- Functional foods contain an added ingredient not normally found in that food
- Supposed to promote good health and contribute to our welbeing
- We carry 1kg of different types of bacteria in our gut
- Prebiotics and Probiotic boost the number of good bacteria
- Prebiotics contain added sugars called oligosaccharides, when we eat these foods the sugars are food for the 'good' bacteria in our gut
- Probiotics are produced by fermentation, Prebiotics are not
- Benecol is a functional food, it contains stanol ester, which comes from plant sterols, which are fatty substances found naturally in foods like wheat and maize
- Studies have shown that people who include plant stanols in their diet for a year might expect cholesterol levels in their blood to fall by up to 10%
- Many scientists think that the foods should be tested in the same way as new drugs are tested
- A balanced diet provides many of the ingredients added to functional foods
To make yoghut:
- Milk is sterilised by heating it to kill any bacteria that is present
- Then the milk is stirred thoroughly to mix up its ingredients and milk protein is added
- A starter culture of Lactobacillus bacteria is added to the milk while it is still warm
- The Lactobacillus bacteria ferment the sugar lactose into lactic acid
- The lactic acid lowers the pH of the milk (the milk becomes acid) to the point where the milk proteins coagulate (solidify)
- The semi-solid milk is raw yoghurt
- The raw yoghurt is cooled quickly
- Different flavourings of fruit may be added or it may be put into pots as natural yoghurt. The pots are then sealed and ready for sale
Making soy sauce
- Soya beans are cooked, which kills all of the bacteria on their surface
- Mix with ground roasted wheat
- Aspergillus mould is added to the mixture
- The mixture is spread out on warm shallow trays and supplied with air
- Enzymes produced by the Aspergillus mound catalyse the breakdown of the proteins and carbohydrates in the mixture. The amino acid and sugar content of the mixture increases
- Brine (sodium chloride solution) is added to the mixture. It gives soy sauce its salty taste and helps to preserve the final product.
- Yeasts and Lactobacillus, which are able to tolerate high levels of sodium chloride and low levels of oxygen, are added to the brine mixture
- The conditions stop the activities of the Aspergillus mould
- The sugars in the mixture are fermented by the yeasts and Lactobacillus bacteria
- Raw soy sauce is drained from the mixture
- The liquid is filtered and cleared of any sediment
- The liquid is heated to 72 C (pasterurisation) and stored to allow its flavours to develop
- It is then put in sterilised bottles ready for sale
- Rennet is vital to the process of cheese making
- It is a mixture of two protein-digesting enzymes
- These enzymes cause the milk to form solid curds which seperates from the liquid, which is called whey
- The curds are raw cheese
- Traditionally rennet comes from the stomach of slaughtered calves
- Rennet consists mostly the enzyme chymosin
- We can now use GM bacteria to produce chymosin
- It contains fewer impurities and is acceptable to vegetarians
- The cheese made using GM chymosin is itself GM-free because it is not made using GM organisms, even though the enzyme used in its production is made by GM organisms
- Gelling agents are substances added to food to thicken it and make it less runny
- Ice creams, jellies, milk shakes and frozen desserts are some food which contain gelling agents
- Gelatine is made from animal bones which is an everday example of a gelling agent
- Foods containing gelatine are not acceptable for vegetarians
- Carrageen extract is suitable as it comes from the reddish-purple seaweed called carrageen
Aspergillus niger + Corynebacterium + Acetobacter
- It is mould fungus
- It is used to produce citric acid
- When citric acid is added to fizzy drinks, sweets, jams and jellies, it enhances the favour of the foods
- It also prevents the breakdown of vitamin C in food
- It is used to produce the amino acid glutamic acid
- Neutralisation of the acid makes a sodium salt called monosodium glutamate (MSG)
- When MSG is added to food it enhances the food's flavour
- Different species of the bacterium are used to produce vitamin C
- The process is a fermentation on two stages starting with glucose
Saccharomyces cerevisiae + Glucose isomerase
- The yeast fungus is used to produce invertase (also called sucrase)
- The enyzme promotes the breakdown of the sugar sucrose into glucose and fructose
- Sucrose -invertase-> glucose + fructose
- Sweet makers use invertase to convert the solid insides of chocolate to a liquid centre.
- Glucose isomerase is another enzyme used in the sweet industry
- This enzyme converts glucose into fructose which is sweeter
- Fructose syrups which are used to make sweets
Food and drink contain nutrients: Carbohydrates, Proteins, Fats, Minerals and Vitamins, Water, Fibre, Oils
If someone eats more food than is needed for their energy needs, putting on weight is a result.
