meiosis and stuff Flashcards

Question

DNA

Answer 1

DNA stands for deoxyribonucleic acid. It's the chemical that all of the genetic material in a cell is made up from. It contains coded information - basically all the instructions to put an organism together and make it work. So it's what's in your DNA that determines what inherited characteristics you have and its sequence determines how our bodies are made.

Answer 2

Section of DNA found on a chromosone that contains the instructions for a particular characteristic.

Answer 3

Four chemicals found in DNA that make up the base sequence (A, T, C, G)

Answer 4

The sequence of bases within the DNA that ultimately codes for proteins

Answer 5

DNA is made up of a series of repeated units called nucleotides. Therefore, we call DNA a polymer

Answer 6

Each strand of DNA is made of a sugar-phosphate backbone (held together by phosphodiester bonds) The two halves of the helix are held together by weak hydrogen bonds. C-G = 3 H bonds A-T = 2 H bonds

Answer 7

A and T always are complementary (they are always linked together on opposite strands) C and G are complementary. The bases consist of A Adenine T Thymine G Guanine C Cytosine

Answer 8

The Genome is the entire genetic material of an organism

Answer 9

Search for genes linked to different diseases Better understand and possibly treat inherited disorders Trace human migration patterns from prehistory - The human genome is mostly identical in all individuals, but as different populations of people migrated away from Africa, they gradually developed tiny differences in their genomes. By investigating these differences, scientists can work out when new populations split off in a different direction and what route they took.

Answer 10

Mutations occur continuously. They can occur spontaneously, e.g. when a chromosome isn't quite replicated properly. However, the chance of mutation is increased by exposure to certain substances or some types of radiation.

Answer 11

Enzymes are proteins, if the shape of an enzyme's active site is changed, its substrate may no longer be able to bind to it - see page 120. Structural proteins like collagen could lose their strength if their shape is changed, making them pretty useless at providing structure and support.

Answer 12

Not all mutations have a serious effect. We have two copies of every gene so if one is faulty, one may be okay. Sometimes if a base is changed in the DNA it does not code for a different amino acid/protein (silent mutation). If it is coding for an enzyme it may not lose its function.

Answer 13

Some mutations change the DNA base sequence, and a different amino acid is coded for, so we get a different protein. If this is an enzyme, it may mean it is not folded correctly (it would alter the intermolecular forces holding it in its 3D shape). This means the shape of the active site may be incorrect, so the enzyme doesn’t work.

Answer 14

If a mutation occurs in a body cell it may lead to cancer.

Answer 15

If a mutation occurs in the egg or sperm it can lead to the offspring having a genetic disorder

Answer 16

mutations in introns could cause the gene to be switched on or off when it should not be. This would affect how genes are expressed. E.g. we might get no protein synthesis when we need it, or we could get proteins made unnecessarily. Why may this be bad? - We may lack a protein we need - We may make a protein when we don’t need it. If this is an enzyme it may catalyze a reaction we don’t want to happen, or simply waste energy making proteins we do not need.

Answer 17

Introns are non-coding pieces of DNA – but they are used in gene expression. They ‘switch on’ genes, meaning they control whether their respective exon needs to undergo protein synthesis.

Answer 18

Cystic fibrosis is an inherited disorder of the cell membranes. It results in the body producing a lot of thick sticky mucus in the air passages (which makes breathing difficult). It also results in movement of substances in and out of a cell becoming more difficult

Answer 19

Its caused by a recessive allele. Therefore, the presence of two alleles will be needed to cause the characteristic to be seen in the phenotype . because its recessive, people with only 1 copy of the allele won't have the disorder - they're known as carriers - they carry the faulty allele, but don't have any symptoms.

Answer 20

Polydactyly is an inherited disorder where a baby's born with extra fingers or toes. It doesn't usually cause any other problems so isn't life-threatening.

Answer 21

Its caused by a dominant allele and so can be inherited if just one parent carries the defective allele. The parent that has the defective allele will have the condition too since the allele is dominant.

