Unit 4 Genetics
Ch. 13 Genetic Engineering
Selective Breeding
• Selective breeding - allowing animals
with desired characteristics to
reproduce
• It takes advantage of naturally
occurring genetic variation in plants,
animals, etc.
Selective Breeding
• Humans use selective breeding to pass
desired traits on to the next
generation of organisms
• Nearly all domestic animals (horses,
cats, etc.) & most crop plants have
been produced by selective breeding
Selective Breeding
• Hybridization - crossing dissimilar
individuals to bring together the best
of both organisms
• The organisms produced,
hybrids, are usually
hardier than both parents
Selective Breeding
• Inbreeding - continued breeding of
individuals with similar characteristics
• Many breeds of dogs are maintained
by inbreeding
• It helps to ensure the characteristics
of each breed are
preserved
Increasing Variation
• Selective breeding can increase
genetic variation in a population by
causing mutations to occur
• SB was used to create oil-eating
bacteria, used to clean
up oil spills
Manipulating DNA
• Scientists study & change DNA
molecules
• Different techniques are used to
extract (remove) DNA from cells, to
cut DNA into smaller pieces, to
identify the sequence of bases in a
DNA molecule, & to make unlimited
copies of DNA
The Tools of Molecular
Biology
• Genetic engineering - making changes
in the DNA code of a living organism
The Tools of Molecular
Biology
• Cutting DNA:
• DNA molecules are too large to be
analyzed, so biologists cut them precisely
into smaller fragments
• Restriction enzymes enzymes that cut DNA
at a specific sequence
of nucleotides
The Tools of Molecular
Biology
• Separating DNA:
• Gel electrophoresis - a mixture of DNA
fragments is placed at 1 end of a gel, &
an electric voltage is applied to the gel
• When the power is turned on, DNA
fragments move toward the + end of the
gel
• Smaller DNA fragments move faster &
farther
Gel Electrophoresis
Using the DNA
Sequence
• Cutting & pasting:
• DNA sequences can be changed
• Restriction enzymes - used to take a gene
from 1 organism & attach it to the DNA of
another organism
• Recombinant DNA - DNA molecules
produced by combining DNA from
different sources
Using the DNA
Sequence
• Making copies:
• Polymerase chain reaction (PCR) technique that allows biologists to make
many copies of a
particular gene
Cell Transformation
• During transformation, a cell takes in
DNA from the outside (DNA from
another organism)
• That external DNA combines with the
cell’s DNA
• As the cell copies its own DNA, it also
copies the external DNA, since the 2
were combined during transformation
Transforming Bacteria
• Plasmid - circular DNA of bacteria
Applications of
Genetic Engineering
• Genetic engineering makes it possible
to transfer DNA sequences, including
whole genes, from 1 organism to
another
• It has spurred the growth of
biotechnology, a new industry that is
changing the way we interact with the
living world
Transgenic Organisms
• Transgenic - organisms have genes
from other species
• A gene from 1 organism can be
inserted into cells from another
organism
• Those transformed cells can be used
to grow new organisms
Transgenic Organisms
• Transgenic Animals:
• They have been used to study genes &
improve the food supply
• Mice have been produced with human
genes that make their immune systems
similar to ours
• Livestock have extra copies of human
growth hormone
Transgenic Organisms
• Transgenic Plants:
• Many crop plants contain genes that
produce a natural insecticide
• Others have genes that allow them to
resist weed-killing chemicals
• Rice has been genetically modified to
contain Vitamin A, essential for human
health
Cloning
• Clone - a member of a population of
genetically identical cells produced
from a single cell
Cloning