6.4 Cloning and Biotechnology Flashcards
What is an immobilised enzyme?
An enzyme thats held in place so it doesn’t diffuse through the solution
What does immobilising an enzyme ensure?
That the enzyme will not mix with the product and that the enzyme can be reused.
What are the 4 methods of immobilising an enzyme?
- Adsorption
- Covalent Bonding
- Entrapment
- Membrane Separation
Describe adsorption as a way to immobilise enzymes
When the enzyme is bound to a surface (e.g clay or resin) using ionic bonds and hydrophobic interactions. The active site of the enzyme is exposed, however the bonds are weak and the enzyme can become detached.
Describe covalent bonding
When the enzyme is bound to a surface using covalent bonding and a crosslinking agent. The bonds are strong, however they can change the shape of the active site.
Describe entrapment
When the enzyme is trapped in a matrix (e.g cellulose). The enzyme is protected from outside conditions, however the substrate and product need to be small enough to diffuse into and out of the matrix.
Describe membrane separation
When the enzyme is separated from the outside solution via a partially permeable membrane. However, the substrate and product need to be small to be able to diffuse into and out of the membrane.
Give 2 examples of reactions catalysed by immobilised enzymes.
- glucose to fructose with glucose isomerase
- lactose to glucose and galactose with lactase
What are the 4 growth phases in a culture
Lag Phase
Log (exponential) phase
Stationary Phase
Death (decline phase)
Which type of population usually experiences the death phase?
A closed culture
Describe the lag phase.
Where there are a small number of organisms reproducing so the population does not grow quickly. This is because the population is small and the organisms are adjusting to their environment.
Describe the log phase.
Where the population grows exponentially as there are sufficient nutrients, space and other required resources.
Describe the stationary phase.
Where the population reaches its maximum capacity and then slightly declines to a more stable rate. It can be subject to small fluctuations due to changing factors. The rate of death = the rate of reproduction.
Describe the death/decline phase.
Where the rate of death>the rate of reproduction as resources are running out.
Give 5 limiting factors for organism growth.
- food
- shelter
- disease
- oxygen
- space
What are the 3 main steps in growing microorganisms on agar plates?
Sterilisation
Inoculation
Incubation
Describe sterilisation
When the medium is heated in an autoclave to 121°C to kill all living organisms.
Describe inoculation
Introducing the microorganisms to the sterile medium often through streaking, seeding or spreading.
Describe incubation
When the petri dishes are sealed and placed upside down (to prevent condensation) in a warm environment before the culture is left to grow.
What is the purpose of aseptic techniques?
To reduce the risk of contamination of the culture from unwanted microorganisms.
What are primary metabolites?
Substances produced by an organism all the time as part of its normal growth
