Biological MoleculesWater- Reactant in lots of chemical reaction, solvent, transport medium andtemperature control.Hydrogen Bonds• Absorb lots of energy gives water high specific heat capacity• Lots of energy to break, high latent heat of evaporation, good for cooling• Very cohesive due to polar molecules, helps water transport substances• Ions dissolve in water due to the atom charges +ve & -ve, water’spolarity makes it useful as a solvent.
ProteinsPrimary Structure- the number and sequence of amino acids.Secondary Structure- hydrogen bonds form between amino acidsto make Beta pleated sheets or alpha helix coils.Tertiary Structure- further coils or folding to from globularproteins.Quaternary Structure- several polypeptides held together bybonds, these bonds determine the quaternary structure e.ghaemoglobin.
Different bonds, different structures• Primary- Peptide• Secondary- Hydrogen Bonds• Tertiary- Ionic interactions, disulphide bridge, hydrophilic/phobicinteractions, hydrogen bonds• Quaternary- determines by tertiary structure, uses all bondsShape related to functionCollagen- Fibrous, supportive tissues, strong.- 3 polypeptide chains, triple helix, chains linked by strong covalent bonds- Minerals bind to helix to increase rigidity.Haemoglobin-Globular protein, contains Haem group, binds to oxygen.- Hydrophillic on outside, hydrophobic on inside.- Make haemoglobin soluble, good for transport.
CarbohydratesHydrolysis- add watermolecule, two separatemoleculesCondensation- removewater molecule, twobonded molecules by aglycosidic bond.
Starch• Mixture of amylose & amylopectin• Amylose – long, unbranched, coils, good for storage• Amylopectin – long, branched, side branches, allows easy breakdown,quick energy release• Insoluble, doesn’t affect water potential, good for storageGlycogen• Polysaccharide of alpha glucose• Similar to amylopectin, more side branches, quick energy release• Very compact, good for storageCellulose• Long, unbranched Beta glucose• Bonds between 1-6, chains are straight• Chains linked by hydrogen bonds, to form microfibrils, provides structuralsupports e.g. in plants
LipidsTriglycerides• TailsHyrdophobic• Makes lipidsinsoluble• Hydrocarbontails varies - RPhospholipids• Hydrophilic head• Hydrophobic tailsCholesterol• Soluble in water• Not soluble in blood, so carried bylipoproteins
Lipid structure to functionTriglycerides• long hydrocarbon tails, lots of chemical energy, when brokendown twice as much energy per gram of carbohydrate• Insoluble, don’t affect water potential, bundle as insolubledroplets, tails are hyrophobic, tails face in, heads outwards.Phospholipids• Form double layer• Membrane acts as barrier, water cant pass throughCholesterol• Flat rigid shape, bind tails in membrane, increase rigidity,lower fluidity
Biochemical tests for moleculesReducing sugars – Add Benedict’s to sample & heat, don’t allowto boil. Colour change Blue-Green-Yellow-Orange-Brick Red. Canfilter & weigh precipitate when comparing, more accurate.Non-reducing sugar – boil solution with dilute hydrochloric acidsolution & neutralise with sodium hyrdrogencarbonate solution,then carry out Benedict’s, if test positive do reducing sugar test.Iodine test – Add iodine disolved in pottasium iodide solution totest sample. If starch present = browny-orange -> blue-blackBiuret test – add sodium hydroxide then copper (ii) sulphate. Ifprotein present purple layer forms, if not stays blue.Emulsion test – shake solution with ethanol, pour solution intowater, goes milky if lipid present, milkier the solution, more lipid.
