Cloning and biotechnology Flashcards
1
Q
what do organisms from when they divide asexually?
A
clones
2
Q
what happens in mitosis?
A
Two identical copies of the DNA are created in mitosis, each copy is then are separated into one of two genetically identical nuclei.
3
Q
define clones
A
Organisms or cells that are genetically identical
4
Q
what are some examples of organisms that are capable of asexual reproduction to form clones?
A
bacteria and plants
5
Q
what are some advantages of natural cloning?
A
- Reproduction can occur without needing another organism of the same species for sexual reproduction. This is more convenient as you can produce many offspring in a smaller time frame
- It allows an organism to take advantage of favourable environmental conditions; if the parents are suited to the environmental conditions, their offspring will be too
6
Q
what are some disadvantages of natural cloning?
A
- There is less genetic diversity in the population, with only mutations giving rise variation. Selection is not possible
- If environmental conditions alter, the entire population will be affected as they will be less able to adapt
- As cloning produces many offspring, this could lead to eventual overcrowding within the population
7
Q
what is meant by totipotent?
A
able to differentiate into any cell
8
Q
what is the benefit of many plant cells being totipotent?
A
- This allows adult plants to form natural clones through a process known as vegetative propagation.
- The plants reproduce through the vegetative parts of a plant (e.g. roots and leaves)rather than the reproductive structures (e.g. petals).
9
Q
define vegetative propagation
A
Asexual reproduction from the vegetative parts of a plant rather than through specialised sexual reproductive structures.
10
Q
what is the benefit of the vegetative parts of the plant which are over-wintering (perennating organs)?
A
they allow plants to survive through the winter
11
Q
what are the 2 types of over-wintering organs that are used for vegetative propagation?
A
- bulbs
- tubers
12
Q
describe the structure and function of bulbs
A
Bulbs consist of an underground stem fromwhich fleshy leaf bases sprout. This leaf base contains food reserves that allow the plant to survive adverse environmental conditions (e.g. winter). The bulb also contains apical buds, which develop into new shoots and eventually new plants during the growing season. The new individual plants that grow are natural clones of the old plant. Corms are similar to bulbs but are solid rather than fleshy. They are underground stems with scaly leaves and buds which also remain in the ground during winter.
13
Q
give some examples of bulbs
A
daffodils and onions
14
Q
describe the structure of tubers
A
Tubers consist of underground stems which become large, underground structures as they become swollen with stored food. Tubers also form buds that often can go on to form shoots, which can then develop into cloned plants.
15
Q
give some examples of tubers
A
potatoes and sweet potatoes
16
Q
what is meant by horizontal stems?
A
Some plants are able to develop stems that grow horizontally away from the parent plant and are able to form roots of their own.
17
Q
what are the 2 kinds of horizontal stems?
A
- Runners/stolons — when the horizontal stems run above the ground
- Rhizomes — when the horizontal stems go underground
18
Q
what is meant by ‘suckers’ and what do they do?
A
- When a new stem grows from the roots of a plant, they are called suckers.
- They can either grow near the base of the original stem or further away from it.
19
Q
what happens to the original stem of suckers?
A
The original horizontal stem often dies leaving the new stem as a separate individual
20
Q
explain how vegetative propagation happens in leaves
A
- vegetative propagation can also occur in leaves.
- Smaller plants grow along the leaf margin and eventually drop from the leaf on to the ground.
- These can then go on to form their own roots and grow, being a clone of the parent plant
21
Q
what are plant cutting used to do?
A
Cuttings exploit vegetative propagation in order to create clones of a plant. This technique can be used to produce large numbers of plants very quickly.
22
Q
describe the 2 step method used to clone plants using plant cuttings
A
=Cuttings are primarily made from stems.
- The stem is cut between two leaf joints (nodes) and the cut end is replanted into the soil
- Parts of tissues in the stem develop into new roots — this can be promoted by submerging the base of the cut stem in rooting hormone
23
Q
where in plants can cuttings be taken from?
A
- stem
- roots
- leaves
24
Q
if a cutting is taken from the roots, what happens?
A
If taken from the roots, the cut root is buried just below the soil surface and goes on to develop shoots and eventually new plants
25
if a cutting is taken from the leaf, what happens?
If taken from a leaf, the cut leaf is placed on moist soil. It then develops new shoots and roots
26
why were methods of artificial cloning developed when we have natural cloning methods?
- natural cloning can be very time-consuming and only a limited number of cuttings can be taken from one plant.
- Therefore, methods of artificial cloning have been developed so that hundreds of plants can be rapidly cloned.
27
name some methods of artificial cloning
micropropagation and tissue culture
28
define micropropagation
The process of growing large numbers of cloned plants from meristem tissue taken from a sample plant
29
what are some factors that make micropropagation possibel?
- Micropropagation is possible because meristem plant cells are totipotent.
- Micropropagation also requires the use of plant tissue cultures.
- In these cultures, cells, tissues, and organs are grown from a small sample of cells or tissue.
30
define tissue culture
The growth of tissues or cells in an artificial medium taken from tissues of a sample plant.
31
what are the conditions of the medium that tissues are cultured on to allow maximal growth?
- It contains nutrients necessary for growth such as glucose and phosphates
- The medium also usually contains a mixture of plant hormones (e.g. auxin and cytokinin) essential for the promotion of cell differentiation
- The medium must also be sterile to prevent the growth of unwanted bacteria and/or fungi – meristem tissue is usually used as it is typically virus-free
32
what is the 6 step method used to carry out micropropagation?
1--Small samples of plant meristem tissue, called explants, are dissected from the plant
2. The explants are sterilised using either bleach or ethanol to kill any unwanted microorganisms which often compete with plant cells, limiting their growth
3. The explants are then placed on a sterile culture medium which contains the necessary nutrients and plant hormones. This helps stimulate growth via mitosis and forms a mass of undifferentiated cells called a callus
4. The main callus that was formed is then divided into a large number of smaller clumps of cells. These are then moved to another culture medium that stimulates the development of roots
5. Once the roots have developed, the clump of cells is then transferred to a different culture medium that stimulates the development of shoots. This results in the formation of tiny plants (plantlets)
6. The plantlets are then potted in soil to grow into larger plants. These plants are all genetically identical clones of the original sample plant
33
what are some advantages of using artificial cloning in agriculture and horticulture (6)?
- New plants can be grown quicker than growing plants from seeds,so it is more time efficient and produces more plants in the same time-frame
- Desirable traits can be retained more reliably than traits derived from sexual reproduction
- Allows for the development of plants that are naturally hard to grow from seeds such as orchids
- The method of micropropagation ensures that the developing plant is free from viruses so is more likely to grow
- Provides a means of increasing the numbers of rare or endangered plants
- The new plants’ phenotypes are uniform, making them easier to harvest and grow
34
what are some disadvantages of using artificial cloning in agriculture and horticulture (3)?
- Artificial cloning produces a monoculture of genetically identical plants with no variation. This makes it more susceptible to diseases or pests as they will not be able to acclimatise to changes in environmental conditions
- Micropropagation is expensive and labour intensive
- Large numbers of plants can also be lost if the culture is contaminated with bacteria or fungi
35
why is using natural cloning advantageous in animals?
as it can produce a large number of animals possessing the desirable trait.
36
why cells are used for artificial cloning of plants?
-with plants, artificial cloning uses totipotent cells (able to differentiate into every cell type),therefore only early embryonic stem cells are used (the only type of cell in humans that is totipotent).
37
what are 2 methods currently used to produce artificial clones?
- Embryo splitting
| - Somatic cell nuclear transfer (SCNT)
38
explain embryo splitting
- Artificial embryonic twinning normally splits the early embryos manually into two, forming two independent, genetically identical embryos.
- However, artificial embryo splitting splits the same early embryo into many embryos,all of which are genetically identical.
- This gives rise to clones which are genetically identical to one another, but not the parent
39
define embryo twinning
The process of splitting an early embryo in half to create two genetically identical embryos
40
describe the 5 step process in which artificial embryo splitting occurs
1-A female animal with desirable traits is treated with hormones resulting in the release of many eggs (ova)
2. The eggs are then either:
* Fertilised inside the female animal and once the early embryos are formed, they are flushed out
* Removed from the female animal and fertilised in the lab by in vitro fertilisation (IVF)
3. Whilst the embryonic cells are still totipotent, they are manually split to produce many smaller embryos (embryonic splitting)
4. The split embryos are then left to carry on dividing in vitro for a few days to ensure development proceeds correctly
5. If divided correctly, each embryo is then placed into the uterus of a surrogate mother. The embryos then develop into foetuses and are born normally. Ultimately many genetically identical cloned animals are produced
41
which organisms are cloned using somatic cell nuclear transfer (SCNT)?
-adult animals
42
what does SCNT stand for?
somatic cell nuclear transfer
43
what were 3 things that were required to cone Dolly the sheep?
=This required three animals of the same species to achieve:
• A female egg donor
• A female surrogate mother
• The animal to be cloned
44
define somatic cell nuclear transfer (SCNT)
Method of cloning that is achieved by transferring the nucleus from a somatic (body) cell of an adult animal into an egg cell.
45
what is the 6 steps that artificial embryonic splitting occurs in?
1- The egg cell (ovum) is harvested from a female animal and the nucleus is removed in a process known as enucleation
2-. A somatic (body) cell from the adult animal to be cloned is then isolated
3. The somatic cell is then either:
* Enucleated (i.e. nucleus is removed), and transferred into the enucleated egg cell
* Joined together with the enucleated egg cell using electrofusion
4. Both procedures require an electric shock which stimulates the division of the reconstructed egg cell
5. The cell then undergoes many rounds of mitosis to form an embryo which is subsequently implanted into the uterus of a surrogate mother
6. The embryo develops into a foetus and a clone of the original animal is born
46
what is the difference between embryo splitting and SCNT?
embryo splitting, the clones are genetically identical to one another and not the parent; whilst in SCNT the cloned animal is genetically identical to the parent.
47
what is non- reproductive cloning?
Non-reproductive cloning is the production of cloned cells and tissues for use outside of reproduction.
48
what are cloned cells used for + its benefit?
- for therapeutic reasons – specifically for the growth of replacement organs/tissues.
- This is advantageous,as the cells will be genetically identical to the patient’s own cells,and there will be no issue with rejection.
49
what can cloned tissues/cells be used for?
- for medicinal drug testing
- cloned embryos can be used to determine the impact genes can have on development.
- They are also useful for scientific research looking into the action of genes that control development and differentiation
50
what are some advantages associated with artificial cloning? (6)
- Splitting embryos allows for large numbers of animals to be produced from parents with desirable genes
- Clones as embryos can be frozen to ensure the desirable genes were passed on before allowing them to develop
- SCNT allows for genetically identical copies of high-value organisms such as GM animals to be developed
- SCNT can also be used to clone rare or endangered species to increase their numbers in a population
- Can test medicinal drugs on cloned cells/tissues, avoiding animal testing (which has ethical issues of its own)
- It can be used to form tissues and cells for repairing damage caused by disease or accidents. These tissues and cells are genetically identical to the patient so therefore are not rejected
51
what are some disadvantages associated with artificial cloning? (4)
- Reduces genetic variation so the clones are more prone to diseases and pests
- SCNT brings up ethical issues regarding the use of multiple eggs in which only one successful clone is produced
- Many embryos formed from SCNT fail to develop normally,resulting in miscarriages or malformed offspring
- Clones that have been brought to term may have numerous health problems and often have shorter life spans, e.g. Dolly the sheep
52
define biotechnology
Use of living organisms or parts of living organisms (e.g. enzymes) in industrial processes to produce food, drugs or other products.
+ other processes that mix tech and living organisms:
• Gene therapy
• Genetic modification of plants, animals and microorganisms
• Artificial cloning of plants and animals
• Selective breeding of crops and animals
• Synthetic biology
53
what organisms are used in biotech?
microorganisms including: bacteria and fungi
54
what are some areas that microorganisms are used in?
* Food — e.g. ethanol in the production of beer which uses yeast
* Pharmaceutical drugs — e.g. penicillin which uses the fungus penicillium
* Enzymes — e.g. lipase and protease in washing power which uses bacteria
* Green technology — e.g. biogas (methane and carbon dioxide) which uses decomposers
55
what are some advantages of using microorganisms in biotechnology? (8)
* Microorganisms have a rapid growth rate which means large quantities of them can be produced in a smaller timeframe
* The nutrient requirements of microorganisms are simple, as they can use waste materials to grow, and so are relatively cheap to produce
* Production takes place at atmospheric pressure and low temperature which reduces costs and increases safety
* Microorganisms produce their own enzymes so expensive catalysts are not required, and they are also very diverse,so are capable of synthesising and degrading many products/reactants
* Microorganisms often secrete the products into the surrounding medium,so they are easier to isolate
* Microorganisms are one of the easiest organisms to genetically modify,so specific products can be made, and there are fewer ethical concerns related to this
* The production process is independent of the climate and therefore can take place in any part of the world
* Pure products are released into the surrounding medium from the microorganisms, making them easier to harvest and lowering downstream processing costs
56
what are some foods that microorganisms are used to make?
- yogurt
- cheese
- bread
- alcoholic beverages
57
describe the 3 step method for how microorganisms are used in baking bread using bacteria
1. Flour, water, salt and sugar are mixed with yeast and kneaded to produce dough (mixing)which is left to rest in a warm place for three hours (proving)
2. The yeast in the dough respires anaerobically to form carbon dioxide which causes the dough to rise (fermentation)
3. The dough is then cooked in a hot oven which causes the carbon dioxide bubbles to expand and the bread to rise further (cooking). The cooking process kills the yeast cells and evaporates the ethanol that was produced by the yeast during anaerobic respiration
58
describe the 5 step method for how microorganisms are used to make yogurt using bacteria
1. Milk is pasteurised, which involves heating the milk to 95oC for 20 seconds to kill off any harmful bacteria
2. The milk is then homogenised which disperses the fat droplets evenly in the milk and is then mixed with bacteria which produce lactic acid from the lactose in the milk
3. The acidified milk is then mixed with rennet which contains the enzyme rennin (also known as chymosin). Rennin causes the milk protein casein to curdle in the presence of calcium ions (breaks down kappa-casein making the casein insoluble) which causes the milk to separate into solid curds and liquid whey
4. For most cheese, the curd is cut, stirred and cooked in the whey and then strained through a cheesecloth (for cottage cheese, the curd is separated from the whey)
5. The curd is then pressed into moulds and left to dry, mature and ripen. During this, the bacteria continue to grow and produce lactic acid,which changes the texture and taste of the cheese; e.g. the fungi Penicillium can be added to produce blue cheese
59
describe the 4 step method for how microorganisms are used in brewing beer using yeast
1. Beer is made by using germinating barley seeds which produce enzymes that breakdown starch to maltose. The barley seeds are then killed by slow heat, but the activity of the enzymes is retained to produce malt
2. The malt is mixed with hot water to produce a liquid containing maltose (called wort) in a process known as mashing. Hops are added to provide a bitter flavour and the wort is sterilised, cooled, and then inoculated with yeast which ferments the wort by using maltose in anaerobic respiration
3. Anaerobic respiration results in increasing concentrations of ethanol and carbon dioxide,which eventually inhibits the yeast
4. The beer is then left to mature at a cold temperature for up to a month and then filtered, pasteurised and made ready for sale
60
what are some advantages of using microorganisms in protein production? (5)
* SCP is a good source of protein because it has a very high protein content
* SCP does not contain any animal fat or cholesterol,so is a healthier protein option than protein from animals
* Waste products can be used to grow microorganisms, so the production of SCP can be combined with the removal of waste products
* The production of SCP by microorganisms is very fast compared to animal protein production and can be increased and decreased easily according to demand
* Producing protein from microorganisms results in there being no animal welfare issues and not as much land is required
61
what are some disadvantages of using microorganisms in protein production? (5)
* The conditions that microorganisms grow in to produce the proteins are ideal for pathogens, so care needs to be taken to prevent infections
* People may not wish to eat fungal protein because it is grown on waste
* The SCP needs to be isolated and purified to ensure it is not contaminated by the microorganisms or the waste material it grew on, so it may be costly
* SCP tends to have a different texture and taste to traditional protein so people may dislike it
* The amino acid profile of SCP is quite different to that of animal protein (specifically being deficient in methionine), however, the microorganisms can be genetically modified to change the amino acid content of the protein
62
what is bioremediation used for?
