ch 8 Microbial Genetics FOR TEACHERS.ppt
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About This Presentation
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Slide Content
Microbial Genetics
The how and why of information flow in
living things.
What exactly is living?
The how and why of information flow in
living things.
What exactly is living?
Genetics Terms
•Genome:
•Chromosome
•Gene
•Base pair
•Genetic code
•Genotype
•Phenotype
•Genome:
•Chromosome
•Gene
•Base pair
•Genetic code
•Genotype
•Phenotype
The Polymers of life
•Define Polymer
•Define Monomer
•What are the polymers of life?
•Why use polymers?
•Define Polymer
•Define Monomer
•What are the polymers of life?
•Why use polymers?
Clinical Focus, p. 223
Determine Relatedness
Determine Relatedness
Determine Relatedness
Strain
% Similar to
Uganda
Kenya 71%
U.S. 51%
•Which strain is
more closely
related to the
Uganda strain?
Strain
% Similar to
Uganda
Kenya 71%
U.S. 51%
•Which strain is
more closely
related to the
Uganda strain?
The genetic Code
•Name the monomers that make up the
genetic code.
•Name the monomers that make up
Proteins
•Name the monomers that make up the
genetic code.
•Name the monomers that make up
Proteins
What is the flow of genetic
information in the bacterial cell?
Verb Enzyme SubstrateProduct
information in the bacterial cell?
Verb Enzyme SubstrateProduct
Figure 8.1b
Genetic Map of the
Chromosome of E. coli
Genetic Map of the
Chromosome of E. coli
Figure 8.2
The Flow of Genetic Information
The Flow of Genetic Information
DNA 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.
•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.
Figure 8.3a
Semiconservative Replication
Semiconservative Replication
Figure 8.4
DNA Synthesis
DNA Synthesis
DNA 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
•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
Transcription
•A sequence of DNA is relaxed and opened
up.
•RNA polymerase synthesizes a strand of
RNA
•RNA uses ACGU
•Starting point is a promoter
•A sequence of DNA is relaxed and opened
up.
•RNA polymerase synthesizes a strand of
RNA
•RNA uses ACGU
•Starting point is a promoter
Figure 8.7
Transcription
Transcription
Figure 8.7
The Process of Transcription
The Process of Transcription
Translation
•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.
•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.
Degenerate: 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.
code for by more than one codon.
•64 codons
•3 are nonsense
•Start codon Aug is for methionine.
•See the codon sequence.
Figure 8.8
The Genetic Code
The Genetic Code
Figure 8.10
Simultaneous Transcription &
Translation
Simultaneous Transcription &
Translation
Figure 8.9
The Process of Translation
The Process of Translation
Figure 8.9
The Process of Translation
The Process of Translation
Figure 8.9
The Process of Translation
The Process of Translation
Figure 8.9
The Process of Translation
The Process of Translation
Figure 8.9
The Process of Translation
The Process of Translation
Figure 8.9
The Process of Translation
The Process of Translation
Figure 8.9
The Process of Translation
The Process of Translation
Figure 8.9
The Process of Translation
The Process of Translation
Info
•From information storage to reality.
•What determines what info is used
•What determines how information is
moved about.
•From information storage to reality.
•What determines what info is used
•What determines how information is
moved about.
Regulation
•Constitutive genes are expressed at a
fixed rate
•Other genes are expressed only as needed
–Repressible genes
–Inducible genes
–Catabolite repression
•Constitutive genes are expressed at a
fixed rate
•Other genes are expressed only as needed
–Repressible genes
–Inducible genes
–Catabolite repression
Figure 8.12
ANIMATION Operons: Overview
Operon
ANIMATION Operons: Overview
Operon
Figure 8.12
Induction
Induction
Figure 8.12
Induction
Induction
Figure 8.13
Repression
Repression
Figure 8.13
ANIMATION Operons: Induction
ANIMATION Operons: Repression
Repression
ANIMATION Operons: Induction
ANIMATION Operons: Repression
Repression
Figure 8.14
(a) Growth on glucose or lactose alone (b) Growth on glucose and lactose
combined
Catabolite Repression
(a) Growth on glucose or lactose alone (b) Growth on glucose and lactose
combined
Catabolite Repression
•Lactose present,
no glucose
•Lactose + glucose
present
Figure 8.15
no glucose
•Lactose + glucose
present
Figure 8.15
Types of Bacterial sex
Name Process What it isComments
Name Process What it isComments
Genetic Recombination
•The rearrangement of genes.
