Download Biotechnology

APPLIED GENETICS
SELECTIVE BREEDING
• Breeders chose organisms with desirable
traits to be the parents of the next
generation.
• Requires time, patience and many
generations before desired trait becomes
common in a population.
• Examples: cows, chickens, largest grain
heads, largest fruits.
I AM THE
GREATEST!!
Breeding for desirable traits
I’M A
HANDSOM
E
SPECIMEN
I’M SO
PRETTY
INBREEDING
• Mating between closely related individuals
• Ensures offspring are homozygous for most
traits.
• However, also brings out harmful recessive traits
since closely related organisms are more likely
to carry recessive alleles for traits.
• Pure breeds: dogs, horses
• A breed/cultivar: selected group of organisms
within species that has been breed for a
particular characteristic.
Recessive traits appear!
• The dachshund breed of
dogs was developed to dig
out rodents however it’s
long slim body also makes it
prone to slipped or ruptured
disks in its vertebrae.
• The large dogs such as St.
Bernard’s have a problem
with their hip bones
developing arthritis as the
dog gets old because of
their size.
MY BACK
HURTS!
HYBRIDIZATION
• Hybrids are produced by crossing two unlike
organisms.
• Corn - bred for high yield (domestic varieties)
and disease resistance (wild varieties - maize)
• Mule - female horse x male donkey
– bred for size and strength
– STERILE
WE CAN’T
HAVE BABIES?
DETERMINING GENOTYPE
• Test cross is used to determine parental
genotype.
• Cross the parent with unknown genotype
with an organism that is homozygous
recessive for the trait.
• Observe the offspring.
• Numerous test crosses required to be sure
you findings are correct.
RECOMBINANT DNA
TECHNOLOGY
GENETIC ENGINEERING TOOLS
Electrophoresis Chamber
DNA molecule
PLASMID
GENETIC ENGINEERING
• Or Recombinant DNA Technology
• Fast, more reliable method for increasing
frequency of specific allele in a population.
• A small fragment of DNA is cut from one
organism and inserted into another host
organism of a different species
• Recombinant DNA forms when DNA fragments
from different species is combined.
• Resulting transgenic organisms contain
functional recombinant DNA
3 STEPS TO MAKE A
TRANSGENIC ORGANISM
1. ISOLATION OF FOREIGN DNA: a specific
restriction enzyme is used to cut the required
fragment of DNA
2. ATTACH DNA FRAGMENT TO A VECTOR: for
transportation into the host. Vectors maybe
plasmids, viruses, tiny metal bullets,
micropipettes. (Gene splicing in plasmids.)
3. TRANSFER OF VECTOR INTO HOST
ORGANISM - creating a transgenic organism.
A transgenic organism reproduces a copy of
the recombinant DNA, when it divides, and can
use that gene as it was used by the original
organism.
APPLICATIONS OF
DNA TECHNOLOGY
3 MAIN AREAS OF USE
1. INDUSTRY
2. MEDICINE
3. AGRICULTURE
TRANSGENIC BACTERIA
INDUSTRIAL USES
•
•
Breaking down pollutants to harmless products
Degradation of spilled oil, extraction of minerals
from ores, bioremediation.
MEDICINAL USES
•
•
Production of hormones: growth hormone, insulin
Producing phenylalanine for artificial sweeteners
AGRICULTURAL USES
•
•
Reduction of frost damage to plants
Increased rate of nitrogen fixation in the soil
TRANSGENIC PLANTS
•
Plants are more difficult to genetically
engineer than bacteria because
1. No plasmids
2. Thick cell wall
3. Mechanical vectors commonly used
•
Engineered plants may:
1. Resist herbicides
2. Produce internal pesticides
3. Increase protein production
TRANSGENIC ANIMALS
•
•
•
Used for studying diseases and roles
played by specific genes with a view
to curing some human diseases
Commonly used animals mice,
roundworms and fruit flies
Examples:
1. Goats engineered to produce high levels of
human protein to dissolve blood clots.
2. Cows engineered to produce higher milk
yields
CLONING
• Cloning is a type of genetic
engineering in which an
exact duplicate of an
organism is created from a
single body cell.
• This is done in trees to
produce many organisms
from a single organism in
order to reforest certain
areas
• It has only been the last few
years that it has been
possible in mammals as
well. This type of genetic
engineering is artificial and
done in a laboratory. Dolly
THE HUMAN
GENOME
HUMAN GENOME PROJECT
• Organized in 1990, completed in 2003
• Worldwide collaborative project
• Objective was to completely map and
sequence the human genome (3 billion
base pairs in 20,000-25,000 genes on 46
chromosomes)
SEQUENCING DNA
• Allows scientists to
identify and study specific
genes and fragments of
DNA that regulated the
transcription of the genes.
• Millions of copies of the
DNA fragment are cloned
and fragmented further
for analysis.
• Analyzed using GEL
ELECTROPHORESIS,
produces a pattern of
dyed bands on a gel.
LINKAGE MAPS
• Show the location of genes on a
chromosome
• Historically produced by analyzing
crossed-over traits in families:
inefficient due to few offspring and
generation time.
• Genes are now mapped using
PCR polymerase chain reaction.
• Millions of copies of DNA
fragments are cloned in hours
from sperm cells of one person
and analyzed for crossing over.
• Machines are used for the
analysis
APPLICATIONS OF
THE HUMAN
GENOME PROJECT
DIAGNOSIS OF GENETIC
DISORDERS
• DNA from people
suffering from a disorder
are analyzed for common
patterns
• Fetal cells are collected
• Fetal cells are grown on a
cell culture
• Fetal cell DNA analyzed
for pattern associated
with disorder
•
A gene at site 4p16.3 was
found which had a variable
trinucleotide repeat (CAG).
This gene is directly related
to Huntington's Disease
and the production of the
protein "huntingdin". The
role of this protein is not yet
know, much to the chagrin
of researchers.
GENE THERAPY
• Insertion of normal genes
into human cells to
correct disorder
• CF: see picture
• SCIDS: Missing an
enzyme due to faulty
gene. Cells are removed,
enzyme producing gene
incorporated and return to
patient. (Genes do not
remain active long term)
DNA FINGERPRINTING
• Shows the DNA sequences of
an individual
• DNA samples from hair blood
skin semen are copied using
PCR.
• DNA cut into fragments of
different lengths using
restriction enzymes
• Fragments are separated
using gel electrophoresis
• DNA fingerprints produced are
matched
• NO two individuals have the
same DNA fingerprints