F212 Biology overview

Function:

• A reactant
• A solvent
• Transports substances
• Temperature control

Structure:

• Joined by shared electrons
• Polar - negatively charged (oxygen) on one side, positively charged on the other (hydrogen)

Hydrogen bonding:

• Negatively charged oxygen atoms attract other hydrogen atoms of other water molecules - this is hydrogen bonding.

Water's structure is related to its properties and functions:

• Hydrogen bonds give water a high specific heat capacity - it takes a lot of energy to heat up - useful in living organisms because its stops rapid temp changes, allowing stability.
• Hydrogen bonds give water a high latent heat of evaporation - energy (heat) is used up when water evaporates, useful for cooling things.
• Polarity means its very cohesive.
• Polarity makes it a good solvent - ions will dissolve.

Dipeptides - two amino acids

Polypeptides - more than two amino acids

Proteins - made up of one or more polypeptides

Amino acids 

• a carboxyl group ( -COOH)
• an amino group (-NH2)
• an R group (only variable group)

Link together by peptide bonds (COOH and NH2) of OH and H. Water is released during the reaction (Condensation). The reverse of this adds water (hydrolysis).

• Primary structure - sequence of amino acids (held together by peptide bonds)

• Secondary structure - hydrogen bonds between nearby amino acids. This causes a coil into alpha helix or a fold into a beta pleated sheets.

• Tertiary structure - coiled/folded further. Ionic interactions, disulfide bonds (cysteine), hydrophobic/hydrophillic interactions, hydrogen bonds. For single polypeptide chains this is the final 3D structure of the protein.

• Quaternary - several different polypeptide chains assembled (all with bonds of tertiary). For more than one polypeptide chain this is the final 3D structure.  E.g. Haemoglobin

Proteins adapted to their function: Collagen

• fibrous protein
• supportive tissues in animals - needs to be strong
• three polypeptide chains - tightly coiled - triple helix
• chains interlinked by strong covalent bonds
• minerals bind to triple helix to increase rigidity

Proteins adapted to their function: Haemoglobin

• globular protein
• iron containing haem group that binds to oxygen to carry around the body
• outside - hydrophillic
• inside - hydrophobic
• means soluble in water, so good for transport in blood

They are large complex molecules composed of long chains of monosaccharides.

Glucose is a monosaccharide with six Carbon atoms, has two forms, alpha and beta. For alpha, the H molecule is on the top, for beta H is on the bottom.

Monosaccharides

• joined together by glycosidic bonds
• one hydrogen to a hydroxyl of another, releasing water (condensation)

Disaccharide

• two monosaccharides joined together. E.g. two alpha glucose

Polysaccharide

• more than two monosaccharides. E.g. lots of alpha glucose form amylose

You need to know three polysaccharides

1. Starch (energy storage in plants)

• plants store excess glucose as starch
• mixture of two polysaccharides (both alpha glucose)
• Amylose - unbranched, coiled structure makes it compact so good for storage.
• Amylopectin - branched, side branches allow enzymes to get to glycosidic bonds quickly - release energy quickly
• insoluble in water, doesn't cause water to enter by osmosis - good for storage.

2. Glycogen (energy storage in animals)

• polysaccharide of alpha glucose
• extremely branched, means that stored glucose can be released quickly -  important for energy release in animals.
• very compact - good for storage.

3. Cellulose (structural support in cell walls of plants)

• long, unbranched chains of beta glucose
• bonds between sugars are straight so cellulose chains are straight
• cellulose chains linked together by hydrogen bonds to form fibres (microfibrils) - structural support.

