Cloning And Biotechnology 6.4 Flashcards
Describe a laboratory procedure that the scientists might have used to estimate the bacterial population
(2 marks)
-serial dilution
-grow colonies (only agar plate) and count number of colonies
-scale up/ multiply up to estimate population size
What are clones?
Genetically identical organisms or cells
What are the advantages and disadvantages of natural cloning?
Advantages
-if the conditions 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 the suitable environmental conditions
-reproduction can be carried out even if sexual reproduction is not possible
Disadvantages
-there will be no genetic diversity
-if the environment changes to be less advantageous the whole population is susceptible
What is vegetative propagation?
-the reproduction through vegetative parts of the plant, rather than through specialised reproductive structures
What is an example of natural clones in animals?
-identical twins -twins are formed by embryo splitting
What are some examples of vegetative propagation (natural cloning)?
-rhizomes-horizontal stems that can form roots at certain points, they are called rhizomes if they are underground
-suckers-new stems that grow from the roots of a plant. The horizontal branch may die leaving the new stem as a separate plant
-bulbs
-tubers- a type of underground stem
What is micropropagation?
-growing large numbers of new plants from meristem tissue taken from a sample plant
What is tissue culture?
-growing new tissues organs or plants from certain tissues cut from a sample plant
How are plant cuttings taken?
-cut off a non-flowering stem from a plant using secauteurs or a scalpel , dip it in plant hormones- rooting powder (to encourage growth)
-once new roots have started to grow the cutting can be planted into soil
What is the method for microprogation of plants?
1-suitable plant material is selected and cut into small pieces (e.g. using a scalpel) these are called explants
2-the explants are sterilised using dilute bleach or alcohol (this is essential to kill any bacteria and fungi as these would thrive in the conditions supplied to help the plant grow well)
3-the explants are placed onto a sterile growth medium (usually agar gel) containing suitable nutrients e.g. glucose, amino acids and phosphates the gel also contains high concentrations of plant growth substances e.g. auxin and cytokinin. This stimulates the cells of each explant to divide by mitosis to form a callus
4-the callus is split into small clumps of undifferentiated cells
5- these small clumps of cells are transferred to a new agar plate and are stimulated to grow, divide and differentiate into different plant tissues
6-once plantlets have been formed these are transferred to soil
What are the advantages and disadvantages of artificial cloning in plants?
Advantages
-cloning is a relatively rapid method of producing new plants compared with growing plants from seed
-cloning can be carried out where sexual reproduction is not possible e.g. plants that have lost their ability to breed sexually can be reproduced
-the plants selected will all be genetically identical to the parent plant, they will therefore display the same desirable characteristics e.g. high yield, resistance to pest or disease or a particular colour/flower
-creates disease-free plants
Disadvantages
-it is expensive and requires skilled workers
-if the original cells have a viral infection all plants produced will have the virus too
-Monocultures are grown and all the cloned offspring are genetically identical so will be susceptible to the same pests and diseases
What is a callus?
A mass of undifferentiated, totipotent cells
What is enucleation?
-removal of the cell nucleus
What is the process of artificial embryo twinning ?
-a zygote (fertilised egg) is created by IVF (in vitro fertilisation)
-the zygote is allowed to divide by mitosis to form an embryo this embryo is divided
-the embryos are then inserted into a surrogate mother
How is somatic cell nuclear transfer artificial animal cloning carried out?
-an egg cell is obtained and its nucleus is removed (enucleation)
-a somatic cell (normal body cell) from the adult to be cloned is isolated and its nucleus is injected into the enucleated egg cell
-the complete adult somatic cell or its nucleus is fused with the enucleated egg cell by applying an electric shock, the shock also triggers the egg cell to start developing
-the cell undergoes mitosis
-the embryo is placed into the uterus of a surrogate mother
What are the arguments for and against artificial cloning?
For:
-can produce animals with a high yield or showing unusual combination of characteristics (useful in agriculture)
-produces genetically identical copies of individuals retaining the same characteristics (useful for agriculture e.g. a cow with a high milk yield)
-testing medicinal cells on cloned cells and tissues avoids using animals or people for testing
-can produce cells and tissues genetically identical to the donor (this avoids rejection)
-individuals from an endangered species can be cloned to increase numbers
Against:
-lack of genetic variation
-cloned animals by SCNT have a shorter life cycle
-the success rate of adult cell cloning is very low and the method is a lot more expensive than conventional breeding
What is biotechnology?
-the use of living organisms or parts of living organisms in industrial processes. This could be used to produce food e.g. yeast to make bread rise or drugs penicillium fungus to make penicillin etc
Why are microorganisms used in biotechnological processes?
-microorganisms are relatively cheap and easy to grow
-the production takes place at lower temperatures than would be required to make the molecules by chemical engineering, this saves fuel and reduces costs
-microorganisms have short life cycles
-microorganisms have basic growth requirements
What are the advantages and disadvantages of using microorganisms to make food for human consumption?
What are growing conditions in batch fermentation?
-the fermentation is carried out in a closed fermenter, the microorganisms and nutrients are added and then left to grow for a particular period of time, no further nutrients are added and products are removed at the end of the time period
Batch culture is easier to set up than continuous culture but the growth rate is not as fast in batch culture
However if a batch culture is contaminated only a single batch is lost
-this is known as closed culture
What are the growing conditions in continuous fermentation?
-takes place in an open fermenter, where nutrients are continuously added and products/ waste are removed throughout the process
What is the importance of manipulating the growing conditions in batch and continuous fermentation?
-To maximise the yield of product, the temperature needs to be maintained at the optimum with a sufficient nutrient supply and the aerobic conditions to prevent the formation of undesired products through anaerobic respiration. The pH needs to be kept constant to ensure that the enzyme activity is not altered.
