Cloning and Biotechnology

Question 1

What are natural clones

Answer 1

• these are clones produced by asexual reproduction, this is when the nucleus is divided by mitosis
• mitosis creates two identical copies of the DNA of which are then separated into two genetically identical nuclei before forming two genetically identical cells
• cells may not be physically or chemically identical as after division, they may differentiate to form two different types of cell

Question 2

Advantages of natural cloning

Answer 2

• if the conditions for growth are good for the parent then they will be good for the offspring
• cloning is rapid so population will increase quickly
• reproduction can be carried out even if there is only one parent and sexual reproduction is not possible

Question 3

What are the disadvantages of natural cloning

Answer 3

• offspring may become overcrowded
• there will be no genetic diversity- except that caused by mutation during DNA replication
• the population shows little variation
• selection is not possible
• if the environment changes to be less advantageous the whole population is susceptible

Question 4

What is vegetation propagation

Answer 4

Reproduction from vegetative parts of the plant usually an over wintering organ

Question 5

describe plant cloning by vegetative propagation

Answer 5

• the differentiation of many plant cells is not as complete as that in animals
• many parts of plants contain cells that retain the ability to divide and differentiate into a range of types of cells
• means that plants are able to reproduce by cloning
• natural cloning involves a process called vegetative propagation
• this is the process of reproduction through vegetativ3e parts of the plant rather than through specialised reproductive structures

Question 6

Describe bulbs

Answer 6

• bulbs are an over wintering mechnisms for many perennial monocotyledonous plant s
• bulbs consist of an underground stem from which grow a series of fleshy leaf bases
• there is also an apical bud which will grow into a new plant in the spring
• often a bulb contains more than one apical bud and each will grow into a new plant
• store of food

Question 7

Describe corns

Answer 7

• solid rather than fleshy like a bulb
• underground stem with scaly leaves and buds
• remain in the ground over winter in the spring the buds grow to produce one or more new plants

Question 8

Describe leaves

Answer 8

• reproduce asexually
• as clones grow on the leaf margins
• the immature plants drop off the leaf and take root
• Kalanchoe leaves

Question 9

Describe tubers

Answer 9

• tubers are another type of underground stem
• they act as a food store for plants
• potatoes are tubers
• one potato will grow into one or more plants, each new plants can then produce many new tubers later that year

Question 10

Describe natrual cloning in animals

Answer 10

• animals do not clone as often as plants there are examples of natural cloning
• mammals clone when identical twins are formed
• occurs when a fertilised egg divides as normal, but the two daughter cells then split to become two separate cells
• each cell grows and develops into a new individual
• water fleas reproduce asexually in order to produce clones

Question 11

Describe how to do cuttings

Answer 11

• to make a cutting a stem is cut between leaf joint, and leaves are removed from the lower end, using a scalpel
• cut end of the stem is then placed in moist soil which contains hormones to increase root growth
• new roots will grow from the tissues in the stem usually from the node, but they may grow from other parts of the buried stem
• then plant the cutting into a growth medium
• warm and moist environemnet - cover pot with plastic bag or by putting it in a propagator
• when cutting is formed can plant it elsewhere to continue growing

Question 12

describe tissue culture

Answer 12

1. cells are taken from the original plants that is going to be cloned
   2, cells from the stem and root tips are used becasue they are stem cells
2. the cells are sterilised to kill any microorgansism - bacteria and fungi compete for nutrients with the plant cells which decreases their growth rate
3. the cells are placed on a culture medium containing plant nutrients and growth hormones
4. when the cells have divided and grown into a small plant they are taken out of the medium and planted in soil, they develop into plants that are genetically identical to the original plant

