Cloning and biotechnology Flashcards
What are natural clones
- Identical twins
- Produces genetically identical copies
- Asexual reproduction (mitosis)
- Genetically identical copies
What are the advantages of using natural cloning in plants
- Conditions: if conditions good for parent they will be good for offspring
- Rapid population increase
- Reproduction can occur with one parent asexually
- Used to produce many of the worlds food crops e.g. bananas or sugar cane
What are the disadvantages of using natural cloning in plants
- Offspring may become overcrowded
- No genetic diversity which could cause mutation
- Little variation
- Selection not possible
- Whole populations susceptible to changes in the environment
What is vegetative propagation
- Plants can reproduce by cloning as they have many cells that retain ability to differentiate (in meristem)
- Leaves: leaflets grow off leaf margins
- Runners: strawberry plant/ spider plants have these that run horizontal along the ground
- Suckers: When old branch may die, new one replaces it
- Bulb: overwintering mechanism
- Corms: solid, not fleshy like bulbs
- Tuber: underground stem
- Rhizome: underground horizontal stem
How do you take cuttings
- Use a non-flowering stem
- Make an oblique cut in the stem
- Use hormone rooting powder
- Reduce leaves to two or four
- Keep cutting well-watered
- Cover the cutting with plastic bag for a few days
Define the term clone
genetic copy of another single organism
Define the term tissue culture
growing new tissues, organs or plants from certain tissues cut from sample plants
Define the term micro-propagation
• growing large numbers of plants from meristem tissue taken from sample plants. It exploits vegetative propagation of plants
How is micropropagation done and when is it used
- Used when plant doesn’t produce many seeds, naturally clone, rare, genetically modified or needs to be pathogen free
- First, take small sample of desired plant – explant
- Secondly, sterilise explant using antiseptic solution
- Thirdly, explant needs to be placed on a nutrient jelly in a petri dish e.g. auxin and gibberellum
- Next, it must be grown in aseptic conditions
- Platelets grow and once large enough they can be transferred to the soil
What are the advantages of micropropagation
- Rapid growth
- Disease free plants
- Increased number of rare plants
- Large number of seedless plants e.g. grapes and bananas
- Naturally infertile plants can be grown e.g. orchids
What are the disadvantages of micropropagation
- Monoculture (all susceptible)
- Expensive and tricky
- Explants/platelets are vulnerable to mould
- If plant source is diseased, so are the new plants
- Large numbers of new plants are lost during the process in some cases
Give examples of natural cloning in invertebrates
- Starfish can regenerate entire animals from fragments of the original if they’re damaged
- Flatworms and sponges fragment and form new identical animals as part of their natural reproductive process
- Hydra produce buds on their body that pop off and develop into genetically identical clones
- However, high mutation rates mean the offspring are often not true clones
Give examples of natural cloning in vertebrates
• Main form of vertebrate cloning is the formation of monozygotic twins (identical twins where 1 embryo splits into 2)
• Some amphibians/reptiles produce offspring when no male is available
o Offspring are often male not female therefore not clones but genetically identical
Process of artificial embryo twinning
- Cow with desirable traits is treated with hormones (superovulation)
- Ova is fertilized, egg cell is extracted and placed in petri dish (or fertilized in dish)
- Around 6 days later embryo splits up into smaller embryos (totipotent)
- Each split embryo grown in lab for a few days before implantation into mother (surrogate)
- Embryos may be frozen and assessed for genetic stock e.g. if for dairy – female is needed
Process of somatic cell nuclear transfer
- Nucleus removed from the somatic cell of adult sheep
- An oocyte is removed from a different female animal of the same species and nucleus is removed to form an enucleated oocyte
- Nucleus of sheep A is placed into enucleated oocyte of sheep B and its given electric shock so it fuses and begins to divide (electrofusion)
- Embryo is then transferred into uterus of sheep C, where it develops to term
- Newly born animal is a clone of sheep A BUT mitochondrial DNA comes from egg cell
Uses of SCNT
- Cloning for research pharming e.g. milk
- Produce GM animals for organs
- Save endangered animals from extinction
Arguments for artificial cloning in animals
- E.T.: Enables high yielding from animals to have more than normal numbers of offspring
- E.T.: Enables success of a sire at passing on determined desirable genes
- SCNT: Enables GM embryos to be duplicated and developed
- SCNT: Enables scientists to clone specific animals
- SCNT: Potentially can enable rare, endangered or extinct animals to be reproduced
- Infertile animals can be reproduced
- Can occur at any time (NOT in breeding season)
- Help us develop disease treatments
Arguments against artificial cloning in animals
- SCNT: inefficient (takes many eggs for 1 offspring
- SCNT: unsuccessful in increasing populations or bring back extinct – difficulties in life span, deformity etc.
