Microorganisms, Genetic Engineering and Cloning

Question 1

What are viruses?

Answer 1

Microorganisms that are much smaller than bacteria
They are not cells
Do not respire
Do not excrete
Can not reproduce without a host cell
Can be thought of as halfway between a living organism and a chemical

Question 2

What is biotechnology

Answer 2

The use of microorganism a to make products useful to humans

Question 3

How do temperature and pH affect the rate of CO2 production by yeast (answers useful for any question like this)

Answer 3

Temperature - affects enzyme reactions, provides kinetic energy for molecules, so higher temperature means higher chance of successful collisions

pH - affects enzymes, the enzymes have to work within an active range so the active site doesn’t denature because it will then change shape

Question 4

What is a fermenter?

Answer 4

A large container that is full of liquid called ‘culture medium’ in which microorganisms can grow and reproduce.
The conditions inside the fermentation vessels are kept at optimum levels for growth - so that the yield of the product can be as big as possible

Question 5

Why is there a stirrer in a fermenter?

Answer 5

They are there to mix up the contents. Microorganisms are kept in contact with the fresh medium by paddles that agitate the medium around the vessel - this increases the product yield because microorganisms can always access the nutrients needed for growth
To even out the temperature and distribute heat

Question 6

Why does the jacket contain cooling water?

Answer 6

To prevent the contents from overheating as fermentation produces heat and to keep the temperature at the optimum temperature for the enzymes so that the reaction will be efficient and not denature

Question 7

Why is air pumped through the fermenter?

Answer 7

If the microorganisms need oxygen for respiration, it’s added by pumping in sterile air - this increases the product yield because microorganisms can always respire to provide the energy for growth

Question 8

How and why is the pH monitored in a fermenter?

Answer 8

By adding acid or alkali
It is kept at the optimum level for the enzymes to work efficiently - this keeps the rate of the reaction and product yield as high as possible

Question 9

Why do fermenters have to be made of materials such as steel?

Answer 9

So that they will not corrode as many microorganisms produce acidic waste products

Question 10

What is a microorganism?

Answer 10

A living thing that you can only see with the help of a microscope

Question 11

What are aseptic conditions?

Answer 11

Ways used to prevent contamination by unwanted microorganisms such as filtering the air and sterilising the fermenter

Question 12

Describe the process of beer making (8 steps)

Answer 12

1) barley grains are allowed to germinate for a few days, during which starch in the grains is broken down into sugar by maltose. Then the grains are dried in a kiln - malting
2) the malted grain is mashed up and water is added to produce a sugary solution, which is sieved to remove bits
3) Hops are added to give the beer its bitter flavour
4) yeast is added and the mixture is incubated. The yeast ferments the sugar (glucose) into alcohol (ethanol)
5) the rising concentration of ethanol in the fermentation mixture due to anaerobic respiration eventually starts to kill the yeast, slowing fermentation
6) beer is drawn off and some times clarified
7) beer is then pasteurised to stop it from spoiling
8) beer is then casked

Question 13

What is genetic engineering

Answer 13

The manipulation of the genetic information of an organism with the use of enzymes

Question 14

Why is genetic engineering possible?

Answer 14

Because DNA is the universal code for proteins

Question 15

What is recombinant DNA?

Answer 15

Two different bits of DNA stuck together

Question 16

What does the universal DNA code mean and therefore what can happen

Answer 16

The same base sequence will always code for the same amino acid in all organisms
When a gene is transferred from one species to a completely different one it will still produce the same protein

Question 17

What are restriction enzymes?

Answer 17

Enzymes that recognise specific sequences of DNA and cut the DNA at these points

Question 18

What are DNA ligases?

Answer 18

Enzymes that are used join pieces of DNA together

Question 19

What is a vector?

