Patient Counselling. Definition of patient counseling; steps involved in pati...
Evolution & Gen. Engineering
1. 8.1 Development of the Phenotype
Today’s Learning Objectives:
State the two influences on the phenotype of an
organism.
Give examples of how environment can influence the
phenotype of human identical twins during growth.
Give examples of how environment can influence the
phenotype of humans after growth is complete.
Explain why changes in the phenotype caused by the
environment are not important in evolution of new
species.
2. Genotype is not the only influence on phenotype.
Phenotype is also dependant on the environment
which the organism has grown and developed.
GENOTYPE + ENVIRONMENT = PHENOTYPE
3. 8.2 Natural Selection and Evolution
Today’s Learning Objectives:
Describe how organisms such as mice, can produce
more offspring than can survive.
List some factors which prevent all offspring from
surviving.
State why organisms such as mice are not
genetically identical.
State the meaning of the term ‘natural selection’.
State the meaning of the term ‘evolution’.
Describe the role of natural selection in evolution.
Describe the evolution of cichlid fish in Lake
Victoria.
4. Breeding and Survival
Starvation
- Not good at
competing for food
Disease
-weaker offspring
Predators
-poorly camouflaged
-slow reactions
Exposure
-Thinner coats
- not good at
competing for
shelter
Only rabbits with
the best
characteristics will
survive.
5. Only organisms with the best combination of
genes for their environment will survive.
This means that their gene combinations will be
passed on to the next generation.
Organisms with less useful genes will die out and
therefore not pass on their genes.
This process is known as Natural Selection.
If natural selection operates over millions of years
it can give rise to new species… EVOLUTION!!
6. 8.3 Natural Selection- A Case Study
Today’s Learning Objectives:
Describe the adaptation of the speckled form of
the peppered moth.
State the meaning of the term melanic.
Explain why the melanic moths usually failed to pass
on their genes in the early 19th
Century.
Describe the effects of the burning of coal on
lichens and on exposed surfaces.
Describe how natural selection changed the survival
chances for melanic moths in industrial areas.
State why the varieties of the peppered moth have
not become two species.
7. The Peppered Moth
Speckled Variety Melanic Variety
-A nocturnal insect, rests on tree surfaces during
the day.
-Is preyed upon by insect eating birds which pick
them up from exposed surfaces.
8. •In the early 19th
century the speckled moths were
well adapted to camouflage themselves against the
lichen covered tree and avoid predation.
•The melanic version (all black) showed up against the
lichens and were easier for birds to spot. Melanic
version rarely survived to pass on genes.
9. •The Industrial revolution (late 19th
century) saw the
use of coal burning industry. Sooty smoke and sulphur
dioxide was lethal to lichens and covered exposed
surfaces.
•Speckled moths were now easier to spot and the
melanic moths had a greater chance of survival to
pass on their genes.
10. 8.4 Selective Breeding
Today’s Learning Objectives:
Define the term ‘selective breeding’.
Give examples of animals which have been
selectively breed.
Give examples of characteristics in farm animals
that have been improved by selective breeding.
State the meaning of the term ‘hybridisation’.
State some of the limitations or problems of
selective breeding.
11. The process of natural selection has led to great
biodiversity.
For many centuries, humans have also altered the
characteristics of organisms by deliberately choosing
which individuals to breed:
SELECTIVE BREEDING
This involves breeding desirable characteristics to
produce them in the next generation.
e.g Animals
Cattle for milk and beef
Sheep for wool
Poultry for egg production
12. Limitations of Selective Breeding
-New combinations are limited to the genes that the
organism naturally possesses. The gene for a desired
characteristic may not be present.
-Difficulties in getting selected individuals to breed.
-May take months or years to achieve one generation.
-Fertilisation = random variation, so hybrids by
chance may have an inferior combination of genes.
-Can increase the frequency of recessive (often
inferior) genes.
Relies on sexual reproduction:
13. 8.5 Genetic Engineering
Today’s Learning Objectives:
Define the term ‘genetic engineering’.
State what the genes of an organism are made of.
Describe how plasmids are used in genetic
engineering.
State which organisms are most commonly used to
make useful products in genetic engineering.
State some advantages of genetic engineering
compare to selective breeding.
State some of the disadvantages of genetic
engineering.
15. Insulin gene cut and
removed from human
chromosome.
Human chromosome
Insulin gene
Plasmid removed
from bacterial
cell
Human insulin gene
placed into
bacterial plasmid.
16. Plasmid containing
insulin gene placed
into new bacterial
cell
Plasmid multiplies
inside bacterial cell.
More insulin is
produced
Bacterial cell grows
and divides
producing more cells
containing many
more plasmids and
much more insulin
Human insulin is
collected and
purified from
bacterial cell
17. Advantages of Genetic Engineering:
DNA from completely different species can be
combined.
Recessive genes not a problem, desired
characteristics can be specifically selected.
Can produce large quantities of desired proteins
(e.g. Insulin) which are easy to purify and not
contaminated.
Only needs one generation to produce results.
18. Disadvantages of Genetic Engineering:
Multicellular animals are much more complex than
bacteria – only a few plant cells are able to take up
plasmids.
Inserting genes using syringes instead can often
damage the cell and the inserted genes often only
work for a short time.
Inserting new genes into an animal may affect it’s
biochemistry so that it is producing harmful by-
products or long term effects.
19. 8.6 Uses of Genetic Engineering
Today’s Learning Objectives:
Describe how insulin is produced by genetic
engineering and state the advantages of producing it.
State the meaning of the term ‘haemophilia’.
State the advantages of producing blood-clotting
proteins by genetic engineering.
Describe how genetic engineering could help people
with defective genes.
Explain how genetic engineering can help fight
disease.
Name some plants used to make oral vaccines.
Nam the type of medically useful substances which
can be produced in the milk if genetically engineered
animals.
20. Insulin
Used to treat diabetes
Animal Insulin
Extracted from pancreas
of cattle and pigs.
Similar to human insulin
but not identical
Injected to treat
diabetes.
Works well but can be
seen as a foreign
protein and trigger an
allergic reaction.
Genetically Engineered
Insulin
Gene for human insulin isolated
and inserted into a bacterium.
Bacteria grow and multiply
and produce human insulin.
Insulin purified and injected
to treat diabetes.
Identical to human insulin so
does not cause allergic
reactions.
21. 8.7 Issues in Genetic Engineering
Today’s Learning Objectives:
State the meaning of the term ‘Gene Therapy’.
Explain how gene therapy could lead to a cure for
cystic fibrosis.
State the meaning of the term genetically modified
organism.
Give examples of improvements that can be seen in
GM crops.
State some problems with GM crops.
State the meaning of the terms ‘pharming’ and
‘xenotransplantation’.
22. Gene therapy is the replacement of a defective gene,
which causes a genetic disorder, with a functional gene.
A genetically modified organism is an organism which
has had genes inserted from another organism.
The development of crop plants and farm animals to
make medically useful products is called ‘pharming’,
short for pharmaceutical farming.
GM animals could be developed with organs that
would not be rejected when transplanted into
humans. This is called xenotransplantation.