Triglycerides

• one glycerol and three fatty acids
• fatty acids - have long tails made of hydrocarbons
• the tails are hydrophobic - makes lipids insoluble in water
• all fatty acids consist of some basic structure but hydrocarbon tails vary

Phospholipid

• lipids found in cell membranes
• similar to tryglicerides - except one of the fatty acid is replaced by a phosphate group.
• phosphate group is ionised (electrically charged) which makes it attract water.
• so phosphate - hydrophillic
• fatty acid tails - hydrophobic

Cholesterol

• found in cell membranes
• used to make steroids as well
• has a hydrocarbon ring structure attached to a hydrocarbon tail
• hydrocarbon ring has a polar hydroxyl group which makes cholesterol soluble

How structure of lipids relate to their function

Triglycerides - tails contain lots of chemical energy (2 x energy as carbohydrates), insoluble - so don't cause water to enter by osmosis.

Phospholipids - acts as barrier to substances as centre is hydrophobic

Cholesterol - strengthen by interacting with phospholipid tails - small size and flattened shape allow in between phospholipids, causing them to pack closely together - helps make membrane rigid.

Sugars - Benedicts test

• Reducing sugars - add Benedict's reagent (blue) to a sample and heat it,(don't boil), if the test is positive it will form a coloured precipitate (red).
• Non reducing sugars - boil with dilute hydrochloric acid and then neutralise with sodium hydrogencarbonate, then reducing sugar test.

Starch - Iodine test

• iodine dissolved in potassium iodide solution , if starch is present-blue/black.

Proteins - Biuret test

• two stages - add drops of sodium hydroxide solution then add copper sulfate solution
• if present, purple layer, if not stays blue

Lipids - Emulsion test

• shake with ethanol then pour into water, if present it will turn milky

• used to determine the concentration of a glucose solution
• uses a colorimeter - measures the strength of a coloured solution
• measures absibance, more concentrated the colour the higher the absorbance
• higher the glucose solution the lower the absorbance of the solution

How to do the test

Make a calibration curve:

1. Do a benedicts test on several glucose solutions of different known concentrations (same volume). Use same amount of Benedicts solution in each case.

2. Remove any precipitate (leave for 24 hours so precipitate settles or centrifuge them) an use the colorimeter to measure absorbace of Benedicts remaining in each tube, use results or calibration curve. (x axis = glucose)

3. Then you can test for a unknown solution (assay) using the calibration curve to find its concentration

DNA (deoxyribonucleic acid) contains genetic information - coiled up very tightly. They have a paired structure which allows self replication.                                    DNA contain genes - sections of DNA that code for a specific sequence of amino acids that forms a particular protein.

DNA is a polynucleotic (lots of nucleotides), a nucleotide is made from

• deoxyribose sugar
• a phosphate group
• nitrogen containing base
• base can vary - adenine, thymine, cytosine, guanine
• adenine and guanine are purine, thymine and cytosine are pyrimidines

DNA polynucleotides join between phosphate group of one and sugar of another .

Two DNA polynucleotide strands join together by hydrogen bonds between bases. A-T has two hydrogen bonds, C-G has three hydrogen bonds.                            Two antiparallel polynucleotide strands twist to form the DNA double helix

DNA

• nucleotides containing deoxyribose, phosphate and nitrogen containing bases
• double helix, anti-parallel two polynucleotide strands
• has bases purine, adenine, guanine, pyrimidine, thymine, cytosine

RNA

• nucleotides containing ribose, phosphate and nitrogen containing bases
• single polynucleotide strand
• has bases purine, adenine, guanine, pyrimidine, uracil (pairs with A), cytosine

Before cell division:

1. Hydrogen bonds between two polynucleotide DNA strands break and the helix unzips.

2. Each original strand acts as a template for a new strand, free floating DNA nucleotides join to exposed bases by complementary base pairing.

3. Nucleotides on the new strand are joined together by enzyme DNA polymerase, hydrogen bonds form between the bases on the original and new strand.

4. Each new DNA molecule contains one strand from the original DNA and one new strand.

DNA contains genes which are instructions for proteins, it is the order of nucleotide bases in a gene that determines the order of amino acids in a particular protein.

