biotechnology and genetic engineering Flashcards
Use of Bacteria
Microorganisms can be used by humans to produce foods and other useful substances
The most common type of microorganisms used in biotechnology are bacteria
They are useful because they are capable of producing complex molecules (eg certain bacteria added to milk produce enzymes that turn the milk into yoghurt)
They are also useful because they reproduce rapidly, meaning the amount of chemicals they can produce can also rapidly increase
Biofuels
Yeast is a single-celled fungus that uses sugar as its food source
When it respires, the following products are made:
glucose → ethanol + carbon dioxide
C6H12O6 → 2C2H5OH + 2C02
The ethanol produced in this reaction is increasingly being used as a biofuel (a fuel made from living organisms rather than a fossil fuel like oil, coal or gas)
In countries such as Brazil, biofuel is partly replacing petrol as the fuel for cars and other vehicles
Plant material is used as the substrate for producing the ethanol – it is chopped up into small pieces and mixed with yeast which respires and produces ethanol
The liquid is separated from the remaining solids and any water is removed, leaving a concentrated solution of ethanol
Sometimes the waste parts of crop plants, such as the stalks or outer leaves, are used, but in other places, crops are grown specifically to be harvested for making ethanol
In some places, this is causing concern that there is less land available for local people to grow food crops needed for survival
Bread Making
Yeast will respire anaerobically if it has access to plenty of sugar, even if oxygen is available
This is taken advantage of in bread making, where the yeast is mixed with flour and water and respires anaerobically, producing carbon dioxide:
Fruit Juice Production
Fruit juice is produced by squeezing the fruits to remove the juice
Chopping the fruit up before squeezing helps to release a lot more juice, but this does not break open all the cells so a lot of juice is lost
By adding an enzyme called pectinase to the chopped up fruit, more juice is released
Pectinase works by breaking down a chemical called pectin that is found inside plant cell walls
Once pectin is broken down, the cell walls break more easily and more juice can be squeezed out of the fruit
Adding pectinase to fruits also helps to produce a clearer juice as larger polysaccharides like pectin can make the juice seem cloudy – once they are broken down into smaller molecules, the juice becomes clearer
Biological Washing Powders
Many stains on clothes are organic molecules – oil from skin, protein from blood, fat and protein from food
Detergents that only contain soap can remove some of these stains when mixed with hot water, but it can take a lot of time and effort and very high temperatures to remove the stains entirely
Biological washing powders contain enzymes similar to the digestive enzymes produced in the alimentary canal that help to break down large food molecules
Using biological washing powders has several advantages, including:
Quickly breaking down large, insoluble molecules such as fats and proteins into smaller, soluble ones that will dissolve in washing water
They are effective at lower temperatures, meaning less energy (and money) has to be used in order to wash clothes to get them clean as washing water does not need to be heated to higher temperatures
They can be used to clean delicate fabrics that would not be suitable for washing at high temperatures
Lactose-Free Milk
Lactose is the sugar found in milk
Human babies are born with the ability to produce lactase, the enzyme that breaks down lactose
In certain areas of the world, many people lose the ability to produce lactase as they get older
This means that they can become lactose intolerant and react badly to the lactose in milk and products made from milk (cheese, yoghurt etc)
Symptoms of lactose intolerance include nausea, flatulence and diarrhoea as their digestive system is upset by the lactose
Milk can be made lactose free by adding the enzyme lactase to it and leaving it to stand for a while to allow the enzyme to break down the lactose
Penicillin Production
Penicillin was the first antibiotic discovered in 1928 by Alexander Fleming
He noticed that some bacteria he had left in a Petri dish had been killed by the naturally occurring Penicillium mould
The penicillium mould produces a chemical to prevent it being infected by certain types of bacteria
The chemical was isolated and named penicillin
Since the discovery of penicillin, methods have been developed to produce it on a large scale, using an industrial fermenter
Genetic engineering is
changing the genetic material of an organism by removing, changing or inserting individual genes from another organism
The organism receiving the genetic material is said to be
‘genetically modified’, or is described as a ‘transgenic organism’
The DNA of the organism that now contains DNA from another organism as well is known as
‘recombinant DNA’
There are many examples of genetically modified organisms, including
The gene for human insulin has been inserted into bacteria which then produce human insulin which can be collected and purified for medical use for diabetics
Crop plants, such as wheat and maize, have been genetically modified to contain a gene from a bacterium that produces a poison that kills insects, making them resistant to insect pests such as caterpillars
Crop plants have also been genetically modified to make them resistant to certain herbicides (chemicals that kill plants), meaning that when the herbicide is sprayed on the crop it only kills weeds and does not affect the crop plant
Some crops have been genetically modified to produce additional vitamins, eg ‘golden rice’ contains genes from another plant and a bacterium which make the rice grains produce a chemical that is turned into vitamin A in the human body, which could help prevent deficiency diseases in certain areas of the world
Process of Genetic Engineering
The gene that is to be inserted is located in the original organism (for example, this could be the gene for human insulin)
Restriction enzymes are used to isolate the required gene, leaving it with ‘sticky ends’ (a short section of unpaired bases)
A bacterial plasmid is cut by the same restriction enzyme leaving it with corresponding sticky ends (plasmids are circles of DNA found inside bacterial cells)
The plasmid and the isolated gene are joined together by DNA ligase enzyme
If two pieces of DNA have matching sticky ends (because they have been cut by the same restriction enzyme), DNA ligase will link them to form a single, unbroken molecule of DNA
The genetically engineered plasmid is inserted into a bacterial cell
When the bacteria reproduce, the plasmids are copied as well and so a recombinant plasmid can quickly be spread as the bacteria multiply, and they will then all express the gene and make the human protein
The genetically engineered bacteria can be placed in a fermenter to reproduce quickly in controlled conditions and make large quantities of the human protein