Answer 22

During IVF, it's possible to remove a cell from each embryo and analyse its genes. Embryos with 'healthy' alleles would be implanted into the mother - the ones with 'faulty' alleles destroyed.

Answer 23

CVS involves taking a sample of cells from part of the placenta (where the baby's umbillical cord joins with the mothers uterus) and analysing their genes. The part of the placenta that's taken and the embryo develop from the same original cell - so they have the same genes. If the embryo is found to have an inherited disorder, the parents can decide whether or not to terminate (end) the pregnancy.

Answer 24

Embryonic screening is a way of detecting inherited disorders in embryos

Answer 25

* It helps to stop people having certain inherited disorders that could negatively affect their health * Treating disorders costs the Government (and the taxpayers) a lot of money, so screening embryos could reduce healthcare costs. * During IVF, most of the embryos are destroyed anyway. PGD just ensures that the selected one is healthy.

Answer 26

* Implies those with genetic disorders are undesirable – could increase prejudice * Screening embryos is expensive * Could lead to screening to select desirable traits - e.g. they want a green-eyed, black-haired, intelligent boy. * After PGD, the rejected embryos are destroyed-they could have developed into humans, so some people think destroying them is unethical. * There's a risk that CVS could cause a miscarriage. And if an inherited disorder is diagnosed through CVS, it could lead to a termination (abortion).

Answer 27

DNA unzips (this is done using RNA polymerase enzymes & only the gene that needs transcribing is unzipped) RNA polymerase binds to and starts ‘reading’ the DNA template strand Complementary RNA nucleotides line up alongside the DNA template strand - In RNA, the base T is replaced with U e.g. mRNA: AGCUCA DNA template strand TCGAGT A single stranded copy of the DNA is made – this copy is called mRNA. We only make mRNA of the genes that we need – not the whole DNA strand. (The double stranded DNA is too large to leave the nucleus so a smaller single stranded mRNA is needed to fit through the nuclear membrane) Once the mRNA is made, it is released from the DNA, and the DNA reforms the double helix The introns (non-coding regions) are cut out mRNA leaves the nucleus and moves to the ribosomes in the cytoplasm

Answer 28

mRNA binds to the ribosomes. Here, the ribosome reads the mRNA in groups of 3 bases – a triplet (codon). 3 bases codes for 1 amino acid Carrier molecules (tRNA) with the complementary base sequence to the mRNA triplet bind to the mRNA at the ribosome. Attached to the other end of the carrier molecule is an amino acid. The next three bases are read and another carrier molecule (with a complementary base sequence to the mRNA) brings in another amino acid A peptide bond forms between the amino acid. The first carrier can now leave. A third amino acid is brought in by another carrier molecule, which forms a peptide bond to the growing chain. Once all the mRNA has been read, we are left with a sequence of amino acids. We call this a polypeptide chain (primary structure). It can then fold into a 3D shape

Answer 29

Type of reproduction - sexual/asexual Type of cell division - meiosis/mitosis No of parents - 2/1 Is there variation - yes/no

Answer 30

All genes exist in different versions called alleles. Gametes only have one allele of each gene, but all the other cells in an organism have two one on each chromosome in a pair. This is because we inherit half of our alleles from our mother and half from our father. In genetic diagrams, letters are usually used to represent alleles.

Answer 31

Homozygus dominant

Answer 32

hetrozygus

Answer 33

Homozygus recessive

Answer 34

at least 1 copy of the dominant allele Dominant musks recessive

Answer 35

at least 2 copies of the recessive allele

Answer 36

There are 23 pairs of chromosomes in every human body cell. Of these, 22 are matched pairs of chromosomes these just control your characteristics. The 23rd pair are labelled XY or XX. They're the two chromosomes that decide your sex whether you turn out male or female.

Answer 37

Males have an X and a Y chromosome: XY The Y chromosome causes male characteristics.

Answer 38

Females have two X chromosomes: XX The XX combination allows female characteristics to develop.

Answer 39

only males can get it because only males have the Y chromosones.

