Topic 4

Learning objectives: By the end of the lesson you should be able to:

Explain the impact of the environment on the phenotype of an organism.

Describe how identical twins or clones can be used to assess the impact of the environment on a organisms phenotype.

State whether environmental impact on phenotype can be passed on to the next generation.

1: Environmental effects on the Environment

For most polygenic characteristics the phenotype is determined by _______________

____________ which determines the ___________ development of the individual

•_______________ which influences the _________ development of the individual

two factors

genotype potential

environment

actual

The combined effect of genotype and phenotype is often shown as

e.g. over the last century the average height of humans has increased as their diet has improved

• e.g. For chlorophyll formation in tomatoes, a mutant tomato plant which is white will turn green if grown in temperatures above 26 oC

Genotype

Environment

Phenotype

2: Environmental effects and inheritanceChanges in phenotype are not inherited

and so do not affect evolution.The ______________________ on the phenotype can be

dramatic e.g. a land mine may deprive a person of a leg.

•_____________________________, so only changes to a person’s genotype can affect ___________________, and therefore _______________

•e.g. The land mine victim with one leg can have healthy children with 2 legs

effect of the environment

Only the genotype is inherited future

generationsevolution

3: Studying the effects of the environment on the phenotypeClones are genetically identical individuals

The effects of the ____________ on the _______________

_______________ is studied using _________

environment development

of characteristics clones

•Cloned plants grown in ___________________ show effects of that condition on the development.

•Since the genotypes are the same, __________________________

e.g. Plants grown in light are green and healthy but clones grown in the dark are yellow and sickly

different conditions

Any difference in the plant must be due to the environment

Identical twins are _________ and are useful in studying the effects of “nature” (genotype) and “nurture” (environment on development

Differences between identical twins must be due to the _____________________________

clones

effects of the environment

Learning objectives: By the end of the lesson you should be able to:

Define the term Natural Selection. Describe the mechanisms which drive natural

selection Explain how natural selection has acted on the

peppered moth

4: Evolution and natural selectionEvolution is the scientific explanation for the

____________________________________ over the 3.5 billion years since life first appeared on Earth.

The current theory of evolution was first proposed by ______________ in the 1850’s

• It is based on simple observations

Changes seen in species and biodiversity

Charles Darwin

• Organisms _____________________ than the environment can support

This results in _____________ for limited resources

There is a __________________ the effects of

• Lack of water / food

•Lack of shelter•predation•disease

produce more offspring

competition

struggle to survive

Members of species show ___________________ due to the expression of different alleles

Those individuals with ________________________ to the environment are more likely to _____________

____________________

Those individuals with ______________________ to the environment are more likely to ____________

________________________

inherited variation

phenotypes better suited survive and

breed and so pass on their genes

phenotypes less suited Die so do

not pass on their genes

This process is called __________________ and results in ________________________

Over ______________________ the characteristics of ____________________ e.g. the peppered moth story

natural selectionsurvival of the fittest

many generationsspecies may change

5: The environment and evolutionIf the environment __________________ there is

no pressure for a successful species to evolve

E.g. coelacanth is a deep sea fish which looks exactly the same today as 80 million years ago

does not change

If the environment ________________________ then species may become ____________

E.g. 65 million years ago many species including the dinosaurs disappeared due perhaps to the impact of a large asteroid

Changes too rapidlyextinct

________________ are causing __________________ and so many species which cannot adapt quickly enough will become extinct.

Borneo

Human activities

rapid environmental change

Learning objectives: By the end of the lesson you should be able to:

Explain the process of selective breeding. Describe the advantages and disadvantages of

selective breeding.

6: Selective breedingFor thousands of years __________ have been

_______________________________________________ to produce the next generation.

This is in the hope of _____________ certain characteristics

humansselecting individuals with favourable characteristics

improving

• This process is called artificial selection or _______________ ________________________

selective breeding

• In this way most of the animals and plants used by humans have been ___________________________________

modified from their ancestors

Some examples of characteristics which have been ____________ areSize and taste of __________________

Beef and milk yield in _________________

• Disease resistance in ___________________• Egg production and growth in ______________•Varieties of ________

improved food

plantscattle

crops

poultry

dog

(note: fish and timber are still harvested from the wild, but the supplies are running low due to poor management of these resources)

Learning objectives: By the end of the lesson you should be able to:

Describe the process of genetic engineering from the identification of a desired gene to the synthesis of the desired product.

7: Genetic engineeringGenetic engineering involves altering the

genetic material of an organism.

This can be done in two ways

• Altering or removing genes

• Adding genetic material from another organism

Using Genetic Engineering to modify bacteria

Result of genetic engineering

Produces individuals ________________________ called _________________________ (GM) or transgenic organisms

Has led to _____________ and ___________________ of medicines

showing new characteristicsgenetically modified

faster larger scale production

Learning objectives: By the end of the lesson you should be able to:

State some of the medicinal products produced by genetic engineering.

Describe the advantages and disadvantages of genetic engineering.

GM _______________ are used to produce the proteins needed by humans

e.g. diabetics can now use human insulin produced by bacteria which have had the human insulin gene inserted into then.

In the past diabetics had to use animal insulin

bacteria

8: Genetic engineering compared with selective breeding

Feature Genetic engineering Selective breeding

DNA can be introduced from ___________________

DNA only comes from ______________________

Advantages

Genes

Time Changes appear in the _________ generation

Changes take _________ generations

Offspring

Will ________________ the improvement

May or _____________ show the improvement

any species

one species

nextmany

definitely show may not

Disadvantages

Feature Genetic Engineering Selective Breeding

Public Acceptance

Safety

People are ______________of the new technology____________________of GM organisms

The _________________ of producing new varieties

_______________________ seen as safe

suspiciousaccepted way

concern over the release

natural process