Unit 7- Knockout Mice And GM Plants

Question 1

How can we discover the function of a gene using mice?

Answer 1

Make a knockout mouse

- where a gene is inactivated, we can compare this knockout mouse to a normal one to see the function of the gene

Question 2

How is a knockout mouse made?

Answer 2

• the process is called gene targeting
• modifying embryonic stem cells which develops into heterozygous adults carrying the modification
• when the adults then breed some of the offspring will have the inactivated gene

Question 3

Give an example of what a knock out mouse has been used for?

Answer 3

They have inactivated the CFTR gene and found that these knockout mice developed cystic fibrosis

Question 4

What are some uses of knockout mice?

Answer 4

• to study diseases linked to faulty genes in humans (cycstic fibrosis, Parkinson’s, cancer)
• to trial gene therapy cures/treatment

Question 5

Give some examples of diseases caused by inactive genes that both humans and mice share

Answer 5

• cystic fibrosis, we share the gene that suppresses CF
• cancer, some genes suppress cancer growth
• Parkinson’s, mice can be made to produce low levels of dopamine which mimics the disease
• obesity

Question 6

What is a transgenic organism ?

Answer 6

An organism with a foreign gene copied into its genome

Question 7

Give an example of a gene product:

Answer 7

• yeast and bacteria have been genetically modified to produce insulin

Question 8

Soya beans are used to make healthy vegetable oil as they are rich in fatty acids (linoleic acid), what are some problems with soya been oil and how has this been combatted?

Answer 8

• linoleic acid oxidises very easily becoming rancid
• linoleic is polyunsaturated, and monounsaturated fatty acids are better for our health
  Soya beans have been genetically modified to produce more oleic acid and less linoleic acid
• oleic acid is monounsaturated
• oleic acid is not easily oxidised

Question 9

What are better for humans, polyunsaturated or monounsaturated fats?

Answer 9

Monounsaturated

Question 10

How have soya plants been genetically modified?

Answer 10

• The desired gene was inserted into a bacterial plasmid
• the plant was infected with the modified plasmid
• the plasmid becomes part of the plant DNA, so the plant expresses the gene
• plant cells can easily be cloned into new plants

Question 11

Describe 2 ways in which genetic modification has improved the value of some crops

Answer 11

1) fatty acid content of soya has been changed to reduce spoiling by oxidation
2) pest resistance has been improved to increase crop yield

Question 12

How other than lipid composition have soya bean plants been modified?

Answer 12

• they have been genetically modified by a bacterium which is not affected by herbicides
• fields of soya beans can be sprayed with herbicides, which kills weeds reducing competition increase crop yield

Question 13

What are the positives of genetically modified organisms?

Answer 13

• Medicines and drugs can be produced safely
• agricultural productivity can be improved without the use of chemicals
• GM crops are healthier and can improve the health of millions of consumers

Question 14

What are the ethical issues of GM foods and organisms?

Answer 14

• the organisms being genetically modified are at risk to painful diseases such as cancer
• releasing marker genes such as antibiotic resistance into the natural world
• GMOs may irreversibly effect the food web
• introduced genes may spread uncontrollably eg by pollen
• against ingesting food containing foreign DNA
• could potentially harm third world societies who rely on 1 export, eg bananas could get modified to grow in England so Caribbean suffers