Answer 40

Whatever allele is on the x chromosone of the male is inherited. If its recessive there is no opportunity for it to be musked by a dominant

Answer 41

There are 2 x chromosones so the only way to get the disease is for it to be rr to not get the disease it can be RR or Rr

Answer 42

differences in the characteristics of individuals in a population

Answer 43

There are many variations between organisms that belong to different species. These differences can help us to classify them.

Answer 44

Organisms that are in the same species also show variation, although they will always have more in common with each other than they will with members of another species.

Answer 45

Hair colour and length Language Scars Tattoos

Answer 46

Blood group Eye colour Natural colour of hair Shape of earlobe

Answer 47

Height Skin colour Weight Sporting achievements

Answer 48

Properties: - No distinct categories - No limit on the value - Tends to be quantative Examples: - Height - Weight - heart Rate - Finger length - leaf length continuous variation is represented by a line graph

Answer 49

Properties: - distinct categories - No in between categories - Tends to be qualitative Examples: - Tongue rolling - finger prints - eye color - blood groups discontinuous variation is represented by a bar graph

Answer 50

Meiosis -crossing over Sexual Reproduction - random fertilisation Mutations

Answer 51

Evolution is described as a ‘**change in the inherited characteristics** of a population over time through a process of **natural selection**.’ Evolution may result in the f**ormation of a new species.** The theory of evolution states that the species alive today have evolved from simple life forms that first developed more than 3 billion years ago Evolution requires three ‘ingredients’? 1. Variation 2. Selection 3. Time

Answer 52

Within a species, organisms all start off looking very similar Some individuals would change as a result of use or disuse of a part of the body e.g. repeated use of an arm would increase its size. This gives the individual an acquired characteristic Offspring would inherit their parent’s acquired characteristics (the trait is inherited by the offspring) and develop it further Eventually, over time, the environment would have directly affected individuals so changing the nature of the species similar change- use/disuse inherit acuired charicteristic from parent

Answer 53

1) Within a species, there is always variation 2) A random, chance mutation occurs that alters the genotype and the phenotype of some individuals 3) Those with the mutation (altered phenotype) have a survival advantage in that particular environment 4) These individuals are more likely to survive, reproduce and pass on the gene for the desirable characteristic to their offspring. It is an inherited characteristic. 5) Over time, the 'mutated'/new phenotype becomes the normal. 6) This is called natural selection. Nature is effectively selecting the organism with the most useful genes.

Answer 54

Use of brightly colours to deter predators Predators learned to avoid animals with these colourations – they are likely to taste bad, be poisonous or cause injury Wallace realised warning colouration must be passed on by natural selection Wallace’s ideas led to our modern understanding of mimicry

Answer 55

During his career, Wallace independently came up with the idea of natural selection and published work on the subject together with Darwin in 1858. This then prompted Darwin to publish 'On the Origin of Species' in 1859.

Answer 56

A species is groups of organisms which have similar characteristics, and can successfully breed with each other (interbreed) to produce fertile offspring.

Answer 57

Formation of a new species over a long period of time, through separation of a population

Answer 58

Continental drift (islands splitting apart) Mountain formation Splitting of habitats Building of roads Deforestation

Answer 59

A population becomes **geographically isolated** from the original population. E.g. by continental drift or a mountain. The new population is **exposed to different environmental** conditions e.g. different habitats or food sources on the other side of the mountain. **Mutations** may occur, **creating variation** in the new population, there will be new phenotypes. **Natural selection **occurs, whereby the **best adapted** individuals in the new population **survive** and reproduce. **Others will not survive** Over a long period of time the new population changes to the point where it **can no longer interbreed** with the **old population** to give **fertile offspring.** Speciation has occurred. geog isolated different conditions mutations - variation natural selection cant breed w old population

Answer 60

A fossil is the remains of organisms that lived millions of years ago

Answer 61

* **mineral replacement** - hard body parts, such as bones and shells, which do not decay easily or are replaced by minerals as they decay * **parts of organisms that have not decayed** because one or more of the conditions needed for decay are absent. For example, dead animals and plants can be preserved in amber, peat bogs, tar pits, or in ice * **preserved traces** of organisms, such as footprints, burrows and rootlet traces - these become covered by layers of sediment, which eventually become rock

Answer 62

* An organism dies and sinks to the bottom of the water * The organism becomes covered in sediment, the soft parts of the body decay, the sediment begins to turn to rock. * More sediment settles, more organisms die and the sediment is compressed as more layers are added. Minerals replace the bone and the skeleton turns to rock. * Rock layers become lifted up, they are eroded by wind and rain, faults in the rocks expose the fossils.

