Cloning and biotechnology

Cloning and biotechnology

Natural clones

• - Clones - genetically identical cells/organisms - produced by asexual reproduction
• - Cells may not be physically or chemically identical after differentiation
• Advantages:
• - If conditions for growth are good for parents then will be for offspring
• - Relatively rapid
• - Only needs one parent
• Disadvantages:
• - Overcrowding
• - No genetic diversity
• - Little variation
• - Selection not possible
• - Less advantageous conditions will effect all population
• Vegetative propagation
• - Reproduction from vegetative parts of plants
• - Runners + Stolons - Stems that grow horizontally above ground
• - Rhizomes - Horizontal stems that grow underground
• - Suckers - New stems that grow from roots of a plant
• - Bulbs - Over-wintering mechanism consisting of udnerground stem that fleshy leaf bases grow from - apical grows in spring
• - Corms - Underground stem with scaly leaves and buds
• - Leaves - Clones grow on leaf margins, drop off and take root
• - Tubers - Underground stem - multiple from one - potatoes
• Cloning in animals
• - Identical twins form when fertilised egg (zygote) divides and daughter cells split into two separate cells
• - Water flea and greenfly commonly reproduce asexually

Clones in plants

• Using natural clones
• - Made via cuttings - geraniums and blackberry plants root easily
• - Wounding or removing bark from cut end helps root easier
• - Cuttings can be taken from roots, leaves and scions (twigs)
• Micropropagation
• Small tissue pieces = explants
• 1 - Tissue cut up small (often meristem)
• 2 - Sterilised using dilute bleach or alcohol to kill bacteria
• 3 - Placed on sterile growth medium (agar gel) with suitable nutrients + growth substances (cytokinin+auxin) to form a callus
• 4 - Callus divided to produce smaller clumps
• 5 - Small clumps stimulated to grow - go to growth medium that is 100 auxin : 1 cytokinin then to a 4:1 medium
• 6 - Small plants moved to greenhouse to grow in correct conditions in soil
• Advantages of artificial cloning:
• - Rapid
• - Useful for plants that cannot breed sexually or are hard to grow
• - Have the same desirable characteristics
• - Combination of specific characteristics are retained
• - Uniform in phenotype - easier to grow and harvest
• - New plants are free from viruses due to sterile conditions
• Disadvantages of artificial cloning:
• - Labour intensive
• - Expensive facilities needed
• - Can fail due to microbial contamination
• - Genetically identical means susceptible to same pests
• - No genetic variation except mutations

Artificial clones in animals

• Totipotent cells can divide and differentiate into all types of cells - in humans these are very early embryo cells
• Reproductive cloning used for:
• - Elite farm animals produced by selective breeding
• - Genetically modified animals with unusual characteristics - ie goats that produce spider silk
• Technique 1: Embryo splitting
• 1 - Zygote created by in vitro fertilisation (IVF)
• 2 - Zygote divides by mitosis to form a small ball of cells
• 3 - Cells separated and allowed to continue dividing
• 4 - Small mass of cells put into uterus of surrogate mother
• Precise genotype ad phenotype of offspring depends upon sperm and egg used
• Technique 2: Somatic cell nuclear transfer (SCNT):
• Only way to clone adults and know the phenotype
• 1 - Nucleus removed from egg cell - known as enucleation
• 2 - Body cell from adult to be cloned isolated and nucleus may be removed
• 3 - Body cell/its nucleus fused with empty egg cell by applying electric shock
• 4 - Egg cell starts developing following shock
• 5 - Cell undergoes mitosis to produce small ball of cells
• 6 - Young embryo placed into surrogate mother's uterus
• Therapeutic cloning:
• - Skin used for grafts
• - Cells used to repair spinal cord or pancreas to produce insulin
• - Potential to grow whole organs
• Tissues grown this way will be identical to patients so avoid rejection

Arguments for and against artificial cloning

• For:
• - Can produce a whole herd with unusual combination of characteristics or high yield etc
• - Copies of high value individuals with same characteristics
• - Genetically identical embryos used in research mean effects of genes and hormones can be assessed with no interference from different genotypes
• - Increases numbers of endangered animals
• - Test drugs on these tissues rather than animals or humans
• - Used to produce genetically identical tissues to repair damage
• Against:
• - Lack of genetic variation and concern for lack of concern for their welfare when being bred
• - Success rate in adult cell cloning is very poor and a lot more expensive, especially considering they tend to be less healthy and have a shorter life
• - Does not help increases genetic diversity

Introduction to biotechnology

• Biotechnology: the use of living organisms or parts of living organisms in industrial processes
• - Used for years to make yoghurt and cheese, as well as in brewing
• - Chlostridium acetobutylicum used to produce acetone for explosives in WW1
• - Manufacture penicillin from Penicillium notatum in WW2
• Uses:
• - Food: ethanol, CO2, LActic acid, mycoprotein, soya
• - Pharmaceutical drugs: penicillin, insulin
• - Enzymes: protease, lipase, pectinase, sucrase, amylase
• - Other products: biogas, citric acid, bioremediation
• Adavantages of using microorganisms:
• - Relatively cheap and easy to grow
• - Takes place at low temps + pressure - saves fuel + cheap
• - Not dependent on climate - can occur anywhere
• - Microorganisms can feed on by-products - less waste + cheap
• - Reproduce quickly so large populations quick
• - Can be genetically modified easily
• - Few ethical considerations
• - Product easy to harvest, purer and easier to isolate
• - Mammals are also sometimes genetically modified to produce useful proteins, ie goats secret spider silk in their milk and cows make human antibodies which can be isolate from their blood

Using biotechnology to make food

• Yoghurt:
• - Bacteria converts lactose to lactic acid, causing the proteins to denature and coagulate - bacteria partially digests the milk
• - Probiotics can be added to benefit human health
• Cheese:
• Baking: