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Chapter 15
Studying and Manipulating
Genomes
15.1 Tinkering with the Molecules of
life



1953 James Watson and Francis Crick
1972 Paul Berg Recombinant DNA
1978 Allan Maxam, Walter Gilbert, Fred Sanger
develop methods for determining Nucleotide
sequences of cloned DNA Fragments,
15.1 Tinkering with the Molecules of
life

Recombing DNA?
Frederick Griffith’s Experiment
 1928,
Tried to find a vaccine against
pneumonia.
 Caused by a pneumococcus bacteria
 Two types of bacteria:
–
Type S or smooth covered capsule,
 causes
–
pneumonia
Type R or rough covered capsule
 Does
not cause pneumonia
First
Step
Type-S
bacteria
Type-R
bacteria
Heated
Type-S
bacteria
Second
Step
Type-S
bacteria
Type-R
bacteria
Heated
Type-S
bacteria
Third
Step
Type-S
bacteria
Type-R
bacteria
Heated
Type-S
bacteria
Fourth
Step
Type-S
bacteria
Type-R
bacteria
Heated
Type-S
bacteria
The DNA Soap Opera”
by Watson, Crick, Wilkins and Franklyn
1952: Kings College
X-ray crystallography
Died 1958
Watson and Crick
Won the 1962 noble prize in
science for their discovery”
the double helix”
15.1Genome / Genetic Code

All of the DNA in a haploid number of
chromosomes.
–
All of the DNA from each chromosome
A genetic code contains the information for
the sequence of amino acids in a particular
protein
 This code is present in mRNA molecules
and is three bases long. This is known as a
codon
Ex: UAG - is a codon

5.1 Human Genome Project

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1988
NIH lead by Walter
Gilbert
–
Reassigned on Patent
issues
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1993 replaced by
Francis Collins 1993

1998-2003 Craig
Venter, Celera
Genomics
Challenged US
government
99% accurate
21,000 genes identified
5.1 Human Genome Project

Videosaywhat?
15.2 Molecular Toolkit
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Restriction enzyme: DNA scissors
Looks for specific 4-8 base pairs

Ex. EcoRI looks for GAATTC
–

Makes a fragment
DNA Ligase seals up
15.2 Genetic Engineering


Now that we understand genes we can change the
DNA of a cell.
The procedure for producing altered DNA is called
genetic engineering

Altered DNA is called Recombinant DNA.
 Gene splicing involves the breaking of a DNA
molecule and inserting or attaching new genes by
means of a chemical splice.
Plasmids


Are small DNA
fragments, are known
from almost all bacterial
cells.
Plasmids carry
between 2 and 30
genes. Some seem to
have the ability to move
in and out of the
bacterial chromosome
Recombinant DNA


Allows scientists to
insert the insulin gene
into bacterial plasmids.
The bacteria that contain
this gene produce
insulin, which is used by
people with diabetes.
What is Gene Splicing?
A dessert?
Gene Splicing
Transgenic mice:
Slicing jellyfish DNA in a mouse's
genome!!!
Superhero Gene Splicing
Gene Splicing
Gene Splicing
15.2 Genetic Engineering
Recombinant DNA due to Gene splicing

Medical
–
–
–
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Human insulin producing bacteria
Human Growth Hormone (HGH) producing bacteria
Diabetic-donor corrective gene therapy
Agriculture and Forestry
–
–
–
–
Pest Resistant Crops (corn)
Antibiotic Rich Corn
HGH infused trout (live stock)
Inc Growth rate in trees and insect repellent trees (logging)
15.3
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Gene library:
–
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Probe: short stretch of DNA labeled radioactively
Nucleic Acid Hybridization:
Polymerase Chain Reaction (PCR): gene
replication
15.4 Separation Techniques
Chromatography-to make visible
pigments and extracts
 Centrifuge-separates based on densities
 Gel Electrophoresis: Separates into DNA
fragments

15.4 Gel Electrophoresis

is a procedure for separating a mixture of
DNA molecules through a stationary
material (gel) in an electrical field.
15.5 Automated DNA sequencing
15.6 Practical Genetics
Genetic Engineering

Genetic Engineering- is a new technology that
humans use to alter the genetic instructions in
organisms.
a) Biotechnology- The application of
technology to biological science.
ex: removal of dinosaur DNA from a
mosquito’s last meal.
b) Selective Breeding- A process that
produces domestic animals and new varieties
of plants with traits that are particularly
desirable.
DNA Technology

Makes it possible to put “new” genes into
organisms.
1. Human genes can be inserted into bacteria.
2. These altered bacteria become factories that
produce human protein.
ex: Gene Splicing
Recombinant DNA
Genetic Engineering and Therapies

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Genetic engineering attempts to correct genetic
defects, alter foods , and fight diseases.
Gene therapy replaces defective genes with
normal genes.
Gene splicing using plasmids (ring shaped
sections of bacterial DNA) can be used to create
desirable traits.
Selective Breeding,, easy stuff first
An Example of Selective Breeding
Brahman cattle:
Good resistance
to heat but poor
beef.
English
shorthorn cattle:
Good beef but
poor heat
resistance.
Santa Gertrudis
cattle: Formed
by crossing
Brahman and
English
shorthorns; has
good heat
resistance and
beef.
Gene Splicing
Transgenic mice:
Slicing jellyfish DNA in a mouse's
genome!!!
Cloning from Adult Vertebrate Cells
Cloning

A clone is a group of individual organisms that
have exactly the same genes.
Organisms that reproduce asexually produce
clones, since each offspring receives an exact
copy of the genes of the parent.

Dolly, 276 tries, 277= dolly

Cloning
Population Genetics
A population is a group of organisms of the
same species living together in the same
region (interbreeding).
 Population genetics: is the study of
changes in the genetic makeup of populations.
 Gene Pool: The total of all the genes in a
population at any given time.

Population Genetics
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Gene frequencies: how often (frequent)
a specific gene shows up in a population.
Population Genetics
The Hardy Weinberg Law: Under certain
conditions the relative frequencies of alleles
for a given trait in a population do not
change. For this to be true:
1) The population must be large
2) Individuals must not migrate into or out of
the population.
3) Mutations must not occur
4) Reproduction must be completely random.
Cloning
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Is a technique that accomplishes the same end result as asexual
reproduction.
It is a way of making identical genetic copies.
Cloning is done by inserting a nucleus from a “parent” organism’s
cell (one that has a complete set of genetic information from that
individual) into an egg cell from which the nucleus has been
removed. The result is an egg that now contains not 50%, but
100% of the genetic information from a single parent.
If this new egg cell with all of its genes can be made to develop
normally, the resulting offspring is a clone of the individual that
donated the original cell (In mammals, the egg would be implanted
and develop inside the body of the female).
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