Answer 63

As preserved traces of organisms, such as footprints, burrows and rootlet traces can be buried under layers of sediment that eventually become rock

Answer 64

Whole insects or plant parts become trapped in resin/sap from a tree The resin must fall into water and become covered in sediment (oxygenless) Organisms can also be preserved in ice Volcanic ash can cover a tree branch and prevent it from decaying

Answer 65

As each layer of rock is added the one on top must be younger than the one below so we can tell the relative ages of rocks. It also shows us how organisms that lived in the past differ from those living today It shows us how long a species existed for – when does it disappear from the fossil record?

Answer 66

* Fossils are formed under very specific conditions. The remains of the organisms are usually washed into water and buried by the mud or silt. If there is any oxygen at all, the remains would decay and there would be nothing left. * The hard parts of the organism are replaced by minerals. If an organism is completely soft bodied like an earthworm, there are no hard parts and a fossil will not be formed. It is a very rare event for all these conditions to be met. * Finally the fossils need to be found. They are usually in rocks beneath the sea or river bed, or brought to the surface by tectonic plate movement. Only weathering and erosion can expose them here, which takes a long time.

Answer 67

Extinctions occur when there are no remaining individuals of a species still alive…

Answer 68

Changes to the earths environment is believed to have caused the dinosaurs to become extinct, other reasons Illegal wildlife trade Overfishing Exponential population growth Overconsumption Pollution Destruction of natural habitats / Habitat loss Climate change Invasive or alien species (be new predators, competition for food or introducing new diseases)

Answer 69

Classification is the grouping of organisms according to differences and similarities in their structure and characteristics

Answer 70

Linnaeus created the 5 kingdom system. Below kingdom there are smaller subdivisions… As you descend the classification system, organisms grouped within it get more similar. Traditionally, organisms have been classified according to a system first proposed in the 1700s by Carl Linnaeus, which groups living things according to their characteristics and the structures that make them up. In this system (known as the Linnaean system), living things are first divided into the 5 kingdoms (e.g. Animals, plants, Fungi, Protists, Prokaryotes). The kingdoms are then subdivided into smaller and smaller groups - phylum, class, order, family, genus, species.

Answer 71

In the binomial system, every organism is given its own two-part Latin name. The first part refers to the genus that the organism belongs to. This gives you information on the organism's ancestry. The second part refers to the species. They are written in italics and the genus starts with a capital letter e.g - Humans are known as Homo sapiens. Homo is the genus and 'sapiens' is the species. The binomial system is used worldwide and means that scientists in different countries or who speak different languages all refer to a particular species by the same name avoiding potential confusion.

Answer 72

n 1990, Carl Woese proposed the three-domain system. Using evidence gathered from new chemical analysis techniques such as RNA sequence analysis, he found that in some cases, species thought to be closely related in traditional classification systems are in fact not as closely related as first thought - Archaea & bacteria In the three-domain system, organisms are first of all split into three large groups called domains: 1. Archaea Organisms in this domain were once thought to be primitive bacteria, but they're actually a different type of prokaryotic cell. They can be found in extreme places such as hot springs and salt lakes. 2. Bacteria This domain contains true bacteria like E. coli and Staphylococcus. Although they often look similar to Archaea, there are lots of biochemical differences between them. 3. Eukaryota This domain includes a broad range of organisms including fungi, plants, animals and protists (page 136). These are then subdivided into smaller groups kingdom, phylum, class, order, family, genus, species.

