Selective Breeding, Cloning and Genetic Modification

describe the steps of selective breeding

1. select desired characteristic in organism

2. select individuals with the desired characteristic

3. breed together

4. select the offspring with the desired characteristic and breed together

5. repeat over many generations

what are the disadvantages of selective breeding

1. reduces genetic variation

2. if a disease was to arise it could affect a lot of the population

3. increases the chance of inheriting a genetic disease

4. slow process as it takes many generations

what traits may be selected for in a farm of animals

1. process more product e.g. meat, milk, wool, eggs

2. produce more vitamins and minerals in their milk

3. produce more offspring

4. show resistance to disease and parasites

what treats may be selected for in plants

1. resistant to disease

2. resistant to pests

3. more hardy so can survive harsher climates or productive for longer periods of the year

4. more attractive

5. more productive i.e. produce larger leaves or more fruit

why might arterial insemination be used rather than natural breeding methods when selective breeding

1. semen can be transported rather than the animal- cheaper and quicker

2. semen from one ejaculation can be split and used to inseminate multiple females

3. the semen can be stored for many years, meaning the animals it came from does not have to be living to still produce offspring

what is genetic engineering

alternating an organisms genome by adding a gene from another organism to produce an organism with desired characteristics

give 2 advantages of genetic engineering

1. very accurate as single genes can be targeted

2. quicker than selective breeding as can happen in one generation

what is a transgenic organism

contain DNA from another organism

name the 2 enzymes needed in genetic engineering

• restriction enzyme

• ligase enzyme

what is a vector

something that is used to transfer DNA into a cell, usually a plasmid or bacteriophage

what is a plasmid

a small circular piece of DNA that can be transferred between bacteria

what is recombinant DNA

DNA from different species that have been joined together

what does ligase do

joins the sticky ends together

what do restriction enzymes do

cuts DNA at a specific place, leaving sticky ends

why do you need to cut the target gene out and the plasma with the same restriction enzyme

to get complementary sticky ends

describe the steps of genetically engineering bacteria to produce human insulin

1. identify the insulin (desired) gene from the donor

2. cut gene out of DNA using restriction enzyme

3. remove a plasmid from the bacterial cell and use the same restriction enzyme to cut the plasmid so it has complementary sticky ends

4. ligase enzyme joins complementary sticky ends together to stick DNA together- forming recombinant DNA

5. dan inserted back into bacteria- forming transgenic bacteria

6. bacteria reproduce asexually and the recombinant DNA is copied to form clones of GM bacteria all with insulin gene

7. bacteria will all produce human insulin

why do type 1 diabetes need insulin

1. pancreas no longer makes insulin

2. so they cant take up glucose into liver an muscle cells to convert into insoluble glycogen

3. so your blood glucose levels stays high

give 4 advantages of producing insulin using transgenic bacteria rather than animal derived alternatives

1. low price

2. low dosage needed than using insulin from animals

3. fewer ethical objections

4. less risk of allergic reaction

define the term transgenic

organism which contains genes transferred from another species

why might you want to genetically modify crop plants

• pest resistance

• herbicide resistance

• add vitamins to crops

• increase yield

• increase shelf life

what are the risks of genetic engineering

• don’t know long term effects

• may eventually lead to health problems

• GM crops may cross pollinate with wild plants introducing a new gene into wild plants, this could disrupt the balance of the ecosystem

• there are ethical objections to altering an organisms genome

what is a clone

a genetically identical organism

what is an explant

a small fragment cut off the parent plant to be cloned

how can you ensure the explanation does not have pathogens on its surface

the scalpel used to cut it and the explant should be sterilised with bleach

what should you do with the explant once it has been cut

place it onto sterile agar containing growth medium- this should contain a source of carbohydrate, mineral ions and auxin

once platelets have developed what should be done

planted into compost and put into a greenhouse to grow

how can GM and micropropagation be used together

once plant can be genetically modified then micropropagation can be used to quickly make thousands of clones of this GM plant

what does enucleated mean

nucleus removed

why is the egg cell nucleus removed and replaced with a body cell nucleus

the egg cell nucleus is haploid an the body cell nucleus is diploid

describe the stages of cloning

• remove diploid body cell

• insert nucleus of diploid body cell into enucleated egg cell from another organism

• give egg cell an electric shock

• to stimulate mitosis

• implant embryo into uterus of surrogate mother

describe how a single cell develops into an embryo

divides by mitosis

cells specialise