6.2.1 Cloning and Biotechnology COMPLETE Flashcards
Clones
- Genetically identical copies
- Reproduces Asexually
- Mitosis creates two identical copies of DNA which is separated to form 2 genetically identical cells
- Clones are also formed in nature
Examples of natural clones
- Identical twins
- Spider plant
- Bacteria
Advantages of Natural Cloning
- Quick, reproduce rapidly
- Don’t need a mate
- If parent was well suited their offspring will be the same
Disadvantages of Natural Cloning
- No genetic variety
- Equally vulnerable to disease
- High intraspecific competition
Vegetative cloning
The production of structures in an organism that can grow into new individual organisms.
Offspring contain the same genetic information as the parent therefore clones
Examples of Vegetive Cloning
Root suckers Tubers Bulbs Runners Rhizomes Corms
Root suckers
New stems that grow from the roots from the meristem tissue close to the ground
e.g. Raspberry
Tubers
Specialised underground stems become swollen with nutrients, forming tubers
e.g. Potato
Bulbs
Condensed shoots with very short stems and fleshy leaf bases form, contain nutrients, buds at the sides develop into new bulbs
e.g. Onion
Runners
Specialised stems grow along the ground from the parent plant, at the tips they form roots and shoots
e.g. Strawberries
Rhizomes
A specialised horizontal stem running underground, often swollen with food. Buds develop and vertical shoots become independent plants.
e.g. Marram grass
Corms
Often mistaken for bulbs, however sold rather than fleshy. It is an underground stem with scaly leaves and buds.
Method: Cuttings
Produces large quantities of genetically identical plants quickly
- Cut stem between the leaf nodes
- Dip into rooting powder
- Place in damp soil
- Cover in plastic bag to prevent evaporation of water
Method: Grafting
Used to ensure vigorous growth via selected rootstock. Can be used for new plants or to produce trees of different varieties
- Cut Scion from the desired plant
- Insert into the stem of rootstock, lining up vascular tissue
- Treat to prevent pathogens entering tissue
- Secure with tape
Problems with taking cuttings and grafting
- Cant produce huge numbers or cloned plants easily or quickly
- Some plants are not suitable
- Takes up space
- May die
Tissue Culture
- Growing new tissues, organs or plants from certain tissues cut from a plant
- The undifferentiated callus tissue is grown in nutrient rich medium containing plant hormones that stimulates development of the plant
Advantages of Tissue Culture
- Very large quantities of genetically identical and disease free plants can be produced from one or very few parents, quickly
- Can be carried out at anytime of year, regardless of seasons
- Long term storage which can easily be modified
- Easier transport between countries as no need for quarantine
- Produce seeds of rare plants
Steps involved in micropropagation
- A small piece of tissue taken from shoot tip, contains meristem cells
- Explants are sterilised using dilute bleach
- Placed on a nutrient rich medium containing ingredients for photosynthesis and hormones
- Cells divide but do not differentiate forming a mass of undifferentiated cells called a Callus
- After a few weeks its removed and placed on another growing medium for shoot and root growth. (contains hormones)
- The plantlets are then transferred to sterile compost and acclimatised in a greenhouse.
Why are meristem cells used in micropropagation?
Free from viral infections
What is inside the medium used in micropropagation?
Glucose, amino acids, phosphates for photosynthesis.
Auxin and Cytokinins to stimulate mitosis
Why does micropropagation need to be carried out in sterile conditions?
The medium used for growth also provides the perfect growing conditions for the growth of bacteria
Advantages of artificial cloning Plants
- Faster growing from seeds
- Reduce genetic variation to keep only useful features
- Some plants are unable to reproduce sexually
- Plants will be uniform in phenotype
- Uses apical bud which is free from infection
Why is the meristem tissue free from viral infection?
- Not enough time to reproduce as the tissue is also regenerating
- No access to the vascular tissue
- High levels of auxin may inactivate the virus
Disadvantages of Artificial cloning Plants
- Labour intensive
- Expensive to set up the facilities
- Can all fail if infected
- Genetic uniformity means all equally susceptible to new pests, diseases and environmental change
- No variation except mutation
Reproductive cloning of animals:
1. Embryo Splitting
- Collect eggs from high value female
- Collect sperm from high value male
- In Vitro Fertilisation
- Grow to a 16 cell embryo
- Implant into surrogate mothers, each calf being a clone
Reproductive cloning of animals:
2. Somatic Cell Nuclear Transfer
- A differentiated somatic cell from an adult is taken and the nucleus placed in an enucleated cell
- Electrofusion takes place
- The fertilised egg is implanted into a tied oviduct of a sheep to develop into an embryo
- Embryo removed and placed into a surrogate
- The resulting individual contains genetic information from the inserted nucleus
Types of Reproductive cloning of animals
- Embryo splitting
2. Somatic Cell Nuclear Transfer
Non Reproductive cloning of animals
Production of genetically identical cells, not used to produce organisms
Cloning for scientific research
The human cell line derived from cancer cells taken from Henrietta lacks who died in the 50s, without permission
The cells are immortal a grow when the divide
Therapeutic Cloning
New tissues grown as a replacement, i.e. for skin grafts one burns
Cloned cells can help repair spinal chord of a mouse.
Potential to grow new organs
Advantages of artificial cloning in animals
- High value animals can be mass cloned
- Rare animals can be cloned
- GM animals can be quickly reproduced
- Repair damage to donors
- Numbers of endangered species can be increased
Disadvantages of artificial cloning in animals
- High value animals not reproduced with welfare in mind
- Uniformity in species makes it hard to adapt to change
- Unclear whether cloned animals remain healthy in long term
- Genetic diversity decreases
Using Stem Cells in non reproductive cloning
Hopefully can be used to treat diseases where cells stop working, i.e. diabetes
Difficult to obtain adult stem cells
Embryonic stem cells are totipotent so could theoretically be used to grow unless cells
Biotechnology
The use of living organisms or parts of living organisms in industrial processes, i.e. to produce food, drugs