Answer 73

Evolutionary trees show how scientists think different species are related to each other. They show common ancestors and relationships between species. The more recent the common ancestor, the more closely related the two species and the more characteristics they're likely to share. Scientists analyse lots of different types of data to work out evolutionary relationships. For living organisms, they use the current classification data (e.g. DNA analysis and structural similarities). For extinct species, they use information from the fossil record

Answer 74

1. Animals within a population show genetic variation. Humans select two individuals that have the required characteristics - e.g. speed. 2.These individuals are allowed to mate; if they are from different breeds this is known as cross-breeding. 3.When the offspring are produced the ones with the most desirable characteristics are chosen and mated 4.This happens for many generations until the animal with all the right characteristics is produced.

Answer 75

Selective breeding is when humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics remain in the population. Organisms are selectively bred to develop features that are useful or attractive: e.g. . Animals that produce more meat or milk. . Crops with disease resistance. · Dogs with a good, gentle temperament. · Decorative plants with big or unusual flowers.

Answer 76

A breeder selects the individual from the group with most muscle Offspring are produced from the chosen parents Some of the offspring are more muscular than others Most muscular offspring are selected (after checking that they are healthy) and bred together to produce offspring An increased number of the population will be muscular

Answer 77

The main problem with selective breeding is that it reduces the gene pool - the number of different alleles (forms of a gene) in a population. This is because the farmer keeps breeding from the "best" animals or plants - which are all closely related. This is known as inbreeding. Inbreeding can cause health problems because there's more chance of the organisms inheriting harmful genetic defects when the gene pool is limited. Some dog breeds are particularly susceptible to certain defects because of inbreeding - e.g. heart disease is common in boxer dogs. There can also be serious problems if a new disease appears, because there's not much variation in the population. All the stock are closely related to each other, so if one of them is going to be killed by a new disease, the others are also likely to succumb to it.

Answer 78

Produces individuals with desired characteristics New varieties may be economically important Animals can be selected that cannot cause harm, for example cattle without horns

Answer 79

Inbreeding will reduce variation (reduced gene pool) Reduced genetic variation can lead to disease susceptibility of all offspring, which could be extremely destructive rare disease genes can be unknowingly selected as part of a positive trait, leading to problems with specific organisms, e.g., a high percentage of Dalmatian dogs are deaf

Answer 80

Selective breeding is also used to produce new plant varieties. Plants may be bred for their: * disease resistance * Increased yield * Increased quality * Quick growing and mature quickly * Have a distinctive taste, aroma and or color * Have a long shelf life, store well or can be frozen

Answer 81

There are two main methods for cloning plants: Taking cuttings – original method Tissue culture – more modern method

Answer 82

1. Choose the parent plant with the most desirable charicteristics 2. cut a small section of the plant e.g. Shoots, sections of stems 3. trim the end - make sure the equipment is clean to avoid infection by microbes 4. dip it in hormonal rooting powder to encourage root growth 5. plant in moist compost & keep in humid atmosphere until roots develop to reduce water loss through leaves

Answer 83

1. Take a few cells from a plant. 2. Grow them with 'plant hormones' to stimulate them to divide. 3. Grow in different hormones to stimulate them to grow into small plants. 4. Expensive but you can grow thousands of plants from a small amount of tissue. 5. Guarantees the plants you grow have the characteristics you want.

Answer 84

Farmers can use embryo transplants to produce cloned offspring from their best bull and cow: 1. Sperm cells are taken from a prize bull and egg cells are taken from a prize cow. The sperm are then used to artificially fertilise an egg cell. 2. The embryo that develops is then split many times (to form clones) before any cells become specialised. 3. These cloned embryos can then be implanted into lots of other cows... 4. where they grow into calves (which will all be genetically identical to each other).

Answer 85

Adult cell cloning can also be used to make animal clones. Adult cell cloning involves taking an unfertilised egg cell and removing its nucleus. The nucleus is then removed from an adult body cell (e.g. skin cell) and is inserted into the 'empty' egg cell. The egg cell is then stimulated by an electric shock - this makes it divide, just like a normal embryo. When the embryo is a ball of cells, it's implanted into the uterus (womb) of an adult female (the surrogate mother). Here the embryo grows into a clone of the original adult body cell as it has the same genetic information.

