Summary notes for OCR A specification A-level biology Cloning and Biotechnology. Helped achieve an A* in 2022. Covers animal cloning, micro-organisms, microbial growth curves, immobilised enzymes and industrial production.
Arti cial twinning: manually splitting the embryo into multiple/ two
foetuses to form identical twins.
- A cow with desirable traits is treated with hormones so she super-
ovulates, producing many eggs at once. The eggs are fertilised
and ushed out of the mother and placed in surrogates.
- Early embryos are split into smaller early embryos which are then
grown in a lab for a few days. If they develop correctly they can
be implanted into surrogate mothers.
SCNT: laboratory strategy for creating a viable embryo from a body cell and an egg cell.
- Takes an enucleated oocyte and implant a donor nucleus from a somatic cell.
- Used in both therapeutic and reproductive cloning.
Uses of microorganisms:
- indirect production: speed up the process of making particular foods. e.g. yeast in break
making
e.g. Baking:
active yeast mixture is added to our and other ingredients. It is mixed and left in a warm
environment to rise. Excess air is removed from dough and kneaded, shaped and left to rise
again. Carbon dioxide is produced by fermentation of sugars. It is cooked in a hot oven. The
carbon dioxide bubbles expand so the break rises more. Yeast cells are killed during cooking
- Direct production: the microorganisms are consumed, not the products of their reactions. e.g.
quorn is fungus.
Compare and contrast embryo twinning and SCNT (6 marks)
Embryo twinning involves taking an egg cell from the organism whereas SCNT involves taking a
somatic cell. Embryo twinning involves DNA from one organism whereas SCNT requires cells from
two di erent organisms as the nucleus from the somatic cell is put into an egg cell from a di erent
organism. Both methods require a surrogate for the egg cell to be put into and both produce
clones of one of the original organisms, however embryo twinning produces many more clones
than SCNT, which only produces one. In embryo twinning, the early embryo is split into individual
cells which each develop into an embryo which is implanted into a di erent surrogate. All
o spring from embryo twinning are clones of one another as well as clones of the original
organism. SCNT produces clones of an existing adult whereas twinning is just clones of each
other (o spring)
Insulin Production: genetic engineering
Penicillin production: produced by fungus, byproduct of fungus. Original method- low yield.
Needs high oxygen levels and nutrient medium. It is very sensitive to temperature and pH. A semi
continuous batch process is used. In the rst stage the fungus grows, in the second stage it
produces penicillin. The drug is then extracted from the medium and puri ed. The process uses
small fermenters because it is di cult to maintain high levels of oxygenation in large bioreactors.
The mixture is continuously stirred to keep it oxygenated, there is a nutrient rich medium and the
growth medium contains a bu er to maintain pH at around 6.5, the bioreactors are maintained at
around 25-27 degrees.
Other medicines from microorganisms: antibiotics, anti tumour agents, immunomodulators,
enzyme inhibitors
Bioremediation:
The process of using natural or GM microorganisms to remove pollutants from the environment.
e.g. cleaning up oil spills.
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