Body mass index = body mass (kg) / (body height)2 (m2)
- <18.5 Underweight
- 18.5 - 24.9 Healthy weight
- 25 - 29.9 Overweight
- 30 and greater Obese
Plant breeding + Genetic Engineering
- Plant breeding programmes produce new varieties of high-yielding crops
- The new varieties are produced bt crossing two different varieties (hybridisation)
- Each variety has desirable characteristics (e.g. resistance to diseasem high yield) and crossing concentrates the desirable characteristics into the new hybrid variety which is then reproduced asexually.
- Breeding new varieties of rice plants has boosted yields by more than 25% since the 1970s
- GE is a lot quicker
- This means that crops with desirable characteristics can be produced more quickly
- Golden rice: rich in minerals and vitamins
- Helps in developing countries
- SCP is a food produced from microorganisms grown in fermenters
- SCP could be useful as it is fast growing, had a high protein and vitamin and mineral content
- Microorganisms double their mass within hours, whereas plants and animals we eay may take weeks or months to grow to fill size
- The microorganisms multiply using the nutrients in the fermenter as a source of energy and materials for their growth
- Using the nutrients is an example of fermentation in action and nutrient is replaced as it is used up
- The fermenters are run for months at a time during which microbial mass is removed at regular intervals and processed into food
- SCP can be grown in large quantities in fermenters whcih are a controlled environment independent of weatherrr and which take up little space
- The technology is established and can be used in developing countries where food may be in short supply
Genetically modified plants - Agrobacterium tumefa
- The cells of some plants contain a gene which protects plants from the effects of herbicides. The plants are herbicide resistant
- We can us GE to intoduce into crop plants the gene which controls herbicide resistance
- Agrobacterium tumefaciens is a bacteria which lives in the soil, when a plant is infected it produces a cancerous growth called a crown gall.
- We can use Agrobacterium as a vector for transfering genes (herbicide resistance) into the genetic material of plant cells
- The Agrobacterium cell has a small loop of DNA called the Ti plasmid (Tumor inducing). The herbicide resistance gene is inserted into rhw Ti plasmid using a ligase enzyme. The plasmid causes a plant infected to produce a crown gall. The cells of the gall each contain a Ti plasmid with the herbicide resistant gene in place. Pieces of tissue cut from the crown gall are cultured and grow into plants. Each plant is genetically modifed to be resistant to herbicides.
- The bacterium Bacillus thuringiensis kills lead-eating caterpillars and the larvae of flies and mosquitoes.
- The damage is caused by a toxin called insecticidal crystal protein (ICP) which is produced by the bacterium. ICP attacks the caterpillar's gut and the caterpillar stops feeding and dies.
- Crop plants have been genetically modifed using the gene ICP from Bacillus thuringiensis with Agrobacterium as the vector.
- The gene controlling the production of ICP is inserted into the Ti plasmid of Agrobacterium. This is the same method as the herbicide resistant plants
Should GM crops worry us?
Some people claim that:
- It's not natural
- Eating GM food may affect our health
- GM crops may harm wildlife
- Pollen from crops genetically modified to resist herbicides may transfer to wild plants. If these plants are weeds, there is a danger of weeds developing which are herbicide resistant
The benefits of GM crops:
- It is easier and safer for farmers to control the weeds and insects that reduce the amount of food produced
- The volume of herbicides and insecticides is reduced
- Reducing the use of herbicides and insecticides reduces the risks to wildlife and damage to the environment
GM crops: other developments
- Grow in places where rainfall is low
- Resist the microorganisms which cause crop diseases
- Produce their own fertiliser
Genetically engineered insulin
- Scientists at Genentech developed the idea
- Human insulin gene is cut out with a restriction enzyme,
- baterial plasmid is cut open with a restriction enzyme,
- ligase enzyme sticks insulin gene into plasmid,
- plasmid is put into bacterium,
- bacteria with insulin gene is grown in fermenter,
- insulin is seperated off and purified
- The conditions inside huge fermenters encourage the rapid multiplication of bacteria.
- The fermeners are filled with a solution of all the substances the bacterial cells need to grow.
Why GE insulin?
- People with diabetes do not produce enough insulin in their pancreas
- Daily injections of insulin control this condition
- Before GE, people used insulin sourced from cows and pigs
- Unsuitable for vegetarians and certain religious beliefs
- It was expensive
- Sometimes caused allergies
- All of these problems were overcome when GE insulin was developed
- It is cheap and safe to use because chemically it is the same as the insulin our cells produce naturally
- 1982 start of general use of GE insulin
- DNA consists of thousands of building blocks called nucleotides.
