Module 6.4 Flashcards
cloning and biotechnology
what are natural clones
when organisms reproduce asexually producing genetically identical copies
advantages of natural cloning
if conditions for growth are good for parent they will be good for the offspring
quick - population can increase quickly to take advantage of suitable environment
reproduction only needs one parent
disadvantage of natural cloning
overcrowding of offspring
no genetic diversity
little variation
selection is not possible
if environment changes whole population is susceptible
what is vegetative propagation
the process of reproduction through vegetative parts of the plant rather than through specialised reproductive structure
examples of vegetative propagation
runners, stolons, rhizomes and suckers
bulbs
corms
leaves
tubers
natural clones in animals
twins formed by embryo splitting
how is a cutting taken
a stem is cut between two leaf joints (nodes)
The cut end of the stem is placed in moist soil
new roots will grow from the tissue of the stem
the stem can be dipped in rooting hormone to help stimulate root growth
why is tissue culture used instead of cuttings in some cases
cloning by cutting can be time consuming and needs a lot of space
what is tissue culture
a series of techniques used to grow cells, tissues or organs from a small sample of cells or tissue
how is tissue culture carried out
small sample of cells or tissue taken
placed on a nutrient medium under sterile conditions
application of plant growth hormones at the correct time can encourage the cells in the growing tissue to differentiate
how is micropropagation carried out
plant material selected and cut into small pieces called explants
explants sterilised and placed on a sterile growth medium containing nutrients and growth hormones
the cells of the explants divide by mitosis to form a callus
the callus is divided to produce more small clumps of cells
clumps of cells are stimulated to grow divide and differentiate into different plant tissues by using mediums with different concentrations of auxin and cytokinin
once tiny plantlets have formed they are transferred to a greenhouse to be growing in compost or soil
what is a callus
a mass of undifferentiated totipotent cells
advantages of artificial cloning
rapid compared to growing from seed
can be carried out where sexual reproduction is not possible
all plants genetically identical so display the same desirable characteristics
if original plant had unusual characteristics this can be preserved
new plant uniform in phenotype to easier to grow and harvest
using meristem as explant ensures new plants are free from viruses
disadvantages of artificial cloning
labour intensive
expensive
can fail due to microbial contamination
genetically identical can mean all are susceptible to same pests/diseases
no genetic variation
what are the two main techniques used to produce artificial clones in animals
embryo twinning
enucleation and somatic cell nuclear transfer
how is embryo twinning carried out
zygote created by IVF
zygote allowed to divide by mitosis into small ball of cells
cells separated and allowed to continue dividing
each small mass of cells placed into the uterus of a surrogate mother
how is somatic cell nuclear transfer carried out
egg obtained and nucleus removed by enucleation
somatic cell from the adult being cloned isolated and nucleus removed
somatic cell nucleus fused with the empty egg
electric shock applied to trigger the cell into developing
cell undergoes mitosis
young embryo placed into surrogate mother
how is cloning used in medicine
new tissues and organs can be grown for replacements
e.g.
skin can be grown in vitro for skin grafts
how is cloning used in research
cloned identical embryos can be used to research into the action of genes that control development and differentiation
can grow tissues or organs for testing of drugs
how is cloning used in agriculture
cloning elite farm animals
cloning genetically modified animals with unusual characteristics
arguments for artificial cloning in animals
can produce many members of a herd with an unusual characteristic
produces genetically identical copies of high value individuals
helps research into genes as genotype is identical
use in drug testing avoids animal or human testing
produce cells and tissues genetically identical to the donor so no risk of rejection
cloning endangered species
Arguments against artificial cloning in animals
lack of genetic variation can expose whole herds to diseases or pests
animals may be produced with little regard for their welfare
success rate is low
expensive
cloned animals may be less healthy and have shorter life spans
ethical issues regarding keeping embryos and whether it is right to create life to destroy it in research
cloning endangered species will not increase genetic diversity
what is biotechnology
the use of living organisms or parts of living organisms in industrial processes
why are microorganisms used in biotechnology
relatively cheap and easy to grow
production takes place at lower temperatures that would be used if chemically engineered to saving fuel and costs
uses normal atmospheric pressure - safer
process not dependent on climate
microorganisms can be fed by-products of other food industries
short life cycle and reproduce quickly so large population can grow very quickly
what are the four main areas where microorganisms are used in biotechnology
food
pharmaceutical drugs
enzymes
other products e.g. biogas
advantages of using microorganisms in food production