- In bioremediation microorganisms are used to clear toxic pollutants by converting them to less harmful substances.
- Bioremediation is most commonly used to clean polluted water and soil.
- In bioremediation, microorganisms use pollutant contaminants as a source of food and convert them to less harmful substances.
63
what are the optimal conditions used to grow the microorganisms needed for bioremediation in polluted areas?
* Water availability
* Optimal pH
* Optimal temperature
64
what is meant by in situ modification? + give examples
If the conditions are not favourable for microorganism growth, they can be modified on-site.
e.g.
oxygen may be pumped into the area so as to meet the suited conditions for microorganisms which respire aerobically.
65
what is meant by ex situ modification? + give examples
If the conditions are not favourable for microorganism growth, they can be modified off-site.
e.g.
the soil can be dug up and treated elsewhere
66
why is bioremediation advantageous? (3)
* It is a natural process;very little waste is produced (usually in the form of carbon dioxide and water) and therefore it is not harmful to the environment
* Does not require much equipment or labour to carry out
* The workers do not need to be exposed to the toxic material, so there is less risk of humans being harmed
67
what is a disadvantage of bioremediation?
, there are some types of waste material that bioremediation cannot be used to clear,such as heavy metals (for example, cadmium) so this technique is somewhat limited in use
68
explain how large scale drug production occurs using microorganisms
- Microorganisms are often used to produce drugs,such as penicillin.
- Commercial drug production takes place on a large-scale using fermenters, which allow for certain conditions to be carefully controlled so that a high yield is obtained.
69
why does temperature need to be controlled during large scale drug production using microorganisms?
Temperature — high temperatures cause the denaturation of enzymes; low temperatures reduce the growth of the microorganisms
70
why does pH need to be controlled during large scale drug production using microorganisms?
pH — if the pH is too acidic or too alkaline thiscan cause enzymes to denature
71
why does oxygen availability need to be controlled during large scale drug production using microorganisms?
Oxygen availability — some microorganisms respire aerobically as aerobic respiration produces more energy than anaerobic,so stable levels of oxygen are required
72
why does nutrient availability need to be controlled during large scale drug production using microorganisms?
Nutrient availability — microorganisms require nutrients to grow and synthesise the required product
73
why does product concentration need to be controlled during large scale drug production using microorganisms?
Product concentration — if the product concentration becomes too high, the synthesis process can be inhibited
74
what are the 2 types of culture that can be made?
continuous and batch
75
what is meant by primary metabolites?
Products which are synthesised by actively growing microorganisms in normal conditions are called primary metabolites.
76
describe continuous culture? what happens to primary metabolites?
- Primary metabolites are continually released by the microbes then removed from the fermenter.
- When the primary metabolites are being made, nutrients are regularly added to the fermenter; some cells are removed to prevent the population from becoming too dense.
- This allows for the microorganisms to continue growing at a specific growth rate.
- This type of culture is called continuous culture
77
what is meant by secondary metabolites?
other products which are produced when the microorganisms are stressed
78
how are secondary metabolites produced? and describe batch culture
- Secondary metabolites are produced when the microorganism population has reached a certain size and cannot increase any further.
- The microorganism population is allowed to ferment for a specific time,then the fermenter is emptied,and the secondary metabolite collected.
- batch culture is done in separate batches
79
what is meant by asepsis?
Asepsis is the process of ensuring that sterile conditions are maintained.
80
why do fermenters need to be sterilised?
+
what would happen if we did't sterilise them?
+
how are fermenters sterilised?
- Fermenters need to be thoroughly sterilised to prevent the growth of unwanted microorganisms such as pathogens.
- The growth of unwanted microorganisms would not only reduce yield (as they compete with cultured microorganisms for nutrients and space) but may also produce toxins, killing the cultured microorganisms and destroying their products
- Fermenters are therefore sterilised regularly using superheated steam to avoid these issues.
81
what are some drugs that can be synthesised through the use of microorganisms?
- penicillin
| - insulin
82
what fungus produces penicillin?
Penicillium chrysogenum
83
is penicillin a primary of secondary metabolite and why?
- Penicillin,however, is only produced by the fungus when its population has reached a certain size and is under stress.
