Primary metabolites 3 - Heterologous proteins

Question 1

what is a heterologous protein

Answer 1

A protein that is produced in a different host organism from where the native gene/protein is originally found

Question 2

3 advantages of heterologous proteins

Answer 2

• ethics - not harming/taking things from animals
• quicker - animals take longer to grow and already know how microo’s grow
• less toxic substances produced

Question 3

3 disadvantages of heterologous proteins

Answer 3

• genes from eukaryotes have introns which bacteria can’t process- need to be removed before expressed in mRNA
• glycosylation - bacteria can’t add sugars correctly
• Need to be correctly folded

Question 4

what is a carrier protein and what are they for

Answer 4

they fuse onto the end of the target protein - the thing that you want to produce meaning you can recover the protein product

Question 5

what is used to cut a protein in half

Answer 5

Kexin protease

Question 6

why do we have multiple copies of the gene of interest

Answer 6

to get more gene translation, therefore more gene product

Question 7

what can be used to increase heterologous gene production and how does it work

Answer 7

strong gene promotors - genes that are expressed in high levels in the cell have a special element in their promotor region, meaning the gene is highly transcribed

Question 8

why would you reduce the number of proteases in a cell of an organisms producing a heterologous protein

Answer 8

as the organism might recognise it as a foreign protein and break it down

Question 9

what is insulin

Answer 9

a hormone secreted by the pancreas, controls blood sugar levels

Question 10

describe insulins structure

Answer 10

A and B portions, held together by disulphide bonds

Question 11

what happens to proinsulin to create insulin and where did it used to be obtained from

Answer 11

the connecting polypeptide is removed, pigs

Question 12

what organism is insulin made from now

Answer 12

S cerevesiae

Question 13

what is rennet and what is it used for

Answer 13

chymosin - a protease enzyme that helps produce curds in cheese making

Question 14

how does chymosin work

Answer 14

cleaves casein - breaking it down into smaller insoluble units - the protein colaguates and precipitates taken out - these are the curds

Question 15

where do companies get the chymosin (rennet) from

Answer 15

produced in fungi by big company DSM

Question 16

what is interesting about chymosin production

Answer 16

it cleaves itself from its pro-sequence, doesn’t need kexin protease to cleave it