6.4 Flashcards
what are clones
clones are genetically identical copies (this can be for organisms or cells
what type of reproduction produces clones
asexual reproduction produces clones
what type of cell division forms clones
mitosis
why may not cells produced from mitosis be genetically identical after division
because after division, they may differentiate to form two different types of cell
any organism that reproduces asexually produces clones of itself, give examples
single celled yeast reproduce by budding
-bacteria reproduce by binary fission
what are the advantages of natural cloning ( reproduction by cloning) for plants
-if the conditions for growth are good for the parent, then they will also be good for the offspring
-cloning is relatively rapid- so the population can increase quickly to take advantage of suitable environmental conditions
-reproduction can be carried out, even if there is only one parent and sexual reproduction is not possible
what are the disadvantages of natural cloning ( reproduction by cloning) in plants
-the offspring may become overcrowded
-there will be no genetic diversity (except that causes by mutation during DNA replication)
-the population shows little variation
-selection is not possible
-if the environment changes to be less advantageous, the whole population is susceptible
why can plants reproduce by natural cloning
because they contains cells which retain the ability to divide and differentiate
natural cloning involves a process called vegetative propagation
what is vegetative propagation
this is reproduction from vegetative parts of a plant (usually an over-wintering organ) rather than through specialised reproductive structures
-its a natural cloning method
describe runners or stolens and how they allow for natural cloning in plants
many plants can grow horizontal stems that can form roots at certain points, these stems can be called runners or stolens if they grow on the surface of the ground. this means plants can reproduce by cloning
describe rhizomes and how they allow for natural cloning in plants
many plants can grow horizontal stems that can form roots at certain points, these stems can be called rhizomes if they are underground. this means plants can reproduce by cloning
some rhizomes are adapted as thickened over-wintering organs from which one or more new stems grow in the spring
describe suckers and how they allow for natural cloning in plants
suckers are new stems that grow from the roots of a plant- these may be close to the base of an older stem or could be some distance away. In all cases, the original horizontal branch may die, leaving the new stem as a separate individual
describe bulbs and how they allow for natural cloning in plants (how it undergoes vegetative propagation)
bulbs (e.g onions) are an over-wintering mechanism for many perennial monocotyledonous plants. Bulbs consist of an underground stem from which grows a series of fleshy leaf bases. There is also often an apical bud, which will grow into a new plant in the spring. Often a bulb contains more than one apical bud and each apical bud will grow into a new plant.
describe corms and how they allow for natural cloning in plants (how it undergoes vegetative propagation)
corms are often mistaken for bulbs. However, corms are solid rather than fleshy like a bulb. A corm is an underground stem with scaly leaves and buds. Corms remain in the ground over winter. In the spring, the buds grow to produce one or more new plants.
Croci and Gladioli reproduce using corms
describe leaves and how they allow for natural cloning in plants (how it undergoes vegetative propagation)
The Kalanchoe plant reproduces asexually, as clones grow on the leaf margins. the immature plants drop off the leaves and take root
describe tubers and how they allow for natural cloning in plants (how it undergoes vegetative propagation)
tubers are another type of underground stem. Potatoes are tubers. One potato will grow into one or more plants. Each new plant can then produce many new tubers (potatoes) later that year.
who clones more often, animals or plants?
plants
when do animals/ mammals clone
mammals clone when identical twins are formed. This occurs when a fertilised egg (zygote) divides as normal, but the two daughter cells then split to become two separate cells. Each cell grows and develops into a new individual.
what are the examples of the two animals that commonly reproduce to produce clones
-the water flea (daphnia) and the greenfly
gardeners have made use of vegetative propagation, what is the easiest way to make clones
the easiest way to make clones is through cuttings
how do you make cuttings
to make a cutting, a stem is cut between two leaf joints (nodes). The cut end of the stem is then placed in moist soil. New roots will grow from the tissues in the stem- usually from the node, but they may grow from other parts of the buried stem,
This technique can be used to produce large numbers of plants very quickly
some plants such as geraniums and blackberry take root easily from cuttings, if this is not the case how is it achieved
-dipping the cut stem in rooting hormone helps stimulate root growth.