Question 13

describe micropropagation

Answer 13

• often involves taking a small piece of plant tissue (the explant) and using plant growth substances to encourage it to grow
  1. suitable plant material is selected and cut into small pieces these are called explants, explants could be tiny peices of lead stem, root or bud. meristem is often used as this is always free from viral infection
  2. the explants are sterilised using dilute bleach or alcohol whcih kills any bacteria and fungi as these would thrive in the conditions supplied to help the plant grow well
  3. the explants are placed on a sterile growth medium containing suitabel nutrietns such as glucose, amino acid and phosphates.
  4. the gel also contains high concentrations of the plant growth substances auxin and cytokinin stimulating the cells of each explant to divide by mitosis to form a callus
  5. once a callus has formed it is divided to produce a larger number of small clumps of undifferntiated cells
  6. these small clumps of cells are stimulated to grow, divide and differentiate into different plant tissues, this achieved by moving the cells to different growth media, each medium contains the different rations of auxin to cytokinins
  6. once tiny plantlets have been formed these are transferred to a greenhouse to be grown in compost or soil and acclimatised to normal growing conditions

Question 14

Describe disadvantages of artifical cloning

Answer 14

• tissue culture is labour intensive -
• it is expensive to set up facilities - high energy use and trianign of skilled workers therefore it is unsuitable for small scale work
• can fail due to microbial contamination
• all the cloned offspring are genetically identifal and are therefore susceptible to the same pests and diseases crops grown in the monocultures allow rapid spread of a disease or pest between the closely planted crop plants
• there is no genetic variation excpet that introduced by mutation
• undesirable genetic characterstics are always pass on

Question 15

Describe arguments for artificial cloning in animals

Answer 15

• can produce a whole herd of animals with a high yield or showing an unusal combination of characterstics such as producing silk in their milk
• produces genetically identical copies of very high value individuals retaining the same characterstics
• using genetically identical embryos and tissues for scientific research allows the effects of genes and hormones to be assessed with no interference from different genotypes
• testing medicinal drugs on cloned cells and tissues avoids using animal or people for testing
• can produce cells and tissues genetically identical to the donor for use in repairing damage caused by disease or acciednets
• individuals from an endangered species can be cloned to increases numbers
• less space is required
• lot of plant quickly compared to the time it would take them to grwo from seeds
• allows plants to gro in any season
• desriable genetic characterstics are passed on to clones this doesnt always happne when plants reproduce sexually

Question 16

describe naturally cloning in aniamls

Answer 16

• some invertevrate speices such as greenfly and water fleas have evolved the ability to clone naturally
• in other species it is rare event
• starts with cells that are totipotent as they can divide and differentiate into all types of cell found in the adult organisms these are early embryo cells
• identical twins

Question 17

describe embryo twinning

Answer 17

• mammals can produce identifical offspring if an embryo splits very early in development
  1. a zygote is created by IVF
  2. the zygote is allowed to divide by mitosis to form a small ball of cells
  3. the cells are separated to continue dividing
  4. each small mass of cells is placed into the uterus of a surrogate mother

Question 18

what is embryo twinning

Answer 18

splitting an embryo to create two genetically identical embryos

Question 19

what is somatic cell nuclear transfer

Answer 19

a technique that involves transferring the nucleus from a somatic cell to an egg cell

Question 20

What are the other forms of biotechnology

Answer 20

• gene technology
• genetic modification and gene therapy
• selective breeding
• cloning by embryo splitting and micropropagation
• the use of enzymes in industrial processes
• immunology

Question 21

advantages of using microorganism in biotechnology

Answer 21

• cheap and easy to grow
• production process takes place at lower temperature than would be required to make the molecules by chemical engineering means saving fuel and reducing costs
• production process can take place at normal atmospheric pressure, which is safer than using chemical reactions that may require very high pressure for successful manufacture of certain molecules
• not dependent on climate so it can happen any place in the world
• microorganism can be fed byproducts from other food industries
• microorgansism have short life cycle and reproduce quickly, some microorgansism may grow very quickly inside the reaction vessle - fermenter
• microorganissm can be gentically modified relatively easily allowing the specific production processes to be achieved
• there are fewer ethical considerations to worry about
• the products are often released from the micoorganism into the surrounding medium this makes the product easier to harvest
• the product is often more pure or easier to isolate than in conventional chemical engineering processes this means lower downstream processing costs

