6.4 Flashcards
(161 cards)
1
Q
what are clones
A
clones are genetically identical copies (this can be for organisms or cells
2
Q
what type of reproduction produces clones
A
asexual reproduction produces clones
3
Q
what type of cell division forms clones
A
mitosis
4
Q
why may not cells produced from mitosis be genetically identical after division
A
because after division, they may differentiate to form two different types of cell
5
Q
any organism that reproduces asexually produces clones of itself, give examples
A
single celled yeast reproduce by budding
-bacteria reproduce by binary fission
6
Q
what are the advantages of natural cloning ( reproduction by cloning) for plants
A
-if the conditions for growth are good for the parent, then they will also be good for the offspring
-cloning is relatively rapid- so the population can increase quickly to take advantage of suitable environmental conditions
-reproduction can be carried out, even if there is only one parent and sexual reproduction is not possible
7
Q
what are the disadvantages of natural cloning ( reproduction by cloning) in plants
A
-the offspring may become overcrowded
-there will be no genetic diversity (except that causes 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
8
Q
why can plants reproduce by natural cloning
A
because they contains cells which retain the ability to divide and differentiate
natural cloning involves a process called vegetative propagation
9
Q
what is vegetative propagation
A
this is reproduction from vegetative parts of a plant (usually an over-wintering organ) rather than through specialised reproductive structures
-its a natural cloning method
10
Q
describe runners or stolens and how they allow for natural cloning in plants
A
many plants can grow horizontal stems that can form roots at certain points, these stems can be called runners or stolens if they grow on the surface of the ground. this means plants can reproduce by cloning
11
Q
describe rhizomes and how they allow for natural cloning in plants
A
many plants can grow horizontal stems that can form roots at certain points, these stems can be called rhizomes if they are underground. this means plants can reproduce by cloning
some rhizomes are adapted as thickened over-wintering organs from which one or more new stems grow in the spring
12
Q
describe suckers and how they allow for natural cloning in plants
A
suckers are new stems that grow from the roots of a plant- these may be close to the base of an older stem or could be some distance away. In all cases, the original horizontal branch may die, leaving the new stem as a separate individual
13
Q
describe bulbs and how they allow for natural cloning in plants (how it undergoes vegetative propagation)
A
bulbs (e.g onions) are an over-wintering mechanism for many perennial monocotyledonous plants. Bulbs consist of an underground stem from which grows a series of fleshy leaf bases. There is also often an apical bud, which will grow into a new plant in the spring. Often a bulb contains more than one apical bud and each apical bud will grow into a new plant.
14
Q
describe corms and how they allow for natural cloning in plants (how it undergoes vegetative propagation)
A
corms are often mistaken for bulbs. However, corms are solid rather than fleshy like a bulb. A corm is an underground stem with scaly leaves and buds. Corms remain in the ground over winter. In the spring, the buds grow to produce one or more new plants.
Croci and Gladioli reproduce using corms
15
Q
describe leaves and how they allow for natural cloning in plants (how it undergoes vegetative propagation)
A
The Kalanchoe plant reproduces asexually, as clones grow on the leaf margins. the immature plants drop off the leaves and take root
16
Q
describe tubers and how they allow for natural cloning in plants (how it undergoes vegetative propagation)
A
tubers are another type of underground stem. Potatoes are tubers. One potato will grow into one or more plants. Each new plant can then produce many new tubers (potatoes) later that year.
17
Q
who clones more often, animals or plants?
A
plants
18
Q
when do animals/ mammals clone
A
mammals clone when identical twins are formed. This occurs when a fertilised egg (zygote) divides as normal, but the two daughter cells then split to become two separate cells. Each cell grows and develops into a new individual.
19
Q
what are the examples of the two animals that commonly reproduce to produce clones
A
-the water flea (daphnia) and the greenfly
20
Q
gardeners have made use of vegetative propagation, what is the easiest way to make clones
A
the easiest way to make clones is through cuttings
21
Q
how do you make cuttings
A
to make a cutting, a stem is cut between two leaf joints (nodes). The cut end of the stem is then placed in moist soil. 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,
This technique can be used to produce large numbers of plants very quickly
22
Q
some plants such as geraniums and blackberry take root easily from cuttings, if this is not the case how is it achieved
A
-dipping the cut stem in rooting hormone helps stimulate root growth.
