Biology Notes Unit One

8/2/2019 Biology Notes Unit One

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Biology Notes

Surface area to volume ratio Mass transport systems: have branching vessels, make sure of ideal substance direction and movement and have a medium. Dipole: slight separation of charge between oxygen and hydrogen atoms. There are weak bonds between many molecules, this gives water high surface tension Water is amphoteric: can mop up h+ and oh- to maintain PH Water can dissolve: ionic substances, polar substances (covalent) and non-polar to form colloids. Emulsions: L+L, Suspensions: S+L Cardiovascular system: carrying hormones, defence, even temp, carries away waste food, delivers food to cells.

Blood takes food from intestines to store and from storage to cells, carries excretion, carries hormones, acts as a buffer, maintains temp Leucocytes either produce antibodies and antitoxins or engulf pathogens by phagocytosis O2 from lungs diffuses in RBC, the cytoplasm keeping the gradient stable, some O2 is then diffused into tissue, this process of oxygen disassociation

gives a sigmoid curve.

Carbon dioxide diffuses into plasma, reacts with water with the catalyst carbonic anhydrase, forms carbonic acid which separates into hydrogenand hydrogencarbonate ions. The haemoglobin acts as buffer, and with the hydrogen makes haemoglobinic acid, while the hydrogencarbonate

ions move out the plasma to allow chloride ions in, making the chloride shift

Serotonin minimises blood flow by contracting vessels while thromboplastin is an enzyme that converts fibrinogen into fibrin, forming a mesh andprothrombin into thrombin with the help of calcium ions.

CO2+H2O H2CO3 HCO3-+H

+


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Tough tissue

Double circulation system:o Systemic: carries oxygenated blood from heart to cells, takes cells deoxygenated blood back to hearto pulmonary: carries deoxygenated blood from heart to lungs, takes lungs oxygenated blood to heart

The mass and pressure of blood is suited to the type of tube it is carried by, similar to roads.

Angiogenesis is formation of blood vessels, cancer cells stimulate this to produce activator molecules, this spreads the cancer to surroundingepithelial cells, by stopping this and blocking blood supply it combats cancer.

Dr.Ruoslahti-blocks blood vessels Dr Fidler-blocks receptors

Found nanoparticle peptide bindswith blood clots on the endothelium

of only cancerous vessels, this

blockage starves the tumour of 20%

of oxygen and nutrients

Drug resistant Mice were giventraditional cancer treatment

combined with Glivec, this gave

optimum results by blocking

receptors receiving growth signals

Mices genes can be silenced or replaced to develop diseases, ethical issues considered.

Enterocytes: cells of the superficial layer of the intestines

Exceptions to blood

oxygen levels

appearance Notes

Arteries

Arterioles

Aorta

Carries blood away

from heart to cells

Deoxygenated when

-pulmonary carries

from heart to lungs

-umbilical cord

carries from fetus to

placenta

-blood pressure and

lumen diameter in

peripheral arteries

decrease with

increasing distance

from the heartLumen

Elastic fibres

and muscle


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Veins

Venules

Carries blood back

to heart from the

cells

oxygenated when

-pulmonary carries

from lungs to heart

-umbilical cord

carries from

placenta to fetus

-inferior and superior vena cava are the

veins that carries blood to heart.

-veins carry a lot of blood at a low pressure,

blood is taken to the heart by semilunar

valves that detect and adjust mechanically

the blood flow direction by musclescontracting

Capillaries

Allow in waste

material, diffuses

out food and oxygen

Small lumen for RBC

to pass through

Delicate structure,

blood coming into

capillaries from

arteries oxygenated,

when it leaves its

deoxygenated

Outer collagen layer

Wall of epithelial cells


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1

2

3

4

5

6 7

8

9


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The right side of the heart receives blood from the body and pumps it to the lungs. The left side is larger because it has to receive the blood formthe lungs and pump it around the whole body.

