cloning and biotechnology
natural clones
Clones= genetically identical organisms or cells
produced by asexual reproduction in which the cell is divided by mitosis
Advantages
if conditions for growth are good for parent, they will be good for offspring
cloning is relatively rapid - so population can increase rapidly and take advantage of suitable environmental conditions
reproduction can be carried out even when there is only one parent so sexual reproduction isnt possible
disadvantages
the offspring can become overcrowded
no genetic diversity (except from mutations)
population will show little variation
selection isnt possible
if environment changes to be less advantageous, whole population is susceptible
plant cloning by vegetative propagation
vegetative propagation= reproduction from vegetative parts of plant rather than through specialised reproductive structures
runners, stolons, rhizomes and suckers
stolons grow on surface of ground
rhizomes grown underground
suckers are new stems that grow from root of a plant
horizontal branch dies leaving the new stem to separate as an individual
stems which grow horizontally
bulbs
bulbs are an over wintering mechanism
bulbs consist of an underground stem from which grow a species of fleshy leaf bases
apical bud grows into new plant in spring (bulb can contain multiple)
corms
corms are more solid than bulbs
a corm is an underground stem with scales leaves and buds
remain underground until spring where the buds grow one or more new plants
leaves
kalanchoe plants reproduce asexually as clones grow on leaf margins which drop off and take root
tubers
a type of underground stem
cloning in animals
identical twins= when a fertilised egg (zygote) divides as normal daughter cells then split to become separate cells and develop individually
clones in plants
cuttings
stem is cut between two nodes and implanted into soil
could be dipped into rooting hormone to stimulate root growth
cuttings can be taken from: roots, stems, scions, leaf
tissue culture
tissue culture= growing new tissues, organs or plants from certain tissues cut from a sample plant
is used in micropropagation
micropropagation
micropropagation= growing large numbers of new plants from meristem tissue taken from a sample plant
1) suitable plant is selected and a cutting is taken (explant)
2) explants are sterilised using bleach/ alcohol
3) explants are placed in sterile growth medium (agar) containing nutrients e.g. glucose and amino acids. Also contains growth hormones e.g. auxin whicb stimulates mitosis
4) once a callus is formed its is divided to produce a larger number of undifferentiated cells
5) these are stimulated to grow and once tiny plantlets have formed, they are transferred into soil
advantages
rapid
can be carried out where sexual reproduction isnt possible
plants will be genetically identical, have same desirable characteristics
uniform phenotype
using meristem ensures they are free from viruses/ infection
disadvantages
tissue culture is labour intensive
expensive
can fail if contaminated
genetically identical offspring are more at risk to disease
no genetic variation
Artificial clones in animals
reproductive cloning is used for: selective breeding of animals with desired characteristics or genetic modification
embryo splitting
embryo twinning= splitting an embryo to create 2 genetically identical embryos
1) a zygote is created by IVF
2) the zygote is allowed to divide by mitosis to form a small ball of cells
3) the cells are separated and continue dividing
4) each small mass of cells is placed into the uterus of a surrogate mother
precise phenotype is unknown until animal is born (depends on phenotypes of sperm and egg used)
Somatic cell nuclear transfer (SCNT)
SCNT= a technique which involves transferring the nucleus of a somatic cell to an egg cell
1) an egg is obtained and enucleated
2) a normal body cell (somatic cell) from the animal is isolated and may ave nucleus removed
3) somatic cell/ its nucleus is fused with egg cell by applying an electric shock
4) the shock triggers egg to start developing as if it had been fertilised
5) cell undergoes mitosis to produce ball of cells
6) the young embryo is placed into uterus of a surrogate mother
phenotype is know before process
therapeutic cloning
new tissues/ cells can be grown as replacement parts
tissues grown from patients own cells will be genetically identical so there will be no rejection
advantages
genetically identical
individuals from endangered species can be repopulated
can produce animals with desired characteristics
disadvantages
lack of genetic variation increases risk of disease
low success rate
ethical issues
expensive
introduction to biotechnology
biotechnology= the use of living organisms or parts of living organisms in industrial processes, this could be to produce food, drugs etc
examples
-food: ethanol for beer and carbon dioxide for bread are made from yeast
-pharmaceutical drugs: penicillin made from Penicillium fungus, insulin made from genetically modified bacteria
-enzymes: protease and lipase in washing powders
advantages
microorganisms are cheap and easy to grow
production process can take place at lower temps , saving money