Question 22

describe the history of biotechnology

Answer 22

• biotechnology is the use of living organisms or parts of living organism in industrial processes this could be to produce food, drugs or other products
• he was a hungarian agricultural engineer who set up a huge industrialised farming unit
• used the term to describe any technological process that made use of living organisms or part of living organisms
• has been in use for long time
• used in the production of beer or ale 7000 years ago
• brewing makes use of yeast to ferment maltose sugars in germinating barley
• more recent examples include use of bacterium to produce acetone which was needed to make explosives in world war 1
• manufacture of penicilin during world was 11
• these examples and other shifted the emphasis of biotechnology away from food towards the manufacutre of drugs
• however the new science of DNA tecnology brought biotechnology to its current postion
• our increasing understanding of genetics and genetic engineering along with the ability to manipulate the living conditions of living organisms has led to an expansion in biotechnology, biggest expansion is the use of microorganisms in the industrial process

Question 23

Describe how biotechnology is used today

Answer 23

• food
• pharmecutical drugs
• enzymes
• other uses

Question 24

describe food

Answer 24

• ethnaol in beer and wine
• carbon dioxide used to make bread rise
• lactic acid used to make yoghurt and cheese
• myoprotein a filamentous fungus protein used to make vegetarian food
• soya - soya beans are fermented to produce soy sauce

Question 25

describe pharmaceutical drugs

Answer 25

- penicillin - other anitbiotics - insulin

Question 26

describe enzymes

Answer 26

- protease and lipase used in washing powders - pectinase sued to extract juice from fruit - sucrase used to digest sugar to make food sweeter - amylase to digest starch into sugar to produce syrup used as a sweetener in food production - protease used to tenderise meat - lactase to make lactose free milk - removing sticky residues from recycled paper

Question 27

describe other products for biotechnology today

Answer 27

- biogas which is a combination of carbon dioxide and methan - citric acid is a food preservative - bioremediation - cleaning waste water

Question 28

describe using other organisms in biotechnology

Answer 28

- genetically modified mammals can be useful proteins - some mammals proteins can be incorporated into the milk for example goats have posses the genetically modified to possess the gene for spider silk

Question 29

describe how yoghurt is made

Answer 29

- yogurt is a milk that has undergone fermentation by lactobacillus bulgaricus and streptococcus thermophilus - bacteria convert lactose to lactic acid - acidity denatures the milk protein casuign it to coagulate - bacteria partially digests the milk making it easy to digest - fermentation also produces the flavours characteristic of yogurt - other bacteria are added as probiotics this is bacteria that may benefit human health by improving digestion of lactose and aiding gastrointestinal function and stimulating immune system

Question 30

Describe how cheese is made

Answer 30

milk is usually pre-treated with a culture of bacteria that can produce lactic acid from lactose - once it is acidified the milk is mixed with rennet - rennet contains the enzyme rennin which is found in the stomachs of young mammals - rennin coagulates the milk protein in the presence of calcium ions 1. Kappa-casein keeps the casein in solution this is broken down making the caesin insoluble 2. the casein is precipitated by the action of calcium ions which bind the molecules together - resulting solid is curd which is separated from the liquid by cutting stirring and heating - bacteria continues to grow producing more lactic acid and curd is then pressed into moulds - flavour is determined by later ripening and maturing processes, the cheese can then be given additional flavour by inoculation with fungi to produce blue cheese

