Unit 2 - Metabolism and Survival (Genetic Control of Metabolism)

Question 1

What are the two ways in which wild strains of micro-organisms can be improved?

Answer 1

1. Mutagenesis
2. Recombinant DNA technology

Question 2

What is mutagenesis?

Answer 2

Mutagenesis is exposing micro-organisms to UV light and other forms of radiation or mutagenic chemicals resulting in mutations.
Some mutations may produce an improved strain of micro-organism.

Question 3

What are the two main types of mutagenic agents?

Answer 3

1. Radiation - UV light, X-rays and gamma rays
2. Chemical - mustard gas and lead oxide

Question 4

What is involved in recombinant DNA technology?

Answer 4

• Recombinant Plasmids
• Artificial chromosomes

Question 5

What is a vector?

Answer 5

A vector is a DNA molecule used to carry foreign genetic information into another cell.
Artificial chromosomes and plasmids are examples of vectors used in recombinant DNA technology. Artificial chromosomes are preferable to plasmids as vectors when larger fragments of foreign DNA are required to be inserted.

Question 6

What is the role of restriction endonucleases in recombinant DNA technology?

Answer 6

Restriction endonucleases cut open plasmids and leave sticky ends. Complementary specific ends (sticky ends) are produced when the same restriction endonuclease is used to cut open the plasmid and the gene from the chromosome.

Question 7

What is the role of ligases in recombinant DNA technology?

Answer 7

Ligase will seal the gene into the plasmid.

Question 8

What are the four components a plasmid or artificial chromosome must contain?

Answer 8

1. Restriction sites
2. Regulatory sequences
3. Origin of replication
4. Selectable markers

Question 9

What are restriction sites?

Answer 9

Contain target sequences of DNA where specific restriction endonucleases cut.

Question 10

What are regulatory sequences?

Answer 10

Control gene expression.

Question 11

What is the origin of replication?

Answer 11

Allows for self-replication of the plasmid/artificial chromosome.

Question 12

What are selectable markers?

Answer 12

Protect the micro-organism from a selective agent (antibiotic) that would normally kill it or prevent it from growing. The selectable marker gene ensures that only the micro-organisms that have taken up the vector grow in the presence of the selective agent (antibiotic).

Question 13

Which safety mechanism is often used in recombinant DNA technology?

Answer 13

Genes are often introduced that prevent the survival of the micro-organism in an external environment. This acts as a safety measure that decreases the chances of an uncontrollable outbreak of a micro-organism.

Question 14

What is the use of recombinant yeast cells in recombinant DNA technology?

Answer 14

Recombinant yeast cells can be used as a vector to produce proteins that would normally be found in animals or plants.
Recombinant yeast cells are used during DNA Recombinant technology as they produce active forms of the protein. Bacterial recombinant DNA may produce animal or plant protein chains (polypeptides) that are inactive as the polypeptides are incorrectly folded. The proteins in the bacteria may not be modified correctly after protein synthesis.

Question 15

What are the potential problems in using micro-organisms?

Answer 15

• Risk of uncontrolled dispersal into the natural environment.
• Micro-organisms are highly adaptable to different ecological niches and could disrupt those environments.
• Sideways transfer of genetic material to different species could occur.
• Unforeseen metabolic modifications could be hard to control.
• Creation of new pathogenic micro-organisms is a possibility.