1. Microbial Genetics - DNA Transfer
Review of Information Transfer in Cell
Recombination
Transfer of DNA &Genetic Recombination in Bacteria
Conjugation
Transformation
Transduction

2. Microbial Genetics - DNA Transfer

3. Microbial Genetics - DNA Transfer
Recombination – process by which DNa is broken and repaired resulting in an exchange of DNA between two DNA molecules to form new combinations of genes
Eukaryotic - crossing over during meiosis
Prokaryotic - occurs when DNA is transfered from one cell to another (transfer from a doner to a recipient)

4. Microbial Genetics - DNA Transfer
Recombination

5. Microbial Genetics - DNA Transfer
Conjugation

6. Microbial Genetics - DNA Transfer
Normal or Low Frequency Conjugation

7. Microbial Genetics - DNA Transfer
High Frequency Conjugation

8. Transformation

9. Transduction

10. Microbial Genetics - Regulation
Three types of regulation
Constitutive - gene is always turned on
Repression - gene is normally turned on but can be turned off in response to a metabolic signal
Induction - gene is normally turned off but can be turned on in response to a metabolic signal

11. Microbial Genetics - Regulation
Regulation of Gene Activity
Genes turned on or off as needed - saves energy
Enzymes can be regulated by feedback, by control of mRNA sysnthesis or the control of translation

12. Microbial Genetics - Regulation
Three types of regulation
Constitutive - gene is always turned on
Repression - gene is normally turned on but can be turned off in response to a metabolic signal
Induction - gene is normally turned off but can be turned on in response to a metabolic signal

13. Microbial Genetics - Regulation
Types of Regulation of mRNA synthesis
Induction - lac operon
Repression - trp operon

14. Microbial Genetics - Regulation

15. Microbial Genetics - Mutation
Mutation - Introduction
A mutation is a change in the DNA sequence that results in a change in the product protein
Mutations can be neutral, harmful (most) or beneficial
Mutation is the basis of variation within a species and thus provides an important mechanism to evolution

16. Microbial Genetics - Mutation
Types of Mutation
Base-pair substitution - misssense change in amino acid sequence
Base-pair substitution - nonsense change in DNA sequence - premature stop
Frameshift
Insertion
Deletion

17. Microbial Genetics - Mutation
Normal gene
DNA transcribed
mRNA translated
No change in gene product

18. Microbial Genetics - Mutation
Missense mutation
Base substitution
Changes amino acid sequence by one amino acid
May or may not affect activity of protein

19. Microbial Genetics - Mutation
Nonsense mutation
Mutation changes codon to stop codon
Premature termination of protein
Almost always destroys activity of protein

20. Microbial Genetics - Mutation
Frameshift mutation
inserts or deletes a base in the DNA
Protein may be of correct size (approximately)
Protein sequence altered significantly

21. Microbial Genetics - Mutation
Mutatgens
Chemicals that modify DNA
Deaminating agents
Methylating agents
Intercalating agents
Radiation
UV - UV repair system
X-Rays

22. Effect of UV Light
Production of
Thymine Dimers
Repair of
Tymine Dimers

23. Microbial Genetics - Mutation
Frequency
Rate at which change occurs usually low
Mostly random although there are “hot spots”
Low rate necessary to provide genetic diversity
Rate can change depending upon what population of cells is exposed to