Nucleic AcidsDNA- deoxyribose nucleic acidBasesAdenineThymineCytosineGuanineDouble helix formation• Hyrdrogen bonding between bases- complementary basepairing• A-T & G-C• Antiparallel polynucleotide strands pair and twist to form theDNA double helix
DNA self replication1. Hydrogen bonds between strands breaks, helix unzips2. Each strand acts as a template for free-floating bases to join to the exposedbases by complementary base pairing3. Nucleotides on new strand are joined together by DNA polymerase to formthe backbone & hydrogen bonds form between the base4. Each DNA molecule has one original & one new strand.DNA copied for protein synthesis1. All organisms need proteins, instructions for them are in the nucleus2. Ribosomes make proteins but don’t fir into the nucleus so DNA is copied intoRNA3. RNA leaves the nucleus via the nuclear pores & joins with the ribosome inthe cytoplasm where it can synthesise a protein4. DNA & RNA are vital for all organisms to grow & developRNA• Sugar is ribose sugar instead of deoxyribose• Nucleotides form a single strand• Uracil replaces thymine, so U-T• Everything else is the same as DNA
Enzymes• Catalyse metabolic reactions• Intra or extracellular action• Globular proteins• Specific active site for specific substrates• Specific shape determined by tertiary structure• For enzyme to work substrate must fit into specific active siteEnzymes reduce activation energy• Joining of enzyme & molecule reduces repulsion so they bondeasier• In a catabolic reaction an enzyme is breaking down, it puts strain onthe substrate in the active site, this helps the substrate break moreeasilyLock and key modelEnzymes are picky so substrate must be perfect match for active site orelse they won’t bind.Induced fit modelSubstrate must be right shape & make enzyme change in the right way.
Factors affecting enzyme activityTemperature, pH, Enzyme concentration, Substrate concentrationCofactors- non-protein substance that binds to the enzymeInorganic molecules – help binding, not used up [cofactors]Organic molecules – needed for reaction & changed [coenzymes]Enzyme InhibtionCompetitive- similar shape, block active site, no reactionNon-competitive- bind away from active sire, alters active siteIrreversible = strong covalent bondsReversible = weak hydrogen bonds/ionic bondsCyanide irreversibly inhibits cytochrome c oxidase which catalyses respiration. Cellsthat can’t respire die.Some antibiotics inhibit transpeptidase which catalyses protein formation in bacterialcell walls. This weakens the cell & causes it to burst & die.
Diet & Food ProductionHDL transport cholesterol from body tissues to the liver. Reduce cholesterol istoo high.LDL transport cholesterol from liver to blood if levels are too low.Food productionAnimals given antibiotics to kill bacteria & increase food production bypromoting growth.Microorganisms & foodAdvantages• Rapid Growth• Inexpensive• Easy to create• Artificially controlled• Longer shelf lifeDisadvantages• High risk ofcontamination• Small environmentalchange can killbacteriaFood Spoilage• Salting- prevent micro-organisms taking in water• Sugar- same as salting• Freezing slows growth• Pickling prevents growth• Heat treatment kills• Irradiation kills
Health & DiseaseHealth- a state of physical, mental, & social well being includingthe absence of disease & infirmityDisease- a condition that impairs the normal functioning of anorganismPathogen- an organism that infects and can cause damage to itParasite- an organism that lives on or in another & cause itdamageMalaria- cause by Plasmodium, it disrupts liver, RBCs and bloodsupply to vital organs.AIDs- infects WBCs & kills them when it leaves, needs WBCs ashost for reproduction.TB- caused by Mycobacterium tuberculosis, “droplet infection”
Global impact of these diseasesThey are common in sub-Saharan Africa as there’s limitedhealthcare & equipment, so drugs aren’t always available orcan’t reduce chance of diseasing. Poor health education sopeople are unaware how to prevent spread of HIV &overcrowded conditions, so TB is spread easily.Studying global distribution of disease can:• Find where people are most at risk• Predict where epidemics are most likely to occur• Provide aid where needed• Important for research e.g. how it’s spread
Immune SystemImmune response- body’s reaction to a foreign antigen4 ways body brings about immune response1. Phagocytes engulf pathogens- recognise foreignantigen, engulf, digestive enzymes, present antigens2. Phagocytes activate T lymphocytes- releasesubstances to kill B lymphocytes, attach to pathogenantigens & kill it, some become memory cells3. T lymphocytes activate B lymphocytes which divideinto plasma cells- antibodies bind to antigens, Blymphocytes activated by T, divides into plasma &memory cells.
