Biotechnology

what is selective breeding?

the process by which humans breed plants and animals for particular genetic characteristics.

Humans have been doing this for thousands of years since they first bred food crops from wild plants and domesticated animals

4 steps of selective breeding

1. choose parents with desired characteristic from a varied population

2. they are bred together

3. breed together offspring with desired characteristics

4. repeat this process over many generations which results in ALL offspring showing desired characteristic

4 things you might selective breed for

• disease resistance in food crops

• animals which produce more meat or milk

• domestic dogs with a gentle nature

• large or unusual flowers

artificial selection can lead to ____ this can lead to ___ + ____

• inbreeding

• disease (e.g arthritis in dogs)

• inherited defects (squashed face = breathing difficulties in pugs)

what is cloning?

the process of producing clones (organisms that are exact genetic copies)

how to do cuttings

old, simple technique

• fragments of plant seperated from parent

• rooting powder

• magnesium = chlorophyll

• nitrate = protein

• transparent container = light for photosynthesis, barrier against pathogens

• reproduces by mitosis - asexual = clones

advantage of tissue culture vs cuttings

produces many more clones

how to do tissue culture?

• a few cells are removed from meristem of plant

• treated with plant hormones to make them divide by mitosis

• grown in nutrient medium (auxin, magnesium+nitrogen ions)

both tissue culture and cuttings ___ + ____

• produce large number of cloned plants

• result in offspring that are genetically identical to each other AND parent

why do we clone plants?

• to preserve rare plant species

• plant nurseries

2 techniques of animal cloning

• embryo transplant

• adult cell cloning

4 steps of embryo transplant

1. egg + sperm from selected animals collected and fertilised in a petri dish to form a zygote

2. zygote divide by mitosis to form an embryo

3. BEFORE the cells specialise split them into individual cells or small groups of cells

4. grow these cells into embryo and then transplant the gentically identical embryos into host/surrogate mothers

5. the offspring will be genetically identical to each other BUT NOT the parents

5 stages of adult cell cloning

1. nucleus is removed from unfertilised egg

2. take a body cell from animal that is being cloned (eg skin cell)

3. nucleus of body cell is removed and inserted into empty egg

4. electric shock the egg cell to start mitosis, egg cells divide to form an embryo

5. the embryo is inserted into the uterus of a surrogate mother, offspring are genetically identical to animal 2.

5 advantages of cloning

1. large number of clones

2. conserve endangered species from extinction

3. genetically identical organs for transplantation

4. quicker and more precise than selective breeding

5. can allow cloned GM animals or plants

4 disadvantages of cloning

1. potential harmful side effects to clones

2. reduces genetic variation of population…could lead to extinction

3. ethical objection

4. expensive + difficult to do on animals

what is genetic engineering

• changing the genome of an organism by introducing a gene from another organism

• can be done using human (plant + bacteria as well) chromosomes to isolate human genes

4 steps of genetic engineering

1. enzymes are used to isolate the required gene

2. insert the gene into a vector by another enzyme, usually a bacterial plasmid or a virus

3. the vector inserts the gene into the required cells.

4. if this is done at an early stage of development then they will develop with the desired characteristic

3 uses of genetic engineering

1. genes can be transferred to bacteria from humans to make human proteins (eg insulin)

2. GM crops can be engineered to be resistant to pests + herbicides, have larger fruits, improve nutritional value + drought resistant = increased yield

3. potentially to genetically modify organisms to overcome certain inherited disorders (gene therapy for cystic fibrosis)

5 advantages of genetic engineering

1. make human hormones and medicines

2. improve growth rates of plants and animals

3. improve food value

4. produce plants that make their own pesticides, easier for farmers (won’t wash away)

5. potential cure for genetic diseases