-it may also be helpful to wound or remove the bark from the cut end of the stem, as this encourages the plant to produce a callus
23
Q
cuttings can also be made successfully from other parts of a plant, state these 3 ways (excluding cutting a stem between two leaf joints)
A
-root cuttings, in which a section of root is buried just below the soil surface, and produces new shoots
-scion cuttings, which are dormant woody twigs
-leaf cuttings in which a leaf is placed on moist soil. The leaves develop new stems and new roots. Some leaves may produce many new plants from one cutting
24
Q
what cloning technique are used by common houseplants
A
cloned using tissue culture techniques
25
define tissue culture
growing new tissues, organs or plants from certain tissues cut from a sample plant.
its carried out in a nutrient medium under sterile conditions. Application of plant growth substances at the correct time can encourage the cells in growing tissue to differentiate
26
define micropropagation
growing large numbers of new plants from meristem tissue taken from a sample plant
micropropagation involves taking a small piece of plant tissue (the explant) and using plant growth substances to encourage it to grow and develop into a new plant
27
what are the 6 steps of micropropagation
1. suitable plant material is selected and cut into small pieces. These are called explants. Explants could be tiny pieces of leaf, stem, root or bud. Meristem tissue is often used, as this is always free from virus infection
2. The explants are sterilised using dilute bleach or alcohol to kill 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 (usually agar gel) containing suitable nutrients such as glucose, amino acids and phosphates. The gel also contains high concentrations of the plant growth substances auxin and cytokinin. This stimulates the cells of each explant to divide by mitosis to form a callus ( a mass of undifferentiated, totipotent cells)
4. Once a callus has formed, its divided to produce a larger number of small clumps of undifferentiated cells
5. These small clumps are stimulated to grow, divide and differentiate into different plant tissues. This is achieved by moving cells to different growth media. Each medium contains different amounts of auxin and cytokinin. The first medium contains the ratio 100 auxin : 1 cytokinin, and this stimulates roots to form. The second medium contains the ratio 4 auxin : 1 cytokinin, which stimulates the shoots to form.
6. once tiny plantlets have been formed, these are transferred to a greenhouse to be grow in compost or soil and acclimatised to normal growing conditions.
28
what type of species have involves the ability to clone naturally
some invertebrate species such as the greenfly and water fleas have evolved the ability to clone naturally
29
what type of cells are needed in order for cloning to be successful
totipotent cells (these cells have the ability to divide and differentiate into all types of cell found in the adult organism ( in animals these are found in early embryo cells))
30
what is reproductive cloning able to produce
can produce a large number of genetically identical animals
31
what are two ways in which reproductive cloning may be useful
cloning may be useful for:
-elite farm animals produced by selective breeding (artificial selection) or genetic modification. E.g. a particularly good individual bull whose value is a stud- supplying sperm for artificial insemination
-Genetically-modified animals developed with unusual characteristics, e.g. goats produce spider silk in their milk and cows produce less methane
32
what are the two main ways to achieve reproductive cloning
-embryo twinning
-somatic cell nuclear transfer (SCNT)
33
when can mammals produce identical offspring (twins)?
and what has this given rise to?
-mammals can produce twins if an embryo splits very early in development.
- this process has given rise to an artificial technique of embryo splitting
34
outline the process of embryo splitting
1. a zygote (fertilised egg) is created by in vitro fertilisation (IVF)
2. The zygote is allowed to divide by mitosis to form a small ball of cells
3.The cells are separated and allowed to continue to dividing
4. Each small mass of cells is placed into the uterus of a surrogate mother
35
why is artificial embryo splitting used and what are the downsides
-its used to clone elite farm animals or animals for scientific research.
-However, the precise genotype and phenotype of the offspring produced will depend upon the sperm and egg used thus the precise genotype will be unknown until the animals are born
36
give a brief overview of what Somatic cell nuclear transfer is (SCNT)
SCNT is the only way to clone an adult.
The advantage is that the phenotype is known before the cloning starts.
This process was first successfully performed to produce Dolly the sheep
37
outline the process of Somatic Cell Nuclear Transfer
1. An egg is obtained and its nucleus is removed, known as enucleation
2. A normal body cell (somatic cell) from the adult to be cloned is isolated and may have the nucleus removed
3. The complete adult somatic cell or its nucleus is fused with the empty egg by applying an electric shock
4. The shock also triggers the egg cell to start developing as though it had just been fertilised
5. the cell undergoes mitosis to produce a small batch of cells
6. The young embryo is placed into the uterus of a surrogate mother
38
what is non-reproductive cloning
non-reproductive cloning is the production of cloned cells and tissues for purposes other than reproduction
39
describe therapeutic cloning with examples
in therapeutic cloning, new tissues and organs can be grown as replacement parts for people who are not well
-skin can be grown in vitro to act as a graft over burned areas
-cloned cells have been used to repair damage to the spinal cord of a mouse and to restore the capability to produce insulin in the pancreas
-there is potential to grow whole new organs organs to replace diseased organs
tissues grown from the patient's own cells will be **genetically identical and so avoid rejection**, which is a problem when transplanting donated organs
40
why is cloning used for scientific research
cloning genetically identical embryos can be used for scientific research into the **action of genes** that control development and differentiation.