4. Plasma cells make more antibiotics to aspecific antigen-Antibodies help clear infection by:• Agglutinating pathogens- clump pathogens• Neutralising toxins- antibodies bind to toxins• Prevent pathogen binding tohuman cells- block cells surfacereceptor , pathogen can’t bindor infect target host cell
Immunity & VaccinationActive- Long term immunity, memory cells producedPassive- Short term immunity, no memory cellsproducedVaccination contains antigens that cause your body toproduce memory cells against a pathogen withoutcausing disease. Results in immunity without symptomsNatural ArtificialActive Immune after catching a disease Immune after vaccinationPassive Baby recieves mother’s antibodiesvia the placenta & breast milkImmune after injection of someoneelse’s antibodies
Herd Immunity- most people in a community vaccinated so diseasebecomes rare, people not vaccinated are unlikely to get the disease.New flu vaccines required each year as new strains are formedregularly.Possible medical sources needing to be protected:1. Many drugs are made from natural compound; animals, plants,fungi etc.2. Small proportion of organisms have been discovered, chances aresome undiscovered could hold a cure for ‘incurable’ diseases.3. Possible sources of drugs may not have been studied for medicinalproperties.4. New techniques are developing which may mean alreadydiscovered, known sources of medicine may have more than oneuse/application than previously known.
Smoking & DiseaseAtherosclerosis- lining of artery damages, plaque builds up,forms atheroma, restricts blood flow, high blood pressure.Nicotine cause high blood pressure.CHD- coronary arteries have atheromas, causing angina or heartattack.Stroke- rapid loss of brain function due to disruption of blood tobrain. Can be caused by clot in artery leading to the brain.Nicotine- increase BP, makes platelets clot.Carbon Monoxide- reduces oxygen available as it binds tohaemoglobin.Chronic Bronchitis- Inflammation of lungs, cilia damages, gobletcells produce more mucus. Increased coughing, decreased gasexchange.
Lung cancer- carcinogens cause mutation of lung cells whichleads to formation of a malignant tumour, which causes reducedgaseous exchange & blocks air flow. Tumour cause weight loss asit requires nutrients.Emphysema- Foreign particles trapped in alveoli. Phagocytesenter area & break down elastin. Alveolar walls destroyed, lungselasticity lost. Alveoli SA decrease so rate of gas exchange doestoo. Shortness of breath, wheezing, increased breathing rate.Linking smoking to disease or death- how to improve• Larger sample size- more reliable• Lies told may reduce reliability• Who study is done on can affect results e.g. doctors may bebias, so they seem healthy• Control as many variables as possible
BiodiversityBiodiversity- the variety of living organisms in an areaSpecies- a group of similar organisms able to reproduce to give fertileoffspring.Habitat- the area inhabited by a species, including physical & living factors.Habitat diversity- no of different habitats in an areaSpecies Diversity- no of different species & abundance of each species in anarea.Genetic diversity- variation of alleles within a speciesSpecies richness- no of different species in an area, higher the number,greater the richness.Species evenness- measure of relevant abundance of each species in an area.The more similar the population size of each species, the greater the speciesevenness.
Sampling• Choose sampling area• Count number of species, plants=quadrat, flying insects=net,ground=pitfall trap, aquatic = net• Repeat, better indication of habitat• Use results, estimates total number of individual or of speciesin habitat.• Use same sampling technique when comparing differenthabitats.• Sampling MUST be random.Simpson’s index of diversity:n= total no of individuals in a speciesN= total no of organisms of all species
What affects biodiversity:Climate- temperature, CO₂ levels, rainfall could cause species to migrateor to become extinct if they can’t migrate.Disease- insects carrying disease become greater, and can move withclimate change, e.g. area becomes warmer, mosquitoes move in.Agricultural Problems- land previously is available after climate change,can affect crops, food chains. Crop failure affect food chains.Importance of biodiversityEconomy- Food, drink, clothing, drugs, fuels, paper, oils, rubber, pesticide.Ecological- disruption of food chains & nutrients cycles, loss of habitats,habitat destruction.Ethical- organism has right to exist, moral responsibility, religion.Aesthetic- rich biodiversity=attractive, more biodiversity=more visitors(£’s)Agriculture- pollinators, source of food for livestock, pest control (naturalpredators), new varieties (selective breeding), protection against disease,more variety more chance of resistant individual.
