22.1-3 Flashcards
what is the term for natural plant cloning?
vegetative propagation.
what is the term for artificial plant cloning?
micropropagation
what is the general idea of vegetative propagation?
taking cuttings from plants and growing them naturally in the soil.
what are the four types of plants that natural plant cloning occurs in?
- Bulbs: e.g. onions, daffodils
- runners: e.g. strawberries
- rhizomes e.g. marram grass
- stem tubers e.g. potatoes
how do you take cuttings from plants? what is the purpose of this?
just cut a section of the stem, leaf or root. works to induce vegatative propagation.
what are some advantages of cuttings vs seeds?
it is much faster, time from planting to cropping is less, the offspring is genetically identical, good if a good crop is used.
what are the steps of micropropagation?
- remove tissue from plant, typically the meristem tissue is dissected, this is called the explant.
- it is steralised using ethanol/ bleach.
- explant is placed on a sterile culture medium (e.g. agar), which contains nutrients and growth hormones, mitosis is stimulated. the cells proliferate and a callus is formed.
- the callus is then divided up and clumps are transferred to a new culture medium which contains hormoned to stimulate growth of small identical plants.
- the young plants are then planted to produce a crop.
what are some advantages of micropropagation?
- rapid production of large numbers of plants
- culturing meristem tissue means disease free plants
- allows reproduction in any season
- way to increase endangered plants
- less space to grow than from seeds
- always have desirable characteristics passed on
- new seedless, sterile plants
what are some disadvantages of micropropagation?
- produces a monoculture, so all of the plants are susceptable to the same diseases, no variation in immunity.
- relatively expensive process and requires skill
- the explants and plantlets are at risk by moulds and diseases during their production process
- if the source plant was infected, all the new plants will be too.
- in some cases, large numnbers of plants are lost at once during the process.
- all plants will have any undesirable characteristics
what are some examples of natural cloning in animals?
- identical twins from embryo splitting
- asexual reproduction in some insects
what is a method for a cutting of stem?
- take a 5-10 cm cutting of stem, ideally below a leaf node, using sterile scissors,
- remove lower down leaves
- dip cut end into rooting powder
- plant in suitable soil.
how does artificial embryo twinning work?
fertilised embryo removed or egg fertilised in vitro (out of body), the embryo is then separated and multiple identical embryos formed, places into surrogate mother and all offspring are identical.
what are the forms of artificial animal cloning?
- artificial embryo twinning
what are some of the problems that have been seen with artificially cloning animals?
there has been an issue with the longevity of cloned animals, dolly the sheep (a cloned animal) had to be put down at just six years old after suffering with arthritis and lung disease.
what is the process of somatic cell nuclear transfer (SCNT)?
- the nucleus is removed from a somatic cell of an adult animal
- nucleus removed from a mature ovum harvested from a different female of same species
- the nucleus from the adult somatic cell is placed into the enucleated ovum and given a mild electric shock to fuse. it begins to divide. sometimes the nucleus of the adult cell is not removed and simply placed next to enucleated ovum for them to fuse and divide under influence of the electric current.
- the embryo that develops is transferred into the uterus of a third animal, where it develops to term.
- the new animal is a clone of the first animal, wehich the somatic cell was removed from, although the mitochondrial DNA will come from the egg cell.
