Advanced Biology

1. Advanced Biology Mutations

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

3. 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. Gene Mutation • Normal mRNA reads: • AUG AAG UUU GGC GCA UUG UAA • Met Lys Phe Gly Ala Leu Stop. • Mutated mRNA reads: • AUG AAG UUGGCG CAU UGU AA… • Met LysLeu 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. Gene Mutation • 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 PheVal Arg Ile Val

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

9. Gene Mutation • Normal mRNA reads: • AUG AAG UUU GGC GCA UUG UAA • Met Lys Phe Gly Ala Leu Stop. • Mutated mRNA reads: • AUG AAG UUU AGCGCA 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.

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.