-it may also be helpful to wound or remove the bark from the cut end of the stem, as this encourages the plant to produce a callus
cuttings can also be made successfully from other parts of a plant, state these 3 ways (excluding cutting a stem between two leaf joints)
-root cuttings, in which a section of root is buried just below the soil surface, and produces new shoots
-scion cuttings, which are dormant woody twigs
-leaf cuttings in which a leaf is placed on moist soil. The leaves develop new stems and new roots. Some leaves may produce many new plants from one cutting
what cloning technique are used by common houseplants
cloned using tissue culture techniques
define tissue culture
growing new tissues, organs or plants from certain tissues cut from a sample plant.
its carried out in a nutrient medium under sterile conditions. Application of plant growth substances at the correct time can encourage the cells in growing tissue to differentiate
define micropropagation
growing large numbers of new plants from meristem tissue taken from a sample plant
micropropagation involves taking a small piece of plant tissue (the explant) and using plant growth substances to encourage it to grow and develop into a new plant
what are the 6 steps of micropropagation
- suitable plant material is selected and cut into small pieces. These are called explants. Explants could be tiny pieces of leaf, stem, root or bud. Meristem tissue is often used, as this is always free from virus infection
- The explants are sterilised using dilute bleach or alcohol to kill any bacteria and fungi as these would thrive in the conditions supplied to help the plant grow well
- The explants are placed on a sterile growth medium (usually agar gel) containing suitable nutrients such as glucose, amino acids and phosphates. The gel also contains high concentrations of the plant growth substances auxin and cytokinin. This stimulates the cells of each explant to divide by mitosis to form a callus ( a mass of undifferentiated, totipotent cells)
- Once a callus has formed, its divided to produce a larger number of small clumps of undifferentiated cells
- These small clumps are stimulated to grow, divide and differentiate into different plant tissues. This is achieved by moving cells to different growth media. Each medium contains different amounts of auxin and cytokinin. The first medium contains the ratio 100 auxin : 1 cytokinin, and this stimulates roots to form. The second medium contains the ratio 4 auxin : 1 cytokinin, which stimulates the shoots to form.
- once tiny plantlets have been formed, these are transferred to a greenhouse to be grow in compost or soil and acclimatised to normal growing conditions.
what type of species have involves the ability to clone naturally
some invertebrate species such as the greenfly and water fleas have evolved the ability to clone naturally
what type of cells are needed in order for cloning to be successful
totipotent cells (these cells have the ability to divide and differentiate into all types of cell found in the adult organism ( in animals these are found in early embryo cells))
what is reproductive cloning able to produce
can produce a large number of genetically identical animals
what are two ways in which reproductive cloning may be useful
cloning may be useful for:
-elite farm animals produced by selective breeding (artificial selection) or genetic modification. E.g. a particularly good individual bull whose value is a stud- supplying sperm for artificial insemination
-Genetically-modified animals developed with unusual characteristics, e.g. goats produce spider silk in their milk and cows produce less methane
what are the two main ways to achieve reproductive cloning
-embryo twinning
-somatic cell nuclear transfer (SCNT)
when can mammals produce identical offspring (twins)?
and what has this given rise to?
-mammals can produce twins if an embryo splits very early in development.
- this process has given rise to an artificial technique of embryo splitting
outline the process of embryo splitting
- a zygote (fertilised egg) is created by in vitro fertilisation (IVF)
- The zygote is allowed to divide by mitosis to form a small ball of cells
3.The cells are separated and allowed to continue to dividing
- Each small mass of cells is placed into the uterus of a surrogate mother
why is artificial embryo splitting used and what are the downsides
-its used to clone elite farm animals or animals for scientific research.
-However, the precise genotype and phenotype of the offspring produced will depend upon the sperm and egg used thus the precise genotype will be unknown until the animals are born
give a brief overview of what Somatic cell nuclear transfer is (SCNT)
SCNT is the only way to clone an adult.
The advantage is that the phenotype is known before the cloning starts.