The blood from each side of the heart never mixes and the heart is made or unique non-fatiguing cardiac muscle. The tricuspid valve has three flaps while the bicuspid valve has 2 flaps. LubDub heartbeat sound, separation of 0.8s. Systole: the contraction of the heart Atrial systole: when atria contracts together forcing blood into the ventricle Ventricular systole: when the ventricle contracts and forces blood into the aorta and

pulmonary artery

Diastole: between contractions when the heart relaxes and fills with blood During diastole the semilunar valves are closed and the atrioventricular valves are

open, the opposite goes for systole.

ECG: electrocardiogram graph: display of electrical activity of the heart Intrinsic rhythmicity: the continuing contractions of the heart that starts before the heart is even formed, as a result of maintained electrical

excitation or impulse.

Cardiovascular centre: the part of the brain that receives messages about carbon dioxide concentrations in the blood from the receptors, in turnorders nerves to slow or speed up the heart rate, it is needed for the heartbeat to react to situations such as fear or exercise. Hormones, drugs and age can affect heart rate. When the heart contracts there is high blood pressure, when it relaxes, there is low blood pressure. Peripheral resistance: friction between blood and vessel walls, which slows the flow down.

1. IVC carrying carbon dioxide rich deoxygenated blood from lower body parts.2. SVC carrying carbon dioxide rich deoxygenated blood from upper body parts.3. RA collects all this blood and contracts, semilunar valves at entrance stops blood flowing back down VCs.4. Increasing pressure forces TV to open also called atrioventicular valve, tendinous cords stop TV turning inside out

by contracting pressure.

5. RV fills with blood and contracts to force blood into PA, semilunar valves stop blood flowing Back into RV.6. Here the deoxygenated blood is carried to the lung alveoli, to gain oxygen.7. Oxygenated blood is passing through the PV, into the LA which contacts and the BV allows blood to LV and prevents

backflow.

8. The LV contracts high-pressure blood to force it into the A, semilunar valves prevents backflow.9. The A carries blood away and supplies the body with blood.

Key:

IVC: inferior vena cava

SVC: superior vena cava

RA:right atrium

VCs: venae cavae

TV:tricuspid valve

PA:pulmonary artery

RV:right ventricle

PV:pulmonary vein

LA: left atrium

BV: bicuspid or mitral valveLV: left ventricle

A: aorta


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This ECG graph shows the pressure and volume changes on the left side of the heart during the human cardiac cycle
http://upload.wikimedia.org/wikipedia/commons/5/5b/Cardiac_Cycle_Left_Ventricle.PNGhttp://upload.wikimedia.org/wikipedia/commons/5/5b/Cardiac_Cycle_Left_Ventricle.PNG


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Blood pressure falls due to greater distance from pulsing heart, increased friction of narrow vessels and loss of fluid into the tissues. Temporary changes in blood pressure such as exercise, cause arteries to constrict (narrow) or dilate (widen), but permanent changes in pressure or

flow rate can cause health issues.

Blood pressure is measured in the old unit mm Hg

Systolic blood pressure: high pressure blood that passes the cuff first when the heart is strongly contracting. Diastolic blood pressure: low pressure blood that still pushes through the cuff, and when the blood sound appears normal. Normal blood pressure: systolic 120 mm Hg, diastolic 80 mm Hg (120/80) Hypertension: a sustained high blood pressure value perhaps caused by damaged blood vessels Hypotension: a sustained low blood pressure value perhaps caused by a weakened heart CVDs: cardiovascular diseases which account for of the UK premature deaths e.g. strokes. Artherosclerosis: the build-up ofplaque in the coronary (heart) or carotid (neck) arteries which restricts or blocks blood flow. Commonly caused by

high blood pressure or tobacco smoke (less likely in low pressure veins).

Manual Professional Automatic non-professional Calculated professional

A sphygmomanometer uses a cuff connected

to a stethoscope and mercury manometer to

stop blood supply to the lower arm. The

stethoscope listens to the sound of blood

passing through blood vessels at the elbow as

blood is slowly allowed through the cuff.

Automatic sphygmomanometers has a

microphone in the cuff that detects the sound

of blood flow and displays a reading on screen

patients can readings over time at home.

A machine detects blood flow through thumb

or wrist, and is converted into a reading that

would have been on the arm by a calculation.