- Each nucleotide has a base as part of its structure. There are four bases: Adenine, Thymine, Guanine and Cytosine
- A gene is a section of DNA
- The order of bases of our genes is our genetic code. The code is a set of instructions for combining amino acid units in the correct order to make a molecule of protein or part of a protein
- Triplet bases
- A genome is all of the DNA in each cell of an organism
- Genomics is the science of working out the sequence of the bases in the strand of DNA which make up a genome
The Human Genome Project
- The Human Genome Project in order to work out the order of bases of the 3.1 billion nucleotides
- Samples of cells were taken from anonymous volunteers. The chromosomes of the cells were broken up into pieces to get at their DNA. Thousands of copies of the pieces of DNA were made to provide enough material to work on
The aim is to:
- Find which gene(s) code(s) for which protein(s)
- Show in which cells a gene is active (controlling production of its protein)
- Show when each gene is active
Bioinformatics is helping to make a molecular atlas of the cell. The map will show where the proteins coded for by our genes are normally found.
- Your responce to a drug often depends on your DNA
- Millions of people suffer from adverse drug reactions and some die because of them
- Combining genomics with pharmacology (the science of drugs and their affect on the body) offers the potential to make drug treatments that suit the genetic make up of each individual. This area of science is referred to as pharmacogenomics
- Salbutamol is used to treat people suffering from asthma, the drug acts on the muscles which control the opening and closing of the tubes which take air into and out of the lungs. There are different versions of muscles and some may be unresponsive to salbutamol so being able to identify the genes and being able to provide with an alternative medication
- Enzymes in the liver would also benefit, variations in the genes that code for the enzymes mean that their action in some people is more effective than in other. The people with less effective enzymes are more likely to experience adverse drug reactions. Genomics could be used to find out how effective the enzymes are and can be used to guide the choice of drug and its dosage.
Outcomes of genomic medicine
- Better medicines: Drug companies will be able to produce treatments which target particular diseases. Damage to healthy tissues will be reduced.
- Safer drugs: The likelihood of adverse drug reactions will be reduced or removed altogether
- More accurate drug dosages: At present drug dosages are based on the age and mass of the person being treated. In the future dosages will be based on the individual's genomic profile
- Better vaccines: New vaccines will be made from genetic material, and will have the benefits of existing ones without the risk of side-effects. These occur because some of us are allergic to the substances used to make today's vaccines.
- Modern drugs still come from plants
- Strychnos plants of the Amazon rainforest are a source of curare, a substance which relaxes muscles. Small doses are used during surgery to relax the muscles of the patients, making it easier to control their breathing
- 6000 plant species are interesting from a medical point of view. The substances they produce fall into several groups.
- These substances can be extracted from plants in the lab and made up into medicines and drugs.
- The active ingredient is salicin and was extracted from willow bark in 1828. Salicylic acid can be made from salicin. It is a more effective pain killer but it irritates the lining of the stomach and intestine
- Aspirin contains a version of salicylic acid which reduces pain without the adverse side-effects. As well as relieving pain it acts to reduce: swelling in joints and other tissues (anti-inflammatory), the formation of blood clots and fever in epople whose body temperature is high than normal.
Malaria and Quinine
- Malaria flourishes in the warmer tropical regions of the world.
- The disease is caused by a single-cell parasite called Plasmodium. Once the parasites are in the blood stream they attack red blood cells. The infected person suffers flu-like symptoms followed by high fevers, heavy sweating and teeth-chattering chills.
- The Plasmodium parasite is carried by female Anopheles mosquitoes. It passes from person to person when the mosquitoes feed on the blood of people infected with malaria. The female Anopheles mosquito is the vector or Plasmodium
- Since the 1600s we have known that chewing the bark and leaves of the Cinchona tree is a useful treatment for malaria.
- The active ingredient is quinine and was extracted from Cinchona bark in 1820. The drug lowers body temperature and kills Plasmodium parasites in the red blood cells.
- Some strains of Plasmodium have become resistant to the drugs (like chloroquine) and in some parts of the world quinine is once more the antimalarial drug of choice
- Artemisinin is widely used in China and south-eat Asia for the treatment of malaria
- It is extracted from leaves of the shrub Artemisia annua
- Artemisinin and its derivatives kill Plasmodium, it also prevents Plasmodium from reproducing inside its mosquito vector, therefore reducing transmission from person to person
- It is only active inside the body for a few hours.
- However, combination with other antimalarial drugs increases its effectiveness. The combination treatment is called artemisinin-based combination therapy (ACT) and its use is recommended by the World Health Organization in places where the malaria parasite has developed resistance to the antimalarial drug chloroquine
- The shortage of Artemisia leaves has prompted research into ways of making artemisinin in the lab. GE yeast cells produce a substance like artemisinin which can easily be converted into artemisinin itself. LT have showsn that the substance is more effective than the natural product is active in the body for longer and is cheaper to produce.
- Artemisinin may also be useful in the treatment of cancer. Early tests show that it damages cancerous cells without affecting healthy ones.
