A revision summary of OCR A level Biology Cloning & Biotechnology 6.2.1
Made by a student who achieved A* in A level Biology.
Covers all the points within the OCR Biology Specification.
Condenses 3 OCR specification books and class notes.
Natural Cloning in plants – genetically identical copies. Natural cloning in animals
- In asexual reproduction & mitosis - Invertebrates (starfish) - regenerate entire organism from fragments of
Vegetative propagation – process of reproduction through original.
vegetative parts of plant (roots, stem, shoot, leaves) - Vertebrates (humans) - fertilised egg (zygote) splits into 2 groups of cells
1. Runners (strawberry/ spider plant) Artifical clones in animals
- Lateral stem grows away from parent plant & roots develops. Artificial embryo twinning
(Rhizomes = underground, Stolens = overground) - Fertilised egg will divide to form a ball of cells (each totipotent)
2. Suckers – new stem grows from the root of plant 1. Fertilised egg (zygote) created using IVF.
3. Bulbs (onions) – underground stem grows apical bud(s), 2. Zygote divides by mitosis into ball of cells (each totipotent)
over-wintering mechanism. . 3. Cells are manually separated into smaller embryos (totipotent) which can
4. Tubers (potatoes) – each plant can produce stems (tubers) continue dividing & develop into organisms.
that can grow into new plants 4. Mass of cells placed into surrogate mother. All offspring genetically
Adv Disadv identical
Conditions good for Overcrowding Adv Diasdv
parent = good for No genetic diversity Genetically identical characteristics Cannot control exact features
offspring Little variation Not guaranteed embryo will develop
Predictable Whole pop is susceptible to Expensive
characteristics change Somatic cells nuclear transfer (SCNT)
Rapid = ↑population Some plants cannot asexually… 1. Enucleation of somatic cell of adult animal
Quicker - Only 1 parent 2. Enucleation of mature ovum harvested from different female animal of
At any time/ season same species
Artificial cloning in plants 3. Nucleus from adult somatic cell placed into enucleated ovum. Electro
Tissue Culture (Small scale) – Rooting hormone can be applied fused & begins to divide.
to encourage growth. 4. Embryo develops
- increase plant numbers, genetically identical, faster growth, 5. Embryo split into many cells, each placed in surrogates
guarantee quality, less time consuming 6. New animal is clone of animal which original somatic nucleus was derived.
Micropropagation (large scale) – making large no. of Adv Diasdv
genetically identical offspring from single parent plant using All have desirable characteristics Many abnormally large organs/
tissue culture techniques. Mass production of animals used to deformed
1. Cells taken from explant - actively growing region of supply human products No genetic variability
undifferentiated cells, sample is taken & cut into pieces. Avoids mating risks Health problems – ↓life span
2. Explant sterilised to remove pathogens (competitors) Know gender Few embryos survive until birth
3. Placed on sterile growth medium agar of glucose, aa, Producing human embryos for stem cells ↑Expensive & labour intensive
phosphate, auxin, cytokinin to stimulate cell division.
4. Callus culture – mass of undifferentiated totipotent cells
form.
5. Callus culture divided into lots of small clumps
6. Clumps moved through series of different growth mediums
Adv Disadv
7. Plantlets transferred into a greenhouse to grow.
Rapid Expensive
Control variables (↑conditions, no Requires expertise
pathogens) Vulnerable to mould
Reliable quality ↓biodiversity
To plants with inability to reproduce Infected source = infected plants
Genetically identical Monoculture susceptible to disease
↑population of rare species
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