Chapter 13 Genetics and Biotechnology

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Oct 23, 2013 (3 years and 9 months ago)

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Chapter 13 Genetics
and Biotechnology

13.1 Applied Genetics

Selective Breeding


The process by which desired traits of
certain plants and animals are selected
and passed on to their future generations
is called selective breeding.

Selective Breeding


Hybridization is crossing parent organisms
with different forms of a trait to produce
offspring with specific traits.


Hybrid organisms can be bred to be more
disease
-
resistant, to produce more

offspring, or to grow faster.


A disadvantage of hybridization is that it is
time consuming and expensive.



Selective Breeding


Specific traits in
breeds can be
maintained by
inbreeding (breeding
two closely related
organisms)


Clydesdale horses
have been inbred to
retain the desired
traits: strength, agility,
and obedient nature



Selective Breeding


Disadvantages of
inbreeding is that
harmful recessive
traits can also be
passed to future
generations

German Shepherd hip dysplasia

Test Cross


A test cross
involves breeding
an organism that
has the unknown
genotype (PP or
Pp) with one that is
homozygous
recessive (pp) for
the desired trait

Chapter 13 Genetics
and Biotechnology

13.2 DNA Technology

Genetic Engineering


Technology that
involves manipulating
the DNA of one
organism in order to
insert the DNA of
another organism,
called exogenous
DNA.


Genetic Engineering


Production of human
insulin by bacteria
was one of the first
commercially
successful uses
genetic engineering
technology.

Genetic Engineering

Genetically engineered organisms are used:

1.
to study the expression of a particular
gene.

2.
to investigate cellular processes.

3.
to study the development of a certain
disease.

4.
to select traits that



might be beneficial


to humans.

Genetic Engineering


Many bizarre and
interesting uses for
genetic engineering
technologies have
been reported.

DNA Tools


An organism’s
genome

is the total DNA in
the nucleus of each cell.


DNA tools can be used


to manipulate DNA and to


isolate genes from the


rest of the genome.


DNA Tools


Restriction Enzymes are proteins used to
cut DNA at specific sequences in specific
ways.


Restriction enzymes are naturally present
in bacteria to cut and thus restrict foreign
DNA from interfering with the bacterial
DNA

Restriction Enzymes


EcoRI

specifically
cuts DNA containing
the sequence
GAATTC.


The ends of the DNA
fragments, called
sticky ends, contain
single
-
stranded DNA
that is
complementary.



Restriction Enzymes

Gel Electrophoresis


An

electric current is used
to separate DNA
fragments according to
the size of the fragments
in a process called gel
electrophoresis.


When an electric current
is applied, the DNA
fragments move toward
the positive end of the
gel.


The smaller fragments
move farther faster than
the larger ones.

Gel Electrophoresis


The unique pattern
created based on the
size of the DNA
fragment can be
compared to known
DNA fragments for
identification.


Recombinant DNA Technology


Recombinant DNA is DNA combined from
two (or more) sources.

Recombinant DNA Technology

1.
A gene of interest from one organism’s
DNA is cut out with a restriction enzyme.

2.
Another organism's DNA is cut open with
the same restriction enzyme.

3.
The gene that was cut out is inserted in
the open DNA of the second organism.

4.
Result is a transgenic organism


Easy to insert genes into bacteria; more
difficult with other organisms

Recombinant DNA Technology


To make a large quantity of recombinant plasmid DNA,
bacterial cells are mixed with recombinant plasmid DNA.


Some of the bacterial cells take up the recombinant
plasmid DNA through a process called transformation
.


Large numbers of


identical bacteria, each


containing the inserted


DNA molecules, can


be produced through a


process called cloning.

Recombinant DNA Technology


To understand how
DNA is sequenced,
scientists mix an
unknown DNA
fragment, DNA
polymerase, and
the four
nucleotides

A, C,
G, T in a tube.

Recombinant DNA Technology


Each nucleotide is
tagged with a
different color of
fluorescent dye.


Every time a
modified
fluorescent
-
tagged
nucleotide is


incorporated into
the newly
synthesized strand,
the reaction stops.



Recombinant DNA Technology




The sequencing reaction is complete when the
tagged DNA fragments are separated by gel
electrophoresis.


Recombinant DNA Technology


A technique called the
polymerase chain
reaction

(PCR) can
be used to make
millions of copies of a
specific region of a
DNA fragment.

Recombinant DNA Technology

Uses of Recombinant DNA

Biotechnology


Organisms genetically
engineered by
inserting a gene from
another organism are
called
transgenic
organisms
.

Biotechnology


Transgenic animals
are produced for
biological research.

Biotechnology


Transgenic plants are
produced to solve
food or nutritional
problems

Genetically engineered cotton

resists insect infestation of the


bolls.

Rice plants with increased iron and

vitamins could decrease malnutrition
.

Biotechnology


Insulin, human growth
hormone and substances
that dissolve blood clots
are made by transgenic
bacteria.


Transgenic bacteria slow
the formation of ice
crystals on crops to
protect them from frost,
clean up oil spills, and
decompose garbage.

Chapter 13 Genetics
and Biotechnology

13.3 The Human Genome

The Human Genome Project


International Project to sequence the
entire approximately three billion
nucleotides that make up the human
genome.


Began in 1990 and completed in 2003;
ahead of schedule and under budget.


Found that less than 2% of all the
nucleotides in the body code for all of the
approximately 100,000 proteins in the
body.

DNA Fingerprinting


Using noncoding sequences that are unique to
each individual (except identical twins),
scientists can identify individuals by their DNA.


Any cell of the body can be used since all cells
have the same DNA (except red blood cells that
do not have a nucleus).


The amount of DNA is magnifed by PCR, then
cut with restriction enzymes and separated by
gel electrophoresis.

DNA Fingerprinting


Banding patterns are
unique to each
person


Used to identify
suspects and victims
in a crime, determine
paternity, and identify
soldiers killed in war.


Also used to
determine
evolutionary
relationships


Identifying Genes


After sequencing the DNA the next step is
identifying genes.


Originally thought that humans had
100,000 genes because we have 100,000
proteins (one gene
-
one protein)


Now know that we have 20,000
-
25,000
genes.


Complicated analysis that uses
information from other genomes DNA
sequences along with computer algorithms

Bioinformatics and DNA
Microarrays


Bioinformatics is a field of study creates
and maintains databases of biological
information.


DNA microarrays are tiny microscope
slides or silicon chips which contain the
genes of an organism (a few genes or the
whole genome).

The Genome and Genetics
Disorders


More than 99% of an individuals DNA
sequence is the same as any other
individual.


Some of the differences that exist are a
result of a mutation to cause a genetic
disorder.


HapMap project seeks to identify common
genetic variation that occur in humans.

The Genome and Genetics
Disorders


Pharmacogenomics is the study of how
genetic inheritance affects the body’s
response to drugs.


Gene therapy is a technique used to
correct mutated genes.


Viruses are used as a vector to insert the
“good” gene into the patients cells


All gene therapy trials stopped in 2003 due to
a death caused by a reaction to virus

Genomics and Proteomics


Studying the genome
is genomics.


Genes are storage
units


Proteomics is the
study of the structure
and function of
human proteins.


Proteins are machines
of the cell