Applications of Genetics - My Class Sites


Oct 23, 2013 (3 years and 7 months ago)



Mr. Tabone

Manipulating Genes

Even before Mendel humans have been using
selective breeding
to manipulate plant and animal

Domesticating dogs, increasing milk or wool
production from livestock, using seeds from a hardy

Selective Breeding


Desirable traits can be kept and undesirable trait
can be eliminated from future generations


Low genetic variety

Susceptibility to disease

High chance for expression of harmful recessive
alleles (
. albinism)


When 2 different species are bred together to create a
new species

The new species is sometimes fertile and sometimes

: Loganberries are fertile hybrids of blackberries
and raspberries

: Seedless watermelons are sterile hybrids

Done to create crops resistant to weather conditions or
disease, or to have desirable characteristics (no seeds)


Cloning is a term that refers to creating an exact copy of
an organism from one single cell

This is exactly what happens in mitosis

The biotechnology technique is slightly different from
normal mitosis however

Multicellular organisms have two classes of cells

Stem cells and Specialized cells

Specialized cells have specific functions and are quite
different from one another (muscle vs. brain vs. skin etc.)

Stem cells can divide and create any type of specialized cell


Since specialized cells do not normally divide to create
different specialized cells

Muscle cells only divide into muscle cells, they do not create
brain cells (for example)

Adults are mostly composed of specialized cells, with very
few stem cells

Therefore creating a clone animal out of a specialized cell is

Traditionally stem cells have been used for the purpose of


Recently there have been many breakthroughs in this
area, and some specialized cells can now be turned into
clone cells and used for cloning

This is still a very active area of research

Dolly the sheep

Many species of animals have been successfully cloned

All have had short life spans and exhibited many
physiological problems, like arthritis, premature aging,
and lung disease

Click and Clone

Applications of Cloning

We can genetically modify certain organisms to give
them advantageous traits and then clone them to
produce several identical organisms

: Producing corn plants that can grow in cold weather,
or cows that produce more milk than normal

Cloning allows us to produce several organisms with our
specific modifications

We already do this for several of our fruits and

Homework pg 151 #1
9, 11, 12

Gene Therapy

Using genes to treat disease

Used in two different ways

A normal gene product can be given to affected

Manipulate genes in parents or offspring to treat
the disease

Gene Therapy

Using gene products to treat disease

Leptin and obesity

Obese mice lack the receptor for the

protein leptin

Leptin controls appetite

Leptin injections can help control obesity

Gene Manipulation

Involves replacing defective genes with properly
functioning ones

: replacing the non
functional gene that codes for
leptin receptors in obese mice with a properly
functioning one

Will often use specially
tailored viruses to deliver

Difficult to get copies of the desired gene into enough
cells in the target tissues

Gene Manipulation

Problems with immune response to the viruses

Problems with division in the new cell line

Some success has been seen with adenosine

deficiency (ADA)

Defect in a key protein involved in the immune

Bone marrow stem cells are removed, manipulated,
and replaced


How are different alleles created?

One way is by mutations

Mutations are changes in the DNA sequence

Since DNA codes from protein synthesis, changing the
DNA can alter the proteins made or stop them from
being made all together

This can be both useful and detrimental


Mutations can be caused
several different ways,


One base pair change


Removing a section of DNA


Inserting a section of DNA


Anything that alters DNA is labelled
as a mutagen

Radiation and several chemicals
can act as mutagens

Mutations in somatic cells often go

Mutations in gamete cells are passed

Cancer can be caused by mutation

Sickle Cell Anemia

A blood disorder caused by a recessive

mutation on an autosomal chromosome

Blood cells are shaped like crescents

instead of their normal shape

Sickle cells are not efficient at carrying oxygen

Being heterozygous for sickle cell anaemia confers
resistance to malaria

Genetic Screening

Geneticists can identify if a person has an increased
risk of inheriting a disorder

Genes can give an increased susceptibility to certain

Huntington Disease

Autosomal dominant

Onset after 30
40 years of age

Diminished mental capacity and uncoordinated
muscle movements

Genetic Screening

Cystic fibrosis

Large amount of mucus lining the lungs and
digestive tract

Autosomal recessive trait

Would you want to know if you were susceptible to a
certain disease?

Or if your kids would be susceptible?

Genetic Counselling

Counsellors determine whether an individual is at risk
of inheriting detrimental traits

Such as sickle cell anemia, or a predisposition for

It is possible that in the future we can know all the
susceptibilities and predispositions an individual will

What implications does this have for society?

Prenatal Diagnosis

Testing a fetus for problems before birth

Process is called amniocentesis

Extracting amniotic fluid (which contains some
cells) with a syringe

Guided by ultrasound

Allows parents to be

prepared for any special

needs before birth