produces protein faster than animal and plant proteins
biomass has very high protein content
no animal welfare issues
microorganisms good protein source
the protein produced contains no animal fat or cholesterol
genetic modification can be used to adjust amino acid content
production is independent of seasonal variations
not much land is required
some can be grown on waste materials
disadvantages of using microorganisms in food production
some people may not want to eat fungal protein or food grown on waste
protein had to be isolated from the material on which they grow
microbial biomass can have a high proportion of nucleic acids which must be removed
protein had to be purified to ensure it is uncontaminated
amino acid profile may be different from traditional animal protein
the conditions needed for the microorganisms to grow are also ideal for pathogens so care must be taken to ensure the culture is not infected with the wrong organisms
does not have the same taste or texture of traditional protein sources
examples of fungus use in food production
baking - yeast causes bread to rise
alcohol - yeast respiration
single cell protein like quorn - microorganism is direct food product
Examples of bacteria used in food production
yoghurt - milk that has undergone fermentation by bacteria
cheese - milk is treated with bacteria which produces lactic acid from lactose
what do fermenters do
control the growing conditions for microorganism to ensure the best possible yield of the product
what conditions may be controlled by a fermenter
temperature
nutrients available
oxygen availability
pH
concentration of product
what is continuous culture
Products are removed from the fermenter regularly
the fermenter is topped up with nutrients
regularly the fermentation mixture is removed to extract product and remove cell to prevent the population from becoming too dense
keeps the microorganisms growing at a specific growth rate
when can continuous culture be used
when products are synthesised by microorganisms during normal metabolism when they are actively growing so the products are being continually released
When is batch culture used
when product is only produced when the cells are placed under stress such as high population density or limited nutrient density
what is batch culture
the fermenter is fully emptied after the the culture is allowed to ferment with limited nutrients for a specific amount of time
why is asepsis important
unwanted microorganisms:
compete with cultured microorganisms for nutrients and space
reduced the yield of useful products
spoil the product
may produced toxic chemicals
may destroy the cultured microorganisms and their products
steps for aseptic technique
wash your hands
disinfect working area
bunsen burner nearby
pass vessels through flame when opening and closing bottles
any glassware or metal equipment should be passed through flame before and after contact with microorganism
sterilise agar with autoclave
what are immobilised enzymes
an enzyme that is held in place and not free to diffuse through the solution
what are the advantages of immobilised enzymes
enzymes don’t mix with the product so extraction costs are lower
enzymes can easily be reused
the enzymes are protected from extreme conditions so higher temps or pH can be used without denaturing
4 methods for enzyme immobilisation
adsorption
entrapment
covalent bonding
membrane separation
what is adsorption
enzyme immobilised by being bound to a supporting surface by hydrophobic interactions and ionic links
bound with active site exposed
active site may be slightly distorted by interactions - affecting enzyme activity
what is covalent bonding for enzyme immobilisation
enzymes are bonded to a supporting surface using strong covalent bonds - bonded by a cross-linking agent which may also link them in a chain
can be expensive and can distort active site reducing activity
what is entrapment
enzyme molecules trapped inside a matrix that does not allow free movement
substrate molecules have to diffused into the matrix and products must diffuse out - so must be small
enzyme is unaffected
what is membrane separation
enzymes separated from reaction mixture by a partially permeable membrane
substrate and product must be small enough to diffuse through membrane
what is a closed culture
a culture which has no exchange of nutrients or gases with the external environment
what are the phases of population growth within a closed culture
lag phase
exponential/log phase
stationary phase
death or decline phase
what is the lag phase
the early part of population growth
growth is slow as population is still small and organisms are adjusting to their environment e.g. taking up water, cell growth, switching on certain genes, synthesising specific proteins
What is the exponential/log phase
organisms have adjusted to their environment and each has sufficient nutrients and space to grow rapidly and reproduce
population doubles in size with each generation
what is the stationary phase
eventually the increasing number of organisms use up the nutrients and produce increasing amounts of waste products
the rate of population growth declines and the number of individuals dying increases until the reproduction rate equals the death rate
there is no populations growth
what is the death/decline phase
the nutrients run out and the concentration of waste products may become lethal
more individuals die that are produced and the population begins to fall
eventually all the organisms will die