They can also be used to grow specific tissues or organs for use in tests on the **effect of medicinal drugs.**
41
what are the arguments against artificial cloning in animals
-lack of **genetic variation/ genetic diversity** may expose the herd to certain **diseases** or pests.
-Animals may be produced with little regard for their **welfare**, which may have undesirable side effects such as meat-producing chickens that cannot walk
-The **success rate** of adult cell cloning is very poor and the method is a lot more expensive than conventional breeding. Cloned animals may be less healthy and have shorter life spans.
-There are **ethical** issues regarding how long the embryo survives and whether it is right to create a life to simply destroy it
42
what are the arguments for artificial cloning in animals
-can produce a whole herd of animals with a **high yield** or showing an unusual combination of characteristics (such as producing silk in their milk)
-produces genetically identical copies of very **high value** individuals retaining the same characteristics
-using genetically identical embryos and tissues for **scientific research** allows the effects of **genes and hormones** to be assessed with no interference of different genotypes.
-**testing medicinal drugs** on cloned cells and tissues avoids using animals or people for testing
-can produce cells and tissues **genetically identical to the donor**, for use in repairing damage caused by disease or accidents.
-individuals from and endangered species can be cloned to increase numbers
43
define biotechnology
the use of living organisms or parts of living organisms in industrial processes. This could be used to produce food, drugs or other products.
This can include the domestication of animals, planting of crops, mechanisation of agricultural processes and selective breeding of plants and animals over many generations.
44
what is the oldest documented example of biotechnology.
the production of beer or ale 7000 years ago
other early examples of biotechnology includes making yogurt or cheese as well as baking
45
what does brewing make use of
brewing makes use of yeast (a single-celled fungus) to ferment maltose sugars in germinating barley
46
what are some more recent examples of biotechnology
more recent examples of biotechnology include:
-the use of the bacterium *Clostridium acetobutylicum* to produce acetone, which was needed to make explosives during WW1
-the manufacture of penicillin from the fungus *Penicillium notatum* during WW2
-these examples and others shifted the emphasis of biotechnology away from food towards the manufacture of drugs.
47
what has led to a huge expansion in biotechnology in our current day society
-new science of DNA technology has brought biotechnology to its current position
-Our increasing understanding of genetics and genetic engineering has led to a huge expansion in biotechnology. The biggest expansion is in the use of microorganisms in industrial processes
48
what are the 4 main areas in which microorganisms are used in biotechnology
-food
-pharmaceutical drugs
-enzymes
-other products
49
how are microorganisms used in biotechnology for food (give examples)
-ethanol in beer and wine. organism used: yeast (*S. cerevisiae*)
-carbon dioxide used to make bread. organism used: yeast (*S. cerevisiae*)
-lactic acid to make yoghurt and cheese. organism used: *Lactobacillus bacteria*
-mycoprotein- a filamentous fungus protein used to make vegetarian food. organism used: *Fusarium venenatum* fungus
-soya- soya beans are fermented to produce soy sauce. organism used: yeast or *Aspergillus*
50
how are microorganisms used in biotechnology for pharmaceutical drugs (give examples)
-penicillin. organism used: *Penicillium* fungus
-other antibiotics. - other fungi and bacteria used
-insulin and other therapeutic human proteins- organism used: genetically modified bacteria
51
how are microorganisms used in biotechnology for enzymes (give examples)
-protease and lipase are using in washing powders- (bacteria)
-pectinase used to extract juice from fruit
-sucrase used to digest sugar to make food sweeter- (yeasts)
-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
52
how are microorganisms used in biotechnology for the product of other products (give examples)
-biogas, which is a combination of carbon dioxide and methane - uses anaerobic bacteria (decomposers)
-citric acid, E330, a food preservative- uses a fungus
-bioremediation- cleaning waste water- uses a variety of bacteria and fungi
53
what are the advantages of using microorganisms in biotechnology
+microorganisms are relatively **cheap** and **easy** to grow
+In most cases, the production process takes place at a **lower temperature** than would be required to make the molecules by chemical engineering means. This **saves fuel** and reduces costs
+The production process can take place at **normal atmospheric pressure**, which is **safer** than using chemical reactions which may require a high pressure for successful manufacture of certain molecules.