•Crossing over is where genes are
recombined within a chromosome.
•The rearrangement of genes.
•Crossing over is where genes are
recombined within a chromosome.
Transformation
•Naked DNA is transferred from one
bacteria to another.
•Was the first experiment that showed DNA
was the genetic information
•Naked DNA is transferred from one
bacteria to another.
•Was the first experiment that showed DNA
was the genetic information
Figure 8.25
Genetic Recombination
Genetic Recombination
Figure 8.24
ANIMATION Transformation
Genetic Transformation
ANIMATION Transformation
Genetic Transformation
Conjugation
•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.
•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.
Figure 8.26
Bacterial Conjugation
Bacterial Conjugation
Figure 8.27a
Conjugation in E. coli
Conjugation in E. coli
Figure 8.27b
Conjugation in E. coli
Conjugation in E. coli
Figure 8.27c
Conjugation in E. coli
Conjugation in E. coli
Transduction
•DNA is passed from one bacterium to
another in a bacteriophage and put into
recipients DNA.
•DNA is passed from one bacterium to
another in a bacteriophage and put into
recipients DNA.
Figure 8.28
Transduction by a Bacteriophage
Transduction by a Bacteriophage
Alternate 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?
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?
Control of gene expression
•Repression
•Induction
•Repression
•Induction
The Operon Model of gene
expression
•Repression:
regulatory mechanism
inhibits gene
expression
•Induction: a process
that turn on gene
expression
expression
•Repression:
regulatory mechanism
inhibits gene
expression
•Induction: a process
that turn on gene
expression
Repressible Operon
Inducible operon
Where are the points of control
If a cell has all the genes that
are needed then why are they
not expressed at one time?
are needed then why are they
not expressed at one time?
Mutations
•What are they?
•What are they?
Mutations
•What can they do
•What can they do
Mutation
•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
•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
•Base substitution
(point mutation)
•Missense mutation
Mutation
•Change in one
base
•Result in change in
amino acid
Figure 8.17a, b
(point mutation)
•Missense mutation
Mutation
•Change in one
base
•Result in change in
amino acid
Figure 8.17a, b
•Nonsense mutation
Mutation
•Results in a
nonsense codon
Figure 8.17a, c
Mutation
•Results in a
nonsense codon
Figure 8.17a, c
Mutation
•Frameshift mutation
•Insertion or deletion
of one or more
nucleotide pairs
Figure 8.17a, d
•Frameshift mutation
•Insertion or deletion
of one or more
nucleotide pairs
Figure 8.17a, d
The Frequency of Mutation
Figure 8.19a
Chemical Mutagens
Chemical Mutagens
Radiation
•Ionizing radiation (X rays and gamma
rays) causes the formation of ions that can
react with nucleotides and the deoxyribose-
phosphate backbone
•Ionizing radiation (X rays and gamma
rays) causes the formation of ions that can
react with nucleotides and the deoxyribose-
phosphate backbone
Figure 8.20
Radiation
•UV radiation
causes thymine
dimers
Radiation
•UV radiation
causes thymine
dimers
Figure 8.20
Repair
•Photolyases separate thymine dimers
•Nucleotide excision repair
Repair
•Photolyases separate thymine dimers
•Nucleotide excision repair
Selection
•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
•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
Figure 8.21
Replica Plating
Replica Plating
Figure 8.22
Ames Test for Chemical
Carcinogens
Ames Test for Chemical
Carcinogens
The old and new genetics
•Screening and selection of mutants
•Screening and selection of mutants
What do you think we would call
the new genetics?
the new genetics?
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