA from a cell is isolated and DNA is produced (called reverse transcription). This single stranded DNA is converted to a double strand and this double strand is the desired gene.

23. Technology
In use today – goats that produce a human blood clot dissolving factor.
Plants that are disease resistant.
Plants that are larger than normal.