+the production process is **not dependent on climate**- so it can take place anywhere in the world with the resources to build and run suitable equipment
+the microorganism can be **fed by-products** from other food industries, e.g. starch, waste water or molasses. (Note: however, that the starting ingredients often have to be pre- treated, which adds to the cost)
+Microorganisms have a **short life cycle and reproduce quickly**. Some microorganisms may reproduce as often as every 30 minutes under ideal conditions. Therefore, a large population can grow very quickly inside the reaction vessel (fermenter)
+Microorganisms can be **genetically modified** relatively easily. This allows specific production processes to be achieved
+There are fewer **ethical considerations** to worry about in using microorganisms
+The products are often released from the microorganism into the surrounding medium. This makes the product **easy to harvest**
+The product is often **more pure or easier to isolate** than in conventional chemical engineering processes. This means **lower downstream costs.**
54
microorganisms are not the only organisms used in biotechnology, name some other organisms used
genetically modified animals such as sheep, goats and cows can be used to produce useful proteins
55
how can proteins be harvested from animals and genetically modified animals
-in some mammals, proteins are incorporated into the milk so are easily harvested.
For example, goats have been genetically modified to possess the gene for spider silk which is secreted into their milk.
-in other cases proteins may be secreted in the blood, cows have been genetically modified to synthesise human antibodies which can be isolated from their blood.
56
biotechnology means 'using organisms in production processes' but what other processes does biotechnology encompass
biotechnology also encompasses processes such as:
-gene technology
-genetic modification and gene therapy
-selective breeding
-cloning by embryo-splitting and micropropagation
-the use of enzymes in industrial processes
-immunology
57
do the qs on page 250 xx
xx5t
58
what is yoghurt
yoghurt is milk that has undergone fermentation by *Lactobacillus bulgaricus* and *Streptococcus thermophilus*.
59
what is fermentation
the breakdown of organic molecules in the absence of oxygen; anaerobic respiration
60
what is the function of *Lactobacillus bulgaricus* and *Streptococcus thermophilus* in yoghurt production
They (the bacteria) convert lactose to lactic acid.
The acidity denatures the milk protein causing it to coagulate.
They (the bacteria) partially digest the milk, making it easy to digest
Fermentation also produces the flavours characteristic of yoghurt.
61
what other bacteria may be added to yoghurt and why
other bacteria such as *L. acidophilus*, L. subsp.*casei* and *Bifidobacterium*, may be added as probiotics. This is bacteria that benefits human health by improving digestion of lactose, aiding gastrointestinal function and stimulating the immune system.
62
how is cheese made
milk is usually pre-treated with a culture of bacteria (*Lactobacillus*) that can produce lactic acid from the lactose. Once it is acidified, the milk is mixed with rennet.
Rennet contains the enzyme rennin (chymosin), which is found in the stomach of young mammals. Rennin coagulates the milk protein (casein) in the presence of calcium ions.
Kappa-casein, which keeps the casein in solution, is broken down. This makes the casein insoluble.
The casein is precipitated by the action of calcium ions, which bind the molecules together.
The resulting solid called curd, is separated from the liquid component (whey) by cutting, stirring and heating. The bacteria continue to grow producing more lactic acid. The curd is then pressed into moulds.
63
what part of cheesemaking determines the cheeses characteristics
treatment while making and pressing the curd determines the characteristics of the cheese.
64
how is flavour determined when making cheese
flavour is determined during the later ripening and maturing process.
the cheese can be given additional flavour by inoculation with fungi such as *Penicillium* to produce 'blue' cheese.
65
what is bread a mixture of
bread is a mixture of flour, water and salt with some yeast (which is a single celled fungus, *Saccharomyces cerevisiae*
66
what are the three main steps of bread making
1. mixing- the ingredients are mixed together thoroughly by kneading. This produces dough.
2. Proving/ fermenting- the dough is left in a warm place for up to 3 hours while the yeast respire anaerobically. This produces CO2 bubbles, causing the dough to rise. Ethanol is also produced
3. Cooking- the risen dough is baked. Any alcohol evaporates during the cooking process.
67
simply, what process makes alcoholic beverages?
alcoholic beverages are also the product of anaerobic respiration of yeast (S.cerevisiae)
68
how is wine made
wine is made using grapes that naturally have yeasts on their skin.
grapes contain the sugars glucose and fructose.
when the grapes are crushed, the yeast uses sugar to produce carbon dioxide and alcohol.
69
how is ale or beer made
Ale or beer is brewed using barley grains that are beginning to germinate.
This process is called malting.
As the grain germinates it converts stored starch to maltose, which is respired by the yeast. Anaerobic respiration again produces carbon dioxide and alcohol. Hops are used to give a bitter taste to the liquid.
70
more recently, how are microorganisms being used in food?
more recently, microorganisms are being used to manufacture a protein that is used directly as food. The microorganism used most frequently is the fungus *Fusarium venenatum*
The fungal protein or mycoprotein is also known as single-cell protein
71
Although microorganisms are generally used indirectly to produce food, they have recently been used directly to make food: what is the frequently used fungus that directly makes proteins to be used in food
The fungus Fusarium venenatum directly produces mycoprotein, also known as single cell protein (SCP).
72
what is the best known example of a mycoprotein/ single-cell protein (SCP)
Quorn which was first produced in the early 1980s.
