Recombinant proteins

Question 1

Give 3 examples of therapeutic recombinant proteins.

Answer 1

1. Hormones like insulin
2. Vaccines
3. Antibodies

Question 2

What are diagnostic proteins?

Answer 2

Those used to determine an outcome.

Question 3

Give 3 examples of diagnostic proteins.

Answer 3

1. Enzymes
2. Antibodies
3. Biosensors

Question 4

Commercial enzymes can be used in a) industry and b) biotechnology. Give examples of each.

Answer 4

a) Food production

b) Restriction enzymes, thermostable polymerases etc.

Question 5

In order to recombine proteins you must first obtain pure forms of those you wish to combine. Can you get these from natural sources?

Answer 5

Yes if they are abundant in a particular cell or tissue.

Question 6

What are 3 disadvantages to purifying proteins from natural sources?

Answer 6

1. Cost
2. Ethical considerations
3. Contamination/infection

Question 7

You can obtain proteins for recombination from a transformed bacterial host instead. Give 5 advantages of this.

Answer 7

1. Produces large volumes of protein by clonal growth
2. Genetic engineering allows for high expression of required protein
3. Reduced cost
4. Reduced risk of contamination
5. More ethically acceptable

Question 8

If you are transforming bacteria with eukaryotic DNA what must you use and why?

Answer 8

cDNA because it contains no introns.

Question 9

Promoters are usually organism-specific and thus un-transferable. True or false?

Answer 9

True, for example a human promoter will not work in yeast.

Question 10

You must always use endogenous promoters in protein production. These are not only organism specific but tissue specific as well. True or false?

Answer 10

True.

Question 11

The genetic code is degenerate. What does this mean?

Answer 11

Multiple codons code for the same amino acid.

Question 12

Different organisms display preference for some codons. True or false?

Answer 12

True - because the code is degenerate several codons produce the same AA, and some species have higher proportions of particular codons.

Question 13

What is codon optimisation?

Answer 13

Adapting the genetic code to suit the host organism, e.g. using codons that they prefer.

Question 14

Give 4 methods of delivery of synthetic genes into a host.

Answer 14

1. Electroporation
2. Chemical treatment
3. Biolistics
4. Microinjection

Question 15

Define electroporation.

Answer 15

Delivering a pulse of electricity that momentarily opens the pores of a cell.

Question 16

Define biolistics.

Answer 16

Whereby tiny metal pellets coated in DNA are propelled into living cells at high velocities.

Question 17

The expression of a protein in a host does not always work as it creates negative selection against the host. True or false?

Answer 17

True.

Question 18

Inserted proteins may not always be expressed in the host. Give 3 reasons why.

Answer 18

1. Point mutations
2. Methylation
3. Chromosomal rearrangements

Question 19

If the inserted protein is negatively selected for, why might it not be expressed?

Answer 19

Because it is unfavourable.

Question 20

Expression can go wrong and result in a) degradation and b) aggregation. What does this mean?

Answer 20

a) Where the protein is broken down and becomes non-functional
b) Too much is produced and clumps together, also reducing function

Question 21

Where is hGH produced?

Answer 21

In the pituitary gland.

Question 22

Animal hGH is compatible with humans. True or false?

Answer 22

False - it was isolated from human cadavers but there were major issues with HIV and prion proteins and this is now banned.

Question 23

How is hGH produced now?

Answer 23

With E. coli as a host.