Bacteria ferments milk to produce yoghurt by:
- Equipment is sterilised to kill microbes
- Milk is then pasteurised (heated for 72C for 15 seconds)
- Milk is cooled then starter culture of bacteria is added, then mixture is incubated (heated for 40C) in a fermenter
- Bacteria ferments the lactose sugar in the milk to form lactic acid, which causes the milk to solidify and clot into yoghurt then flavours and colours are added.
- Cooked soy bean and roasted wheat are mixed together
- Mixture is fermented by aspergillus fungus then by yeast
- Then by Lactobacillus bacterium
- The liquid is then filtered to remove any bits
- Lastly it is pasteurised to kill microbes and put into sterile bottles
Plant stanol esters are:
- Chemicals which lower blood cholesterol and reduce heart disease
- Used in spreads and dairy products
- They occur naturally in plants but in very small quantities
- It can be grown commercially by using bacteria which convert sterols into stanol.
- Carbs such as Oligosaccharides, they are food for good bacteria
- However they can not be digested by humans or bad bacteria, because we do not have the right enzymes.
- They occur naturally in onions, leeks and oats
Microorganisms and food
- Enzymes such as invertase are used by Manufactures in sweets and other food
- They change sucrose a sugar into glucose and fructose which taste sweeter
- So less sugar is needed for the same sweetness, so money is saved and lower calorie sweets are made
- Invartase is made form a yeast called Sccharomyces cerevisiae
- Cheese is made from rennet, which used to come from lining of a calfs's stomach and contains enzyme called chymosin this clots the milk
- Vegetarians do not like this so the chymosin is made from GMOs
- Chymosin was put into yeast cells to make it.
- Used in dietary supplements, drinks to stop them going off, bacterium Acetobacter which naturally produces a chemical easily converted to V C
Microbes and food
- Used i flavouring and preservative added to fizzy drinks
- found in citrus fruit
- Aspergillus niger produces it commercially
Monosodium glutamate (MSG):
- MSG is a flavour enhancer added to food
- Made from glutamic acid, which makes bacterium corynebacterium glutamicum
- Bacteria secrete glutamic acid (amino acid) into the medium they're grown in, glutmaic acid is then used to make MSG salt.
- A gelling agent extracted from seaweed carregeen
- Used as an emulsifier in ice cream, jellies etc
Diet and obesity
Carbs- provide energy
Fats- provide energy, provide insulation, form cell membranes and steriod hormones
Proteins- needed for growth and repair tissues, provide energy in emergencies
Vitamin- Various functions, V c needed to maintain healthy connective tissues
Minerals- Various functions such as iron needed to make haemoglobin for healthy blood
Water- needed to replace water loss through sweating, breathing etc
Unbalanced diet can cause health problems such as malnutrition, also deficiencies of vitamins, minerals or proteins
Protein deficency can cause a condition called Kwashiorkor
Vitamin deficiencies include the scurvy which doesn't give enough vitamin c
Mineral deficiencies- lack of iron can cause anaemia a blood disorder
Obesity and GM plants
Obesity is a disorder when you are 20% or more over weight of you recommened body weight
It can be caused by too much sugary, fatty or little exercise
Also it can be due to underactive thyroid gland, obesity can cause coronary heart disease, high blood pressure, diabetes and sometimes cancer.
You can modify GM crops:
- So that they can be resistant to herbicide, this will kill the weeds but not the crops
- Also GM crops can be resistant to pests or disease
- It increases the nutritional value of the foods
- Can be modified to grow in extreme conditions
- Produces food containing vaccines or other medical benefits
*gene- A section of DNA which controls the synthesis of a protein or part of a protein.
*genetic modification- A species into which genes is said to be genetically modified (GM). The genes are transferred using the techniques of genetic engineering.
*herbicide- A chemical used to kill weeds.
*resistant- The process where disease- causing organisms can withstand the action of drugs which previously would have killed them.
*toxin- A poison
*vector- A carrier of genes from the cells of one species to the cells of another species; a carrier of disease- causing organisms from one individual to another individual.
1)To make herbicide- resistant plants. Herbicides are used to remove weeds because the weeds compete with the crops for light and nutrients. Example: a bacterium called Bacillus thuringiensis produces a toxin (poison) that kills many insect larvae but is harmless to humans. The gene for this can be inserted into plants to make them resistant to pests. 2)To make plants resistant to pests or disease. 3)To increase the plants’: shelf-life; nutritional value; flavour; texture; or create foods containing fewer things people are allergic to. 4)To modify crops so that they can grow in extreme environments. 5)To produce foods containing vaccines or with other medical benefits.
