2.3 Environmental & Genetic code of metabolism

Question 1

three domains on micro-organism

Answer 1

bacteria, archae, eukaryotes

Question 2

why micro organisms can be used to make an range of micro organisms

Answer 2

micro organisms use a wide variety of substrates for metabolism and can produce a range of products from their metabolic pathways.

Question 3

state three reasons why micro organisms can be used to produce a range of products

Answer 3

• adaptability
• ease of cultivation (growth)
• speed of growth

Question 4

energy sources needed for culture of micro organisms

Answer 4

complex chemical molecules for biosynthesis, sterile culture, temperature, oxygen, pH.

Question 5

requirements for growth (energy source) complex chemical molecules for biosynthesis

Answer 5

some produce amino acids, fatty acids or vitamins for biosynthesis, others require these to be supplied in the growth media e.g agar plates.

Question 6

sterile culture

Question 7

temperature

Answer 7

there will be an optimum temperature range for the particular micro organism enzyme.

Question 8

oxygen

Answer 8

some micro organisms require a supply of oxygen by aeration for respiration. others only survive in low or no oxygen

Question 9

pH

Answer 9

pH kept constant using buffers/buffer solution

Question 10

growth phases of micro organisms

Answer 10

lag, log/ exponential, stationary, Death.

Question 11

lag

Answer 11

slow increase in numbers as cells adjust to conditions. Enzymes are induced to metabolise new substrates.

Question 12

log/ exponential

Answer 12

cell growth at most rapid rate, due to plentiful supply of nutrients. No limiting factors on their growth.

Question 13

stationary

Answer 13

no increase in numbers. Reproduce rate = death rate. Nutrients depleted and secondary metabolites such as antibiotics produced which inhibit growth.

During the stationary stage in wild populations, secondary metabolites (antibiotics) can confer as advantage by allowing the micro organisms which produce them to out compete other micro organisms.

Question 14

death

Answer 14

lack of nutrients in culture & accumulation of toxic metabolites leads to cell deaths.

Question 15

total cell count and viable cell count

Answer 15

viable cell count is the living mirco organisms only. The viable cell count will show a death phase where cell numbers are decreasing.
The total cell count id the count of both viable cells and dead cells.

Question 16

mutagenesis

Answer 16

scientists can cause wild strains of mutation in micro organisms by exposing them to UV rights or X-rays or mutagenic chemicals. This may produce a improved strain of micro organism.

As many of these mutants are genetically instable they may revert back to their original wild type after several generations.

Question 17

recombinant DNA technology & vector

Answer 17

recombinant DNA technology involves the use of recombinant plasmids and artificial chromosomes as vectors. A vector is a DNA molecule used to carry foreign genetic information into another cell.

Question 18

preferred type of vector for use in recombinant DNA technology

Answer 18

artificial chromosomes are preferable to plasmids as vectors when larger fragments of DNA are required to be inserted into another cell.

Question 19

Recombinant DNA technology stages

Answer 19

1) restriction endonuclease enzyme used to
- cut out specific gene from a chromosome
- cut open a plasmid vector from bacterium.

2) same restriction endonuclease enzyme used to cut out the gene and to cut open the plasmid. This produces produce complementary “sticky ends” in the opened plasmid and at either side of the gene.
3) gene sealed into plasmid vector at complementary “sticky ends” using enzyme DNA ligase.
4) Recombinant plasmid (vector) taken up by host bacterium which synthesises required polypeptide/ protein.

Question 20

restriction endonuclease enzymes in DNA recombinant technology

Answer 20

restriction endonuclease enzyme used to

• cut open specific gene from a chromosome
• cut open a plasmid vector from bacterium.

Question 21

complementary “sticky ends”

Answer 21

the sticky ends of the donor DNA are complementary to the opened ends of the vector plasmid. Without complementary sticky ends the ligase would not be able to seal the gene into plasmid.

Question 22

ligase

Answer 22

ligase is an enzyme which joins together complementary DNA strands (plasmid & foreign gene) at sticky ends in recombinant DNA technology.

Question 23

to be an effective vector, plasmid must posses certain structures

Answer 23

selectable markers, regulatory sequences, origin of replication, restriction site.

Question 24

selectable marker

Answer 24

selectable markers (antibiotic resistance) protect the micro-organism from selective agent (antibiotic) that would normally prevent it from growing.
selectable marker genes ensure that only micro organisms that have taken up the vector grow in the presence of selective agent (antibiotic).

Question 25

regulatory sequences

Answer 25

regulatory sequences control gene expression.

Question 26

origin of replication

Answer 26

origin of replication allows plasmid/artificial chromosome to make copies of itself (self replicate)

Question 27

restriction sites

Answer 27

restriction sites ( contain target sequence of DNA on the plasmid) where specific restriction endounuclease can cut.

Question 28

safety mechanism

Answer 28

Genes that act as safety mechanisms are added to bacterial cells which ensure that bacteria are unable to survive in external environment.
E.g - gene that promotes an reliance on a substance that is present in the culture medium but not in the external environment.

Question 29

recombinant yeast cells

Answer 29

recombinant yeast cells may be used to produce active forms of a protein produced by DNA recombinant technology, as plant or animals recombinant DNA may be result in polypeptides in protein being folded incorrectly, leading to inactive protein.

Question 30

recombinant yeast cells

Answer 30

recombinant yeast cells may be used to produce active forms of a protein produced by recombinant DNA technology, as plant or animals recombinant DNA may result in polypeptides in protein being folded incorrectly, forming a inactive protein.