Applied Genetics
Selective Breeding and
Genetic Engineering
Selective Breeding
• = crossing of plants or animals that
have desirable traits to produce
offspring with those traits
• Increased strength
• Leaner meat (less fat)
• Disease resistance
• Larger grain/fruit
• Better taste
hybridization
• = crossing two organisms (same
genus/species, “kind”) with
variations of particular trait(s)
to produce offspring with a
mixture of the trait(s)
• Offspring inherits traits of both
parents
• Donkey X horse = mule
• Modern grains – corn, wheat
• Ancient wild wheat X wild goat
grass = nutritious hybrid wheat
used for bread
• The greater the difference between
“kinds” (genus/species) being
hybridized, the more likely the
hybrid will be sterile
Inbreeding
• = crossing 2 organisms that
have the same or similar trait(s)
to produce animals with the
same trait(s)
• Idea is to preserve the desirable
traits
• Organisms are genetically
similar and can lead to negative
consequences:
• Increased chances of inheriting
disorders
• Increased chances of
contracting certain diseases
• Decreased ability to adapt to
environmental changes
•
•
Weird hybrids
liger = cross between lion
(father) and tiger (mother)
Weird hybrids
• Tigon = cross between male tiger and
female lion
• Beefalo/cattalo = bison x cow
• Hinny
• Female donkey x male horse
Cama = male camel x female
llama
Genetic Engineering
• Process in which genes
(sections of DNA) are taken
from one organism and
transferred to another
Recombinant DNA
• Section of DNA is separated
from strand of one organism
• This is spliced into the DNA of
another organism
• DNA is now combined
• Modified DNA will cause cells
to carryout processes in a
different way
Products resulting from genetic
engineering
• Medicine
Insulin, human growth hormone
(produced by altered bacteria)
Hepatitis B vaccine (produced by
altered yeast cells)
• Genetically Modified Organisms
(GMO)
• Genetically Engineered Organisms
(GEO)
Transgenic crops
GM foods
Transgenic animals
• Much of these are used in
agriculture
transgenic goats
(spider genes for web
silk protein)
(Nexia
Biotechnologies)
Used to manufacture
BioSteel® &
Protexia™
Agricultural uses
• Herbicide-tolerant crops
• Insecticidal crops
• Better taste, texture, longer shelflife, larger size, better suited for
mechanical harvesting
Potential problems
• Cross-pollination of GM crops to
wild varieties can cause weeds to
become herbicide resistant
• Insects may become quickly
resistant to insecticides because
of exposure to GM crops
• Predators that eat insects who have
eaten GM crops can be affected in
unknown ways
• People who eat GM crops can be
affected in unknown ways
Toxic effects
Pathogenic effects
Allergic reactions
Resistance to antibiotics
Terminator genes
• Plants have been developed that
have a trait that kills developing
embryos in seeds so that seeds
from crops cannot be saved &
planted the following season
Warnings
• Genes are now known to control more
than one trait
• By altering/changing a single gene,
multiple traits may be changed in ways
we can’t predict
• Human genes are only a small
percentage of the information contained
in DNA (5% or less)…we don’t know
what most of the rest does
• Humans have only 300 more
genes than what are also found in
mice…
• “This tells me genes can’t
possibly explain all of what
makes us what we are.”
Craig Venter, president of Celera Genomics
(Maryland firm that led one of the mapping
teams for the Human Genome Project)
The Future….
• Chimera – organism or
component composed of
different genetic material
• So far…
• Pigs with human blood
• Mice with human brain cells
• Sheep with human tissues in
hearts & livers
• Fusion of human & rabbit biomatter produced chimeric
embryos