- Failure to develop correctly – miscarry/deformed offspring
- Shortened life span e.g. dolly
- Difficult, time consuming and expensive
- No genetic variation in cloned population
- Cloning is ethically controversial
- Using human embryos as sources of stem cells means embryos destroyed
Describe how penicillin is made
- Produced by batch culture 0 only produced once population has reached certain size
- Fermenter run for 6 days and then filtered to remove cells
- Potassium compounds added and penicillin precipitated as crystals
- Antibiotic then prepared for administration as tablets, syrup or injection
Describe how insulin is produced
- Produced by genetically modifying bacteria using a continuous process
- Human gene for producing insulin is inserted into a bacterium using a plasmid as a vector. The resulting genetically modified bacteria can then produce vast quantities of insulin
Describe the process of bioremediation
- Use of microorganisms to clean the soil and underground water on polluted sites
- First stimulate the growth of a microbe that uses a contaminant as source of food
- The right conditions for growth are required e.g. water, suitable temp, pH, O2
- If conditions aren’t suitable they must be modified by adding suitable substances
- If this isn’t possible in situ, soil may be dug up and treated ex situ
Describe the process of manufacturing single cell proteins
• Many different fungi can be used to create proteins with similar amino acid profiles to that of plants and animals e.g. Quorn
Describe the process of brewing
- MALTING: Barley germinates and enzymes are produced that break starch to sugar for yeast to respire
- MASHING: Malt mixed with hot water (55), enzymes break down starch making wort and then hops are added for flavour
- FERMENTATION: Yeast added to wort, fermentation occurs and yeast eventually killed as the pH lowers, ethanol builds up and O2 decreases
- MATURATION: beer conditioned for 4-29 days (2-6)
- FINISHING: beer filtered and pasteurised to then be bottled/canned
Describe the process of baking
- Active yeast mixture is added to flour and other ingredients to then be left in warm environment to prove and rise
- Dough is knocked back (excess air removed), kneaded and shaped and left to rise again
- Dough is cooked in hot oven so CO2 bubbles expand
- Yeast cells are killed during cooking
Describe the process of cheese making
- MILK PASTURISED: heated to 95 for 20 seconds to kill natural bacteria
- MILK HOMOGENISED: fat droplets evenly distributed, bacteria and chymosin enzyme added so milk separates into solid curds and liquid whey
- COTTAGE CHEESE: curds packaged and sold
- HARDER CHEESE: curds cooked in whey and strained through cheese cloth and may be pressed/matured
- WHEY: used in animal feeds
Describe the process of yoghurt production
- Equipment sterilised (heated to 71 for 20 seconds)
- Milk pasteurised
- Add bacteria culture and incubate (lactobacillus)
- Sampling
- Addition of flavours, colours, packaging
- Quality control and take some culture to add to next batch
Describe the advantages of using microorganisms
- Production of a protein can be much faster than if made by an animal/plant
- Production can be controlled according to demand
- No animal welfare issues
- Protein contains no animal fat or cholesterol
- Microorganisms can be GM to adjust amino acid of the protein
- Not affected by seasonal variations
- Not much land needed
Describe the disadvantages of using microorganisms
- Some may not want to eat fungal protein or food grown waste
- Need to isolate the protein from the medium its grown in
- Protein must be purified
- Culture can become infected easily due to optimum growing conditions
- Different taste/texture to traditional protein sources
Describe aseptic techniques
- Includes washing hands, disinfecting working area, Bunsen burner on near (heats air causing it to rise and prevent airborne microbes settling), flaming necks of bottles as they’re opened and closed to prevent bacteria entering