Answer 19

Something thats used to transfer DNA into a cell

Question 20

What are the two types of vectors

Answer 20

1) plasmids - small, circular molecules of DNA that can be transferred between bacteria
2) viruses - they insert DNA into the organisms they infect

Question 21

What is the process of genetic engineering (using example of insulin)

Answer 21

1) identify and cut out the insulin gene using restriction enzyme
2) the vector DNA is then cut out using the same restriction enzyme
3) the vector DNA and the insulin DNA are mixed together with DNA ligase that join the DNA together to produce recombinant DNA
4) insert the recombinant DNA into the host cell (bacteria)
5) culture transgenic bacteria containing the gene for insulin in fermenter

Question 22

Give examples of uses of genetically modified bacteria

Answer 22

Enzymes for washing powder
Enzymes in the food industry 
Human growth hormone 
Bovine somatotropin (BST) - growth hormone in cattle 
Human vaccines

Question 23

Why are genetically modified bacteria useful for enzymes for washing powder

Answer 23

Many stains on clothing are biological
Enzymes digest the large, insoluble molecules into smaller, soluble molecules that dissolve in the water
Bacteria have been genetically engineered to produce enzymes that work at higher temperatures, allowing faster and more effective action

Question 24

Why are genetically modified bacteria useful for enzymes in the food industry e.g. Glucose isomerase

Answer 24

Turns glucose into fructose which is sweeter

Therefore less is needed to sweeten food and so it saves money and makes food healthier

Question 25

Why are genetically modified bacteria useful for human growth hormones

Answer 25

The pituitary gland in some children does not produce enough growth hormone so their growth is stunted
Injections of growth hormone from genetically modified bacteria restore normal growth patterns

Question 26

Why are genetically modified bacteria useful for BST

Answer 26

Increases milk yield by up to 10kg a day of cows and muscle production in Bulls
To do this they need more food but the money made from the milk is worth the increased cost of food

Question 27

Why are genetically modified bacteria useful for human vaccines

Answer 27

Bacteria have been genetically modified to produce antigens of hepatitis B virus. Used in vaccine against hepatitis B
The body makes antibodies against the antigens but there is no risk of contracting the actual disease from the vaccination

Question 28

Describe the process of making yogurt

Answer 28

1) milk is pasteurised at 93 degrees for 15-30 mins
2) milk is homogenised
3) milk is cooled to 40-45 degrees and inoculated with a starter culture of lactic acid bacteria (lactobacillus)
4) mixture is incubated at this temperature for several hours in a fermenter. The bacteria digest milk proteins and ferment lactose sugar in the milk to form lactic acid
5) lactic acid causes the milk to clot and solidify into yogurt. Thickened yogurt is stirred and cooled to 5 degrees
6) flavourings, colorants and fruit may be added before packaging

Question 29

Why does the milk need to be pasteurised?

Answer 29

To kill of pathogenic bacteria

Question 30

Why does the milk need to be cooled down before the starter culture of bacteria is added?

Answer 30

To maintain the taste and texture of the milk

So the starter culture bacteria are not killed by the high temperature

Question 31

What is lactose and what do the bacteria use it for?

Answer 31

A sugar found in milk

For respiration

Question 32

Why is the thickened yogurt chilled to 5 degrees?

Answer 32

To stop bacteria from respiring to stop it from going off

Question 33

What must happen to fruit before adding it to yogurt

Answer 33

It must be turned into jam, to get rid of any bacteria. This is a way of sterilising it

Question 34

How can genetically modified plants improve food production?

Answer 34

1) resistance to pests and pathogens or herbicides - don’t have to spray as many pesticides and herbicides only harm weeds
2) increased heat, salt and drought tolerance
3) more nutritious crop plants

Question 35

How would you investigate the CO2 production by changing the temperature?