Its marketed as a meat substitute for vegetarians and a healthy option for non vegetarians as it contains no animal fat or cholesterol.
73
why is there a huge potential in Single-cell protein (SCP) production
because microorganisms such as *Kluyveromyces, Scytalidium & Candida* (fungi) can produce protein with a simmilar amino acid profile to animal and plant protein.
They can also grow on any organic substrate including waste materials such as paper and whey (curdled milk from which the curds have been removed)
74
what are the advantages of using microorganisms for protein production directly in food
+ production of protein can be many times faster than that of animal or plant protein.
+the biomass produced has a very high protein content (45-85%)
+ there are no animal welfare issues
+the microorganisms provide a good source of protein
+the protein contains no animal fat or cholesterol
+the microorganism can easily be genetically modified to adjust the 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
75
what are the disadvantages of using microorganisms for protein production directly in food
-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 its 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 can be particularly different in methionine
-infection- the conditions needed for microorganism to grow are also ideal for **pathogenic organisms**. Care must be taken to ensure the culture is not infected with the wrong organisms.
-palatability- the protein does not have the taste or texture of traditional protein sources.
76
what does commercial drug production involve
commercial drug production uses large stainless steel containers called fermenters, in which the growing conditions can be controlled to ensure the best possible yield of the product. The conditions must be controlled
77
what factors must be controlled in commercial drug production
-temperature
-nutrients available
-oxygen availability
-pH
-concentration of product
78
why must temperature be controlled in commercial drug production
too hot and enzymes will be denatured, too cool and growth will be limited
79
why must nutrients available be controlled in commercial drug production
microorganisms require nutrients to grow and synthesise the product. Sources of carbon, nitrogen, minerals and vitamins are needed.
80
why must oxygen availability be controlled in commercial drug production
most microorganisms respire aerobically
81
why must concentration of product be controlled in commercial drug production
if the product is allowed to build up, it may affect synthesis
82
what must a fermenter be sterilised using
a fermenter must be sterilised using superheated steam
83
once a fermenter is sterilised, what is it filled with?
it can then be filled with all the components required for growth and supplied with a starter culture of the microorganism to be used. The culture will be left to grow and synthesise its own nutrients
84
regarding page 253, label the parts of an industrialised fermenter
-pressure vent prevents any gas build up
-air inlet- sterile air provides oxygen in aerobic farms
-water jacket inlet- allows circulation of water around the fermenter to regulate temperature
-outlet tap for draining fermenter
-motor-rotates the blades (impellers) to mix the culture evenly
-inlet for addition of nutrients
-water jacket outlet
-electronic probes for measuring oxygen, pH and temperature levels
-air outlets often in a ring- air bubbles out from outlets, mixing with culture (known as sparging)
-all inlets and outlets are fitted with filters to prevent contamination
85
what are primary metabolites
Primary metabolites produced during the **normal activities** of the microorganism **(and during growth)** will be collected from a fermenter during the exponential phase.
In a fermenter, the population is not kept in a closed culture, but conditions are maintained for optimal growth.
These products are **continually released** from cells and can be extracted continually from the fermenting broth.
86
what is continuous culture
-the broth is topped up with nutrients as these are used by microorganisms.
Some of the broth is removed regularly to extract the product and remove cells from the broth- otherwise the population becomes too dense.
Continuous culture keeps the microorganisms growing at a **specific growth rate**
87
what are secondary metabolites
secondary metabolites are other products produced only where the cells are placed under stress, such as a high population density or limited nutrient availability.
They are produced mostly during the stationary phase of growth
The population must be kept in a closed culture and the metabolites can be collected at the end of the stationary phase or during the decline phase.
88
what is batch culture
batch culture is where the culture is set up with a limited quantity of nutrients and is allowed to ferment for a specific time. After this time the fermenter is emptied and the product can be extracted from the culture.
**Secondary metabolites** can be produced here
89
what is asepsis
asepsis is ensuring that sterile conditions are maintained.
90
when sterile conditions are maintained through asepsis, what does the nutrient medium also allow for
the nutrient medium would also support the growth of unwanted microorganisms which would reduce production for various reasons
91
how do unwanted microorganisms reduce production in a nutrient medium?
unwanted microorganisms:
-**compete** with the cultured microorganisms for nutrients and space
-reduce the **yield** of useful products
-**spoil** the product
-produce **toxic chemicals**
-**destroy** the cultured microorganisms and their products
note: in processes where foods or medicinal chemicals are produced, all products must be discarded if contamination by unwanted organisms occurs
92
how is penicillin successfully mass produced
penicillin is successfully mass produced through fermentation by the fungus *Penicillium chrysogenum*.
modern strains of the fungus have been selectively bred to be more productive than the early strains
93
what type of culture must penicillin be manufactured by and why
penicillin is a secondary metabolite so its only produced once the population has reached a certain size which means it must be manufactured by batch culture
94
outline the process in which penicillin is manufactured by batch culture
1. the fermenter is run for 6 to 8 days. 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
3. The antibiotic is mixed with inert substances and prepared for administration in tablet form, as a syrup or in a form suitable for injection
95
what do microorganisms use to carry out their required processes
-microorganisms use enzymes to carry out the required processes. Any condition suitable for enzyme activity is likely to be suitable for bacterial and fungal growth.