CITES- Convention on international trade of endangered speciesRegulates trade in wild species, makes it illegal to kill endangeredspecies, trade only through licensing, no trade in endangeredanimals/materials, raise awareness of threat via education.Rio convention on biodiversityAims to develop international strategies on conservation, how touse plant/animal resources sustainably, international law thatbiodiversity conservation is a global responsibility, provideguidance guidance to governments on conservation.EIA- Environmental impact assessment• Estimate biodiversity on site, evaluate affect of developmenton biodiversity• Identify how to conserve biodiversity• Identify endangered species & laws regulating them• Decide on planning stipulations
ConservationIn situ-• National parks, protected areas, restrict urban development• Control/prevent introduction of threatening species• Protect habitats• Restore damaged areas• Promote particular species e.g. adjust food source• Legal protection on endangered speciesEx situ-• Relocate organism to a safer area• Breed organisms in captivity & release them into the wild• Botanic gardens preserve rare plants• Seed banks- freeze & store seeds with out fertility loss.
ClassificationDo you wanna King Prawn Curry Fat Greasy Sausage?Kingdoms- Prokaryotae(bacteria), protoctista (algae), fungi,plantae & animaliaPhylogeny- Study of evolutionary history of organismsClassification based on molecular evidence, behaviouralembryological & anatomical evidence.Dichotomous Key- a way to identify organisms using observablefeatures.
EvolutionVariation- the differences that exist between individualsWithin species= intraspecific variationBetween species= interspecific variationContinuous variation; animal mass, no of leaves, length of flagellumDiscontinuous variation; animal sex, plant colour, antibioticresistanceFactors that affect variation:Genes• Different species different genes• Same species, same genes, different alleles• Different genotype = variation in phenotype• Genetic variation is inherited
Environmental• Differences in environment• Characteristics controlled/change by environmentBoth• Height-genes determine height possible, diet affects actual height• Flagellum- genes determine height possible, environment affects actuallength.Adaptions• Being adapted means an organism’s features increase its chance ofsurvival & reproduction• Adaptions develop because of evolution by natural selectionBehavioural Physiological AnatomicalPossums ‘play dead’ Brown bear hibernation Otters have streamlineshapeScorpions dance for mating Bacteria producesantibioticsWhales have thick blubberlayer
DarwinObservations1. Organisms produce more offspring that survive2. Variation of characteristics in same species3. Some characteristic passed on4. Best adapted individuals more likely to surviveTheory• Individuals show variation in phenotype• Predation, disease, competition = struggle for survival• Better adapted individuals more likely to survive & reproduce• Over time, individuals with advantageous adaption increases• Over generations leads to evolution
Evolution can lead to speciationSpeciation- formation of a new species1. A species is defined as a group of similar organisms that canreproduce fertile offspring2. Species can exist as one or more populations3. Speciation occurs when population of the same speciesevolve so different that they can’t produce fertile offspringe.g. Darwin’s finchesEvidence supporting Evolution• Fossil record evidence• DNA evidence• Molecular evidence
Populations of Bacteria can evolve resistance to Antibiotics1. Variation in population of bacteria. Mutations makes some bacteria naturallyresistant2. If population of bacteria exposed, onty mutated bacteria survive to reproduce3. Alleles causing resistance passed on, so population become resistant toantibioticsImplications for humans:• Infections caused by antibiotic resistant bacteria are harder to treat• Bacterium could develop resistance to all known antibioticsPopulations of insects can evolve resistance to pesticides1. Variation in population, mutations causes some insects to be naturally resistant2. If population exposed only mutated individuals would survive & reproduce3. Alleles that cause resistance passed on so population becomes resistantImplications for humans:• Crop infestation with pesticide resistant insects harder to control• If disease carrying insects become resistant the of disease would increase• A population of insects could evolve resistance to all pesticides in use