Chapter 9- Biotechnology and Recombinant DNA (EXAM 2) Flashcards
The manipulation of living
organisms, or cell components to produce useful products.
Biotechnology
Products made by biotechnology
Foods, antibiotics, vitamins, enzymes
– Pest resistant crops
– Bacterial strains for waste treatment, environmental oil
clean-up
– Limited to a cell’s own products until the 1980’s
procedures that are used to join together (recombine) DNA segments in vitro
Recombinant DNA (rDNA) technology/genetic engineering
1) Population of cells arising from a single parent cell
2) Processes used to create copies of DNA fragments
clone
The production of exact copies (_______) of a particular gene or DNA sequence using genetic
engineering techniques.
gene cloning; cloning
Describe the process of gene cloning
almost always with E.coli
- Vector, such as a plasmid is isolated
- DNA is cleaved by an enzyme into fragments
- Gene is inserted into plasmid
- Plasmid is taken up by a cell such as a bacterium
- cells with gene of interest are cloned depending on the goal
What is the goal of gene cloning?
- either to make copies of the gene
2. or to make protein product of the gene
When copies of the gene are harvested what can they be used for?
The gene itself is of interest.
- Plasmid borne genes are
easily manipulated
- Gene for pest resistance is inserted into plants
- Gene alters bacteria for cleaning up toxic waste
When the copies of the gene make a protein product, and the desired proteins are harvested; what can they be used for?
- The product of the gene is
of interest. - Cloning human growth hormone was an early success
- amylase, cellulase, and other enzymes prepare fabrics for clothing manufacture
- human growth hormone treats stunted growth
in nature organisms with
characteristics that enhance survival are more likely to
survive.
natural selection
Why are bacteria good subjects to study natural selection?
Bacteria are a common research subject when studying evolution and adaptation because some colonies of bacteria can produce several generations in one day, letting researchers see a “fast forward” version of evolution and natural selection.
humans select desirable breeds of animals or strains of plants
artificial selection
provide examples of artificial selection
a farmer chooses high milk producing cows for breeding
- Pure bacterial cultures with favorable characteristics
can be selected
- beer brewing (efficiency, taste, alcohol content)
- antibiotic producing bacterial strains (also elevated
expression)
a tool for biotechnology
mutagens
_______________ can be used to increase the chances of obtaining a
desired strain
- Radiating _________ generated a strain that
produced 1000x penicillin
random mutagenesis (mutagen exposure); fungus
a mutation created at a defined site in a DNA molecule
site directed mutagenesis
Why is site directed mutagenesis useful?
Rather than screening/selecting for mutants, site directed mutagenesis (a mutation
created at a defined site in a DNA molecule) can be used to make a specific change in a
gene
Cut DNA at defined positions close to or within their recognition sequences
Restriction enzymes
What is the cutting frequency of restriction enzymes?
typically recognize 4-, 6-, or 8-base sequences
Do restriction enzymes cut the same way each time?
Yes
Some produce _______ ends, others produce ___________ (sticky) ends
blunt; staggered
can be used to join two pieces of DNA with complementary ends
staggered ends
Bacterial source of BamHI
Basicillus amyloliquefaciens
Recognition sequence of BamHI
G|GATCC
GCTAG|G
Bacterial source of EcoRI
Escherichia coli
Recognition sequence of EcoRI
G|AATTC
CTTAA|G
Bacterial source of HaeIII
Haemophilus aegyptius
Recognition sequence of HaeIII
GG|CC
CC|GG
Bacterial source of HindIII
Haemophilus influenzae
Recognition sequence of HindIII
A|AGCTT
TTCGA|A
Recognition sequence of HindIII
A|AGCTT
TTCGA|A
Describe the process of Restriction Enzymes and Recombinant DNA
- restriction enzyme cuts dsDNA at its particular recognition sites
- These cutes produce DNA fragment with two sticky ends
- when two such fragments of DNA cut by the same restriction enzyme come together, they can join by base pairing
- the joined fragments will usually form either a linear molecule or a circular one, as shown here for a plasmid. Other combinations of fragments can also occur
- The enzyme DNA ligase is used to unite the backbones of the two DNA fragments, producing a molecule of recombinant DNA
Compatable cohesive ends
Echo slide 13 (unclear)
Why do bacteria produce restriction enzymes?