Question 31

Describe how alcohol is made

Answer 31

- alcohol is the product of the anaerobic respiration yeast - wine is made using grapes that naturally have yeasts on their skin - grapes contain the sugars fructose and glucose - yeast uses these sugars to produce carbon dioxide and alcohol - ale or beer is brewed using barley grains that are beginning to germinate this is called malting and as the grain germinates it coverts stored starch to maltose which is respired by the yeast - anaerobic respiration produces carbon dioxide and alcohol - hops used to give a bitter taste

Question 32

Describe how single cell protein

Answer 32

- microorganism have been used to manufacture protein that is used directly as food - most frequent used fungus is fusarium venenatum, this is known as myoprotein or single cell protein - best known example is Quorn - can produce protein with a similar amino acid profile to animal and plant protein - can grow on almost any organic substrate including waste materials such as paper and whey

Question 33

describe the advantages of using microorganisms

Answer 33

- production of protein can be many times faster than that of animal or plant protein - biomass produced has a high protein content - production can be increased and decreased according to demand - no animal welfare issues - microorganisms provide good source of protein - protein contains no animal fat or cholesterol - microorganisms can easily be genetically modified to adjust amino acid content of the protein - SCP production could be combined with removal of waste products - production is independent of seasonal variations - not much land is required

Question 34

Describe the disadvantages of using microorganisms

Answer 34

- some people may not want to eat fungal protein or food that has been grown on waste - isolation of the protein - the microorganisms are grown in huge fermenters and need to be isolated from the material on which they grow - the protein has to be purified to ensure it is uncontaminated - microbial biomass can have a high proportion of nucleic acids which must be removed - the amino acid profile may be different from traditional animal protein and it can be deficient in methionine - infection - conditions needed for the microorganisms to grow are also ideal for pathogenic organisms, care must be taken to ensure the culture is not infected with the wrong organism - palatbility - protein does not have the taste or texture of traditional protein sources

Question 35

describe scaling up production of drugs

Answer 35

- fermenters are used, enables growing conditions to be controlled to ensure the best possible yield of the prodct the conditions that must be controlled include - temperautre - nutrients avalibale - oxygen availability - ph - concentration of product - must be sterilised using superheated steam - can then be filled up with all compenents required for growth and supplied with a starter culture of the microorganism to be used - culture is left to grown and synthesise the products

Question 36

describe scaling up production of drugs

Answer 36

- fermenters are used, enables growing conditions to be controlled to ensure the best possible yield of the product the conditions that must be controlled include - temperautre - nutrients avalibale - oxygen availability - ph - concentration of product - must be sterilised using superheated steam - can then be filled up with all components required for growth and supplied with a starter culture of the microorganism to be used - culture is left to grown and synthesise the products

Question 37

describe batch culture

Answer 37

- some products are only produced when cells are put under stress such as high population density or limited nutrient availability, these are secondary metabolites and are produced during the stationary phase of growth - culture is set up with limited quantity of nutrients and allowed to ferment for a specific amount of time - after this time the fermenter is emptied and can be extracted from the culture - this is batch culture

Question 38

describe continuous culture

Answer 38

- some products are synthesised by the microorganism during normal metabolism when they are actively growing these are called primary metabolites - these products are continually released from the cells and can be extracted continuously from the fermenting broth - the broth is topped up with nutrients as these are used by the microorganisms - some broth is removed regularly to extract the product and remove cells from the broth - otherwise the population becomes too dense, this is known as continuous culture - keeps the microorganisms growing at specific growth rate

Question 39

describe the importance of asepsis

Answer 39

- Asepsis is ensuring that sterile conditions are maintained - nutrient medium would also support the growth of unwanted microorganisms which would reduce production because the unwanted microorganisms would .... - compete with the cultured microorganisms for nutrients and space - reduce the yield of useful products - spoil the prodct - produce toxic chemicals - destroy the cultured microorganisms and their products - in processes where food or medicinal chemicals are produced all products must be discarded if contamination by unwanted organisms occur

