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