cloning and biotechnology Flashcards
1
Q
What is another name for
natural cloning?
A
Vegetative propagation
2
Q
What is vegetative
propagation?
A
A structure forms which develops into a fully differentiated new plant • Occurs in many species of flowering plants • The new plant may be propagated from the stem, leaf, bud, or root of the parent, depending on the type of plant • e.g. strawberries and spider plants
3
Q
What does vegetative
propagation often involve?
A
• Perennating organs, which enables plants to survive adverse conditions • These contain stored food from photosynthesis and can remain dormant in the soil • Often not only a means of asexual reproduction, but also a way of surviving from one growing season to the next
4
Q
Give examples of natural plant
cloning
A
Bulbs e.g. daffodil • The leaf bases swell with stored food from photosynthesis • Buds form internally, which develop into new shoots and new plants in the next growing season Runners e.g. strawberry and spider plant • A lateral stem grows away from the parent plant and roots develop where the runner touches the ground • A new plant develops, and the runner eventually withers away Rhizomes e.g marram grass • A rhizome is a specialised horizontal stem running underground, often swollen with stored food • Buds develop and form new vertical shoots which become independent plants Stem tubers e.g. potato • The tip of an underground stem becomes swollen with food to form a tuber or storage organ • Buds on this storage organ develop to produce new shoots, e.g. the ‘eyes’ on a potato
5
Q
How are natural clones used in
horticulture
A
• Splitting up bulbs, removing young plants from runners, and cutting up rhizomes all increase plant numbers cheaply • Taking cuttings of many plants and applying rooting hormone to encourage the growth of new roots
6
Q
What are the advantages and
disadvantages of using
propagation over using seeds?
A
Propagation is much faster as the time from planting to cropping is reduced • Propagation guarantees the quality of the plants as you can take cuttings from good stock and their offspring will be genetically identical • The main disadvantage is the lack of genetic variation in the offspring if a new disease or pest appears, or if climate change occurs
7
Q
Describe how sugar cane is
cloned
A
It is an internationally used crop used to make sugar and biofuels • One of the fastest growing crop plants in the world, and it is usually propagated by cloning • Short lengths of cane around 30cm long with 3 nodes are cut and buried in shallow trenches, covered with a thin layer of soil
8
Q
What is micropropagation?
A
The process of making large
numbers of genetically identical
offspring from a single parent plant
using tissue culture techniques
9
Q
When is micropropagation
used?
A
When a desirable plant: • Doesn’t readily produce seeds • Doesn’t respond well to natural cloning • Is very rare • Has been genetically modified or selectively bred with difficulty • Is required to be ‘pathogen-free’ by growers e.g. strawberries, bananas, and potatoes
10
Q
What are the steps involved in
micropropagation?
A
1. Take a small sample of tissue from the plant to be cloned. Can be leaf, stem, root or bud. Meristem tissue is often used, as this is always free from virus infection 2. This sterilised using dilute bleach, ethanol, or sodium dichloroisocyanurate Essential to kill any bacteria or fungi, as they would thrive in the conditions supplied to help the plant grow well. The material removed from the plant is called the explant 3. The explant is placed in a sterile culture medium with plant hormones (including auxins and cytokinins) which stimulate mitosis. The cells proliferate, forming a mass of identical cells called a callus 4. The callus is divided into individual cells or clumps which are transferred to a new culture medium containing a different mixture of hormones and nutrients which stimulate the development of genetically identical plantlets 5. These are potted in compost where they grow into small plants 6. The young plants are planted out to grow and produce a crop
11
Q
What are the arguments in
favour of micropropagation?
A
• Allows for the rapid production fo larger numbers of plants which will yield good crops • Culturing meristem tissue produces disease-free plants • Makes it possible to produce viable numbers of plants after genetic modification of plant cells • Provides a way of produce overlarge numbers of new plants which are seedless to meet consumer tastes (e.g. grapes) • Provides a way of growing plants which are naturally relatively infertile or difficult to grow from seed e.g. orchids • Can be used to reliably increase the numbers of rare or endangered plants
12
Q
What are the arguments
against micropropagation?