Question 40

describe the production of penicillin

Answer 40

- secondary metabolite - only produced once population has reached a certain size therefore penciliin is done in batch culture 1. fermenter is run for 6-8 days and the culture is then filtered to remove the cells 2. the antibiotic is precipitated as crystals by the addition of potassium compounds, the antibiotic may be modified by the action of other microorganisms or by chemical means

Question 41

describe production of insulin

Answer 41

- synthetic human insulin was developed by genetically modifying a bacterium - gene was combined with a plasmid to act as a vector so the gene could be inserted into the bacterium Esherichia coli - resulting genetically modified bacterium enabled the production of vast quantities of human insulin at relatively low cost - insulin is done by continuous culture

Question 42

describe bioremediation

Answer 42

- used of microorganisms to clean the soil and underground water on polluted sites - organism converts toxic pollutants to less harmful substances - used to break down crude oil and treat oil spills as well as treating solvents and pesticides - it involves stimulating the growth of suitable microbes that use the contaminants as a source of food, requires the right conditions for the growth of microorganisms which are.. - available water - suitable temperature - suitable ph - where conditions are not quite suitable they may be modified by the addition of suitable substances in some cases, additional nutrients such as molasses may be needed to ensure the microorganism can grow effectively, may be necessary to pump oxygen for aerobic respiration

Question 43

describe the advantages of bioremediation

Answer 43

- use natural systems - less labour - treatment in situ - few waste products - less risk of exposure to clean-up personnel on the other hand - only suitable for certain products, heavy metals cannot be treated

Question 44

Describe how to grow microorganisms

Answer 44

- microorganisms will grown on almost any material that provides carbon compounds for respiration and a source of nitrogen for protein sysntheiss - in a lab they are usually grown in one of two types of growth medium - broth - kept in bottles - agar - melted and poured into petri dishes - agar - contains peptones, yeast extract, salts and water may also contain glucose or blood

Question 45

Describe Aseptic techniques

Answer 45

- developed to reduce the likelihood of contaminating the medium with unwanted bacteria or fungi 1. wash hands 2. disinfect working areas 3. bunsen burner operating nearby to heat air - causes air to rise and prevent air-borne microorganisms settling, also creates an area around it of sterile air which the microbiologist can work in - open vessel pass the neck of the bottle over the flame to prevent any bacteria in air entering the bottle - do not lift lid of petri dish completely - any glass ware should be passed through the flame before and after contact with the desired microorganism

Question 46

Describe techniques used in microbiology

Answer 46

1 sterilisation 2. inoculation 3. incubation

Question 47

describe sterilisation

Answer 47

- agar medium and any equipment must be sterilised - medium is steriled by heating in an autoclave at 121 degrees for 15 minutes - kills living organisms - when medium has cooled sufficiently it is poured into sterile petri dishes and left to set - lid kept on petri dish in order to prevent infection

Question 48

Describe inoculation

Answer 48

- streaking - wire inoculating loop is used to transfer a drop of liquid medium onto the surface of the agar - drop is drawn out into a streak by dragging the loop across the surface - seeding - sterile pipette transfers small drop of liquid medium to the surface of the agar or the petri dish before agar is poured in - spreading - sterile glass spread is used to spread the inoculated drop over surface of agar - small cotton swab or bud is moistened with distilled water and used to collect microorganism from a surface then wiped over agar

Question 49

describe incubation

Answer 49

- petri dish is labelled and the top taped to the bottom using two strips of adhesive tape - dont tape it completely - anaerobic bacteria which may be pathogenic - placed in a warm environment - upside down as it prevents drops of condensation falling onto surface of the agar and prevents it from drying to quickly - suitable temperatures - examined after 24-36 hours, - dont open dish - bacteria - visible colonies may be shiny or dull, some are round with entire edges and each colony results from a single bacterium - may grow into hyphae - circular - single celled fungi grow as circular colonies - must be sterilised after use and before disposal - wash hands as moisture could be a source of infection

