Cloning Flashcards
What is vegetative propagation?
Form of asexual reproduction - does not involve fusion
New, genetically identical individuals develop from non-reproductive tissues
offspring are known as clones
Explain how Rhizomes clone naturally?
Specialised horizontal underground stems produce new vertical shoots and roots from buds on nodes along the rhizome
e.g Marram grass
How do stolons clone naturally?
Horizontal stems that grow along the surface of the soil away from the parent plant
Contains nodes or stem tips that can root to form a new plant
e.g Strawberries
How do suckers clone naturally?
Shoots that emerge from the shallow root buds of the parent plant
e.g Elm trees
How do tubers clone naturally?
The tip of a stem becomes swollen with food, with buds on the tuber surface that can develop into new shoots
e.g potatoes
How do bulbs clone naturally?
Leaf base becomes swollen with stored food and the buds inside the bulb form new shoots
How do you artificially propagate plants from stem cuttings?
- Cut a 5-10cm piece from end of parent plants stem using sterilised scalpal
- Remove lower leaves
- Dip cut end in rooting powder
- Plant the cutting in suitable growth medium such as compost
- Place in warm, moist conditions to promote root growth
- Once rooted, transplant new clone
Advantages of vegetative propagation
It is fast
It ensures a high yield
Cost effective
Maintains the quality of crop
Allows plants to survive adverse conditions
How do you artificially propagate root or leaf cuttings?
Root cuttings - take a section of root and cut at an angle before treating it as a stem cutting
Leaf cuttings - Remove entire leaf, score the veins and place it in a growing medium with scored veins facing down
Disadvantages of vegetative propagation?
Results in a lack of genetic variation
Plants are more susceptible to disease, pests and climate change
What is micropropagation?
Technique for producing many identical plant clones from a single parent plant through tissue culture
How is tissue culture used for micropropagation?
Growing plant tissues in a sterile medium enriched with hormones like auxins and cytokinins
Stimulate cell division and growth
Explain step 1 of micropropagation: Explant collection
Small tissue samples called explants are taken from a parent plant to start micropropagation process
Explants are taken from stem and root tips as they have meristem
Meristem is totipotent so differentiate into any cell
Explain step 2 of micropropagation: Sterilisation
Explants are sterilised to remove contaminants such as bacteria and fungi
This reduces risk of infection
Explain step 3 of micropropagation: Culture
Sterilised explant cells are cultured on nutrient rich medium
The medium supplies minerals, sugars, vitamins and growth hormones for cell growth
Explain step 4 of micropropagation: Development
Cells in each explant divide to form undifferentiated mass of cells called a callus
Callus cells are transfered to new medium with specific conditions for shoot and root formation
Allows callus to differentiate and develop into plantlets
Explain step 5 of micropropagation: Transfer
Fully formed plantlets are moved to growth medium like soil
they develop into mature plants
What are the applications of micropropagation?
Rapid and large-scale propagtaion of plants the reproduce slowly
Producing disease free clones of crops
Mass production of genetically modified plants
Produce seedless plants
Advantages of micropropagation
Produces genetically identical plants with reliable traits
Done all year round
Space efficient
Rapidly produces large amounts of plants
Disadvantages of micropropagation
Less variation between plants so are vulnerable to disease
Unintentionally propagate undesirable traits
Expensive and requires skilled technicians
Explants and plantlets are vulnerable
What is natural animal cloning?
Animals produce genetically identical offspring using asexual reproduction
Explain natural cloning in invertebrates
Some invertebrates undergo regeneration or fragmentation
This forms new, genetically identical offspring from parts of body that have broken off
Explain natural cloning in vertebrates
Embryo splits into 2 genetically identical embryos
Each embryo grows independently, resulting in identical offspring
Explain the process of artificial twinning
- A female is treated with hormones to produce multiple egg cells
- Egg cells are extracted and fertilised in a petri dish to produce an embryo
- Embryo divides. While cells are totipotent, the embryo is split
- Each cell is placed in its own petri dish
- Embryos are implanted into the uteruses of the mother for development
What is a somatic cell nuclear transfer?
A process where a nucleus is transferred from a somatic cell of one animal into an ovum of another animal to form an embryo.
Explain the process of an SCNT
- Somatic cell nucleus removed from an animal
- An ovum of another animal of the same species is enucleated
- Nucleus from somatic cell is transferred to enucleated ovum
- Somatic nucleus is fused with enucleated ovum, stimulated by electric shock through electrofusion
- Fused cells begin dividing to form embryo
- Embryo is implanted in uterus
- Mother gives birth to clone of somatic cell donor
What are the applications of animal cloning?
Medical research - drug testing and disease modelling
Conservation - increase number of endangered species
Agriculture - replicate desirable characteristics
Pharming - used to produce therapeutic proteins
Stem cells - provides stem cells for tissue repair
Arguments for animal cloning
Transmission of desirable genetic traits
reproduction of infertile animals
Preserve biodiversity
Increase population size of species
Facilitates medical advancements
Arguments against animal cloning
High costs and technically complex
Reduced genetic diversity
Shorter lifespan in clones
Ethical concerns with destruction of embryo
SCNT is inefficient