Answer 86

* Cloning quickly gets you lots of "ideal" offspring with known characteristics. This can benefit farmers, e.g. if a farmer has a cow that produces lots of milk, he could clone it and create a whole herd of cows that all produce lots of milk relatively quickly. * The study of animal clones could lead to greater understanding of the development of the embryo, and of ageing and age-related disorders. * Cloning could be used to help preserve endangered species.

Answer 87

Cloning gives you a "reduced gene pool" - this means there are fewer different alleles in a population. If a population are all closely related and a new disease appears, they could all be wiped out no allele in the population giving resistance to the disease. It's possible that cloned animals might not be as healthy as normal ones, e.g. Dolly the sheep had arthritis, which tends to occur in older sheep (but the jury's still out on if this was due to cloning). Some people worry that humans might be cloned in the future. If it was allowed, any success may follow many unsuccessful attempts, e.g. children born severely disabled. Also, you'd need to consider the human rights of the clone - the clone wouldn't have a say in whether it wanted to be a clone or not, so is it fair to produce one?

Answer 88

Like all organisms, bacteria sometimes develop random mutations in their DNA. These can lead to changes in the bacteria's Characteristics, e.g. being less affected by a particular antibiotic. This can lead to antibiotic-resistant strains forming as the gene for antibiotic resistance becomes more common in the population. To make matters worse, because bacteria are so rapid at reproducing, they can evolve quite quickly. For the bacterium, the ability to resist antibiotics is a big advantage. Non-resistant bacteria will be killed by antibiotics, but a resistant bacterium is better able to survive, even in a host who's being treated to get rid of the infection. This means it lives for longer and reproduces many more times. This increases the population size of the antibiotic-resistant strain. Antibiotic-resistant strains are a problem for people who become infected with these bacteria because they aren't immune to the new strain and there is no effective treatment. This means that the infection easily spreads between people. Sometimes drug companies can come up with a new antibiotic that's effective, but 'superbugs' that are resistant to most known antibiotics are becoming more common. Examples MRSA (methicillin-resistant Staphylococcus aureus) is a relatively common 'superbug' that's really hard to get rid of. It often affects people in hospitals and can be fatal if it enters their bloodstream. TB is a very serious lung disease caused by a bacterial infection. Multi-drug-resistant TB (also known as MDR-TB) is a form of TB that has developed resistance to multiple antibiotics, making it hard to treat. Scientists in China have reported an MDR-TB epidemic there tens of thousands of Chinese people develop MDR-TB each year.

Answer 89

For the last few decades, we've been able to deal with bacterial infections pretty easily using antibiotics. The death rate from infectious bacterial diseases (e.g. pneumonia) has fallen dramatically. But the problem of antibiotic resistance is getting worse partly because of the overuse and inappropriate use of antibiotics. Examples * Doctors prescribing antibiotics for non-serious conditions. * Doctors prescribing antibiotics for infections caused by viruses. The more often antibiotics are used, the bigger the problem of antibiotic resistance becomes, so it's important that doctors only prescribe antibiotics when they really need to. It's not that antibiotics actually cause resistance they create a situation where naturally resistant bacteria have an advantage and so increase in numbers. If they're not doing you any good, it's pointless to take antibiotics - and it could be harmful for everyone else. It's also important that you take all the antibiotics a doctor prescribes for you. Lots of people stop taking their antibiotics as soon as they feel better, but this can increase the risk of antibiotic-resistant bacteria emerging. Taking the full course makes sure that all the bacteria are destroyed, which means that there are none left to mutate and develop into antibiotic-resistant strains. In farming, antibiotics can be given to animals to prevent them becoming ill and to make them grow faster. This can lead to the development of antibiotic-resistant bacteria in the animals which can then spread to humans, e.g. during meat preparation and consumption. Increasing concern about the overuse of antibiotics in agriculture has led to some countries restricting their use. The increase in antibiotic resistance has encouraged drug companies to work on developing new antibiotics that are effective against the resistant strains. Unfortunately, the rate of development is slow, which means we're unlikely to be able to keep up with the demand for new drugs as more antibiotic-resistant strains develop and spread. It's also a very costly process.

