6.4 - Cloning and Biotechnology Flashcards
What are clones and how are they produced?
clones are genetically identical copies.
they are produced by asexual reproduction in which the nucleus is divided by mitosis.
how does mitosis create a clone?
mitosis creates two identical copies of DNA before cell division. it divides to form two genetically identical cells.
name some advantages of natural cloning.
- if the conditions of growth are good for the parent, then they will be good for the offspring.
- cloning is relatively rapid, the population can increase quickly.
- reproduction can be carried out even if there is only one parent or sexual reproduction is not possible.
name some disadvantages of natural cloning.
- the offspring may become overcrowded.
- there will be no genetic diversity (except any caused by mutations in DNA replication).
- the population shows little variation.
- selection is not possible.
- the whole population is susceptible to changes in the environment.
what is vegetative propagation?
plants are able to clone naturally and vegetative propagation is a process within this cloning.
it is the process of reproduction through the vegetative parts of the plant, rather than through specialised reproductive structures.
what are runners/stolons?
these are horizontal stems that can form roots at certain points on the surface of the ground.
what are rhizomes?
these are horizontal stems that can form roots at certain points underground.
what are suckers?
these are new stems that grow from the roots of a plant. the original horizontal plant may die, leaving the new stem as a separate individual.
what are bulbs?
bulbs are a mechanism that many plants use over winter.
bulbs consist of an underground stem which can grow many fleshy leaf bases.
what are corms?
corms are solid rather than fleshy, like bulbs.
they are an underground stem with scaly leaves and buds.
corms remain in the ground over winter but produce buds in the spring.
how can leaves produce clones?
some leaves reproduce by producing clones on their leaf margins.
these clones drop off the leaf and take root.
what are tubers?
tubers are an example of an underground stem that will grow into many other plants. for example, if you plant a potato, it will grow into one or more plants.
name some examples of natural clones in animals
mammals clone when identical twins are formed.
this occurs when a fertilised egg divides as normal but the two daughter cells then split to become 2 separate cells which then grow and divide into new individuals.
what is the easiest way to clone a plant?
the easiest way to make a clone of a plant is to take a cutting.
how do you clone a plant by a cutting?
to make a cutting:
- a stem is cut between two leaf joints
- the cut end is placed into moist soil
- OPTIONAL - treat the cut end with rooting powder or plant hormones
- new roots grow from the cut stem
where can cuttings be taken from?
- between two leaves on the stem
- roots
- scions
- leaves
what is one disadvantage of cloning plants by cuttings on a large scale?
large scale cloning by cuttings can be time and space consuming.
what is tissue culture?
using cells or tissue to grow cells, tissues or organs.
tissue culture is widely used commercially in micropropagation.
what is micropropagation?
micropropagation involves taking an explant (a small piece of plant tissue) and using growth substances to encourage it to grow into a whole plant.
describe the process of micropropagation.
- suitable plant material is selected - EXPLANTS
- the explants are sterilised using dilute bleach or alcohol. this kills any bacteria or fungi.
- the explants are placed into a sterile growth medium containing suitable nutrients and plant growth substances. a CALLUS is formed.
- once a callus has formed, it is divided into small clumps.
- the small clumps of cells are stimulated to grow, divide and differentiate into different plant tissues by being placed in different mediums with different ratios of growth substances.
- once tiny plantlets have been formed, they are transferred to a greenhouse and grown in compost or soil.
what do the plant growth substances do to the explant?
the growth substances stimulate the cells of each explant to divide by mitosis to form a callus (a mass of totipotent, undifferentiated cells.
what are the advantages of artificial cloning of plants?
- it is relatively rapid compared to growing plants from a seed.
- cloning can be carried out where sexual reproduction is not possible.
- plants that are difficult to grow from a seed can be reproduced.
- the plants selected will all be genetically identical to the parent plant and therefore display the same desirable characteristics e.g. high yield.
- they are all uniform in appearance.
- using plant meristem as an explant ensures that the new plants are free from viruses.
what are the disadvantages of artificial cloning of plants?
- tissue culture is labour intensive.
- it is expensive to set up the facilities to perform tissue culture successfully.
- all cloned offspring are genetically identical and are susceptible to the same pests and diseases.