96
in 1978, synthetic human insulin was developed instead of using pig pancreas, how?
synthetic human insulin was developed by genetically modifying a bacterium.
The gene for human insulin was combined with a plasmid to act as a vector, so the gene could be inserted into the bacterium *Escherichia coli*.
The resulting genetically modified bacterium enabled the production of vast quantities of human insulin at a relatively low cost
97
by what type of culture is insulin manufactured by
insulin is manufactured by continuous culture
98
what is bioremediation
bioremediation is the use of microorganisms to clean the soil and underground water on polluted sites. The organisms convert the toxic pollutants to less harmful substances.
99
what was a modified pseudomona bacterium able to do?
the bacterium was able to breakdown crude oil, and he proposed that it could be used in treating oil spills. solvents and pesticides can also be treated using bioremediation.
100
what does bioremediation involve stimulating
bioremediation involves stimulating the growth of suitable microbes that use the contaminants as a source of food. It required the right conditions of the growth of microorganisms
101
what are the conditions for the growth of organisms
-available water
-a suitable temperature
-suitable pH
-(in some cases, additional nutrients must be needed to ensure the microorganisms grow effectively)
-(it may be necessary to pump in oxygen for aerobic bacteria)
102
what are the advantages of bioremediation
-uses natural systems
-less labour/ equipment is required
-treatment in situ (soil can also be dug up and moved to be treated ex situ)
-few waste products
-less risk of exposure to clean-up personnel
103
what are the disadvantages of bioremediation
-bioremediation is only suitable for certain products: heavy metals such as cadmium and lead cannot be treated)
104
do the explain qs page 255
255
105
what will microorganisms grow on
microorganisms will grow on almost any material that provides the carbon compounds for respiration and a source of nitrogen for protein synthesis
106
in a lab, microorganisms are grown on two types of growth medium, state these:
the two types of growth medium:
-a soup-like liquid called broth, kept in bottles or tubes
-a set jelly-like substance called agar, which is melted and poured into petri dishes
107
what does typical nutrient agar contain?
typical nutrient agar contains peptones ( from the enzymatic breakdown of gelatine), yeast extract, salts and water, it may also contain glucose or blood.
108
why have aseptic techniques been developed
aseptic techniques have been developed to reduce the likelihood of contaminating the medium with unwanted bacteria or fungi.
109
what is the standard procedure of aseptic techniques
1. wash your hands
2. disinfect the working area
3. have a bunsen burner nearby to heat the air. This causes the air to rise and prevents airborne microorganisms settling. It also creates an area around it of sterile air in which the microbiologist can work
4. as you open the vessel, pass the neck of the bottle over the flame to prevent bacteria in the air entering the bottle. The bottle should also be flamed as it is closed.
5. Do not lift the lid of the Petri dish off completely- just open it enough to allow the introduction of the desired microorganism.
6. Any glassware or metal equipment should be passed through the flame before and after contact with the desired microorganisms.
110
what are the three main steps of growing microorganisms on an agar plate
1.sterlisation
2. inoculation
3. incubation
111
how is the medium for growing microorganisms sterilised
the medium is sterilised by heating it in an autoclave at 121 degrees Celsius for 15 minutes (the high temperature is achieved by boiling the water under high pressure inside the autoclave). This kills all living organisms including any bacterial or fungal spores.
112
what occurs to the medium once it is sterilised by heating it in an autoclave and has cooled
once the medium has cooled sufficiently to handle, it is poured into sterile petri dishes and left to set. It is important that the lid is kept on the petri dish to prevent infection
113
what is inoculation
inoculation is the introduction of microorganisms to the sterile medium. This can be achieved in a number of ways
114
what are the 4 ways in which inoculation can occur
inoculation can occur via:
-streaking
-seeding
-spreading
-using a small cotton swab
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what is streaking
streaking is where a wire inoculating loop is used to transfer a small drop of liquid medium onto the surface of the agar. The drop is drawn out into a streak by dragging the loop across the surface.
Take care not to break the surface of the agar
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what is seeding
a sterile pipette can be used to transfer a small drop of liquid medium to the surface of the agar or to the petri dish before the agar is poured in.
