Download Molecular Genetics

Genetics
Viruses & Bacteria
Recombinant Technology
Ch. 19 & 20
Viruses
Contain nucleic acid
(DNA or RNA)
Protein coat – called
CAPSID, protein
subunits called
CAPSOMERES
Some have
ENVELOPE – lipids
and proteins from
host cell
Lytic Infection- death of
host cell
Virus penetrates host
cell
Viral genetic material
uses host enzymes to
replicate and produce
viral proteins
Newly assembled
viruses erupt from
host cell (infect new
cells)
Lytic Infection
DNA viruses


Behaves as host DNA
Utilizes host enzymes
RNA viruses


Behave as mRNA (or
template)
Retroviruses – reverse
transcriptase creates
DNA copy of RNA to
behave as host DNA
Lysogenic Infection- does not destroy host
Viral DNA temporarily incorporated into host DNA
as a PROVIRUS
Provirus replicated along with host DNA
Remains inactive until environmental triggers
Activation leads to lytic cycle
Bacteria
Single, circular DNA
“Naked” chromosome –
no associated proteins
(like histones)
Reproduction: binary
fission
Plasmids – short, circular
DNA (beneficial but not
essential)
Episomes – plasmids that
become incorporated into
genome
Genetic Variation in Bacteria
Conjugation –
exchange of DNA
through pilus (genome
or plasmid)
Transduction – virus
introduces new DNA to
bacterial genome
(virus picked up DNA
from another bacteria)
Transformation –
bacteria absorb DNA
from surroundings and
incorporate into
genome
Recombinant DNA
DNA segments or
genes from different
sources
Natural: transduction,
conjugation,
transposons, crossing
over
Artificial: recombinant
DNA technology
rDNA Technology
Restriction enzymes – from
bacteria (defense against
viruses), cut DNA at specific
sequences
Uneven cuts produce
“sticky ends”
GOI = gene of interest
Vector = method of
introducing foreign DNA into
cell (usually plasmid)
Transformation - uptake of
vector containing GOI
cDNA
Problem: GOI contains
both exons and introns
(introns can suppress
expression)
Solution: copy DNA
from already processed
mRNA using viral
reverse transcriptase
Called complimentary
DNA (cDNA)
PCR
Polymerase Chain
Reaction
Used to amplify
DNA (make a LOT
of copies of a
sample)
Uses DNA
polymerase directly
(and synthetic
primers)
RFLP Analysis
Restriction Fragment Length
Polymorphisms
Polymorphism = variation in
DNA sequences between
individuals
Restriction enzymes from
bacteria cut DNA molecules to
create DNA fragments of
varying lengths
Separate fragments in gel
electrophoresis
DNA fingerprinting (CSI,
paternity)
Bozeman: DNA Fingerprinting
DNA Fingerprinting http://youtu.be/DbR9xMXuK7c (6:10)