+ 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
+ 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