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19.2.119 · Genetic Technology

Recombinant Human Proteins — Cambridge AS & A Level Biology 9700 Revision Notes & Topical Questions

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📚 Cambridge AS & A Level Biology 9700 Hub / Topical Revision
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19.2.1 Recombinant Human Proteins — CAMBRIDGE AS & A LEVEL BIOLOGY 9700 — REVISION NOTES notes: Describe how recombinant human proteins are made and their advantages for insulin, factor VIII and adenosine deaminase.Recombinant DNA (rDNA) — DNA altered by introducing nucleotides f…

  • Transgenic organism
  • Recombinant proteins (RP)
  • Adenosine deaminase (ADA)
  • Post-translational modification
  • Genetic screening
  • Recombinant DNA (rDNA) — DNA altered by introducing nucleotides from another source

Section 1 of 9Recombinant proteins

Recombinant proteins
Recombinant DNA (rDNA)
  • DNA altered by introducing nucleotides from another source.
Transgenic organism
  • Transgenic organism contains nucleotides from a different species;
    • a GMO has received genetic material from any other source.
Recombinant proteins (RP)
  • Recombinant proteins (RP) manipulated forms of the original protein made from rDNA.
They are produced in microorganisms such as bacteria or yeast, or in animal cells in culture.
Uses
  • Uses research and treatments, e.g. diabetes, cancer, infectious diseases and haemophilia.

Section 2 of 9Choosing the host cell

Choosing the host cell
Most recombinant human proteins are made in eukaryotic cells (yeast or animal cells in culture).
Eukaryotic cells carry out post-translational modification, since they have a Golgi apparatus and the enzymes needed.
Bacteria cannot do this, nor splice introns, so they are used for simpler proteins such as insulin.

Section 3 of 9General advantages

1
More cost-effective to produce large volumes, with unlimited availability.
2
Simpler when prokaryotic cells are used, and faster to make many proteins.
3
Reliable supply.
4
Proteins can be engineered to be identical to human proteins or to have beneficial modifications.
5
Avoids moral, ethical or religious concerns about cow- or pig-produced proteins.

Section 4 of 9Recombinant insulin

1
Insulin was the first recombinant human protein approved (1982) for diabetes.
2
Bacterial plasmids are modified to include the human insulin gene.
3
Restriction endonucleases cut the plasmids and DNA ligase splices plasmid and human DNA together.
4
Recombinant plasmids enter Escherichia coli by transformation (calcium ions then heat or electric shock).
5
Transgenic bacteria are identified by markers, isolated, purified and placed in fermenters.
6
They multiply by binary fission and express insulin, which is extracted and purified.

Section 5 of 9Advantages of recombinant insulin

1
It is identical to human insulin unless modified, e.g. to act faster after a meal or more slowly.
2
Supply is reliable and does not depend on meat stock.
3
There are fewer ethical, moral or religious concerns.
4
There are fewer rejection problems, side effects and allergic reactions.
5
It is cheaper in large volumes and suits people who tolerate animal insulin poorly.

Section 6 of 9Factor VIII and adenosine deaminase

1Factor VIII
  • Factor VIII a blood-clotting protein that haemophiliacs cannot make.
  • Genetically modified hamster kidney and ovary cells are cultured in fermenters and constantly express it.
  • Advantagesno need for human blood, less risk of transmitting HIV or other infections, and greater production.
2Adenosine deaminase (ADA)
  • Adenosine deaminase (ADA) enzyme used to treat ADA deficiency, a common cause of SCID, which damages the immune system.
  • Larvae of the cabbage looper moth are genetically modified using a virus vector to make ADA.
  • It is used while patients wait for gene therapy or when gene therapy is not possible.
  • Advantagesno animal source, less risk of infection and reliable, faster production.

Section 7 of 9More from the specification

1Therapeutic proteins from recombinant genes
  • Therapeutic proteins from recombinant genes cloning human insulin genes into expression plasmids yields pure medicinal proteins tested through rigorous clinical trials.
2Faulty allele
  • An allele that causes a disorder.
3Screening
  • Testing blood or people to find infection.
4Somatic
  • Body cells rather than gametes
5Embryo
  • A little ball of cells that forms from the first cell and develops into a baby.
6Medicine
  • A drug used to treat illness.
7Allele
  • A version of a gene.
8Genetic screening
  • Testing DNA for particular alleles.
9Cystic fibrosis
  • A recessive condition causing thick sticky mucus.
10Clinical trial
  • Test of a drug on human volunteers or patients.

Section 8 of 9Key terms

TermMeaning
Recombinant proteinA protein made from recombinant DNA in host cells.
Transgenic organismOrganism with nucleotides from a different species.
Post-translational modificationChanges to a protein after translation, e.g. in the Golgi apparatus.
Factor VIIIBlood-clotting protein lacking in haemophiliacs.
Adenosine deaminaseEnzyme missing in ADA-deficiency SCID.
FermenterVessel giving optimal conditions for growing cells.

Section 9 of 9Exam technique

1
Saying the protein is injected into the bacteria — the host receives the gene and makes the protein.
2
Thinking bacteria can modify any human protein — eukaryotic cells are needed for post-translational modification.
3
Forgetting that the same restriction enzyme and ligase are used to make the recombinant plasmid.
4
Omitting that marker genes are used to identify transgenic bacteria.

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