They RESTRICT the ability of foreign DNA (such as
bacteriophage DNA) to infect/invade the host
bacterial cell by cleaving it)
In bacteria, how is host DNA modified to protect them against bacteriophages?
The host DNA is MODIFIED by methylation of their
sequences at C or A nucleotides
This modification protects the bacterial host DNA from degradation by its own restriction enzyme • Called \_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_\_ system
restriction modification
Autonomously-replicating DNA used to carry the desired gene to a new cell
vectors
Two types of molecules that can be used as vectors. What determines which type will be used in the study?
Plasmids and viruses can be used. (choice depends on organism receiving the gene and size of cloned DNA)
primary vectors in use. Easy to manipulate
plasmids
accept larger pieces of foreign DNA
viruses
types of viruses used to insert correctives genes into human cells
retroviruses, adenoviruses, and herpes viruses
Are there natural mammalian origins (ORIs)?
no (echo-need clarification slide 15)
What are some necessary properties for vectors?
- need to self replicatate
- must be a small size that facilitates manipulation outside the cell
- must be able to avoid destruction by host nucleases (ie. must be circular)
- must be able to carry a selectable marker gene (ie. antibiotic resistance or auxotrophic marker)
Would marker genes that can be phenotypically screened be useful?
Slide 16- Echo
An E.coli plasmid vector used for cloning
Echo slide 17
can replicate in at least two different species
shuttle vectors
Shuttle vectors require ________ _______ _________ and _______ __ __________. Provide some examples.
requires suitable selectable markers and origins of replication (E. coli/yeast, E. coli/ *mammalian*, E. coli/ fungi, E. coli/plant, E. coli/other bacteria)
slide- 18 clarify
distinguishing vector self-ligation from insert ligation
slide 19-clarify
A molecular technique that allows for the detection of
successful ligations in vector based cloning
the blue white screen
Describe the blue white screen
- plasmid DNA and foreign DNA are both cut with the same restriction enzyme. The plasmid has the genes for lactose hydrolysis (the lacZ gene encodes the enzyme B-galactosidase) and ampicillin resistance.
- Foreign DNA will insert into the lacZ gene. The bacterium receiving the plasmid vector will not produce the enzyme B-galactosidease if foreign DNA has been inserted into the plasmid
- The recombinant plasmid is introduced into a bacterium, which becomes ampicillin resistant
- All treated bacteria are spead on a nutrient agar plate containing ampicillin and a B-galactosidease substrate and incubated. The B galactosidase substrate is called X-gal
- Only bacteria that picked up the plasmid will grow in the presence of ampicillin. Bacteria that hydrolyze X-gal produce galactose and an indigo compound. The indgo turns the colines blue. Bacteria that cannot hydrolyze X gal produce white colonies.
Enzymatic method to amplify (make multiple
copies) a piece of DNA to detectable levels
polymerase chain reaction
what is PCR useful for?
This is useful for – Cloning a piece of DNA – Sequencing DNA – Diagnosing genetic diseases (i.e. restriction analysis) – Detecting pathogens
What is the process of PCR?
1) Incubate target DNA, primers, deoxynucleotides
and DNA polymerase at 94C for 1 minute.
This allows separation of the DNA strands
2) Primers attach to a single-stranded DNA during incubation at 60C for 1 min
3) incubate at 72C for 1 minute; during this time, two copies of target DNA are formed
4) repeat the cycle of heating and cooling to make two more copies of target DNA
define denaturation
a process in which proteins or nucleic acids lose the quaternary structure, tertiary structure, and secondary structure which is present in their native state, by application of some external stress or compound such as a strong acid or base, a concentrated inorganic salt, an organic solvent, temperature etc.
What is unique about the DNA polymerase used in PCR?
use a Taq polymerase that can withstand high temperatures (Echo slide 24 to clarify)
What is the significance of the temperatures and times chosen for each step?
Echo slide 25 to clarify
Thermocycler
echo slide 26
Robocycler
echo slide 27
How is the amplified product detected?
echo slide 28