A
• Produces monoculture, and so all the plants are susceptible to the same diseases or changes in growing conditions • Relatively expensive process that requires skilled workers • The explants and plantlets are vulnerable to infection by mould and other diseases during the production process • If the source material is infected with a virus, all of the clones will also be infected • In some cases, large numbers of new plants are lost during the process
13
Q
Which type of animals is
natural animal cloning more
common in?
A
Invertebrate animals
14
Q
Give examples of natural
cloning in invertebrates
A
• Some animals (e.g. starfish) can regenerate entire animals from fragments of the original if they are damaged • Flatworms and sponges fragment and form new identical cloned animals as part of their normal reproductive process • In some insects, females can produce offspring without mating
15
Q
Give examples of natural
cloning in vertebrates
A
• The formation of monozygotic twins (identical twins) - the early embryo splits to form two separate embryos • Some female amphibians and reptiles will produce offspring when no male is available. The offspring are often male rather than female, so are not clones of their mother even though all of their genetic material comes from her
16
Q
What is artificial twinning?
A
The same as natural twinning where an early embryo splits and 2 foetuses go on to develop from the 2 halves of the divided embryo, but instead the split in the early embryo is produced manually
17
Q
What are the stages of artificial
tinning in cattle?
A
1. A cow with desirable traits is treated with hormones so she super-ovulates, releasing more mature ova than normal 2. The ova may be fertilised naturally or by artificial insemination by a bull with good traits. The the early embryos are gently flushed out of the uterus 3. Alternatively the mature eggs are removed and fertilised by bull semen in the lab 4. Around or before day 6, when the cells are still totipotent, the cells of the early embryo are split to produce several smaller embryos 5. Each of the split embryos is grown in the lab before it is implanted into a surrogate mother. Each embryo is implanted in a different mother 6. The embryos develop into foetuses and are born normally, so a number of identical cloned animals are produced by different mothers
18
Q
What is somatic cell nuclear
transfer (SCNT)?
A
A technique that involves
transferring the nucleus from a
somatic cell to an egg cell
19
Q
What are the stages in somatic
cell nuclear transfer?
A
1. The nucleus is moved from a somatic cell of an adult animal 2. The nucleus is removed from a mature ovum harvested from a different female animal of the same species (it is enucleated) 3. the nucleus from the adult somatic cell is place into the enucleated ovum and given a mild electric shock so it fuses and begins to divide. In some cases, the nucleus from the adult cell is not removed - it is simply placed next to the enucleated ovum and the two cells fuse by electrofusion and begin to divide 4. The embryo that develops is transferred into the uterus of a third animal, where it develops to term 5. The new animal is a clone from which the original somatic cell is derived, although the mitochondrial DNA will come from the egg cell
20
Q
What are the arguments for
animal cloning?
A
• It enables high-yielding farm animals to produce many more offspring than normal reproduction • Artificial twinning enables the success of a sire at passing on desirable genes to be determined • SCNT enables GM embryos to be replicated and to develop, giving many embryos from one engineering procedure • SCNT enables scientists to clone specific animals, e.g. replacing specific pets, or cloning top racehorses • SCNT has the potential to enable rare, endangered, or even extinct animals to be reproduced
21
Q
What are the arguments
against animal cloning?
A
• SCNT is a very inefficient process - in most animals it takes many eggs to produce a single cloned offspring • Many cloned animal embryos fail to develop and miscarry or produce malformed offspring • Many animals produced by cloning have shortened lifespans • SCNT has been relatively unsuccessful so far in increasing populations of rare organisms, or allowing extinct species to be brought back to life
22
Q
What is biotechnology?
A
Applying biological organisms or enzymes to the synthesis, breakdown, or transformation of materials in the service of people • Production of cheese, yogurt, wine, bread, and beer • Latest molecular technologies and using DNA manipulation to produce genetically engineered microorganisms synthesising drugs e.g. insulin and antibiotics • Use of biological systems to remove soil and water pollution in processes known as bioremediation
23
Q
What are the most commonly
used organisms in
biotechnology?
A
• Fungi, particularly the yeasts • Bacteria, which are particularly useful in the newer technologies based around genetic manipulation
24
Q
How are enzymes used in
biotechnology?