production process can take place at atmospheric pressure
process is not dependant on climate
MO can be fed waste products
easy to genetically modify
gm mammals are also used in biotechnology
forms of biotech: gene tech, gene therapy, selective breeding, cloning by embryo splitting, immunology, use of enzymes in industrial processes
using bio tech to make food
yogurt
milk undergoes fermentation
bacteria convert lactose to lactic acid
the acidity denatures milk protein causing it to coagulate
fermentation can also produce the flavour
probiotic (good for health) bacteria are often added benefit digestion of lactose
cheese
lactose is treated with bacteria to convert lactose to lactic acid
milk is mixed with rennet once acidified (rennet contains rennin enzyme which is found in stomach of mammals and coagulates milk protein (casein)in prescience of calcium ions
1) kappa caesin keeps casein in solution is broken down making casein insoluble
2) the casein is precipitated by action of calcium ions which bind molecules together
this forms a curd which is separated from liquid (whey) by cutting, heating and stirring
flavour is determined by maturing process but can be given additional flavour using bacteria
alcoholic beverages and mycoprotein
advantages
production of protein is faster
higher biomass
production can be increased/ decreased according to demand
good source of protein
not much land required
disadvantages
some may not want to eat food grown from waste
high risk of infection
different taste
isolation of protein is difficult
other processes involving biotech
what must be controlled in fermentors
temp= too hot, enzymes will denature
nutrients available= microorganisms require nutrients to grow and synthesise product
oxygen availability= respire aerobically
pH= effects growth and synthesis
conc of product= if product is allowed to build up, it may effect synthesis process
batch vs continuous
primary metabolites= continuous , keeps population growing at a specific rate
secondary metabolities= batch, cells must be under stress e.g. lack of nutrients/ high population, produced in stationary phase, allowed to ferment for a specific time before fermentor is emptied
asepsis
ensures sterile conditions
unwanted bacteria will: compete for nutrients and space, reduce yield of useful products, spoil product, reduce toxic chemicals, destroyed cultured organism
penicillin
secondary metabolite so manufactured by batch
1) ferementor is run for 6/8 days and then cells are removed
2) antibiotic is precipitated as crystals by adding potassium
3) antibiotic is mixed with inert substances to be administered as a tablet
insulin
gene for human insulin is combined with a plasmid and inserted into bacteria , allowing it to produce human insulin
biomeditation
= the use of MO to clean soil and underground water on polluted sites
convert toxic pollutants into less harmful ones
advantages= uses natural systems, less labour, in situ, few waste products
micro-organism cultures
growth mediums= agar, broth
aseptic techniques
wash hands and disinfect working area
Bunsen burner= prevents airborne MO settling
do not remove petri dish lid completely
all equipment should be sterilised
sterilisation
heated at high temp
denatures all MO on equipments
inoculation
streaking- use wire inoculating loop to transfer a drop onto agar and dragging
seeding- a sterile pippete to transfer drop
spreading- sterile glass speader
1) heat inoculating loop in blue flame
incubation
partially seal dish with tape and place in incubator/ warm environment
population growth in a closed culture
growth curve
lag phase (small initial population)= cell growth, taking up water, activating certain genes, synthesising proteins e.g. enzymes
log (exponential) phase= rapid growth and reproduction causing increase in population size
stationary phase= increasing population use up nutrients and produce more waste, rate of population growth= death rate
death (decline) phase= nutrients run out an conc of waste products becomes lethal and population size declines
primary metabolites= log phase
secondary metabolites= stationary phase
immobilised enzymes
advantages
enzymes don't mix with product , lower extraction costs
enzymes can be reused
a continuous process is made easier
enzymes are surrounded by immobilising matrix which protects them from extreme conditions so a high temp/ wider pH range can be used
adsorption
bound to surface by hydrophobic interactions and ionic links
suitable surface= clay, carbon, glass beads, resins
active site is exposed and accessible for substrate
bond forces are not always strong so some enzymes may leak into reaction mixture
covalent bonding
bonded to clay by strong covalent bonds
enzymes are bonded by a cross linking agent
can be expensive and act distort active site reducing activity
enzymes are less likely to leak into reaction mixture
entrapment
entrapped in a matrix
enzyme molecules remain unaffected and fully active
normally entrapped in calcium beads or cellulose fibres
only suitable when molecules are small
membrane seperation
separated by a partially permeable membrane
substrate must me small enough to pass through by diffusion
may limit reaction rate