- This means that penicillin is a secondary metabolite,hence it is manufactured by batch culture
84
give a 2 step method describing how penicillin is manufactured
1. The fermenter is run for up to eight days, and the culture is then removed to filter out the fungus cells from the solution containing the antibiotic (penicillin)
2. The antibiotic is precipitated from the solution by adding potassium, and the antibiotic is then mixed with inert substances and prepared as a tablet or in syrup form
85
what is insulin used for?
to treat type 1 diabetes
86
how was insulin obtained in the past?
from the pancreas of animals
87
why do we no longer obtain insulin from the pancreas of animals and how do we now obtain insulin?
- this was not very effective as animal insulin is not identical to human insulin.
- Synthetic human insulin is now produced using genetically modified bacteria by continuous culture
88
give a 2 step method describing how to produce insulin
1. The human gene for insulin is combined with a plasmid and then inserted into the bacteria E.coli
2. The E.coli goes on to synthesise large quantities of human insulin
89
what is the benefit of producing human insulin using genetically modified bacteria over obtaining it from the pancreas of animals?
Human insulin can now be produced in vast quantities at a relatively low cost through manufacturing by continuous culture
90
what is meant by a 'closed culture'
In a batch culture, the microorganisms in a fermenter do not have any exchange of nutrients or gases with the external environment.
91
what are the 4th distinct stages that population growth of the microorganism population will be divided into?
1. Lag phase
2. Log (exponential) phase
3. Stationary phase
4. Death (decline)phase
92
explain the lag phase which is the 1st stage of the growth curve
- the population is very small.
- Growth of the population is also slow, due to the organisms adjusting to their new environment.
- They adjust by initiating cell growth, absorbing water, synthesising enzymes and activating specific genes
93
explain the log phase which is the 2nd stage of the growth curve
- the growth of the population is most rapid.
- The organisms have adjusted to their environment.
- They have adequate nutrients and space to grow,hence their population doubles in size with each generation
94
explain the stationary phase which is the 3rd stage of the growth curve
- the population does not grow and therefore stays the same size.
- The organisms tend to use up more nutrients and produce more waste products like carbon dioxide.
- This causes the rate of death to increase and become equal to the rate of reproduction:
Rate of reproduction = Rate of death
95
explain the death phase which is the 4th and final stage of the growth curve
- the nutrients run out and the concentration of waste products becomes toxic to the organisms.
- This causes the death rate to exceed the reproduction rate until eventually all the organisms die:
Rate of reproduction < Rate of death
96
draw the graph for the phases of the growth curve
insert picture or double check from the snap revise notes- bacterial growth page 1
97
is continuous culture a closed culture? + explain answer
in continuous culture the conditions are altered continuously to allow for optimal growth,therefore continuous culture is not a closed culture.
98
what phase of the growth curve are primary metabolites produced?
Primary metabolites are produced during the log phase as they are made in continuous culture.
99
what phase of the growth curve are secondary metabolites produced and why?
- Secondary metabolites are produced during the stationary phase when there are not enough nutrients for the whole population.
- This is because they are produced in stressful conditions and are therefore made in closed culture (batch culture).
100
what is the equation for the number of organisms?
```
N= N0 * 2n
N= number of individuals present in population (no units)
```
N0= initial number of cells (no units)
n= number of cell divisions (no units)
101
what are enzymes?
Enzymes are large proteins which act on a substrate and catalyse a reaction without being used up.
102
where are enzymes extracted from?
Enzymes can be extracted from microorganisms for use in biotechnological processes.
103
what must happen to enzymes before they can be used?
As enzymes remain in suspension after the reaction reaches completion they must be separated from the product before it can be used.
104
why do we have immobilised enzymes?
- enzymes must be separated from the product before it can be used.
- This process can be very costly; to overcome this, enzymes can be held in place so that they cannot mix freely with the substrate or product.
105
define immobilised enzymes
An enzyme that is not free to diffuse through a solution as it is held in place.
106
what are the 4 main methods used to immobilise enzymes?
* Adsorption
* Covalent Bonding
* Entrapment
* Membrane Separation
107
what is meant by adsorption?
Adsorption involves binding enzymes to a supporting surface (for example, clay and resin)using hydrophobic interactions and ionic linkages.