Genetically modified organisms are made by “cutting and pasting” genes. To make GM plants, a bacterium called Agrobacterium tumefaciens. It naturally invades plant cells and inserts its genes into the plant’s DNA. The Agrobacterium tumefaciens bacterium acts as a vector (See keywords). Example to make a herbicide-resistant plant:
1)You get a plant that already has resistance to the herbicide, work out which gene is responsible. 2)Cut out this gene for herbicide- resistance from one of the plant’s cell. 3)Agrobacterium tumefaciens bacteria contains a circular loop of DNA- removing it from bacterium ‘cut it open’ and insert it into the herbicide-resistance gene. 4)The genetically modified Agrobacterium tumefaciens bacteria will infect cells of the ‘target’ plant. 5)The bacteria will insert their genes (incl. herbicide-resistance gene) into the plant’s DNA. 6)These cells then grow on a medium containing the herbicide. Those that grow must contain the herbicide- resistant gene.
Not everyone thinks that GM crops will help developing countries.
1)People argue that a lack of money to buy food is the problem rather than availability of food, therefore poverty needs to be tackled 1st. 2)Fear of countries may become dependent on companies who sell GM seeds. 3)Sometimes, poor soil is the reason why crops fail, and even GM crops won’t survive.
GM crops may have other disadvantages:
1)Transplanted genes may get out into the natural environment. E.g. herbicide- resistance gene may be picked up by weeds creating “superweeds” 2)Some say that growing GM crops will affect the number of wildlife that usually live in and around the crops- reducing biodiversity. 3)Not everyone is convinced that they are safe. People are worried that they could develop allergies to the food.
How is Human Insulin made?
1.Isolate the human gene which carry the coded for insulin. 2.Transfer the genes from the cells into the bacterial cells. 3.Bacterial cells genetically modified to contain human insulin genes. 4.Bacterial cells multiply. 5.Large amounts of insulin can be made quickly.
•A gene is a section of DNA. Genes code for protein and are paired using “base pairing” • the order of the bases of a gene is called the genetic code. •DNA is made up of many nucleotides. These have bases as part of their structure. •Adenine and Thymine are always paired together and Guanine and Cytosine are always paired. •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 strands of DNA which make up a genome.
In 1986 scientists in the UK and the USA set up the human genome project to sequence human DNA
1.Samples of cells were taken from anonymous volunteers 2.Chromosomes of cells were Brocken down into pieces to get the DNA 3.Thousands of copies of DNA Were made (enough material to work on 4.DNA put into machines called sequencers 5.The most probable order of bases would be displayed on the computer screen
This is how scientists worked out the order of the bases of the 3.1 billion nucleotides which make up the DNA of the human genome.
A gene is identified by comparing the sequence of its bases with the sequence of bases in known genes
Bioinformatics help us find out which gene codes for which protein. This process involves using a powerful computer .
The aim of bioinformatics is to:
•Find which gene codes for which protein •Show in which cells a gene is active (controlling production of its protein) •Show when each gene is active
Bioinformatics also help to show where the proteins coded for by are genes are normally found. This is called a molecular atlas/ map.
•They were first discovered by humans lives depended on what they ate, they discovered this by trial and error, meaning that if you eat less of a plant which is poisonous, it does not poison but cures diseases and relieves aches and pains. •Substances that can be extracted from plants are studied in labs so that scientists can synthesis (make) some of them so that plants are not required, however most of the plants chemical structure is complicate, such as the substance and scientist do not have much knowledge. Plants are like strychnos produce a substance called curare which relaxs the muscles, this can be used to relax a patients muscles when undergoing a surgery. However in a large dose can stop the lung working and effectively killing the person. So small doses are used •75% of all medicinal plants known produce anti cancer substances, which grow in tropical rainforests. Also it is thought that there are many more plants not yet found so many other uses may still be found. Such as Taxol which comes from a bark of the Pacific yew tree.•Digitoxic a substances produced by a plant is used for a many heart problems
The bark and leaves of willow trees have magic stuff inside them that relieve pain. The magic ingredient is called “Salicin” and was extracted in 1828. Salicyclic acid can also be formed from the substance. The acid is a more effective painkiller however it irritates the lining of the stomach and intestines.
Aspirin contains a version of salicyclic acid which reduces pain without the nasty side effects. The drug helps to reduce swelling in joints, reduce the formation of blood clots and reduce fever in people whose body temperature is higher than normal. The tablet is now synthesised (chemically made) although contain some natural salicin.
