MICRV01 - Microbial Genetics (Ch 9)© copyright 2013 Marta D. de Jesus

Textbook associated animations for Ch 9:

I. Structure & function of the genetic material

A. genetics

B. Nucleic Acids

1. structure

a. monomers

b. polymers

1) DNA

2) RNA

2. Central theory

a. within the cell

b. between cells

C. genome

1. chromosome(s)

a. prokaryotic

b. eukaryotic

chromatin

histones

2. genes

prokaryotic

eukaryotic

D. genotype & phenotype

1. genotype

2. phenotype

II. DNA replication

A. semi-conservative replication

B. in more detail: replication fork

1. template strands

2. DNA helicase

3. DNA polymerase III

4. RNA primer

primase

5. leading strand

6. lagging strand

Okazaki frgaments

7. DNA pol I

8. DNA ligase

Structural Basis of DNA Replication (303.0K)

dna replication fork (880.0K)

how nucleotides are added in dna replication (1028.0K)

Other video:

What does DNA gyrase do? precedes helicase & deals with torsional strain

(

C. other details of DNA replication

where starts: origin of replication

DNA can be modified

III. Transcription

A. structures

1. DNA template

2. RNAs

a. messenger RNA (mRNA)

b. ribosomal RNA (

c. transfer RNA (tRNA)

3. regulatory RNAs

B. process

1. RNA polymerase

2. initiation

promoter site

3. RNA nucleotides put together to make new chain (elongation)

4. termination

5. DNA

Transcription of RNA from DNA (116.0K)

Stages of Transcription (965.0K)

C. differences between euks & proks

1. compartments

a. prokaryotes

b. euk version

2. mechanism

3. structure of mRNAs

a. prok mRNAs

b. euk. are processed

exons

introns

IV. Translation

A. structures

1. mRNA

a. The Genetic Code

b. 64 codons

c. universal code

2. ribosomes

3. transfer RNAs

anticodon

amino acids

B. Translation process

1. initiation

initiator codon

Translation Initiation (327.0K)

2. elongation

peptide bond

translation elongation (309.0K)

3. termination

a. stop/nonsense/terminator codon

b. release factor (a protein)

translation termination (146.0K)

protein synthesis1 (851.0K)

protein synthesis2 (1100.0K)

ProteinSynthesis3 (13.0K)

4. differences between pro- & eukaryotes

V. Examples of regulation of gene expression in bacteria

A. operons

B. negative control: inducible operon model (eg: lac operon)

1. regulatory gene

a. repressor proteins

b. inducer

2. in the operon

a. structural genes

b. control region

1) promoter

2) operator

3. positive control

a. CAP = catabolic activator protein

b. cAMP

Combination of Switches The Lac Operon (691.0K)

Another instructor:

C. negative control: repressible operon model (eg: arg operon)

1. regulatory gene

a. repressor protein

b. corepressor

2. structural genes

3. control region

a. promoter

b. operator

similar system: trp operontryptophan repressor (471.0K)

D. other regulatory RNAs

VI. Mutation

A. types of mutations

1. point mutation

a. base substitution

1) silent mutation

2) missense mutation

3) nonsense mutation

b. frameshift mutation

2. up to larger chromosome damage

B. how?

1. spontaneous mutation

2. mutagens

a. chemicals

1) nitrous acid

2) N base analogs

3) many others

b. radiation

1) ionizing

2) non-ionizing

c. biological

C. mutation rate

D. DNA repair mechanisms

1. base-excision repair

E. identifying mutants

1. positive (direct) selection

2. negative (indirect) selection

a. replica plating technique

1) master plate

2) replica plate

E. identifying mutagens (Bruce) Ames test

Salmonellamutant strain

F. identifying carcinogens

VII. Transfer of genetic information

A. genetic recombination

1. vertical transfer

2. horizontal transfer

B. mechanisms only in eukaryotes

1. making haploid cells from diploid

2. sex

C. methods used by prokaryotes

1. transformation - Griffith’s experiment

2. conjugation in E. coli (bacterial “sex”)

a. plasmids

b. conjugation pilus/pili

c. F+ cells

d. F- cells

e. Hfr cells

Bacterial Conjugation-Transfer of a Plasmid (786.0K)

Conjugation Transfer of Chromosomal DNA (618.0K)

3. transduction uses virus

a. bacteriophage

4. transposable genetic elements = transposons = “jumping genes”

transposons shifting segments of the genome (380.0K)

c. structure

1) insertion sequences

simple transposition (259.0K)

2) complex transposons

mechanism of transposition (647.0K)

C. genes and Evolution