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what is spreading
a sterile glass spreader can be used to transfer a small drop of liquid medium to the surface of the agar or petri dish before the agar is poured in
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how can a small cotton swab be used to achieve inoculation
-a small cotton swab or cotton bud can be moistened with distilled water and used to collect microorganisms from a surface then carefully wiped over the surface of the agar medium
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what are the 4 steps of inoculating an agar plate
1. heat inoculating loop in blue flame and allow to cool briefly.
2. remove cap from broth culture and flame mouth of bottle. Dip cool sterile inoculating loop in broth. Flame and recap bottle
3. spread a streak of culture over surface of agar and cover with a lid. Reheat inoculating loop in blue flame
4. Use adhesive tape to hold lid on petri dish and incubate at 25 degrees Celsius
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how should the petri dish be incubated successfully
The peri dish must be labelled and the top taped to the bottom using two strips of adhesive tape.
be careful not to seal the petri dish completely, as this can lead to the selection of anaerobic bacteria which may be pathogenic.
the petri dish is then placed in a suitable warm environment such as an incubator. It should be placed upside down as this prevents drops of condensation falling onto the surface of the agar. It also prevents the agar medium from drying out too quickly.
suitable temperatures will depend on the type of organisms being grown
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in how many hours time can cultures be examined
cultures can be examined after 24-36 hours.
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bacteria grow into visible colonies, how do these colonies look
visible colonies may look shiny or dull.
some colonies are round with entire edges, while others can have crenated edges The colonies can also be a range of different colours.
Each colony results from a single bacterium..
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how do filamentous fungi colonies look
filamentous fungi grow into a mass of hyphae, which may also be circular, but the mass is not so shiny and often looks like cotton wool with fluffy aerial hyphae
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how do single celled fungi colonies look
single-celled fungi (yeasts) grow as circular colonies
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after using a petri dish, what should occur
all petri dishes must be completely sterilised after use and before disposal
thoroughly wash your hands after handling a petri dish, any moisture coming out of the dish could be a source of infection.
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what visible change will liquid broth undergo when bacteria have grown
a liquid broth is in initially clear but will turn cloudy when bacteria have grown.
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what are the positives of using a liquid broth
a liquid broth can be useful to increase the number of microorganisms before transferring to agar plates for counting or identification.
A liquid broth can also be used to investigate population growth (growth rate and population size)
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what is a disadvantage of there being to many individual microorganisms in a broth
in turn there may be too many colonies that merge together making a count impossible
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define serial dilution
a sequence of dilutions used to reduce the concentration of a solution or suspension
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what is a 'closed culture'
a closed culture refers to a population in which all conditions are set at the start and there is no exchange with the external environment.
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what type of production (batch or continuous) is the conditions of a closed culture simmilar to
the conditions for a closed culture are simmilar to the conditions set up for batch production, however , certain substances such as oxygen may be added to keep the population growing until the nutrients are used up.
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name the phases of the growth curve for a closed culture
-lag phase
-exponential phase
-stationary phase
-death or decline phase
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state what is happening during the lag phase
In the early part of population growth, the population does not grow quickly. This is partly because the population is still small, but also because the organisms are adjusting to their new environment
This may involve:
-taking up water
-cell growth
-switching on (activating) certain genes
-synthesising specific proteins (enzymes)
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state what is happening during the log (exponential) phase
In the log (exponential) phase, the microorganisms have adjusted to their environment. They each have the enzymes needed to survive. Each individual has sufficient nutrients and space to grow rapidly and reproduce. The population doubles in size with each generation. In some microorganisms, this can be as frequently as once every 20-30 minutes.
135
state what is happening during the stationary phase on the graph
Eventually the increasing number of organisms use up the nutrients and produce increasing amounts of waste products such as carbon dioxide and other metabolites. The rate of population growth declines and the number of individuals dying increases until the reproduction rate equals the growth rate. This is the stationary phase where there is no population growth.
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state what is happening at the death (decline phase)
The nutrients run out and the concentration of waste products may become lethal. More individuals die than are produced and the population begins to fall. Eventually all the organisms will die.
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when are primary metabolites produced
and
when are primary metabolites collected
primary metabolites are produced during the normal activities of the microorganism
primary metabolites will be collected from a fermenter during the log (exponential) phase
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what type of culture are microorganisms producing primary metabolites/ the population kept in
in a fermenter, the population is not kept in a closed culture, but conditions are maintained for optimal growth
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at what point on the growth curve are secondary metabolites produced
and
when are secondary metabolites collected
secondary metabolites are produced in the stationary phase
the metabolites must be collected at the end of the stationary phase or during the decline phase
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what type of culture are microorganisms producing secondary metabolites/ the population kept in
the population must be kept in a closed culture
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how can some biotechnical processes be simplified
some biotechnical processes can be simplified by taking the enzymes out of the microorganisms
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as enzymes are not used up in a reaction , what needs to happen to the enzymes once the product has been formed in biotechnology
in industrial processes, the product must be isolated from the enzymes before use
this is expensive
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what is an immobilised enzyme
an immobilised enzyme is an enzyme that is held in place and not free to diffuse through solution.
immobilised enzymes are taken out of suspension and held so that they do not mix freely with the substrate
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what are the advantages of immobilised enzymes
+enzymes do not mix with the product, so extraction costs are lower
+the enzymes can easily be reused
+A continuous process is made easier, as there are no cells requiring nutrients, reproducing and releasing waste products.