Answer 35

1) have 5 set ups of the experiment each with the test tube of solution in a different water bath. Each water bath is at a different temperature: 10, 20, 30, 40 and 50
2) make sure that in each set up, you use the same type of yeast and the same volume and concentration of yeast and glucose solution
3) the solution in each test tube should have a concentration of 5% and there should be 10ml of it
4) leave each set up for 10 minutes. Start timing when the contents of the test tube has reached the desired temperature, allowing it to acclimatise. After 10 minutes take all the test tubes out of the water baths at same time
5) record the reading on each gas syringe and compare the volume of CO2 produced in each set up
6) repeat the experiment to improve reliability

Question 36

Why are nutrients needed in the fermenter?

Answer 36

Nutrients are needed by microorganisms for growth and are provided in the liquid culture medium

Question 37

Why are there aseptic conditions in a fermenter?

Answer 37

The vessels are sterilised between uses with super-heated steam that kills any unwanted microorganisms.
Having aseptic conditions increases the product yield because the microorganisms aren’t competing with other organisms
It also means that the product doesn’t get contaminated

Question 38

What does transgenic mean?

Answer 38

The transfer of genetic material from one species to another species, species that contain genes transferred from another species

Question 39

What are the concerns with genetic modification?

Answer 39

Transplanted genes might get out into the environment e.g. herbicide resistance gene could be picked up by weeds, creating a new ‘superweed’ variety
GM crops could adversely affect food chains - even human health
There are worries that changing an organisms gene might create unforeseen problems - which could be passed onto future generations
It is unnatural

Question 40

What is cloning?

Answer 40

A method of producing genetically identical offspring

Question 41

Describe the steps to traditional cloning (taking cuttings)?

Answer 41

1) cut sections of stems, each with a new bud on, from ideal parent plants
2) these cuttings are kept in moist conditions until they are ready to plant and are treated with plant hormones to encourage root growth
3) the new plants are clones of the parent plant

Question 42

What are the benefits of traditional cloning?

Answer 42

It is a simple, fast and cheap method

Question 43

Describe the steps to micropropagation (tissue culture) to clone plants

Answer 43

1) a plant with desirable characteristics (e.g. large fruit) is selected to be cloned
2) small pieces called explants are taken from the tips of the stem and the side shoots of the plant
3) the explants are sterilised to kill any pathogenic microorganisms
4) the explants are then grown in vitro - meaning they’re placed in a petri dish containing a nutrient medium (and growth hormones)
5) cells in the explants divide and grow into a small plant. If large quantities of a plant are required (e.g. to sell), further explants can be taken from these small plants, and so on until enough small plants are produced
6) these small plants are taken out of the medium, planted in soil and put into glasshouses - they’ll develop into plants that are genetically identical to the original plant, sharing the same characteristics

Question 44

Explain how Dolly the Sheep was created

Answer 44

1) the nucleus of a sheep’s egg cell was removed, created an enucleated egg cell
2) the diploid nucleus of a mature udder cell from a different sheep was inserted into the enucleated egg cell
3) the cell was stimulated by electricity and began to divide by mitosis, forming an embryo
4) the embryo was then implanted into the uterus of surrogate mother
5) through further mitosis, the embryo developed into a clone of the sheep from which the udder cell nucleus was taken, forming Dolly

Question 45

What are some uses of cloned transgenic animals?

Answer 45

Animals that can produce medicines in their milk could be cloned. Researchers have managed to transfer human genes that produce other useful proteins into sheep and cows e.g. human antibodies used in therapy for illnesses like arthritis and multiple sclerosis
Cloning of animals for xenotransplantation

Question 46

What are the main benefits of cloning animals?

Answer 46

Useful genetic characteristics are always passed on (which doesn’t always happen with breeding)
Farmers don’t have to wait until the breeding season
Infertile animals can be cloned

Question 47

What are some negatives/risks of using cloned transgenic animals?

Answer 47

Cloned embryos might not develop normally or be healthy
There might be unknown risks
It is difficult, time-consuming and expensive
In xenotransplants there may be a greater immune rejection and the organs may carry pathogens that are harmful to humans but not to the animal
Animal rights issues