108
what does it mean for the active site of the immobilised enzymes to be slightly distorted?
The active site of the enzyme may be slightly distorted due to the interactions the enzyme has with the supporting surface which can reduce enzyme activity; this means that less substrate is ultimately converted into product.
109
what does it mean for the hydrophobic interactions and ionic linkages in immobilised enzymes to be weak?
The hydrophobic interactions and ionic linkages are all quite weak in adsorption, which means the enzymes can easily detach from the supporting surface and enter the solution.
110
why is covalent bonding used as a method to immobilise enzymes?
Covalent bonds are used to bind enzymes to supporting surfaces through a crosslinking agent.
111
describe the properties of covalent bonds and what they do in enzymes
-Covalent bonds are very strong,so enzymes do not easily detach from the supporting surface, however, the bonds distort the active site a great deal causing enzyme activity to be significantly reduced.
112
what is meant by entrapment?
- Entrapment involves trapping enzymes in a matrix (e.g. network of cellulose fibres)that does not allow free movement.
- There is no distortion of the active site, hence the enzyme activity is unaffected.
113
why can the entrapment method be used for reactions which have large substrates or products?
- in entrapment, the substrate and the products have to be small enough to move in and out of the pores in the matrix.
- This means that this method cannot be used for reactions which have large substrates or products
114
what does membrane separation use?
Membrane separation uses a partially permeable membrane to separate the enzyme from the reaction mixture.
115
what is a similarity between membrane separation and entrapment?
Similar to entrapment, the product and substrate have to be small enough to pass through the membrane,hence their diffusion through the membrane towards the enzyme can be slow, limiting the reaction rate.
116
what are some advantages of immobilised enzymes? (3)
* The enzymes do not freely mix with the product meaning that the product extraction process costs are relatively low
* The enzymes can be easily reused which lowers cost in the long run
* When the enzymes are surrounded by an immobilised matrix, they are better protected from extreme conditions, so a higher temperature and more extreme pH can be used without denaturing the enzyme
117
what are some disadvantages of immobilised enzymes? (2)
* Immobilised enzymes are usually less active than free enzymes,which makes the process slower
* In general, it costs more initially to set up immobilised enzymes than to set up free enzymes
118
what are the 5 different things immobilised enzymes are used for?
- glycose isomerase
- lactase
- glucoamylase
- penicillin acylase
- aminoacylase
119
what does the immobilised enzyme glucose isomerase do the production of high fructose corn syrup (HFCS)?
converts glucose to fructose
120
what is HFCS made from?
HFCS is made from fructose, a sweeter sugar compared to sucrose.
121
what is HFCS used in?
HCFS is used as a sweetener in diet foods because less sugar is needed to achieve the equivalent sweetness of sucrose.
122
why do we used HFCS (its benefit)?
It is also cheaper than sucrose so is often used in soft drinks and processed foods
123
how and why do we use the immobilised enzyme lactase?
- Some people are lactose intolerant, meaning they cannot digest the lactose sugar present in milk.
- To make lactose free milk, the lactase enzyme is immobilised and used to convert lactose in milk to glucose and galactose.
- Lactose-free milk provides lactose intolerant individuals with an important source of calcium.
124
how is glucoamylase immobilised?
Glucoamylase is often immobilised in the large-scale conversion of dextrins to glucose.
125
what are dextrins?
Dextrins are short polymers of glucose that are formed during the hydrolysis of starch.
126
what is immobilised glucoamylase used for?
Immobilised glucoamylase is usually used to digest sources of starch such as corn and is also used to convert dextrin to glucose for use in the fermentation process; for example, in the production of alternative fuels for vehicles
127
why is penicilin acylase used for? + why is it advantageous in use?
- Penicillin acylase is immobilised for use in the formation of semi-synthetic penicillins which provides a barrier against antibiotic resistance.
- This is because some penicillin-resistant microorganisms are not yet resistant to the semi-synthetic penicillin,so it is advantageous in use.
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what is aminoacylase and how is it made?
- Aminoacylase is a hydrolase used to synthesise pure samples of L-amino acids (a building block used in the production of certain pharmaceutical compounds).
- It is made by removing the acyl group from the nitrogen of a N-acyl amino acid.
