Download Chapter 6, Section 3: Advances in Genetics

CHAPTER 6, SECTION 3:
ADVANCES IN GENETICS
Science 7
6-3 OBJECTIVES
Describe three ways of producing organisms with
desired traits.
 Identify two applications of DNA technology in
human genetics.

SELECTIVE BREEDING
Selective breeding, cloning, and genetic
engineering are three methods for
developing organisms with desirable traits.
 The process of selecting organisms with desired
traits to be parents of the next generation is
called selective breeding.
 People have used selective breeding with many
different plants and animals.
 Inbreeding and hybridization are two types of
selective breeding methods.

INBREEDING
The technique of inbreeding involves crossing
two individuals that have similar characteristics.
 For example, suppose a male and a female turkey
are both plump and grow quickly. Their offspring
will probably have those desirable qualities.
 In bred organisms are genetically very similar
and therefore inbreeding increases the
probability that organisms may inherit alleles
that lead to genetic disorders (example: hip
problems in dogs).

HYBRIDIZATION
In hybridization, breeders cross two genetically
different individuals.
 The hybrid organism that results is bred to have
the best traits from both parents.
 For example: a farmer might cross corn that
produces many kernels with corn that is resistant
to disease so the offspring with have both traits.

CLONING
A clone is an organism that has exactly the
same genes as the organism from which it was
produced.
 Researchers have cloned plants and animals such
as sheep, dogs and pigs.

GENETIC ENGINEERING
In genetic engineering, genes from one
organism are transferred into the DNA of
another organism.
 Genetic engineering can produce medicines and
improve food crops.

BACTERIA AND GENETIC ENGINEERING
Bacteria have been
genetically engineered to
produce human insulin.
 Insulin is needed for
injections to treat people
with diabetes.
 Bacteria have human
insulin producing genes
inserted into their DNA
to manipulate them into
producing the insulin.

GENETIC ENGINEERING IN OTHER
ANIMALS
Human genes can be inserted into the DNA of
cows so that the cows produce the protein
responsible for blood clotting in their milk. The
protein is then extracted and used to treat
hemophiliacs.
 Genes have also been inserted into plant DNA
which enables plants to survive in cold
temperatures or in poor soil. Some genetically
engineered plants can even resist pests.

GENE THERAPY
Someday it may be possible to use genetic
engineering to correct some genetic disorders in
humans.
 Gene therapy will involve inserting copies of a
gene directly into a person’s cells.
 For example, doctors may be able to cure a
person with hemophilia by replacing the defective
allele on the X chromosome

CONCERNS ABOUT GENETIC ENGINEERING
Some people are concerned about the long term
effects of genetic engineering.
 Some people worry that genetically engineered
crops may not be entirely safe. They fear that
these crops might harm the environment or cause
health problems in humans.
 Scientists are studying these concerns to learn
about the effects of genetic engineering.

LEARNING ABOUT HUMAN GENETICS

Applications of DNA technology include
studying the human genome in detail and
identifying people.
HUMAN GENOME PROJECT
A genome is all the DNA in one cell of an
organism.
 The main goal of the Human Genome Project has
been to identify the DNA sequence of every gene
in the human genome.
 DNA of humans contain at least 30,000 genes
and the average gene has 3,000 bases.

DNA FINGERPRINTING

DNA technology can identify people and show
whether people are related.