Malaria is common mainly in warmer countries and is caused by a single celled parasite called “Plasmodium”. The parasite attack the red blood cells and the person suffers flu-like symptoms (high fevers, sweating and teeth chattering chills). The Plasmodium parasite is carried mainly by females “Anopheles” mosquitoes and infects people through mosquito bits. The mosquito is known as the vector of plasmodium
It has been known since the 1600s that chewing bark and leaves of the “Cinchona tree” is useful for treating malaria. It has the active ingredient, “quinine” which lowers body temperature and kills plasmodium parasite in the red blood cells. For 300 years, it was the best treatment however, in the 1860s, plantations of the Cinchona trees established in Java and Indonesia from seedlings smuggled out ofSouth America. It was the main source of Cinchona bark until WW2. Then, antimalarial drugs like chloroquinine were developed. They are more effective and easier to make than quinine however some parasites are now resistant.
- Artemisinin is a drug that is used to treat multi-drug resistant strains of malaria. Artemisia has been used for thousands of years by herbalist to cure skin diseases and malaria. It is extracted from Artemisia Annua which are leaves from a shrub.
- Artemisinin kill Plasmodium; Plasmodium is the parasite that causes malaria. It also prevents Plasmodium from reproducing inside its Mosquito vector, this reduces transmission from one person to another.
- Unfortunately Artemisinin is only active in the body for a few hours, however scientists have discovered that when Artemisinin is mixed with other anti-malarial drugs it is more effective. This combination treatment is called Artemisinin-based combination therapy. (ACT)
- ACT is recommended by the World Health Organization in places where the malaria parasite has developed resistance to antimalaria drug choloquine.
- The storage of Artemisinin leaves has prompted reasearch into different ways of making Artemisinin in a laboratory. Laboratory trials have shown that the substance made is more effective than the natural process, as it remains active for much longer and is cheaper to produce.
Artemisinin may be useful in the treatment in cancer. Test shows that it damages cancerous cells without effecting the healthy ones.
- Taxol stops cells from dividing, these cells die. There is a huge demand for Taxol as a possible anti-cancer drug, however supplies are limited, and Pacific Yew Tree and one of the slowest growing trees in the world. Only a small amount can be extracted and the tree dies in the process
- An embryonic stem cell potentially can develop into ANY cell in the body theoretically without limit to replenish, and an adult stem cell is only able to mature into a specialised tissue cell from which tissue the cell is located.
- Embryonic stem cells are stem cells derived from blastocyst.
- Blastocyst is the name of the embryo during the first 4-5days of development.
- It can contain up to 50-150 cells.
- Each cell can develop into more than 200 cell types.
- PD is a degenerative disease of the brain
- It affects an individuals motor skills, speech, and other functions.
- It occurs because cells that produce the hormone dopamine die.
Boy or girl
•The gender of the baby has an equal chance of it being either male/ female as 50% of a man’s sperm have an X chromosome and 50% have a Y chromosome. •Eggs are taken from a woman and sperm are added.
•Two or three fertilised eggs are chosen for transfer back into the woman’s womb.
•Embryos are balls of cells.
•Scientists can take one of the cells without harming the embryo, and can test it to see if it has genes that could cause disease.
•Only embryos shown to be free of faulty genes are chosen to be put back into the woman’s womb.
•This is what also makes finding the gender of the embryo possible.
•Some genetic disorders such as: Duchenne Muscular Dystrophy, Fragile X and Haemophilia mostly occur in boys. If the family has a history of male-linked disorders, finding out the gender of the baby before it’s born is extremely useful as a female embryo can be chosen over a male embryo and the chances of the female having a hereditary disease would be less likely.
•To select the sex of the baby, the doctor can either test an embryonic cell to see what sex chromosomes are present in the embryo, or the father’s sperm can be sorted and only the sperm carrying the X or Y chromosome can be used to fertilise the egg.
•In Britain, a parent is allowed to choose the gender of their baby to avoid chances of genetic disorders being inherited by them, but not because they want to choose whether the baby is a girl or a boy. •Some people think that testing embryos and choosing the ones with healthy genes, or choosing the sex of embryos so that faulty genes don’t show themselves seems like a brilliant way of improving human well-being.
•However, some people think that it is unethical in the sense, if we are given more freedom to pick and choose sperm, eggs, or embryos, then it will only be a short step to choosing our characteristics we want to see in our babies. Choosing the genes like intelligence etc determines the idea of designer babies.
- In 1997, Dolly was the first mammal to be cloned from an adult cell. She was put down because she had arthritis and many people think she died because she was a clone. There have been a lot of ethical issues about cloning and whether it would be right or wrong to do this.
- Healthy cells from a sick person can be cloned and used to repair that persons damaged tissues.
- A person needing a transplant could make use of a brain dead clone of himself/herself as a source of tissues and organs for transplantation. The persons body would not reject the transplanted material because it is genetically identical.