Title: Microbial Genetics
1Microbial Genetics
- The how and why of information flow in living
things. - What exactly is living?
2Genetics Terms
- Genome
- Chromosome
- Gene
- Base pair
- Genetic code
- Genotype
- Phenotype
3The Polymers of life
- Define Polymer
- Define Monomer
- What are the polymers of life?
- Why use polymers?
4Determine Relatedness
Clinical Focus, p. 223
5Determine Relatedness
- Which strain is more closely related to the
Uganda strain?
Strain Similar to Uganda
Kenya 71
U.S. 51
6The genetic Code
- Name the monomers that make up the genetic code.
- Name the monomers that make up Proteins
7What is the flow of genetic information in the
bacterial cell?
Verb Enzyme Substrate Product
8Genetic Map of the Chromosome of E. coli
Figure 8.1b
9The Flow of Genetic Information
Figure 8.2
10DNA Replication
- The double strand of DNA is separated.
- DNA polymerase reads the DNA strand and creates
another. - The newly synthesized DNA contains an old strand
and a new strand. - The two new strands are then separated into the
two new daughter cells.
11Semiconservative Replication
Figure 8.3a
12DNA Synthesis
Figure 8.4
13DNA Synthesis
- DNA is copied by DNA polymerase
- In the 5' ? 3' direction
- Initiated by an RNA primer
- Leading strand is synthesized continuously
- Lagging strand is synthesized discontinuously
- Okazaki fragments
- RNA primers are removed and Okazaki fragments
joined by a DNA polymerase and DNA ligase
14Transcription
- A sequence of DNA is relaxed and opened up.
- RNA polymerase synthesizes a strand of RNA
- RNA uses ACGU
- Starting point is a promoter
15Transcription
Figure 8.7
16The Process of Transcription
Figure 8.7
17Translation
- mRNA associates with ribosome's (rRNA and
protein) - 3-base segments of mRNA specify amino acids and
are called codons. - Genetic code relationship among nucleotide
sequence and corresponding DNA sequence.
18Degenerate Most amino acids are code for by
more than one codon.
- 64 codons
- 3 are nonsense
- Start codon Aug is for methionine.
- See the codon sequence.
19The Genetic Code
Figure 8.8
20Simultaneous Transcription Translation
Figure 8.10
21The Process of Translation
Figure 8.9
22The Process of Translation
Figure 8.9
23The Process of Translation
Figure 8.9
24The Process of Translation
Figure 8.9
25The Process of Translation
Figure 8.9
26The Process of Translation
Figure 8.9
27The Process of Translation
Figure 8.9
28The Process of Translation
Figure 8.9
29Info
- From information storage to reality.
- What determines what info is used
- What determines how information is moved about.
30Regulation
- Constitutive genes are expressed at a fixed rate
- Other genes are expressed only as needed
- Repressible genes
- Inducible genes
- Catabolite repression
31Operon
ANIMATION Operons Overview
Figure 8.12
32Induction
Figure 8.12
33Induction
Figure 8.12
34Repression
Figure 8.13
35Repression
ANIMATION Operons Induction
ANIMATION Operons Repression
Figure 8.13
36Catabolite Repression
Figure 8.14
37- Lactose present, no glucose
Figure 8.15
38Types of Bacterial sex
Name Process What it is Comments
39Genetic Recombination
- The rearrangement of genes.
- Crossing over is where genes are recombined
within a chromosome.
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41Transformation
- Naked DNA is transferred from one bacteria to
another. - Was the first experiment that showed DNA was the
genetic information
42Genetic Recombination
Figure 8.25
43Genetic Transformation
ANIMATION Transformation
Figure 8.24
44Conjugation
- DNA transferred from one bacteria to another by a
sex pillus. - Information of transfer coded by a plasmid called
F - Hfr cells occur when F plasmid goes into the
host chromosome and recombines, it will then draw
across the DNA.
45Bacterial Conjugation
Figure 8.26
46Conjugation in E. coli
Figure 8.27a
47Conjugation in E. coli
Figure 8.27b
48Conjugation in E. coli
Figure 8.27c
49Transduction
- DNA is passed from one bacterium to another in a
bacteriophage and put into recipients DNA.
50Transduction by a Bacteriophage
Figure 8.28
51Alternate forms of the chromosome format.
- Plasmids self replicating circular molecules of
NDA - Transposes small segments of DNA that can move
into different parts of the genome. - Can these have an effect on Evolution?
52Control of gene expression
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54The Operon Model of gene expression
- Repression regulatory mechanism inhibits gene
expression - Induction a process that turn on gene
expression
55Repressible Operon
56Inducible operon
57Where are the points of control
58If a cell has all the genes that are needed then
why are they not expressed at one time?
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60Mutations
61Mutations
62Mutation
- A change in the genetic material
- Mutations may be neutral, beneficial, or harmful
- Mutagen Agent that causes mutations
- Spontaneous mutations Occur in the absence of a
mutagen
63Mutation
- Base substitution (point mutation)
- Missense mutation
- Change in one base
- Result in change in amino acid
Figure 8.17a, b
64Mutation
- Results in a nonsense codon
Figure 8.17a, c
65Mutation
- Insertion or deletion of one or more nucleotide
pairs
Figure 8.17a, d
66The Frequency of Mutation
67Chemical Mutagens
Figure 8.19a
68Radiation
- Ionizing radiation (X rays and gamma rays) causes
the formation of ions that can react with
nucleotides and the deoxyribose-phosphate backbone
69Radiation
- UV radiation causes thymine dimers
Figure 8.20
70Repair
- Photolyases separate thymine dimers
- Nucleotide excision repair
Figure 8.20
71Selection
- Positive (direct) selection detects mutant cells
because they grow or appear different - Negative (indirect) selection detects mutant
cells because they do not grow - Replica plating
72Replica Plating
Figure 8.21
73Ames Test for Chemical Carcinogens
Figure 8.22
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76The old and new genetics
- Screening and selection of mutants
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78What do you think we would call the new genetics?