-It’s important for the microorganisms to be manipulated under aseptic conditions, where unwanted organisms are absent. In the case where unwanted organisms are present, the medium is said to be contaminated. This is undesired as contaminants compete with the culture for nutrients and space, thus reducing the product yield. Some contaminants might produce toxic chemicals, thus destroying the culture microorganisms and the products.
List some aseptic techniques
1-wash your hands
2-Disinfect the working area
3-have a Bunsen Burner operating nearby
4- pass any glassware or metal equipment (inoculating loop) through the flame before use
5-do not lift the lid of the Petri dish off completely
What are the 3 main steps to growing microorganisms on agar plates?
1-STERILISATION- the growth medium (e.g. the agar ) is sterilised by heating in an autoclave. When the medium has cooled sufficiently to handle it is poured into sterile Petri dishes and left to set, it is important to keep the lid on the Petri dish to prevent infection
2-INOCULATION- inoculation is the introduction of microorganisms to the sterile medium, it can be done in a variety of ways e.g. Streaking-a wire inoculating loop is used to transfer a drop of liquid medium onto the surface of the agar. The drop is drawn out into a streak by dragging the loop across the surface. Take care to not break the surface of the agar
3-INCUBATION-Use adhesive tape to hold lip on Petri dish taking care to not seal the lid completely as this can lead to the selection of anaerobic bacteria which may be pathogenic. The Petri dish is then placed in an incubator, place it upside down to prevent drops of condensation falling onto the surface of the agar
What is a closed culture?
-a culture which has no exchange of nutrients or gases with the external environment
Draw and label the standard growth curve of a microorganism in a closed culture
What is the lag phase on the standard growth curve of a microorganism in a closed culture?
The early part of population growth, the population does not grow quickly
This partly because the population is still small but also because the organisms are adjusting to their new environment. This may involve:
->taking up water
->cell growth
->switching on (activating) certain genes
->synthesising specific proteins (e.g. enzymes)
What is the log (exponential phase) on a standard growth curve of a microorganism in a closed culture?
-in the log (exponential phase), the organisms have adjusted to their environment
-they each have the enzymes needed to survive and each individual has sufficient nutrients and space to grow rapidly and reproduce
-the population doubles in size with each generation
What is the stationary phase on a standard growth curve of microorganism in a closed culture?
-the stationary phase is where there is no population growth
-as the increasing number of organisms use up the nutrients and produce increasing amounts of waste products (e.g. carbon dioxide)
-the rate of the population growth declines and the number of individuals dying increases until the reproduction rate equals the death rate
What is the death phase on the standard growth curve of a microorganism in a closed culture?
-the nutrients run out and the concentration of waste products may become lethal
-more individuals die than are produced and the population begins to fall, eventually all the organisms will die
What are primary metabolites?
-they are produced during the normal metabolism of the microorganism
-they are continuously released from the cells and can be extracted continuously from the fermenting broth
-the broth is topped up with nutrients that are used by the microorganism and some of the broth is removed regularly to extract the product and remove cells from the broth- otherwise the population becomes too dense. This is known as continuous fermentation and it keeps the microorganism growing at a specific growth rate
Examples of primary metabolites- ethanol, lactic acid
-they are collected during the log phase
What are secondary metabolites?
-products produced only when the cell is placed under stress e.g. there is a high population density or limited nutrients available
-they are produced during the stationary phase of growth and can be collected at the end of the stationary phase or during the death phase
-they are produced using batch fermentation
-penicillin is a secondary metabolite
What are immobilised enzymes?
-an enzyme that is held in place and not free to diffuse through the solution
What are the advantages and disadvantages of immobilised enzymes?
ADVANTAGES
-enzymes do not mix with the product, so extraction costs are lower
-a continuous process is made easier as there are no cells requiring nutrients, reproducing and releasing waste products
-the enzymes are surrounded by the immobilising matrix, which protects them from extreme conditions, so higher temperatures or a wider pH range can be used without causing the enzyme to denature
DISADVANTAGES
-setting up the immobilised enzyme process is more expensive
-immobilised enzymes are usually less active than free enzymes, this makes the process slower
Describe the method of absorption for the immobilisation of enzymes
-ADSORPTION- enzymes bind to a supporting surface by hydrophobic and ionic links, suitable surfaces include clay, glass beads and resins. The enzyme molecules are bound with the active site exposed and accessible to the substrate, however the active site may be slightly distorted by the additional interactions affecting enzyme activity
-the bonding forces are not always strong and enzymes can become detached and leak into the reaction mixture
Describe the method of covalent bonding for the immobilisation of enzymes
-enzymes are covalently bonded to a supporting surface such as clay
-they are also bonded using a cross-linking agent
-this is expensive and can distort the enzyme active site, but they are less likely to become detached and leak into the reaction mixture than when you use the absorption method
Describe the method of entrapment for the immobilisation of enzymes
-enzymes are trapped in a semi-permeable material such as gel beads which allows the passage of substrate and product only
Describe the method of membrane separation for the immobilisation of enzymes
-partially permeable membrane serves to separate the enzymes from the substrate
What are some examples of immobilised enzymes?
Examples of immobilised enzymes in biotechnology include: glucose isomerase for conversion of glucose to fructose, penicillin acyclase for the formation of semi-synthetic penicillins (to which some penicillin resistant organisms are not resistant), lactase for the hydrolysis of lactose to glucose and galactose, aminoacyclase for production of pure samples of L-amino acids
What is the formula for the number of individual organisms?
N- number of individual organisms
N0- initial number
n-number of divisions/generations