More convenient

than being on arm

A professional is needed

to accurately interpret

resultsAccurate as patient

is more relaxed at

home

Expensive

Cheap Possible human error

Slight damage toendothelial lining

leading to formation

oflipids

Platelets cap lipid

formation and

narrows artery

Artery Wall

is less

elastic and

lumen gets

smaller.

Further

damage may

cause a clot

that may block

artery

Leucocytes

arrive carrying

cholesterol and

atheroma

forms

Calcium salts

and fibrous

tissue covers

atheroma to

make plaque


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Aneurysm: when the artery is weakened by blood build-up behind the plaque, resulting in high pressure bulges, it may burst and cause internalbleeding and very low blood pressure.

High blood pressure can affect organs such as the eye (blindness if the retina is starved of oxygen), the kidneys (if proteins are forced out walls andfound in urine) and the brain (where capillary bleeding may cause a stroke).

Angina: when the arteries struggles to supply enough oxygenated blood during exercise and resorts to anaerobic respiration, it causes chest pain,can be helped by improved lifestyle, drugs that dilate arteries and lower heart rate or heart bypass surgery.

Myocardial infarction: heart attack where the heart is starved of oxygen by a blocked artery or coronary thrombosis, causing severe pain or death,the worse place for this to occur is in the bicuspid valve .

Strokes: sometimes can be caused by a clot formed in another part of the body, then transported by the blood into an artery where it becomeslodged, effects include slurred speech or general paralysis on one side of the body, if it occurs in a smaller artery it is more treatable.

(Not sweet)(sweet)(sweet)


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Organic compounds contain carbon, hydrogen and oxygen atoms, they are allowed to be complex because carbon can form 4 strong bonds, makingmonomers or polymers, sometimes in a tetrahedral shape.

Two monosaccharides join by covalent glycosidic bond after condensation reaction wherein H2O is removed. Polysaccharides can be very compact so good for storing carbohydrates during cellular respiration. Through hydrolysis, polysaccharides convert to

monosaccharides because their own structure is inactive and insoluble in water which is needed in water relations like osmosis.

Starch is insoluble and are what sugars from photosynthesis are converted to so glucose can be rapidly produced, it is made up of these compoundso Amylose: unbranched spiral polymer that releases its 200-5000 glucose molecules by enzymes (1,4 glycosidic bonds)o Amylopectin: branched polymer that have lots of terminals (ends) that release glucose molecules at a faster rate, and is in higher

quantities (1,6 glycosidic bonds)

During respiration, the amylopectin helps when outbursts of energy is needed quickly, while amylose keeps you going longer Glycogen: the only carbohydrate found in animal starch, its structure is similar to starch but it has side branches, allowing it to release glucose

faster(combination of 1,4 glycosidic bonds and 1,6 glycosidic bonds)

Hydrolysis is the reversible reaction of a condensation reaction, so H2O is added, it occurs during digestion in the gut where polysaccharides arebroken down into simpler sugars.

Cholesterol, olive oil and butter=lipids, these can form a protective fat layer on organs, sometimes for waterproofing and plays a vital role in cellmembranes, they are used in the myelin sheath because it is a good insulator, it allows faster impulses, lipids have low density that allows floating,

lipids dissolve in organic substances but not water, thus dont interfere in cytoplasm water-based reactions, lipids have +oxygen than carbohydrates

Fatty acids and glycerol=fats and oils Fatty acids have a long hydrocarbon chain (15-17 Cs) and a carboxyl group at the end, and can be saturated (single covalent bonds) or unsaturated

(one-mono or many-poly double covalent bonds), polyunsaturates balance HDLs and LDLs ratios thus lowering cholesterol.

Mono-, di- or triglyceride: when glycerol bonds with one, two or three fatty acids which forms a fat or oil, this is the result of the condensationreaction, esterification where H2O is taken and an ester bond is made between the carboxyl group of a fatty acid and a hydroxyl group of a glycerol.


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Saturated fats can cause obesity or atherosclerosis, unsaturated fats are healthier because the double bond in the chain allows the body to dealwith saturated fats better, polyunsaturated fats are the healthiest.

