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Unit 2
Module 2…read more

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2.2.1 Clones in Nature
· Clone: Genes, cells or whole organisms that carry identical genetic material because they are derived from the same original
· Identical twins are natural clones ­ they are produced when a zygote splits in two.
· Asexual reproduction = mitosis = genetic material replicates + separates to form 2 new nuclei each containing an exact copy
of the original DNA.
Advantages of Asexual Reproduction
· It is QUICK ­ allows organisms to reproduce rapidly + take advantage of the resources in the environment.
· It can be completed if SEXUAL reproduction fails/is not possible.
· All offspring have the genetic information to enable them to SURVIVE in their environment.
Disadvantages of Asexual Reproduction
· Does not produce any genetic VARIETY so any genetic parental weakness will be in all the offspring.
Vegetative Propagation
· Vegetative propagation is the production of structures in an organism that can grow into new individual organisms ­ these
new organisms are clones of the parents.
· This allows the species to survive catastrophes like disease.
· Basal sprouts appear within 2 months of the destruction of the main trunk ­ they grow from meristem tissue in the trunk
close to the ground.…read more

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2.2.2 Artificial Clones + Agriculture
· 2 main methods of artificially propagating valuable plants:
­ TAKING CUTTINGS: a section of stem is cut and is treated with plant hormones to encourage root growth and is then planted. A new plant is
formed that is a clone of the original parent plant.
­ GRAFTING: a shoot section of a woody plant is joined to an already growing root + stem. The graft grows and is genetically identical to the
parent plant but the rootstock is genetically different.
Artificial Propagation using Tissue Culture: Large-Scale Cloning
· Cuttings and Grafts cannot produce huge numbers of cloned plants very easily + some plants do not reproduce well from
these methods.
· More modern methods use tissue culture in order to generate huge numbers of genetically identical plants from a small
amount of plant material.
· Tissue culture is the separation of cells of any tissue type and their growth in/on a nutrient medium.
1. A small piece of tissue is taken from the desired plant, usually from the shoot tip, called the explant.
2. The explant is placed on a nutrient growth medium.
3. Cells in the tissue divide + form a mass of undifferentiated cells called a callus.
4. After a few weeks, single callus cells can be removed from the mass + placed on a growth medium containing plant hormones to encourage
shoot growth.
5. After another few weeks, the growing shoots are transferred onto a different growing medium containing plant hormones to encourage root
6. The growing plants are then transferred to a greenhouse to be acclimatised + grown further before they are planted outside.
Advantages of using Callus Culture
· Farmers know what the plant produced will be like because it is a clone of the original plant.
· Farmers' costs are reduced because all the crop is ready for harvest the same time.
· Much faster than selective breeding because lots of plants can be produced from a small number of plants.…read more

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2.2.3 Cloning Animals
· There are 2 methods of artificially cloning animals:
­ SPLITTING EMBRYOS [ARTIFICIAL IDENTICAL TWINS] = cells from a developing embryo can be separated out where each one goes on to
produce a separate, genetically identical organism.
­ NUCLEAR TRANSFER [USING ENUCLEATED EGGS] = a differentiated cell from an adult can be taken + its nucleus is places in an egg cell
without its own nucleus (enucleated). The egg then develops with the genetic material from the inserted nucleus.
Advantages of Cloning Animals
· High-value animals can be cloned in large numbers.
· Rare animals can be cloned to preserve the species.
· Genetically modified animals can be quickly reproduced.
Disadvantages of Cloning Animals
· High-value animals are not necessarily produced with animal welfare in mind.
· Excessive genetic uniformity in a species makes it unlikely to be able to cope with/adapt to changes in the environment.
· It is unclear whether animals cloned using the nuclear material will remain healthy in the long term.
What is Non-Reproductive Cloning?
· Possible in the future to use cloned cells to generate cells, tissues + organs to replace those damaged by diseases/accidents.
· Advantages of using cloned cells:
­ Being genetically identical to the individual's own cells so they wont be rejected by the immune system.
­ Could end the current problems of waiting for donor organs to become available.
­ Cloned cells can be used to generate any cell type because they are totipotent.
­ Less dangerous then major operations.
· There are many possibilities for non-reproductive cloning:
­ Regeneration of heart muscle cells following a heart attack.
­ Repair of nervous tissue destroyed by diseases like multiple sclerosis.
­ Repair of the spinal cord of those paralysed by an accident.…read more

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2.2.4 Biotechnology Basics
· Biotechnology is technology based on biology and involves the exploitation of living organisms or biological animal
husbandry, food science, medicine and industry.
· In recent years, our growing understanding of genetics and ability to manipulate living organisms in a variety of ways has led
to a huge expansion in biotechnological processes.
· Biotechnology has applications in 4 major areas that affect our lives:
­ HEALTHCARE + MEDICAL PROCESSES: includes the production of drugs by microorganisms + gene therapy to treat some genetic disorders.
­ AGRICULTURE: includes micropropagation of plants + the development of genetically modified plants.
­ INDUSTRY: includes genetically modifying organisms to produce enzymes.
­ FOOD SCIENCE: includes developing foods with improved nutrition or better taste, texture + appearance.
­ BLUE BIOTECHNOLOGY: applied to marine and aquatic environments.
The Use of Microorganisms in Biotechnology
· Many biotechnological processes make use of microorganisms because they:
­ Grow rapidly in favourable conditions.
­ Often produce proteins/chemicals that are given into the surrounding medium and can be harvested.
­ Can be genetically engineered to produce specific products.
­ Grow well at low temperatures.
­ Can be grown anywhere in the world ­ not dependent on climate.
­ Can be grown using nutrient materials that would be otherwise useless/toxic.…read more

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