Natural cloning in plants
Bulbs e.g. daffodils |
Leaf bases contain stored food, buds develop internally and make new shoots. |
Runners e.g.strawberry |
Lateral stem grows, eventually withers away. |
Rhizomes e.g. marram grass |
Specialised horizontal growth, stem develops buds -which becomes new plant. |
Stem tubers e.g. potatoes |
Tip of underground stem becomes swollen with stored nutrients. Buds develop on that storage organisms and form new shoots. |
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Uses in horticulture: |
Can take cuttings from bulbs/runners to increase the yield because it is faster than growing seeds. |
This also guarantees quality (because genetically identical). |
e.g. used in sugar cane cloning. |
Artificial cloning in plants
Micropropagation: |
Sample taken from meristem (sterile conditions). |
Sterilised. Collected tissue = explant. |
Placed in sterile culture medium containing plant hormones. Cells form Mass of identical cells (callus). |
Callus is divided and transferred to different medium. This stimulates the development of genetically identical plantlets. |
Plantlets are planted in compost and grow. |
Young plants planted out to grow as crops. |
Artificial twinning and SCNT
Artificial twinning |
Animal w/ desired trait is given hormones for super-ovulation. |
Ova is fertilised in vitro or by insemination (by desired male). |
Before 6 days, cells are split (still totipotent). |
Each cell becomes an embryo. |
Embryos are inserted in surrogates. |
Develop into foetuses and born normally. |
Somatic Cell Nuclear Transfer (SCNT) |
Transfer nucleus from adult somatic cell into enucleated egg cell (no nucleus). |
Nucleus and egg are fused with an electric shock |
OR electrofusion - Cells are left next to each other with constant current running through. |
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+ More offsprings than usual |
+ Guarantees desirable genes from sire. |
+ Useful in pharming |
+ Can clone rare and endangered animals |
- SCNT = inefficient -- many eggs required to successfully produce one offspring. |
- Cloned embryos fail to develop, produced deformed offsprings... |
- Most clones have a shorter lifespan, which also means we have not been successful in cloning extinct species yet. |
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Biotechnology and microorganisms
Biotechnology: |
Applying biological organisms / enzymes to the synthesis / breakdown / transfer of materials in the service of people |
e.g. foods, penicillin, insulin... |
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Pros / cons of using microorganisms: |
+ No ethics |
+ Easily manipulated genetically |
+ Short life cycles |
+ Simple + cheap nutrient requirements |
+ Growth conditions = low temperatures / oxygen / food... |
- Can produce toxins |
- Have to be separated from nutrient and processed. |
- Sterile conditions needed (increases cost). |
- Less natural flavour. |
Direct / indirect food production
Indirect food prod |
Use microorganisms for their effects on other foods. |
e.g. bread -- yeast caused it to rise.
yoghurt -- bacteria make it sour. |
Direct food prod |
Grow microorganisms to eat |
e.g. Quorn, fusarium venetatum (grown on glucose syrup). |
Brewing
Indirect food production |
Yeast anaerobically respires. |
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Optimum temp about 20-28oC, but can also be genetically modified to function at lower temperatures. |
Malting - Barley germinates and digests starch into sugars so yeast respires.
Mashing - Malt + hot water. Enzymes break down starch, worth is formed.
Fermentation - Wort + yeast. pH a lowered as yeast runs out of O2 and produces ethanol.
Maturation - Low temperatures for about a month.
Finishing - Filtered, pasteurised and bottled with CO2. |
Baking bread
Indirect food prod |
Yeast feeds on sugars and ferments them into ethanol and CO2 which makes the bread rise |
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Optimum temp. of 38-46oC |
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Optimum pH - 5.0 / 5.5 |
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Yeast requires O2 and sugars for fermentation. |
Cheese-making
Indirect food prod |
Bacteria feed on lactose, inhibit growth of bacteria which makes milk go off. |
Pasteurised - 95oC for 20 seconds.
Mixed with bacteria culture and enzymes. The milk is separated into solid curds and liquid whey.
Cheese - Curds are separated and cooked in whey, sometimes pressed and dried. |
Yoghurt-making
Indirect food prod |
Skimmed milk powder, milk is pasteurised and cooked. |
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L. bulgarius / S. thermopilus bacteria added to the milk and milk is stored at cool temepratures. |
Cultivating microorganisms
Inoculating broth |
Bacteria suspension, mixed with sterile nutrient broth. Incubated and shook. |
Inoculating agar |
Inoculating loop Sterile and dipped in suspension. Streaks made across a Petri dish. |
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Bioreactors - making penicillin
Semi-continuous batch
Fungus grows and produces penicillin. The drug is extracted and purified.
The container is sealed to avoid contamination (asepsis).
The mixture is constantly stirred so it stays oxygenated.
Bioremediation
Microorganisms are used to break down pollutants and contaminants in soil / water. |
Natural organisms |
Used on crude oil / sewage. |
GM microorganisms |
Break down material they don't normally encounter (e.g. mercury in water). |
Bacterial growth stages
Lag phase |
Bacteria adapting to environment.
Growing and synthesising enzymes. |
Exponantial phase |
Close to / at theoretical max. |
Stationary phase |
Growth rate = zero --> Cells formed cancelled out by cells dying. |
Death phase |
Reproduction almost stopped, death rate increases (resources used up). |
Immobilised enzymes
Alternative to using microorganisms is to isolated their enzymes. |
Immobilised enzymes are when those enzymes are fixed so substrate washes over them. |
+ Reusable so cheaper, greater temperature tolerance, less downstream processsing. |
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Surface immobilisation - Surface adsorption (sticking to the surface) to inorganic carrier. |
+ Simple and cheap.
+ Activity virtually unchanged. |
- Enzymes can be lost from matrix easily. |
Surface immobilisation - covalent / ionic binding to inorganic carrier. |
+ Enzymes bound strongly, unlikely lost.
+ Accessible to substrate.
+ pH / substrate concentration = little effect on activity. |
- Cost varies
- Active site may be modified. |
Entrapment - in matrix. |
+ Applicable to different processes. |
- Expensive.
- Difficult to entrap.
- Diffusion can be slow. |
Entrapment - encapsulation or semi-permeable membrane. |
+ Relatively simple to do.
+ Small effect on enzymes activity.
+ Applicable to different processes. |
- Expensive.
- Diffusion can be slow. |
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