Answer 90

A process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

Answer 91

Restriction enzymes cut open the plasmid leaving ‘sticky ends’ – one strand of the dsDNA has an overhang

Answer 92

* A plasmid (vector) is obtained from within a bacterium * It is cut open using restriction enzymes * At the same time, the required gene (e.g. coding for the desired characteristic) is cut from the donor organism using the same restriction enzymes used to cut open the vector. * The two sticky ends can overlap and be joined together using DNA ligase. * This is now called recombinant DNA * The recombinant DNA (plasmid + required gene) is inserted into a new bacterium through heat shock, or electroporation - the bacterium is now transgenic * The transgenic organism is checked to check it is expressing the required gene. This is done by inserting a genetic marker gene which could be a fluorescence gene or an antibiotic resistance gene (i.e. if the flourescence gene is inserted, it'll glow OR it'll survive exposure to antibiotics). The assumption is, that if the marker gene has been inserted and expressed, so have the desired gene) * The bacterium is allowed to divide and begins producing the desired protein (insulin) * Insulin can be extracted and purified for use in humans

Answer 93

Scientists use genetic engineering to do all sorts of things: Genetically modified (GM) crops have had their genes modified, e.g. to improve the size and quality of their fruit, or make them resistant to disease, insects and herbicides (chemicals used to kill weeds). Bacteria have been genetically modified to produce human insulin that can be used to treat diabetes. Sheep have been genetically engineered to produce substances, like drugs, in their milk that can be used to treat human diseases. Scientists are researching genetic modification treatments for inherited disorders caused by faulty genes, e.g. by inserting working genes into people with the disorder. This is called gene therapy.

Answer 94

Genetic engineering is an exciting new area in science which has the potential for solving many of our problems (e.g. treating diseases, more efficient food production, etc.) but not everyone thinks it's a great idea. There are worries about the long-term effects of genetic engineering that changing a person's genes might accidentally create unplanned problems, which could then get passed on to future generations. It's the same with GM crops...

Answer 95

On the plus side, the characteristics chosen for GM crops can increase the yield / quality, making more food. Quick way of obtaining desired trait/product - Faster than selective breeding People living in developing nations often lack nutrients in their diets. GM crops could be engineered to contain the nutrient that's missing. For example, 'Golden Rice' is a GM rice crop that contains beta-carotene lack of this substance causes blindness.

Answer 96

GM foods are more expensive Limited long term testing for risks of GM foods - Not everyone is convinced that GM crops are safe and some people are concerned that we might not fully understand the effects of eating them on human health. e.g. Risk of allergic reactions for GM foods – different properties/chemicals to the original food Risk of transgenic genes being transferred by pollinators to non-GM crops. - A big concern is that transplanted genes may get out into the natural environment. For example, the herbicide resistance gene may be picked up by weeds, creating a new 'superweed' variety. Could reduce biodiversity – what if a new disease occurs?

Answer 97

As the population of the world increases, it'll be important to find new food sources to add to those that currently exist. Using modern biotechnology techniques, large amounts of microorganisms can be cultured (grown) industrially under controlled conditions in large vats for use as a food source. A fairly modern food source that is becoming increasingly popular is mycoprotein. Mycoprotein means protein from fungi. It's used to make high-protein meat substitutes for vegetarian meals, e.g. Quorn™. A fungus called Fusarium is the main source of mycoprotein. It is grown in large vats on glucose syrup, which acts as food for the fungus. The fungus respires aerobically, so oxygen is supplied, together with nitrogen (as ammonia) and other minerals. The mixture is also kept at the right temperature and pH. Once ready, the fungal biomass is harvested, purified and dried to make the mycoprotein. It's then processed further by adding flavourings and other ingredients.