Each amino acid is coded for by a sequence of three bases in a gene

DNA is copied into RNA for protein synthesis:

• genes for a protein can be exposed by splitting the hydrigen bonds that bind the double helix
• RNA nucleotides form a complementary strand (mRNA) which peels away.
• the RNA leaves tthe nucleus through a nuclear pore and joins with a ribosome in the cytoplasm,
• transfer RNA (tRNA) molecules bring amino acids to the ribosome in the correct order according to the base sequence on mRNA
• the amino acids join together by peptide bonds

Globular proteins final 3D shape usually has:

• hydrophobic amino acid R groups in centre of 'ball'
• hydrophillic amino acid R groups around outside
• amino acids chains spiral, pleats and turns to form overall structure

Enzymes:

• are globular proteins (soluble)
• are biological catalysts - speed up rates of reactions
• have an active site shaped for a complementary substrate - determined by tertiary structure
• have an active site that is affected by pH, temperature and concentration
• reduce the amount of activation energy needed to allow a reaction to proceed

activation energy - amount of energy needed for a reaction to proceed

Example: phagocytes digest bacteria using lysosomal enzymes

Lock and key model:

• substrate 'key' fits into active site of an enzyme 'lock'
• forms an enzyme substrate complex which forms an enzyme product complex
• enzyme is left unchanged - active site is free to break up more substrate molecules
• the shape of the enzyme's active site is complementary to the shape of the substrate molecule

Induced fit model:

• as substrate collides the enzyme molecule changes shape slightly so the active site fits more closely to the substrate
• also held due to oppositely charged groups on substrate and active site are found near to eachother which forms an enzyme substrate complex
• a enzyme product complex is formed - products are different shapes from substrate

Temperature:

• more kinetic energy, collisions increase rate until optimum temperature
• Too many vibrations can cause bonds (hydrogen and ionic) that hold the active site to break and the tertiary structure is disrupted - denatured

pH:

• H+ and OH- in acids and alkali can interfere with the hydrogen and ionic bonds holding the active site in shape this can alter the tertiary structure
• only denatured at extreme pH changes

Enzyme concentration:

• more enzyme, more collisions, but if substrate is limited (limiting factor) there is a point where increasing enzyme will have no further effect.

Substrate concentration:

• more substrate, more collisions, true up to 'saturation point' active sites full

Cofactors:

• non protein inorganic molecules - help enzyme and substrate bind together
• don't directly participate in reaction so aren't used up or changed in any way
• e.g. manganese ions found in hydrolase

Coenzymes:

• organic molecules - participate and are changed by reaction - often act as carriers moving chemical groups between different enzymes - continually recycled

Competitive inhibitors:

• similar shape to substrate - compete to bind to active site but no reaction takes place (block instead)

Non competitive inhibitors:

• bind away from active site causing it to change shape (prevents substrate reaching enzyme.

Examples:

• cyanide irrevirsable inhibitor of cytochrome c oxidase, an enzyme that catalyses respiration reactions
• drugs, e.g. penicillin inhibits transpeptidase which catalyses the formation of proteins in bacterial walls as a result the cell bursts and bacterium is killed

To little or too much nutrients in diet

• too little of every nutrient
• unbalanced diet: obesity/anaemia
• deficiency illnesses - unable to absorb nutrients

Obseity:

• 20% or more over recommended body weight
• main causes; too much sugary foods and fatty foods, too little excersise
• also caused by underactive thyroid
• increases risk of; diabetes, high blood pressure, CHD and even some forms of cancer

CHD:

• result of reduced blood flow to heart - can lead to  chest pain (angina) and possibly heart attacks - caused by atherosclerosis - narrowing and hardening of the coronary arteries

Atherosclerosis:

• high saturated fat decreases the activity of LDL receptors - raises blood cholesterol - increases fatty deposits
• a diet high in salt can lead to high blood pressure - damages artery walls

HDl's:

• produced by unsaturated fats, cholesterol and protein
• carry cholesterol from body to liver, liver has receptor sites for binding

LDL's:

• produced by saturated fats, cholesterol and protein
• carry cholesterol from the liver to body tissues, which have receptor sites

Fertilisers:

• chemicals that increase crop yields e.g. nitrate, potassium, phosphate
• provide minerals, can be natural or artificial

Pesticides:

• chemicals that increase yields by killing pests
• can be specific or broad - could mean some non-pests are harmed

Antibiotics:

• kill or inhibit bacteria growth, treat or prevent diseases
• animals use energy fighting disease - using antibiotics may increase growth
• also thought that they influence bacteria in gut - digest more efficiently

Selective breeding:

• good characteristics, breed together and continue over several generations with offspring

Examples:

• Bread - yeast turns sugar into CO2 and ethanol - CO2 causes them to rise
• Wine - yeast and grape juice, yeast turns sugar in juice to ethanol and CO2
• Cheese - adding bacteria to milk turns sugar into lactic acid - curdle - enzyme turns into curds and whey, curds are seperated and left to ripen
• Yoghurt - adding bacteria to milk, turns sugar into lactic acid causing it to clot and thicken into yoghurt

Advantages:

• quicker,
• grow on inexpensive material
• artificially controlled environment - easy to create conditions
• lasts longer in storage than original product

Disadvantages:

• high risk of food contamination - conditions are also for harmful bacteria
• small changes in pH or temperature easily kills the microorganisms

Preventing food spoilage:

• salting - prevents microorganisms taking in water - inhibits growth
• adding sugar - same as salting
• freezing - slows growth, freezes water and slows down reactions
• pickling - reduces enzyme activity due to low pH - inhibits growth
• heat treatment (pasteurisation) - kills microorganisms
• irradiation - disrupts DNA structure - kills microorganisms

Health - state if physical, mental and social well being, which includes the absence of disease and infirmity

Pathogen - organism that can cause damage to an organism it infects (host)

Parasite - an organism that lives on or in a host and causes damage

Malaria:

• Plasmodium - transmitted by vector (mosquito) -infects liver and red blood cells

AIDS:

• kills white blood cells it has infected
• immune system deteriorates and fails (opportunistic infections)

TB:

• mycobacterium terburculosis, 'droplet infection'

Primary defences - those that attempt to prevent pathogens entering the body

Immune response - specific response to a pathogen, involves action of lymphocytes and the production of antibodies

Primary defences:

• skin - keratinisation, dead cells on surface, effective chemical barrier, produce's chemicals that are antimicrobial, can lower pH inhibiting growth of pathogens
• mucous membranes - protect body openings exposed to environment
• eyes - antibodies in tear fluid
• ear canal - lined by wax

Antigen - molecule that can stimulate an immune response

Antibodies - molecules that can identify and neutralising antigen

Specificity - an antibody is specific to a particular antigen because of the shape of the variabe region

Phagocytes engulf pathogens:

• neutrophils and macrophages
• pathogen is recognised by its foreign antigen - antibodies attach
• neutrophils receptors bind to the antibodies and envelop pathogen by folding the membrane inwards where pathogen is trapped in a phagosome, lysosomes fuse with the phagosome and release enzymes, the end products are harmless nutrients
• macrophages do not fully digest the pathogen, they become an antigen presenting cell, their function is to find lymphocytes that can neutralise, (colonal selection)

Phagocytes activate T lymphocytes:

• T lymphocytes are covered with receptors - bind to antigens presented on macrophages
• each lymphocyte has different receptor - when it meets complementary it will bind - this activates the T lymphocyte and it divides and differentiates (colonal expansion)

Activated T lymphocytes either:

• some release substances that help activate B lymphocytes (T helper)
• some attach to antigens on the pathogen and kill the cell (T killer)
• some become memory cells (T memory)

Activation of B lymphocytes:

• B lymphocytes are covered with antibodies
• they bind to antigens, creating an antigen-antibody complex
• the binding of the B lymphocytes to complementary antigen activates the B lymphocytes
• B lymphocytes bind by mitosis into plasma cells and memory cells (colonal expansion)

Plasma cells:

• make antibodies specific to the antigen which bind to form antigen-antibody complexes

Structure:

• four polypeptide chains held together by disulfide bridges
• constant region - same in all antibodies - allow to attach to phagocytic cells
• variable region - specific shape due to amino acid sequence - complementary to antigen
• hinge regions - allow flexibility and allow branches to move apart to attach to more than one antigen
• Y shaped

How they work:

• Neutralisation - attaching to an antigen that the pathogen may have had another use for - prevents binding to host cells
• Agglutination - some are larger than Y shapes, have many specific variable regions - so can attach to a number of pathogens at the same time, when the pathogens are stuck together they cannot enter the host cell.

Primary response:

• slow
• pathogens antigens activate the immune response
• slow because not many B lymphocytes that can make an antibody needed
• person experiences symptoms

Secondary response:

• after the first response, B and T memory cells are left in the body for a long time, T memory recognise the specific antigen, whereas B memory remember specific antibodies needed.
• when the same pathogen enters the body again, memory B lymphocytes divide into plasma cells immediately and memory T lymphocytes  divide into correct T killer cells to kill the pathogen.

Vacination - deliberate exposure to antigenic material which activates the immune system to make an immune response and provide immunity

Active immunity - immune system make its own antibodies after being stimulated by an antigen (creates memory cells) - long term

Passive immunity - antibodies that have not been stimulated by recipitents immune system e.g. by a mother across a placenta - short lived

Vaccines:

• live microorganisms - similar antigens e.g. small pox vaccine
• harmless or attenuated version of the pathogenic organism e.g. measels
• a dead pathogen e.g. cholera vaccines
• a preperation of the antigens from another source e.g. hepatitis B
• harmless toxin e.g. tetanus

Herd vaccination - prevention/eradication, vaccinating 95% of population

Ring vaccination - vaccinating in immediate vicinity of new cases e.g. livestock

Active immunity:

• antigen? - exposure to antigen
• how long to develop? - protection takes a while to develop
• how long overall? - long term immunity
• memory cells? - are produced
• natural example - immune after catching a disease
• artificial example - vaccination

Passive immunity:

• antigen? - no exposure to antigen
• how long to develop? - protection is immediate
• how long overall? - short term immunity
• memory cells? - aren't produced
• natural example - baby, through placenta or breastmilk
• artificial example - injection of antibodies of another individual (tetanus)

Influenza:

• caused by virus
• over 65 years of age, risk
• 1918 - flu epidemic killed 40 million worldwide
• 1968/9 - 1 million killed Hong Kong flu - also known as H1N1 strain - pandemic
• UK - vaccination aged over 65 and other 'at risk'
• 2007 - 74% of over 65 about 42% 'at risk' vaccinated
• strains of flu used in this immunisation programme change each year, research is undertaken to determine which of the strains of flu are most likely to spread that year

Finding new drugs:

• using natural compounds e.g. penicillin from fungus, cancer drugs made using soil bacteria
• only small proportion of organisms have been investigated
• if we didn't maintain biodiversity species could die before being studied

CHD - a multifactoral disease:

• Atherosclerosis - carbon monoxide damages inner lining of arteries, damage is repaired by white blood cells that encourge growth of smooth muscle and deposition of cholesterol, the deposits (atheromes) may include fibres, dead blood cells and platelets
• the atheromes may grow enough to break the inner lining of the artery and forms plaque, this may reduce the size of the lumen
• Thrombosis - blood flowing past plaque does not flow smoothly which increases chances of a clot, stickiness of platelets (nicotine) increases chances, if membrane that covers plaque is damaged red blood cells attach to exposed fatty deposits, a blot clot in an a artery (thrombus) may prevent blood flow
• sometimes a clot and or part of a clot may break free and be carried in the blood and lodges and stops bood flow
• coronary arteries carry blood at high pressure, so they are very prone to atherosclerosis, when lumen of coronary arteries is narrowed by plaque, it reduces blood flow to the heart muscle, this leads to CHD
• CHD; angina (pain in chest), heart attack (death of part of a heart muscle, myovardial infarction), heart failure