A
The most stable, convenient, and
effective form of the enzymes is
often a whole microorganism
25
Q
Why are microorganisms ideal
for use in biotechnology?
A
No welfare issues to consider, only optimum conditions for growth needed • Large range of microorganisms capable of carry out many different chemical syntheses or degradations that can be used • Genetic engineering allows us to artificially manipulate microorganisms e.g. to produce insulin • Microorganisms have a very short life cycle and rapid growth rate, so huge quantities can be produce in short periods of time • The nutrient requirements of microorganisms are very simple and relatively cheap. They can be genetically modified to use materials that would otherwise be wasted • The conditions which most of them need to grow include: a relatively low temperature, supply of oxygen and food, and removal of waste gases. They provide their own catalysts (enzymes), making bio-processes relatively cheap
26
Q
What are the disadvantages of
using microorganisms
indirectly in the production of
human food?
A
If the conditions are not ideal, the microorganisms do not grow properly and so don't work efficiently • Conditions that are ideal for the desired microorganisms may also be ideal for microorganisms that cause food to go off or cause disease, and so the processes have to be sterile • Some people have ethical issues with the use of GM
27
Q
Give examples of
microorganisms involved in
commercial processes
A
Baking • Yeast - mixed with sugar and water to respire aerobically • CO2 produced makes bread rise Brewing • Yeast - respires anaerobically to produce ethanol • Traditional yeasts ferment at 20-28°C • GM yeasts ferment at lower, and therefore cheaper, temperatures, and clump together (flocculate) and sink at the end of the process, leaving the beer very clear Cheese-making • Bacteria - feed on lactose in milk, changing the texture and taste, and inhibiting the growth of bacteria which make the milk go off Yogurt-making • Often species that form ethanal and lactic acid • Both produce extracellular enzymes that give yogurt its smooth, thick texture
46
Q
What are the 4 stages of the
bacteria growth curve?
A
Lag phase: when bacteria are adapting to their new environment. They are growing, synthesising the enzymes they need, and are not yet reproducing at their maximum rate • Log/exponential phase: when the rate of bacterial reproduction is close to or at its theoretical maximum • Stationary phase: when the total growth rate is zero. The number of new cells formed by binary fission is cancelled out the number of cells dying • Decline/death phase: when reproduction has almost ceased and the death rate of cells is increasing
55
Q
What are the factors that need
to be controlled in bioreactors?
A
Temperature • If it’s too low the microorganisms will not grow quickly enough • If it’s too high, enzymes will denature and the microorganisms will be inhibited or destroyed • Bioreactors often have a heating/ cooling system linked to temperature sensors, and a negative feedback system to maintain optimum conditions Nutrients and oxygen • Oxygen and nutrient medium can be added in controlled amounts to the broth when probes or sample tests indicate that levels are dropping Mixing things up • Inside the bioreactor there are large volumes of liquid, which may be thick and viscous due to the growth of microorganisms • Simple diffusion is not enough to ensure that all the microorganisms receive enough food and oxygen • Most bioreactor have a mixing mechanisms and many are stirred continuously Asepsis • If a bioprocess is contaminated by microorganisms from the air, or from workers, it can seriously affect the yield • To solve this problem, most bioreactors are sealed aseptic units • If the process involves GM organisms, they must legally be contained within the bioreactor and not released into the environment
63
Q
Describe surface
immobilisation by adsorption
A
Adsorption to inorganic carriers, e.g. cellulose, silica, carbon nanotubes, and polyacrylamide gel Advantages • Simple and cheap to do • Can be used with many different processes • Enzymes are very accessible to substrate and their activity is virtually unchanged Disadvantages • Enzymes can be lost from matrix relatively easily
64
Q
Describe surface
immobilisation by covalent or
ionic bonding to inorganic
carriers
A
Covalent bonding e.g. carriers with amino, hydroxyl, carboxyl groups Ionic bonding e.g. polysaccharides such as cellulose, synthetic polymers Advantages • Cost varies • Enzymes strongly bound and therefore unlikely to be lost enzymes very accessible to substrate • pH and substrate concentration often have little effect on enzyme activity Disadvantages • Cost varies • Active site of the enzyme may be modified in the process, making it less effective