+The enzyme are surrounded by the immobilising matrix, which protects them from extreme conditions- so higher temperatures or a wider pH range can be used without denaturing.
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what are the disadvantages of immobilised enzymes
- setting up the immobilised enzyme process is more expensive
-immobilised enzymes are usually less active than free enzymes making the process slower
146
what are the four methods to immobilise enzymes
-Adsorption
-Covalent bonding
-Entrapment
-Membrane separation
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Adsorption can be used to immobilise enzymes
state what adsorption is
-enzyme 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 affecting enzyme activity.
The bonding forces are not always strong and enzymes can become detached and leak into the reaction mixture.
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Covalent bonding can be used to immobilise enzymes
state what covalent bonding is
enzyme molecules are bonded to a supporting surface such as clay using strong covalent bonds. The enzymes are bonded using a cross-linking agent, which may also link them in a chain.
The production of covalent bonding can be expensive and can distort the enzyme active site, reducing activity. However, the enzymes are much less likely to become detached and leak into the reaction mixture
149
Entrapment can be used to immobilise enzymes
state what entrapment is
Enzyme molecules are trapped in a matrix that does not allow free movement. The enzyme molecules are unaffected by entrapment and remain fully active. However, the substrate molecules must diffuse out. The method is thus suitable only for processes where he 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 cellulose mesh
150
Membrane separation can be used to immobilise enzymes
state what membrane separation is
Enzyme molecules are separated from the reaction mixture by a partially permeable membrane. As in entrapment, the substrate and product molecules must be small enough to pass through the partially permeable membrane by diffusion. This access to the enzymes may limit the reaction rate
151
look at immobilised image
...
152
what are the six industrial immobilised enzymes
- glucose isomerase (also known as xylose isomerase)
-Penicillin acylase (also known as penicillin amidase)
-lactase
-aminoacylase
-glucoamylase
-nitrile hydratase
153
how is the immobilised enzyme glucose isomerase (also known as xylose isomerase) used industrially
-glucose isomerase converts glucose to fructose
-glucose isomerase is probably the most widely used enzyme, because of the number of applications of the syrup produced
-glucose isomerase is used to produce high fructose corn syrup (HFCS) which is much sweeter than sucrose.
154
how are HFCS (produced by glucose isomerase) used in the real world
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 and so is widely used in the food industry to replace sucrose- especially in soft drinks, but also in many processed foods such as breakfast cereals, jam, ice cream, yoghurt and sliced ham
155
how is the immobilised enzyme penicillin acylase (also known as penicillin amidase) used industrially
allowed for the formation of semi-synthetic penicillins, such as amoxicillin and ampicillin. Some penicillin-resistant microorganisms are not resistant to these semi-synthetic penicillins.*
156
what is the industrial use of the immobilised enzyme of lactase
-lactase converts lactose to glucose and galactose by hydrolysis. Used to produce lactose- free milk
157
why is it important that people who are lactose intolerant are given calcium supplements or lactose-free milk
-milk is an important store of calcium, which is needed for strong bones and teeth.
-People with insufficient calcium in their diet are more likely to develop weak bones or osteoporosis.
-lactose intolerant people are unable to digest and absorb lactose in milk so need another way to gain calcium
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what is the industrial use of aminoacylase
aminoacylase is a hydrolase used to produce pure samples of L-amino acids by removing the acyl group from the nitrogen of an N-acyl-amino acid
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aminoacyclase produces pure samples of L-amino acids, what are L-amino acids used as
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 feedstuff
160
what is the industrial use of the immobilised enzyme called glucoamylase
glucoamylase converts dextrins to glucose. During the hydrolysis of starch, short polymers of glucose (dextrins) are formed. Hydrolysis by glucoamylase can be immobilised on a variety of surfaces and used to digest sources of starch such as corn and cassava.
-the 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 used within the food industry to make high fructose corn syrup
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what is the industrial use of the immobilised enzyme called nitrile hydratase
-nitrile hydrase converts nitriles to amides, including acrylonitrile to acrylamide. Acrylamide can be polymerised to form polyacrylamide, which is a plastic used as a thickener.
-the most common use of polyacrylamide is in treatment of water. It 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.
