cloning and biotechnology

Define cloning.

The process of producing genetically identical cells or organisms from the cells of an existing organism.

What is asexual reproduction?

The production of offspring that are genetically identical to the parent without the fusion of gametes.

Define vegetative propagation.

A form of asexual reproduction where new, genetically identical individuals develop from non-reproductive tissues of a parent plant.

What are rhizomes?

Specialised horizontal underground stems that store food and produce new vertical shoots and roots from buds on nodes.

How do stolons (runners) facilitate plant reproduction?

They are horizontal stems that grow along the soil surface, forming new plants at nodes or stem tips upon contact with the ground.

What are plant suckers?

Shoots that emerge from shallow, undeveloped buds on the parent plant.

What are tubers in the context of plant propagation?

Large underground food storage organs with 'eyes' that can sprout to form new plants.

What is the function of rooting powder in stem cuttings?

It contains plant hormones that encourage root growth.

List three advantages of vegetative propagation.

Fast reproduction, high yield, and cost-effectiveness.

What is a primary disadvantage of vegetative propagation?

Lack of genetic variation, making plants more susceptible to disease, pests, and climate change.

What is micropropagation?

A technique for producing many identical plant clones from a single parent through tissue culture on a large scale.

Why are cells sterilized during micropropagation?

To kill microorganisms like bacteria and fungi that compete for nutrients and decrease the growth rate.

What is a 'callus' in tissue culture?

A mass of undifferentiated cells produced by the division of cultured plant cells.

Name two hormones used in tissue culture to stimulate growth.

Auxins and cytokinins.

List two uses of micropropagation.

Rapid propagation of rare or endangered plants and the production of disease-free crop clones.

What is a significant disadvantage of micropropagation?

It is expensive, requires skilled technicians, and contamination can result in the loss of the entire culture.

How do some invertebrates reproduce naturally via cloning?

Through regeneration or fragmentation, where parts of the body break off and grow into new, identical offspring.

How does natural cloning occur in vertebrates?

When an early embryo splits into two genetically identical embryos, such as in the case of identical twins.

Describe the process of artificial embryo twinning.

An embryo is created via fertilization, split while cells are still totipotent, and the resulting embryos are implanted into surrogate mothers.

What is the first step of Somatic Cell Nuclear Transfer (SCNT)?

The nucleus is removed from a somatic cell of an adult animal.

What is an 'enucleated' ovum?

An egg cell from which the nucleus has been removed.

What is the purpose of an electric shock in SCNT?

It is used for electrofusion to stimulate the fusion of the somatic nucleus with the enucleated ovum.

Why are stem cells used in micropropagation?

Because they are undifferentiated and have the potential to develop into any part of the plant.

What is the process of Somatic Cell Nuclear Transfer (SCNT)?

A fused cell divides to form an embryo, which is implanted into a surrogate mother who gives birth to a clone of the somatic cell donor.

List three medical or scientific uses of SCNT.

Drug testing, disease modelling, and providing immunocompatible stem cells for tissue repair.

What are two disadvantages of cloning via SCNT?

Potential for shorter lifespans/health issues in clones and the high inefficiency/failure rate of the process.

Define biotechnology.

The use of living organisms and their components, such as enzymes, to synthesize, break down, and transform materials for human use.

Why are microorganisms ideal for use in biotechnology?

They have short lifespans, grow rapidly, have simple nutrient requirements, and can be grown year-round under easily controlled conditions.

What is the role of Saccharomyces cerevisiae in the food industry?

It ferments sugars anaerobically to produce ethanol and CO2, used in brewing and to make bread dough rise.

What conditions are required for the production of penicillin in a fermenter?

Constant stirring for oxygen, a nutrient-rich medium, a buffer to maintain pH at 6.5, and a temperature of 25-27°C.

What is the difference between primary and secondary metabolites?

Primary metabolites are essential for normal microbial functioning (e.g., ethanol), while secondary metabolites are produced in non-essential processes (e.g., antibiotics).

How does batch fermentation differ from continuous fermentation?

Batch fermentation occurs in fixed volumes until nutrients deplete, whereas continuous fermentation involves the constant supply of nutrients and removal of culture broth.

Why is a water jacket used in a fermentation vessel?

To maintain the optimum temperature, ensuring enzymes work efficiently and reaction rates remain high.

How is contamination prevented in industrial fermenters?

Vessels are sterilized between uses with superheated steam to kill unwanted microorganisms.

What is the purpose of taping Petri dishes during microbial culturing?

To secure the lid while allowing some air exchange, which prevents the growth of harmful anaerobic microbes.

Why should agar plates be incubated upside down?

To prevent condensation from dripping onto the agar surface, which could cause colonies to merge and interfere with observations.

Describe two aseptic techniques used when culturing microorganisms.

Working near a Bunsen burner to create an updraft and flaming the neck of bottles to prevent airborne contamination.

What are the four phases of a microbial growth curve in a closed system?

Lag phase, log (exponential) phase, stationary phase, and death phase.

What characterizes the 'stationary phase' in a growth curve?

Growth rate plateaus as nutrients diminish and waste accumulates; the rate of cell growth equals the rate of cell death.

Why are logarithms used when plotting microbial growth?

Because the number of cells increases exponentially, making standard linear scales difficult to read due to the massive variation in numbers.

How do you calculate the dilution factor in serial dilutions?

Dilution factor = final volume / initial volume.

What is the formula to estimate the number of bacteria in an original culture?

Number of bacteria = colony count × (1 / dilution factor) × (1 / volume plated).

Define immobilised enzymes.

Enzymes that are attached to or enclosed within a solid support or matrix to allow for their reuse in industrial processes.

Name four methods of enzyme immobilisation.

Binding (covalent/ionic), adsorption, entrapment, and encapsulation.

What is a primary advantage of using immobilised enzymes?

They can be reused, reducing costs, and they do not contaminate the final product.

What is a disadvantage of immobilising enzymes?

The process is more expensive and technically complex than using free enzymes, and it may reduce enzyme activity.

Explain how lactase is used to produce lactose-free milk.

Lactase is immobilised on alginate beads in a column; milk flows through, and the enzyme hydrolyses lactose into glucose and galactose.

What is the 'log phase' of microbial growth?

The phase of rapid doubling of cell numbers under ideal conditions, representing the maximum growth rate.

What is the purpose of a spectrophotometer in microbial culturing?

To measure culture turbidity, which serves as an indicator of cell density.

Why is pH monitoring critical in a fermenter?

To keep the environment at the optimum level for enzyme activity, thereby maximizing product yield.

What is the main ethical concern regarding SCNT?

The destruction of the embryo created during the process.