Question 50

Describe using a liquid medium

Answer 50

- broth is clear but will turn cloudy - useful to increase the number of microorganisms before transferring to agar plates for counting and identification - such use similar aseptic techniques - can be used to investigate population growth

Question 51

What is serial dilution

Answer 51

- a sequence of dilutions used to reduce the concentration of a solution or suspension

Question 52

what is a closed culture

Answer 52

- a culture which has no exchange of nutrients or gases with the external environment

Question 53

describe how serial dilution worked

Answer 53

- numbers of individual microorganism in a broth can be high - to many colonies which merge together taking a count impossible so in order to reduce the population density which can be achieved by serial dilution - step wise dilution of the broth culture and each step the broth diluted by a factor of 10 - this takes a 1cm3 sample of the broth and add 9cm3 of distilled water, labelled the diluted borth as 10-1 then take a 1cm3 sample of this diluted broth and add 9cm3 of distilled water and label it as 10-2 - continue this until you have a series of dilutions with suitable levels - add a drop of each dilution to inoculate an agar plate, one of this will produce a culture plate in which the number of colonies can be counted - when recording the population density do not forget to multiply your count by the dilution factor and also by the volume added to the plate

Question 54

DRAW THE GROWTH CURVE

Answer 54

DRAW IT

Question 55

describe the growth curve

Answer 55

- small population of microorganism in a closed culture that contains all the nutrients required for growth will undergo population growth - closed culture refers to a population in which all conditions are set at the start and there is no exchange with the external environment - similar to conditions set up for batch production in a fermenter but in a batch fermenter certain substances such as oxygen may be added to keep the population growing until nutrients are used up

Question 56

Describe the lag phase

Answer 56

- early part of population growth does not grow quickly this is because the population is still small and also because organisms are adjusting to their new environment this involves... - taking up water - cell growth - switching on certain genes - synthesising specific proteins enzymes

Question 57

describe the log phase

Answer 57

- in the log phase organisms have adjusted to their environment - each have the enzymes that they need to survive - each individual has sufficient nutrients and space to grow rapidly and reproduce - population doubles in size with each generation in some microorganisms this can be frequent as once every 20-30 minutes

Question 58

describe stationary phase

Answer 58

- increasing numbers of organisms use up the nutrients and produce increasing amounts of waste products such as carbon dioxide and other metabolites - rate of population growth declines and the number of individuals dying increases until the reproduction rate equals the death rate - no population growth

Question 59

describe the death phase

Answer 59

- nutrients run out and the concentration of waste products become lethal - more individuals die than are produced and the population begins to fall - eventually they all die

Question 60

describe primary metabolites (the growth curve)

Answer 60

- produced during normal activities or the microorganism will be collected from a fermenter during the log phase - in a fermenter the population is not kept in a closed culture but conditions are maintained for optimal growth

Question 61

describe secondary metabolites (the growth curve)

Answer 61

- secondary metabolites are produced in the stationary phase - population must be kept in a closed culture and metabolites can be collected at the end of the stationary phase or during the decline phase

Question 62

What are immobilised enzymes

Answer 62

an enzyme that is held in place and not free to diffuse through the solution

Question 63

what are the advantages of immobilised enzymes

Answer 63

They do not mix freely with the substrate which has the following advantages - enzymes do not mix with the product so extraction costs are lower - enzymes can easily be reused - a continuous process is made easier as there are no cells requiring nutrients, reproducing and releasing waste products - the enzymes are surrounded by the immobilised matrix which protects them from extreme conditions so higher temperature or a wider ph range can be used without causing denaturing - however setting up the immobilised enzyme process is more expensive and immobilised enzymes are usually less active than free enzymes making the process slower