- there is no genetic variation.
what are the only truly totipotent cells in animals and why are they useful in cloning?
the only truly totipotent cells in cloning are early embryo cells.
they are useful in cloning because successful cloning begins with cells that can divide and differentiate into all types of adult cells, which these totipotent cells can.
how can cloning in animals be useful?
cloning can be useful for:
- elite farm animals that are produced by selective breeding.
- genetically modified animals that have been developed with unusual characteristics e.g. cows that produce less methane.
what are the two main techniques used to achieve reproductive cloning in animals?
- embryo twinning
- somatic cell nuclear transfer
describe the process of embryo splitting.
- a zygote (fertilised egg) is created by IVF.
- the zygote is allowed to divide by mitosis to form a small ball of cells.
- the cells are separated and are allowed to continue to divide.
- each small mass of cells is placed into the uterus of a surrogate mother.
can embryo splitting clone an adult?
no. only somatic cell nuclear transfer can clone an adult.
describe the process of somatic cell nuclear transfer.
- an egg cell is obtained and its nucleus is removed - enucleation.
- a normal body cell from the adult to be cloned is isolated and the nucleus is removed.
- the nucleus is fused with the egg cell by applying an electric shock.
- the shock also triggers the effects to begin developing as if it has just been fertilised.
- the cell undergoes mitosis. the embryo produced is placed into a surrogate.
what is non-reproductive cloning?
non-reproductive cloning is when cells or tissues are cloned for purposes other than reproduction.
what is therapeutic cloning?
this is a type of non-reproductive cloning.
new tissues and organs are grown as replacement parts for people who are not well. e.g. skin can be grown to graft over burnt areas.
why are tissues grown through non-reproductive cloning useful?
they are useful as the cells will be identical to the patients own and therefore avoid rejection.
why is cloning useful in scientific research?
cloned genetically identical embryos can be used in scientific research into the action of genes.
tissues or organs can also be grown to test the effects of drugs.
name some arguments FOR artificial animal cloning.
- can produce a whole herd of animals with desirable characteristics.
- produces genetically identical copies of a high value individual.
- testing medicinal drugs upon cloned cells and tissues avoids using people or animals.
- it can produce cells and tissues that are genetically identical to the donor, for use in repairing damage caused by disease or accidents.
- individuals from an endangered species can be cloned to increase numbers.
name some arguments AGAINST artificial animal cloning.
- lack of genetic variation may expose the animals to certain diseases or pests.
- animals may be produced with little regard for their welfare.
- cloned animals may be less healthy and have shorter life spans.
- there are ethical issues regarding how long the embryo survives for and whether it is right to create life to simply destroy it.
- producing members of an endangered species does not help to increase genetic diversity.
how long has biotechnology been used for?
the oldest documented evidence of brewing of beer was 7000 years ago.
give some examples of biotechnology in food.
- Ethanol in beer and wine –> produced by yeast
- Carbon dioxide in bread –> produced by yeast
- Lactic acid used to make yoghurt and cheese –> lactobacillus
- Mycoprotein (Quorn) –> made from a fungus
give some examples of biotechnology in pharmaceutical drugs
- Penicillin –> produced by the penicillium fungus
- Insulin –> produced by GM bacteria
give some examples of biotechnology in enzymes.
- Protease and lipase in washing powder –> bacteria
- Lactase to make lactose-free milk.
give some examples of where biotechnology can be used to produce other products.
- Biogas –> anaerobic bacteria
- Bioremediation –> a variety of bacteria are used.
what are some advantages of using microorganisms in biotechnology?
- they are cheap and easy to grow
- production takes place at lower temperatures which saves fuel and reduces costs
- the production takes place at normal atmospheric pressure. this is safer than using chemical reactions with high pressures.
- the production process is not dependent upon climate so it can take place anywhere
- microorganisms can be fed by-products from other industries e.g. starch or waste water
- microorganisms have a short life cycle and reproduce quickly, therefore, a large population can be grown quickly.
- microorganisms can be genetically modified relatively easily. this means that special production processes can be achieved.
- there are fewer ethical considerations to worry about.
- the products are easy to harvest and this is often purer than in chemical processes, resulting in lower downstream processing costs.
list some forms of biotechnology.
- gene technology
- genetic modification and gene therapy
- selective breeding
- cloning
- use of enzymes in industry
how are microorganisms used to produce yoghurt?
yoghurt is milk that has undergone fermentation by bacteria.
the bacteria convert lactose to lactic acid. the acidity denatures the milk protein and causes it to coagulate.
fermentation also produces flavours that are characteristic to yoghurt.