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Chapter 15 (genetic engineering of plants (ti plasmid (insertion vector,…
Chapter 15
genetic engineering of plants
code plants to kill catepillars
altered plants to help farmers
saves money. makes money
GMO's
obtaining genes is easy
inserting genes is hard
ti plasmid
insertion vector
gene and promoter get attached
bacterium Agrobacterium tumefasciens
analysis of genes and recombinant DNA technique
Nucleic Acid Hybridization
DNA hybridization
reformation of double helix
by cooling a solution of single stranded DNA's
Single strand DNA solution
AKA reannealing
DNA melting
AKA DNA denaturation
separation that produces a single stranded DNA solution
Restriction Endonucleases
class of bacterial enzymes
binds to specific nucleotide sequence
cleaves DNA
palindromes
run opposite of restriction endonuclease
present in both strands
can read forward or backward
Identifying DNA fragments
Evolutionary Studies
DNA fragments are used to study DNA evolution
Restriction map
made by staining
used to see fragments
Restriction fragment length polymorphism
a variation in the length of restriction fragments
produced by a given restriction enzyme in DNA
used in forensic investigations.
and to map hereditary disease
physiological Studies
used if any cell forms a lot of protein
reverse transcriptase
virus enzyme
synthesizes DNA using RNA
complementary DNA
complementary to the exons
exons of a gene
synthesized using fluorescent nucleotides
expression profile
uses cDNA's to examine gene expression
compare development in species
DNA cloning
useful technique
placing DNA fragments in bacteria
plasmid
short, circular piece of DNA
occurs in bacteria
acts like tiny bacterial chromosome
vectors
carriers
plasmid genetically modified to be ideal
DNA sequencing
chain termination method
DNA is first cloned
divided into 4 batches
each batch has enzymes added
dideoxynucleotide can be added to growing DNA
DNA acts as a template, replication begins
pyrosequencing method
DNA added to all enzyme solution
single nucleotide is added
flash of light
Open reading frame
region w/ gene like features
regions searched for
promoters
enhancer
TATA boxes
AUG sites
sequencing entire genomes
organelles are subtracted from cell
DNA circled then cloned
DNA cut into fragments
cut into batches
batches get matched up
storing genetic information
Protecting the genes
important to have DNA longterm
unsafe storage means DNA causes harm
ways to keep DNA safe
Indirect protein synthesis
mRNA carries info from DNA
DNA uses a messenger molecule mRNA
info goes to protein synthesis site
stored in nucleus
protected from cytoplasm
protected by nuclear envelope
protected from cytosol enzymes
histone proteins
holds nuclear DNA
done in inert, resistant forms
nucleosome
spherical structure
histones form aggregates
DNA wraps around them
forming nuclesomes
The genetic code
codons
used in reading nucleotides
used in groups of three
64 possible triplets
stop codons
UAG, UAA, UGA
signals ribosomes stop protein synthesis
start codon
#
AUG
signals where to begin
degenerate
multiple codes exist for amino acids
degeneracy protects DNA
the structure of genes
90% of genes are quiescent
structure allows recognition of gene
structural region
genes are composed of this
codes for amino acid sequence
codes for a promoter
promoter is a controlling region
regulates the synthesis of mRNA
mRNA from the structural region
promoter upstream from structural region
promoter region
intracellular messenger binds to this
or binds with other things who act with this
TATA box
#
short sequence
about 6-8 pairs long
rich in A and T
If damaged, RNA polymerase 2 wont mind
enhancer elements
other promoter sequence
located even farther upstream
in eukaryotic genes
2 distinct regions
introns
sequence of nucleotide not expressed
intervene between exons
exons
sequence of nucleotides
codons are eventually expressed
expressed in sequence of amino acids in protein
transcription of genes
when RNA is created
DNA strands seperate
ribonucleotides diffuse into area
transcription proceeds rapidly
DNA nucleotides that are self complimentary
RNA transcribed from them can double back
hydrogen bonds to itself
results in a small kink
kink named hairpin loop.
affects RNA polymerase
protein synthesis
ribosomes bind to mRNA
read codons
ribosomes catalyze the polymerization of amino acids
ribosomes
small particles
read genetic message in mRNA
construct proteins
80S
ribosomes in cytoplasm of eukaryotes
means they are dense
70s
ribosomes of plastids, mitochondria, and prokaryotes
smaller, lighter
viruses
virus structure
extremely small particles
contain only protein & nucleic acid
cause disease
plant virus have simple morphology
retrovirus
greatest number of known virus
contain single strand RNA
source of reverse transcriptates
split genome viruses
many plant viruses
not all nucleic acid packaged together
consists of 2 different particles
both transmitted to new host cell
virus metabolism
bacteriophages
viruses that attack bacteria
AKA phages
extremely specific virus
virulent
multiplies quickly
dominates the cell
symptoms:
Chlorosis
necrosis
leaf curling
formation of new virus particles
viral components assemble into new particles
tertiary structure causes binding to viral DNA
attracts more viral protein
new viral particle assembles
origin of viruses
viruses are portions of genes
gene of host species
or closely related host species
fragment of a chromosome codes for proteins
self assemble into a crude coat
have infectious potential
could act as forerunner for a virus
Control of protein levels
transcription Factors
controls gene activity
proteins that bind to promoter or enhancer regions
binds to active genes
have a sequence of amino acids
sequence fits into large groove of double helix
recognizing specific sequence of nucleotide basees
must act as dimers
trans-acting factors
come from somewhere else
binds to DNA
cis-acting factors
#
Promoters, enhancers, TATA boxes
part of the gene itself
Micro-RNA's
controlled gene expression
short RNA molecules
some recognize DNA sites and bind
binding inhibits gene expression
what TATA box is
cis-acting factor
open reading frame program searched for AUG