Question 64

describe downfall of normal enzymes

Answer 64

- product has to be isolated from enzymes before use this could be expensive

Question 65

what are the methods used to immobilise enzymes

Answer 65

- adsorption - covalent bonding - entrapment - membrane separation

Question 66

Describe adsorption

Answer 66

- enzymes molecules are bound to a supporting surface by a combination of hydrophobic interactions and ionic links - suitable surfaces include clay, porous carbon, glass beads and resins - the enzyme molecules are bound with the active site exposed and accessible to the substrate - however the active site may be slightly distorted by the additional interactions which effects enzyme activity - bonding forces are not always strong and enzymes can become detached and leak into the reaction mixture

Question 67

describe covalent bonding

Answer 67

- enzyme molecule are bonded to a supporting surface such as clay using covalent bonds - enzymes are bonded using a cross linking agent which may also link them in a chain - product of covalent bonding can be expensive and can distort the enzyme active site reducing the activity - enzymes are much less likely to become detached and leak into the reaction mixture

Question 68

describe entrapment

Answer 68

- enzyme molecules are trapped in a matrix that does not allow free movement - enzyme molecules are unaffected by entrapment and remain fully active - substrate molecules must diffuse into the entrapment matrix and the product molecules must be able to diffuse out - method is only suitable only for processes where the substrate and product molecules are relatively small - calcium alginate beads are often used in schools to immobilise enzymes by entrapment - industrial processes may also use a cellulose mesh

Question 69

Describe membrane separation

Answer 69

- enzyme molecules are separated from the reaction mixture by partially permeable membrane - as entrapment the substrate and product molecules must be small enough to pass through the partially permeable membrane by diffusion - this access to enzymes may limit the rate of reaction

Question 70

describe the industrial use of immobilised enzymes

Answer 70

- glucose isomerase - penicillin acylase - lactase - aminoacylase - glucoamylase - nitrile hydratase

Question 71

describe glucose isomerase

Answer 71

- converts glucose to fructose - probably most widely used enzyme as the number of applications of the syrup produced - used to produce fructose corn syrup whcih is much sweeter than sucrose - HFCS is often used in diet foods as less sugar needs to be added for the equivalent sweetness, it may also be used as a sweetener in foods for diabetics, HFCS is cheaper than sucrose especially in soft drinks but also in many processed foods such as breakfast

Question 72

describe penicillin acylase

Answer 72

- formation of semi-synthetic penicillins such a amoxicillin and ampicillin which were first developed in 1960s - some penicillin-resistant microorganisms are not resistant to these semi-synthetic penicillins

Question 73

describe lactase

Answer 73

- converts lactose to glucose and galactose by hydrolysis used to produce lactose-free milk - milk is an important source of calcium which is needed for strong bones and teeth, people with insufficient calcium in their diet are more likley to develop weak bones or osteoporosis so people who are lactose intolerant are given calcium supplements

Question 74

describe aminoacylase

Answer 74

- a hydrolase used to produce pure samples of L-amino acids by removing the acyl group from nitrogen of an N-acyl-amino acid - L-amino acids are used as the building blocks for synthesis of a number of pharmaceutical and agrochemical compounds, they may also be used as additives for human food and animal feedstuffs

Question 75

describe glucoamylase

Answer 75

- converts dextrins to glucose, during the hydrolysis of starch, short polymers of glucose are formed, hydrolysis by glucoamylase can convert these dextrins to glucose, glucoamylase can be immobilised on a variety of surfaces and used to digest sources of starch such as corn and cassava - enzyme is used in a wide range of fermentation processes including the conversion of starch pulp to alcohol used to produce gasohol - an alternative fuel for motor vehicles it is also used within the food industry to make high fructose corn syrup

Question 76

describe nitrile hydratase

Answer 76

- converts nitriles to amides inclduing acrylonitrile to acrylamide, acrylamide can be polymerised to form polyacrylamide which is a plastic used as a thickener - most common use polyacrylamide is in treatment of water and helps to stick many small contaminants together so that they are precipitated or are easy to filter out of the water - polyacrylamide is also used in paper-making and to make gel for electrophoresis