- The US Cancer Institute set up a programme to look for new anti-cancer drugs and found a substance with anti-cancer activity was extracted from the bark of the Pacific yew tree. The substance was Taxol
- It stops the cells from dividing and the cells die. Cancerous cells are more affected than healthy ones.
- The tree is one of the slowest growing in the world and there was a large demand was it. It's also a protected species.
- Only a small amount of taxol can be extracted from the bark and the tree is killed in the process
- A substance similar is found in the European yew tree. The substance was chemically modifed to form a semi-synthetic version of taxol called paclitaxol
- European yew trees replace their needles quickly.
- Producing enough paclitaxel to meet demands is costly and limits the use of the drug.
- In the future, scientists hope to be able to synthesise the anti-cancer part of taxol in the lab. Alternatively, yew tree cells could be grown as a cell culture on a large scale, produing taxol
Stem cell research
- Once fertilised an egg soon divides into two by mitosis. Repeated divisions follow and a hollow ball of cells called the embryo develops. The cells on the inside of the embryonic ball are all the sae. They are embryonic stem cells.
- Stem cells are unspecialised
- However, as cell division continues and the embryo develops into a foetus, the cells behin to change into the different types of cell that form the tissues and organs of the body. The process is called differentiation and once that is complete, the foetus grows into a fully formed baby.
- Even as adults, some of our stem cells remain. For example there are adult stem cells in the bone marrow, these give rise to blood cells, replacing old.
- It seems likely that small numbers of stem cellls remain in other body tissues as well
- If we can encourage embryonic or adult stem cells to multiply and differentiate, unlimited supplies of different types of cells will be available to treat people. This is called stem cell therapy
- Stem cells could be the source of new cells to replace diseases and damaged tissues in conditions such as Parkinson's, diabetes, different cancers and Alzherimer's disease
- A small cluster of cells in the brain produce a chemical transmitter called dopamine.
- People with pd do not produce enough dopamine
- Their movements are jerky and uncoordinated because the lack of dopamine affects muscle control
- In 1999, US scientists took 10-15 healthy stem cells from the brain tissue of someone suffering from pd. These unspecialised cells were grown in a solution of all the substances needed to keep the cells alive and were encouraged to differentiate into the type of cell that produces dopamine.
- These cells divided by mitosis into millions of cells which were put back onto the person's brain tissue, the person's muscle control improved by 40-50%.
- Sucess shows what may be possible. However, the clinical trials studying the effects of stem cell treatments have only been carried out on small numbers of people and there are some adverse side effects so the results are still uncertain
Girl or boy?
- A baby's sex depends on whether a woman's egg is fertilised by a sperm carrying an X chromosome or one carrying a Y chromosome
- The birth of (almost) equal numbers of girls and boys occurs as 50% of a man's sperm is X and Y
- In-vitro fertilisation (IVF) eggs are taken from a woman and sperm is added. Two or three fertilised eggs are chosen for transfer back into the woman's womb. The embryos consist of a ball of cells. Scientists can take one of the cells without harming the embryo and test it to see if it has genes that could cause disease. Only embryos free of faulty genes are chosen to be put back into the womb. Finding out the sex is also possible
- Some genetic disorders like Duchenne muscular dystrophy, fragile X and haemophilia mostly occur in boys.
- If there is a family history of these disordes then testing to find out the sex of the embryo would be useful
- In 1997 Dolly the sheep was born. She was the first mammal to be cloned from an adult cell.
Some things to consider:
- Healthy cells from a sick person can be cloned and used to repari that person's damaged tissues
- A person needing a transplant could make use of brain-dead clone of themself as a source of tissues and organs. The person's body would not reject the transplanted material because it is genetically identical
- For some people, the thought of using a brain-dead clone as a source of tissues and organs for transplantation is morally wrong. They argue that respect for human life should outweigh the possible benefits to the patient
- We can genetically modify cows to produce hormones such as insulin in their milk - we could then produce many of these cows by cloning.
More about Dolly the sheep
- In 2003, Dolly was found to have arthiritis in her joints. She developed lung disease as well and was 'put down' to prevent her suffering distress.
- By sheep standards Dolly was young.
- It is currently illegal to clone people
- Many people think that research into human reproduction could lead to human cloning, designer babies and much else.
- For example, if a child has a life-threatening disease that could be treated with stem cells, IVF scientists can help the parents to producean embryo which is near a genetic match to the older child. The embryo is put back into the mother where it develops into a healthy baby, when the baby is born the life saving stem cells are taken from the umbilical cord and used to treat the older sick child. The baby is not hurt and no cells are taken from the baby itself. However, the younger child is a designer baby, brought into the world to save someone else.