Transcript of + Bacterial Genetics March 2015. + Terminology Genetics: The study of what genes are, how they carry...
- Slide 1
- + Bacterial Genetics March 2015
- Slide 2
- + Terminology Genetics: The study of what genes are, how they
carry information, how information is expressed, and how genes are
replicated Gene: A segment of DNA that encodes a functional
product, usually a protein Chromosome: Structure containing DNA
that physically carries hereditary information; the chromosomes
contain the genes Genome: All the genetic information in a cell
Plasmid small circular DNA molecule that replicates independently
of the chromosome
- Slide 3
- Slide 4
- + Figure 8.3b DNA Polymer of nucleotides: Adenine, thymine,
cytosine, and guanine Double helix associated with proteins
"Backbone" is deoxyribose-phosphate Strands are held together by
hydrogen bonds between AT and CG Strands are antiparallel
- Slide 5
- + Figure 8.5 DNA Synthesis
- Slide 6
- + Figure 8.6 Replication of Bacterial DNA
- Slide 7
- + Transcription DNA is transcribed to make RNA (mRNA, tRNA, and
rRNA) Transcription begins when RNA polymerase binds to the
promoter sequence Transcription proceeds in the 5' 3' direction
Transcription stops when it reaches the terminator sequence
- Slide 8
- + Figure 8.7 The Process of Transcription
- Slide 9
- + Figure 8.2 Translation mRNA is translated in codons (three
nucleotides) Translation of mRNA begins at the start codon: AUG
Translation ends at nonsense codons: UAA, UAG, UGA
- Slide 10
- + Figure 8.10 Simultaneous Transcription & Translation
- Slide 11
- + Figure 8.24 Genetic Transformation Frederick Griffith
(1920s)
- Slide 12
- + Recombinant DNA Technology Recombinant DNA: DNA made from two
different sources. In the 1960s, Paul Berg inserted animal DNA into
bacterial DNA, and the bacteria produced an animal protein
- Slide 13
- + Recombinant DNA Technology 1941: George Beadle and Edward
Tatum showed that genes encode a cells enzymes 1944: Oswald Avery,
Colin MacLeod, and Maclyn McCarty showed that DNA was the
hereditary material 1961: Francois Jacob and Jacques Monod
discovered the role of mRNA in protein synthesis
- Slide 14
- + Figure 8.2 The Flow of Genetic Information
- Slide 15
- + Vertical gene transfer: Occurs during reproduction between
generations of cells. Horizontal gene transfer: The transfer of
genes between cells of the same generation. Genetic
Recombination
- Slide 16
- + Figure 8.25 Genetic Recombination
- Slide 17
- + Transmission of Genetic Material in Bacterial Cells
- Slide 18
- + Conjugation
- Slide 19
- + Transformation
- Slide 20
- + Transduction
- Slide 21
- + 3 main categories of genes Structural genes Code for proteins
Regulatory genes Control gene expression RNA coding genes
- Slide 22
- + Operons: The Basic Concept Operator -the regulatory switch, a
segment of DNA usually positioned within the promoter Operon (DNA)
includes the operator, the promoter, and the genes that they
control In coordinate control, a cluster of functionally related
genes can be controlled by a single on- off switch
- Slide 23
- Slide 24
- + Activator (protein) when stimulated, changes shape and binds
to the promoter to increase the affinity of RNA polymerase to the
promoter (increasing the rate of transcription). - The lac operon
is stimulated by a small organic molecule known as cAMP that is
produced in response to low cellular glucose. Operons:
Activation
- Slide 25
- + Operon: Lactose Metabolism
- Slide 26
- + Lac Operon: Sensing Glucose vs. Lactose Bacterial will always
prefer glucose over lactose if it is available. Thus, how does E.
coli sense when glucose levels are low? How does it relay that
information to the genome?
- Slide 27
- + Lactose present No glucose Lactose and Glucose present Figure
8.15 Operons: Activation of Lac Operon
- Slide 28
- Slide 29
- + Repressor (protein) switches the operon off Prevents
transcription by binding to the operator and blocking RNA
polymerase the product of a separate regulatory gene can be in an
active or inactive form, depending on the presence of other
molecules Corepressor cooperates with a repressor protein to switch
an operon off Operons: Repression
- Slide 30
- + When a repressor is bound to the operator, RNA poly cannot
bind the promoter and transcription is turned off When the
repressor is not bound to the operator, RNA poly can bind the
promoter and transcription is turned on. Operons: Relieving
Repression
- Slide 31
- + Biotechnology Recombinant DNA technology, a new technique for
biotechnology, enables bacteria and fungi to produce a variety of
proteins including vaccines and enzymes Missing or defective genes
in human cells can be replaced in gene therapy Genetically modified
bacteria are used to protect crops from insects and from
freezing
- Slide 32
- Figure 9.11
- Slide 33
- + pGLO Plasmid DNA
- Slide 34
- + Lac Operon vs Ara Operon
- Slide 35
- + Replacing Ara operon with GFP gene
- Slide 36
- Slide 37
- + Figure 8.26 Bacterial Conjugation
- Slide 38
- + Plasmids Conjugative plasmid: Carries genes for sex pili and
transfer of the plasmid Dissimilation plasmids: Encode enzymes for
catabolism of unusual compounds R factors: Encode antibiotic
resistance
- Slide 39
- + Figure 8.29 R Factor, a Type of Plasmid
- Slide 40
- + Figure 8.27a Conjugation in E. coli
- Slide 41
- + Figure 8.27b Conjugation in E. coli
- Slide 42
- +
- Slide 43
- + Figure 8.28 Transduction by a Bacteriophage