This process was first successfully performed to produce Dolly the sheep
outline the process of Somatic Cell Nuclear Transfer
- An egg is obtained and its nucleus is removed, known as enucleation
- A normal body cell (somatic cell) from the adult to be cloned is isolated and may have the nucleus removed
- The complete adult somatic cell or its nucleus is fused with the empty egg by applying an electric shock
- The shock also triggers the egg cell to start developing as though it had just been fertilised
- the cell undergoes mitosis to produce a small batch of cells
- The young embryo is placed into the uterus of a surrogate mother
what is non-reproductive cloning
non-reproductive cloning is the production of cloned cells and tissues for purposes other than reproduction
describe therapeutic cloning with examples
in therapeutic cloning, new tissues and organs can be grown as replacement parts for people who are not well
-skin can be grown in vitro to act as a graft over burned areas
-cloned cells have been used to repair damage to the spinal cord of a mouse and to restore the capability to produce insulin in the pancreas
-there is potential to grow whole new organs organs to replace diseased organs
tissues grown from the patient’s own cells will be genetically identical and so avoid rejection, which is a problem when transplanting donated organs
why is cloning used for scientific research
cloning genetically identical embryos can be used for scientific research into the action of genes that control development and differentiation.
They can also be used to grow specific tissues or organs for use in tests on the effect of medicinal drugs.
what are the arguments against artificial cloning in animals
-lack of genetic variation/ genetic diversity may expose the herd to certain diseases or pests.
-Animals may be produced with little regard for their welfare, which may have undesirable side effects such as meat-producing chickens that cannot walk
-The success rate of adult cell cloning is very poor and the method is a lot more expensive than conventional breeding. Cloned animals may be less healthy and have shorter life spans.
-There are ethical issues regarding how long the embryo survives and whether it is right to create a life to simply destroy it
what are the arguments for artificial cloning in animals
-can produce a whole herd of animals with a high yield or showing an unusual combination of characteristics (such as producing silk in their milk)
-produces genetically identical copies of very high value individuals retaining the same characteristics
-using genetically identical embryos and tissues for scientific research allows the effects of genes and hormones to be assessed with no interference of different genotypes.
-testing medicinal drugs on cloned cells and tissues avoids using animals or people for testing
-can produce cells and tissues genetically identical to the donor, for use in repairing damage caused by disease or accidents.
-individuals from and endangered species can be cloned to increase numbers
define biotechnology
the use of living organisms or parts of living organisms in industrial processes. This could be used to produce food, drugs or other products.
This can include the domestication of animals, planting of crops, mechanisation of agricultural processes and selective breeding of plants and animals over many generations.
what is the oldest documented example of biotechnology.
the production of beer or ale 7000 years ago
other early examples of biotechnology includes making yogurt or cheese as well as baking
what does brewing make use of
brewing makes use of yeast (a single-celled fungus) to ferment maltose sugars in germinating barley
what are some more recent examples of biotechnology
more recent examples of biotechnology include:
-the use of the bacterium Clostridium acetobutylicum to produce acetone, which was needed to make explosives during WW1
-the manufacture of penicillin from the fungus Penicillium notatum during WW2
-these examples and others shifted the emphasis of biotechnology away from food towards the manufacture of drugs.
what has led to a huge expansion in biotechnology in our current day society
-new science of DNA technology has brought biotechnology to its current position
-Our increasing understanding of genetics and genetic engineering has led to a huge expansion in biotechnology. The biggest expansion is in the use of microorganisms in industrial processes
what are the 4 main areas in which microorganisms are used in biotechnology
-food
-pharmaceutical drugs
-enzymes
-other products
how are microorganisms used in biotechnology for food (give examples)
-ethanol in beer and wine. organism used: yeast (S. cerevisiae)
-carbon dioxide used to make bread. organism used: yeast (S. cerevisiae)
-lactic acid to make yoghurt and cheese. organism used: Lactobacillus bacteria
-mycoprotein- a filamentous fungus protein used to make vegetarian food. organism used: Fusarium venenatum fungus
-soya- soya beans are fermented to produce soy sauce. organism used: yeast or Aspergillus
how are microorganisms used in biotechnology for pharmaceutical drugs (give examples)
-penicillin. organism used: Penicillium fungus
-other antibiotics. - other fungi and bacteria used
-insulin and other therapeutic human proteins- organism used: genetically modified bacteria
how are microorganisms used in biotechnology for enzymes (give examples)
-protease and lipase are using in washing powders- (bacteria)
-pectinase used to extract juice from fruit
-sucrase used to digest sugar to make food sweeter- (yeasts)
-amylase to digest starch into sugar to produce syrup used as a sweetener in food production
-protease used to tenderise meat
-lactase to make lactose-free milk
-removing sticky residues from recycled paper
how are microorganisms used in biotechnology for the product of other products (give examples)
-biogas, which is a combination of carbon dioxide and methane - uses anaerobic bacteria (decomposers)
-citric acid, E330, a food preservative- uses a fungus
-bioremediation- cleaning waste water- uses a variety of bacteria and fungi
what are the advantages of using microorganisms in biotechnology
+microorganisms are relatively cheap and easy to grow
+In most cases, the production process takes place at a lower temperature than would be required to make the molecules by chemical engineering means. This saves fuel and reduces costs
+The production process can take place at normal atmospheric pressure, which is safer than using chemical reactions which may require a high pressure for successful manufacture of certain molecules.
