Variance, Selective breeding, Genetic Engineering, and Cloning Flashcards
What is an phenotype ?
Phenotype is the observable physical properties of an
organism
Examples of phenotype…
This includes appearance, development, behaviour and even functioning of internal systems
For example, feather colour in birds is a phenotype
What is phenotype depended on ?
Phenotype is depended on both genotype and
the environment
What is genotype depended on ?
Genotype is the genes inherited by an
organism
Every organism’s genotype is….
Every organism’s genotype is unique,
except identical twins and clones
What is the environment ?
Environment is the habitat around you
- For example, flamingos are pink
because of pigments in their food
What is Genetic variance ?
Genetic variance refers to the natural
differences in the genotype of a
population of a species
Name the two types of genetic variance
There are two types of genetic variance:
- continuous like height
- dis-continuous, like eye colour
What is a genetic difference due to ?
Genetic differences are due to
random mutations
Do mutations happen all the time ?
Mutations are happening all the time: o Most do not affect phenotype; o Some will influence phenotypes but will not cause a new phenotype; o On rare occasions, a mutation occurs that does create a new phenotype.
How variation occurs step by step …
- Original bird mutates causing new phenotypes
- If the new phenotype is not favoured by females it is not passed on
- If the new phenotype is favoured by females it is passed on and will out compete the old phenotype
What are environmental variations caused by ?
Environmental variations are characteristics caused by
an organism’s environment
Desired characteristics can include (Animals):
- The colour, length and texture of fur
- Produce large amounts of product, such as
eggs and milk - The size of the animal
- Tameness/ gentleness
Desired characteristics can include (Plants):
- Disease and pest resistance
- Produce large amounts of product, such as grains and
fruits - Taste
- Large or unusual flowers
Benefits of Selective Breeding
- New varieties produce more or better products, leading
to more profit. - Animals can be selected to reduce harm, such as
breeding cows with no horns or tame wolfs (that
eventually leads to dogs).
Risks of Selective Breeding
- Reducing the genetic variance can lead to weaknesses to
specific pests and diseases. - Inbreeding – breeding together animals that are too closely
related can result in: - Selecting for rare diseases then selecting another positive
trait, for example, large dogs are prone to bone cancer. - Creating physical problems in the species, for example, pugs
have trouble breeding because of their squished snout.
What is selective breeding ?
Selective breeding is the process by which humans breed
plants and animals for particular genetic characteristics.
Genetic Engineering
is a process that modifies the genome of an
organism, by inserting a gene with a desired
function or outcome, into the organism.
Host bacterium
To carry the inserted gene
DNA vector
This a DNA molecule, normally a virus or
a plasmid that is used to carry a foreign genetic
material into another cell.
Restriction enzymes
cuts DNA at specific sites
Ligases enzymes
joins DNA at specific points
Sticky ends
the cut ends of gene and DNA vector
Genetic Engineering Steps
1) The DNA is removed from the organism with the desired characteristic
2) A plasmid is removed from a bacteria cell
3) The gene of the desired characteristic is cut from the DNA strand using restriction enzymes
4) The plasmid is cut open with restriction enzymes
5) The sticky ends from both the plasmid and the DNA strand, are attached together using the enzyme ligase
6) The plasmid with the desired gene will be absorbed by the host bacteria cell
7) The bacteria reproduces, producing millions of identical bacteria with the desired characteristic
Genetic engineering and crops
- Genetic engineering has been used to produce plants
with increased yield and increase nutrition. - A crop might be genetically engineered to be resistance
to some type of disease or to produce bigger fruits. - These crops are GM (genetically modified) crops.
Some diseases are caused by the mutation of a single
gene.
- These diseases are typically inherited and affect the
quality of life of the person who has it. - In recent years, scientists have developed gene therapy.
- This involved transferring the non-faulty version of the
gene into the person.
Gene therapy has the potential to cure many diseases.
- However, there have been some hurdles to overcome;
- how to target the specific cells,
- unknown side-effects and
finding a reliable way to get the genetic material into the cells.
Benefits of GM in crops
Benefits
o Mass produce hormones that are needed in medicine
o It can improve crop yields by improving growth,
allowing crops to grow in harsh conditions and make
their own herbicide or pesticide
o Extra vitamins can be added to crops and grown where
there are deficiencies
o Greater yield could help solve world hunger
Risks of GM in crops
o Might affect the growth of wildflowers, and the insects that
rely on them.
o Herbicides and pesticides reduce biodiversity
o Could affect human health
o People worry about the ethics of altering nature.
o Might outcompete their wild species, causing them to
become rare
Embryo Cloning
- Parent sheep with desired characteristics are chosen
- The egg is fertilised with the sperm forming an
embryo - The embryo is divided
- The embryos are implanted into surrogate mothers
- The offspring are all identical clones from the same
biological parents
Adult Cell Cloning
1) A diploid cell is taken from the sheep A to be cloned
2) The DNA is extracted
3) An egg cell is taken from sheep B
4) The egg cell is enucleated - the nucleus is removed
5) The DNA from sheep A is combined with the enucleated egg from Sheep B
6) The egg cell is given a mild electric shock to stimulate division by mitosis to from an embryo
7) The embryo is implanted into the surrogate mother
8) BABY
Benefits of Cloning
- Produces many offspring with desirable
characteristic. - The study of clones and cloned embryos could
advance medicine. - It can be used to help endangered species or
even bring back extinct species.
Risks of Cloning
- Leads to shorter lived animals and physical
disabilities. - Many people are worried about the use of
cloning on humans - Reduces the gene pool
- Species with small gene pools are more likely
to be completely wiped out by a disease
What is a clone ?
Clones are two or more individual organism that are
genetically identical
Cloning plants is useful for …..
Cloning plants is very useful for producing large amounts of identical plants quickly and cheaply
What is the definition of tissue culture ?
taking a small sample of a plant and
growing it in growth hormones
What is the definition of tissue cutting ?
taking a large sample of a plant and growing
it in compost with root growth hormones
What is cloning animals useful for ?
Cloning animals is useful for producing identical offspring and for medical research