Stroke:

• death of part of a brain tissue - loss of blood flow
• 1.thrombus floating around in blood blocks a small artery leading to a part of the brain
• 2.an artery leading to the brain bursts (haemorrhage)

Lung cancer:

• carcinogenic compounds in tar enter cells of lung tissues - enter nucleus and affect genetic material (mutation) - then uncontrolled cell division

Chronic bronchitis:

• inflammation of lining of the airways, tar causes damage to cilia and overproduction of mucus, increased risk of lung infection

Emphaysema:

• loss of elasticity in alveoli - burst, less well oxygenated blood

Tar:

• settles in alveoli - reduces diffusion distance of oxygen to blood
• may cause allergic reaction, smooth muscles contract and lumen narrows
• paralyses cilia and stimulates goblet cells to secrete, may block bronchioles
• cough damages lining of airways-scar tissue, smooth muscle thickens
• frequent infections cause inflammation - white blood cells release enzymes (elastase) which damages alveoli causing them to burst

Nicotine:

• causes release of adrenaline - increases heart and breathing rate
• constriction of aterioles and extremities reduces blood flow
• makes platelets sticky - increases risk of thrombus

Carbon monoxide:

• damages lining of arteries
• combines with haemoglobin forms carboxyhaemoglobin, reduces oxygen carrying capacity of blood

Cardiovascular disease:

• diseases that affect the heart and circulatory system
• include atherosclerosis, CHD, stroke, arteriosclerosis

What factors increase risk of CHD:

• age
• sex
• smoking
• obesity
• hypertension
• high blood cholesterol

Smoking links to lung cancer:

• a smoker is 18x more likely to develop lung cancer
• 25% of smokers die of lung cancer

Species - group of individual organisms very similar in appearance, anatomy, physiology, biochemistry and genetics whose members are able to interbreed freely to produce fertile offspring.

Habitat - place where an organism lives

Biodiversity - variety of life, the range of living organisms to be found

Can be considered at different levels:

• range of habitats in which different species live - different habitats in one area
• differences between species, different species and their abundance
• genetic variation between individuals belonging to the same species - alleles

2001 - catalogue of life examples:

• 2007 - contained 1008965 species
• Plants, UK - 4080, world - 293000+
• total, UK - 89000+, world - 1730000+

Qualitative - does not include quantity (no numbers)

Quantitative - involves quantity (numbers)

Random sampling - studying a small part of the habitat and assuming it contains a representative set of species that can be applied to the whole habitat, the sample sites must be random

• take samples at regular distances
• random numbers - generated by computer to ploy coordinates
• select coordinate from a map and use GPS to find exact position

Plants:

• random quadrants - abundance scale (ACFOR), percentage cover, point frame
• transects - line taken across habitat, interrupted belt transect, contineous belt transect

Animal:

• sweep netting - empty contains on white sheet, or pooter to collect before they fly away
• collecting from trees - knock branches with stout stick, collect what falls
• pitfall trap - set in soil, animals fall in
• tullgren funnel - use light to drive animals into jar
• light trap - attract flying insects at night

Importance:

• asses affect of humans on environment
• EIA used to estimate effects of planned development on the environment

Species richness - the number of species present in a habitat - qualitative survey

Species eveness - similar in population sizes of the species means greater species eveness - quantative survey (mark and recapture)

C1 - first sample - mark them

C2 - total captured 2nd sample

C3 - number of already marked in 2nd sample

total population = (C1 x C2) / C3

Simpsons diversity index:

• measures of diversity - takes into account eveness and richness
• D = 1- {E(n/N)^2}
• n = individual species frequency
• N = total frequency of all species
• between 0 and 1, closer to 1 more diverse habitat

Estimates of Global biodiversity:

• named species 1.5 million
• unnamed species - undiscovered etc.,
• estimates total species 5 - 100 million due to different techniques, little is known about some groups e.g. bacteria, varies (biodiversity) in different parts of the world

Genetic diversity:

• humans can affect, reduce overall gene pool for species
• decreases genetic variation and ability of species to evolve
• modern agriculture uses monoculture and selective breeding - reduces variation and genetic diversity - leads to extinction of some varieties within a species - genetic erosion

Climate change:

• species that have lost their genetic variation are unable to evolve, therefore are unable to adapt to climate change means migration instead
• however, obstructions include major human developments, agricultural land, large bodies of water, human activity e.g. hunting

Agriculture:

• higher CO2 levels altering photosynthesis
• higher temp increases growth rates
• longer growing season, greater precipitation
• change in distribution of popoulation
• loss of land - rise in sea level and increases salinity of soil

Disease:

• new diseases and pests
• lower yields - less food
• human diseases, such as Anopheles mosquito carrying malaria

Conservation in situ:

• conserving a species in its normal environment
• e.g. legislation - hunting, logging, development
• conservation parks - e.g. UK national parks and SSSI

Advantages:

• conserved in natural environment
• permanetly protects biodiversity, natural and cultural heritage
• allows management of area,
• opportunities for ecologically sustainable land uses - economic benefits
• facilitates scientific research, possible to restore ecological integrity

Disadvantages:

• protected animals raiding farms out of reserves
• people continuing to hunt for food and illegal harvesting of timber, difficult to enforce legislation
• tourism - litter etc

Conservation ex situ:

• conserving an endangered species by activities that that takes place outside its normal environment
• e.g wildlife parks, botanical gardens, seed banks (wakehurst, Sussex)

Captive breeding - disadvantages:

• animals often fail to breed successully
• space limited - restricts genetic diversity
• lack of variation
• have to survive reintroduction to wild

Botanical gardens - disadvantages

• collection - causes disturbance
• may not be successful in another area
• may not be representative
• may not be viable after time in seed bank
• research conclusions may not be valid for whole species

CITES:

• convention in international trade of endangered species
• worldwide problem -worldwide solution
• 1973 - aim to ensure that international trade in specimens of wildlife do not threaten their survival
• e.g. regulating and monitoring international trade in selected plant and animals
• over 25,000 species of plants and animals have been identified as being at risk from international trade.

Convention on Biological diversity:

• 1992 - dedicated to promoting sustainable development
• aims e.g. conservation of biological diversity , appropriate sharing and transfer of scientific knowledge and technologies
• zoo's, botanical gardens and seedbanks - cooperation is sharing genetic  information and technology - each member must adopt ex situ measures
• since 2000 - 3400 seed collections have been sent out

• aspect of the convection on biological diversity, assessment before any major development

Reasons:

• avoid adverse effects on biological diversity
• ensure consequences are taken into account
• promote communication if development might affect another state

EIA, local criteria:

• size of development
• environmental sensitivity of the location
• types of impact expected

EIA helps ensure importance of the predicted effects is properly understood, can produce improvement in planning and design of development

Classification - process of sorting living things into groups, natural classification does this by grouping things according to how closely related they are

Taxonomy - study of principles of classification, differences between species

Phylogeny - study of evolutionary relationships between organisms - used as a basis for natural classification

DKPCOFGC

• eight taxa
• Aristotle was first to try to classify into groups
• Linnaeus devised system we use today

Binomial system - uses two names to identify each species, the genus name and the species name - Linnaeus devised it - used latin as a universal language

Dichotomous key - uses series of questions with two alternative answers to help you find a specimen