+the production process is not dependent on climate- so it can take place anywhere in the world with the resources to build and run suitable equipment
+the microorganism can be fed by-products from other food industries, e.g. starch, waste water or molasses. (Note: however, that the starting ingredients often have to be pre- treated, which adds to the cost)
+Microorganisms have a short life cycle and reproduce quickly. Some microorganisms may reproduce as often as every 30 minutes under ideal conditions. Therefore, a large population can grow very quickly inside the reaction vessel (fermenter)
+Microorganisms can be genetically modified relatively easily. This allows specific production processes to be achieved
+There are fewer ethical considerations to worry about in using microorganisms
+The products are often released from the microorganism into the surrounding medium. This makes the product easy to harvest
+The product is often more pure or easier to isolate than in conventional chemical engineering processes. This means lower downstream costs.
microorganisms are not the only organisms used in biotechnology, name some other organisms used
genetically modified animals such as sheep, goats and cows can be used to produce useful proteins
how can proteins be harvested from animals and genetically modified animals
-in some mammals, proteins are incorporated into the milk so are easily harvested.
For example, goats have been genetically modified to possess the gene for spider silk which is secreted into their milk.
-in other cases proteins may be secreted in the blood, cows have been genetically modified to synthesise human antibodies which can be isolated from their blood.
biotechnology means ‘using organisms in production processes’ but what other processes does biotechnology encompass
biotechnology also encompasses processes such as:
-gene technology
-genetic modification and gene therapy
-selective breeding
-cloning by embryo-splitting and micropropagation
-the use of enzymes in industrial processes
-immunology
do the qs on page 250 xx
xx5t
what is yoghurt
yoghurt is milk that has undergone fermentation by Lactobacillus bulgaricus and Streptococcus thermophilus.
what is fermentation
the breakdown of organic molecules in the absence of oxygen; anaerobic respiration
what is the function of Lactobacillus bulgaricus and Streptococcus thermophilus in yoghurt production
They (the bacteria) convert lactose to lactic acid.
The acidity denatures the milk protein causing it to coagulate.
They (the bacteria) partially digest the milk, making it easy to digest
Fermentation also produces the flavours characteristic of yoghurt.
what other bacteria may be added to yoghurt and why
other bacteria such as L. acidophilus, L. subsp.casei and Bifidobacterium, may be added as probiotics. This is bacteria that benefits human health by improving digestion of lactose, aiding gastrointestinal function and stimulating the immune system.
how is cheese made
milk is usually pre-treated with a culture of bacteria (Lactobacillus) that can produce lactic acid from the lactose. Once it is acidified, the milk is mixed with rennet.
Rennet contains the enzyme rennin (chymosin), which is found in the stomach of young mammals. Rennin coagulates the milk protein (casein) in the presence of calcium ions.
Kappa-casein, which keeps the casein in solution, is broken down. This makes the casein insoluble.
The casein is precipitated by the action of calcium ions, which bind the molecules together.
The resulting solid called curd, is separated from the liquid component (whey) by cutting, stirring and heating. The bacteria continue to grow producing more lactic acid. The curd is then pressed into moulds.
what part of cheesemaking determines the cheeses characteristics
treatment while making and pressing the curd determines the characteristics of the cheese.
how is flavour determined when making cheese
flavour is determined during the later ripening and maturing process.
the cheese can be given additional flavour by inoculation with fungi such as Penicillium to produce ‘blue’ cheese.