- Autoclave: nutrient medium and all equipment put in to be sterilised by being heated to 121 for 15 minutes killing all living organism
- Streak plating: way to spread individual bacteria and colonies
What is a culture
population of one type of microorganism that’s been grown under controlled conditions (fermentation vessels)
What is batch fermentation
microorganisms are grown in individual batches in a fermentation vessel so when one culture ends another batch of different microorganisms is grown in the vessel
What is continuous fermentation
microorganisms are continually grown in a fermentation vessel without stopping – nutrients are put in and waste products are taken out at a constant rate
What is asepsis
if a bioprocess is contaminated by microorganisms from the air or workers it can affect yield so bioreactor is sealed creating aseptic units
Describe the growth of bacterial colonies
- In a closed culture, such as batch fermentation, a population of microorganisms follows a standard growth curve with 4 phases
- Lag phase: when bacteria adapting to environment, making enzymes they need
- Exponential (log) phase: when the rate of bacterial reproduction is close to or at its theoretical maximum as culture conditions are at their most favourable for reproduction (lots of food and little competition)
- Stationary phase: total growth rate is zero as death rate = reproductive rate
- Death/decline phase: Population size falls as death rate is higher than reproductive rate due to scarce food and waste products are at toxic levels
How do you estimate the number of cells in a culture
- Number of cells in population = initial number of cells x 2n
- N = number of divisions
What are primary metabolites
when the substance wanted is formed as an essential part of the functioning of a microorganism e.g. ethanol, ethanoic acid and a range of amino acids and enzymes
What are secondary metabolites
• when the substance wanted is not essential for organism’s normal growth but are still used by the cells e.g. many pigments, and the toxic chemicals plants use to protect themselves
o Penicillin and many other antibiotics are an example of this
How are enzymes immobilised and how are they used
- Immobilised enzymes used to avoid having to separate normal enzymes out of the mixture which can be complicated and costly
Immobilised enzymes: enzymes attached to an insoluble material so they can’t become mixed with the products
• Three main ways enzymes are immobilised:
1. Encapsulated in jelly-like alginate beads which act as semi-permeable membrane
2. Trapped in silica gel matrix
3. Covalently bonded to cellulose or collagen fibres
What are the advantages to using immobilised enzymes
- Columns of immobilised enzymes can be washed and reused – reduces cost
- Product isn’t mixed with enzymes – no money or time spent separating them
- Immobilised enzymes are more stable and less likely to denature than free enzymes
What are the disadvantages to using immobilised enzymes
- Extra equipment required – expensive to buy
- Immobilised enzymes more expensive to buy so coupled with equipment cost they aren’t always economical for smaller-scale production
- Immobilisation of the enzymes can sometimes lead to reduction in enzyme activity as they can’t freely mix with their substrate
State some common uses of immobilised enzymes
- Conversions of lactose to glucose to galactose: used to produce lactose-free milk
- Production of semi-synthetic penicillin: used to combat penicillin resistant organisms
- Conversions of dextrins to glucose: used to sweeten and thicken foods
- Conversion of glucose to fructose: used as a sweetener in foods as fructose is sweeter but contains less sugar
- Production of pure samples of L-amino acids: used to separate L and D amino acids as L amino acids used more
- Conversion of acrylonitrile to acrylamide: used to produce synthetic polymers (plastics) for a wide range of uses