Prokaryotae:

• single celled
• no nucleus
• less than 5um
• e.g. bacteria

Protocista:

• eukaryotic, mostly single celled
• autotrophic or heterotrophic nutrition
• e.g. algae

Fungi:

• eukaryotic
• mycelium consisting of hyphae
• cell walls made of chitin
• saprophytic
• e.g. mushroom

Plantae:

• eukaryotic
• multicellular
• walls made of cellulose
• contain chlorophyll
• autotrophs - produce own food
• e.g. oak tree's

Animalia:

• eukaryotic
• multicellular
• heterotrophic (consume other animals and plants)
• e.g. Impala

• originally based on observable features
• but then microscopes
• later electron microscopes
• and definition of species 'a group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry and genetics'

Biochemistry in classification:

• cytochrome c - amino acids can be identified and comparison of sequences
• comparison of DNA sequences

Five kingdom and three domain:

• 1990 Woese suggeseted new classification - based on studies of RNA
• divided Prokaryotae into 2 groups, Bacteria and Archae,
• Bacteria have structural differences - cell membrane structure, flagella's internal structure, enzyme for building RNA, mechanisms for DNA replication
• Archae share some features with Eukaryotes - similar enzymes for RNA, similar mechanisms for DNA replication, production of proteins bind to DNA

Variation - presence of variety, of differences between individuals

Genetic variation - caused by differences between genes (alleles)

Variation between species:

• continuous - variation in which there is a full range of intermediate phenotypes between two extremes e.g. length of leaves on oak tree
• discontinuous - variation in which there are discrete groups of phenotypes with no or very few individuals in betweeen e.g. sex - mammals are male or female, flagella - some bacteria have it others don't

What causes variation:

• Genetic - genes inherited, chance of two individuals having same combination of alleles is remote
• Environmental - characteristics affected by environment e.g. weight
• Combination - not all genes are active at any one time e.g. puberty - different genes are becoming active - environment affects which are active

Adaptation - feature that enhances survival and long term reproductive success

Behavioural - aspect of behaviour that allow it to survive in conditions

Physiological/biochemical - ensures correct functioning of cell proccesses e.g. hibernation lowers metabolism

Anatomical - structural features e.g. flagella on bacteria

Xerophytes:

• behavioural - close stomata or only open at night, folding/rolling leaves
• physiological - mechanisms by which plant opens/closes stomata etc
• anatomical - shallow roots spread over wide range or long roots, waxy leaves to prevent water loss

Darwin's natural selection - 'selection' by the environment of particular individuals thats show certain variations - survive to reproduce and pass on variations

The four observations he made:

• offspring generally appear similar to parents
• no two individuals are identical
• organisms have ability to produce large numbers of offspring
• populations in nature tend to remain fairly stable in size

Speciation - formation of a new species (allopatric and sympatric)

Evidence supporting Darwin's theory:

• Barchiopods changed over time and the Armadillo and glyptodont
• evolution of horse over past 55 million years is well documented
• biological molecules are found throughout the living world
• DNA and RNA polymerase found in all living things
• sequence of amino acids in cytochrome c is similar on similar species
• comparison of sequences of bases in DNA

Insecticide resistance:

• if an insect has a form of resistance it will survive - allowing it to reproduce
• the resistance can be developed in a number of ways
• can metabolise the insecticide (enzymes)
• target receptor protein on the cell membrane may be modified
• e.g. mosquito's have grown resistant through metabolising them
• another problem is if resistant insects are eaten by other predators - may move up food chain

Microorganisms and antibiotics:

• overuse and incorrect use of antibiotics have led to strains of bacteria resistant to virtually all antibiotics - some doctors prescribe multi antibiotics which reduces chances that some bacteria will survive
• MRSA 'super bug' is resistant to many drugs  - example of an 'evolutionary arms race'

Antibiotics - drugs that kill or inhibit growth of bacteria