Biology - B6 - Feeding the human race

what two conditions are required for food security to occur?

1. all people are able to access enough safe and nutritious food to meet their requirements for a healthy life

2. must be in a way that is sustainable for the planet into the future

what six factors affect food security?

1. rising population - more people to feed

2. diet changes - food is transported further and more meat is eaten (less efficient to product)

3. pests and pathogens - kill crops and livestock, reducing yield

4. environmental changes due to climate change - decreased food yield (eg. due to inc temp or dec rainfall)

5. agricultural input expenses (eg. animal food, fertiliser, machinery costs) - increase food prices

6. conflict/wars - disrupt transport and production - increased prices, potential famine

what factors aid the need for increased food production, due to higher population and changing diets?

1. clearing of forests and natural land

2. application of fertilisers, pesticides, herbicides and other chemicals

3. selective breeding

4. genetic modification

what does GMO stand for?

genetically modified organism

• an organism whose genome has been modified, normally involving the addition of a helpful gene

the gene toxin, produced naturally by a type of bacteria, can be inserted into plants in order to make them pest resistant (kills insect pests)

Bt toxin

• use of this will increase crop yield (as less pests) and reduce need for use of chemical pesticides

what is an example of a genetically modified crop with increased nutrients?

golden rice - increases vitamin A in body

• useful in parts of the world where vitamin A deficiency causes diseases such as blindness

what are some examples of improved traits that GMOs may possess?

1. drought resistance

2. increased yield

3. herbicide tolerance

4. virus resistance

5. production of certain proteins (eg insulin) or nutrients

6. flood resistance

7. pest resistance

8. disease resistance

9. faster growth

what is selective breeding?

breeding together plants/animals with favourable characteristics in order to pass these onto offspring

how does selective breeding work?

1. select organisms with most favourable characteristics

2. breed these together

3. repeat process with best of next generation, etc

what are the drawbacks of selective variation?

• reduces gene pool of population

• best individuals are often closely related - leads to inbreeding

• less variation within the population

why is inbreeding problematic?

it makes offspring prone to diseases and inherited defects

define ‘gene pool’

the collection of different alleles in a population

why is having less variation within a population problematic?

a single pathogen may wipe out a whole population (as none are resistant to it)

• this could wipe out a farmer’s entire crop at once

what is genetic engineering?

the transfer of a piece of DNA from one organism to another organism

which two enzymes are used during the process of genetic engineering?

• restriction enzymes

  • isolates desired gene, forming sticky ends

  • cuts open plasmids (forming complementary sticky ends)

• DNA ligase

  • used to insert gene into plasmid and recombine sticky ends

what is gene therapy?

using genetic engineering to treat inherited disorders

why is it difficult to use gene therapy for adults?

• the faulty gene is in every cell, so it is hard to transfer the new gene into every cell

• solution: transfer gene at an early stage (eg. egg or embryo stage)

what are the potential problems with genetically modified crops?

• we don’t know if there are any health risks

• there is a small change of genetically modified crops outcompeting wild ones, altering the ecosystem

what are the steps of transferring a gene in genetic modification?

1. find and isolate gene using restriction enzymes

2. insert gene into a vector (bacterial plasmid or virus)

3. introduce the vector into the organism that we want to have the gene

   • cells will take up the vector (and gene) and start producing the protein that the gene codes for

what two things could be used as a vector in genetic engineering?

• virus

• bacterial plasmid

what are the steps of genetic engineering for human insulin?

1. isolate insulin gene from human DNA using restriction enzymes, forming sticky ends

2. use same restrictions to cut open a bacterial plasmid, forming complementary sticky ends

3. insert the insulin gene into the plasmid using the enzyme DNA ligase to form a recombinant plasmid

4. insert the recombinant plasmid into the host bacteria

5. let the bacteria divide and then produce the insulin protein