Proteins: air, nails, skin, enzymes haemoglobin and hormones; contract muscle fibres, protection with antibodies and transport oxygen, proteins arelike the other food groups but in addition contain nitrogen, sulphur and phosphorus.

All amino acids have a carbon atom attached to an amino group (-NH2) and a carboxyl group (-COOH); R-groups are concerned with how aminoacids join into chains and depends on whether the R-group is polar or not; but when there is attraction a condensation reaction occurs and a strong

peptide link bond is made, which results in a structure of a dipeptide, then into a polypeptide, then a protein.

Hydrogen bonds: occur often but are weak and can break to temperature and PH change, as formed when slightly positive amino group and slightlynegative carboxyl group bond.

Sulphur bridges or disulfide link: strong covalent bond where an oxidation reaction occurs rarely between two colliding cysteine or methionine in apolypeptide.

Ionic bonds or salt bridges: occur rarely by ionic boing between strongly negative and positive side chains in the polypeptidePrimary Structure Secondary Structure Tertiary structure Quaternary structure

Linear sequence of amino acids in a

peptide

Hydrogen bonding that repeats the

primary structure e.g. pleated fibrousproteins with cross-linkages

3-D coiled secondary structure

e.g.globular proteins, held by sulphurbridges, hydrogen and ionic bonding

Numerous tertiary structures e.g.

enzymes and haemoglobin

Denatured:when conditions makes the bonding that makes up a proteins 3-D shape are broken and proteins cannot function fibrous proteins: tough and insoluble, good for making the tendon connective tissue and muscles and matrix of bones (collagen) and also as keratin globular proteins: have large spherical shapes that form colloids in water to give structure to the cytoplasm e.g. antibodies Glycoproteins: a protein that is conjoined to a carbohydrate prosthetic group, this allows it to carry water and not be ingested by enzymes, these

properties are useful in mucus, synovial fluid and haemoglobin which releases oxygen with iron.

Lipoproteins: a protein conjoined to a lipid that enables it to combine with cholesterol, there are low density(22 nmd) that form saturatred fatsand high (8-11 nmd) density that form unsaturated fats lipoproteins. HDLs can even lower cholesterol as it takes it to where it can be broken down

To uncover the structure of proteins, scientists use enzymes to break them down into their amino acids, then perform one of three processesTwo-way Paper chromatography (at right angle) Electrophoresis* X-ray crystallography

Drops of amino acid in a solvent is put on Water-soaked

Filter paper,then ninhyrin reveals how far they travelled

A PH constant solution holds amino acids in an unreactive

gel and current is passed,their moving depends on R-group

X rays fired at protein crystal,atoms reflect a pattern back

and printed on photographicplates to be interpreted

*When interpreting chromatograms and electrophoresis apply the ratio of the distance moved by the amino acid to the distance moved by the solvent alone(R f)using this formula


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The committee on medical aspects of food policy COMA reviews scientific research and advice the government and have developed dietaryreference values that show the appropriate intakes for the population, there are LRNI (lower reference nutrient intake), EAR (estimated average

intake e.g. energy, vitamins, minerals, carbohydrates and fat) and RNI (reference nutrient intake e.g. protein, vitamins and minerals)

Energy that comes from food is released when their bonds break, this is measured by calorimetry using a calorimeter:First a quantity of food is oxidised and the energy released is transferred to the water as heat, the d ifference in temperature compares to:

o 4.2 kJ of heat energy raise the temperature of 1kg of water by 1oco Carbohydrates yield 17.2Kj/go Lipids yield 38.5kJ/go Proteins yield 17.2kJ/g

Calories are actually called Kilocalories, 1 Kilocalorie=4.2 Kilojoules Basal metabolic rate(BMR): the energy the body needs to operate organs, metabolism and reactions in the cells,

measured at rest and calculated by noting temperature changes over a period of time, it makes 75% of metabolic needs

BMR also relies on total body mass and lean body mass, this is why those with high proportion of muscle e.g. men have a high BMR as more energyis need to maintain it than fat BMR falls with age as muscle is replaced with fat.

However BMR does not take human activity into account thereby it is of little use, so physical activity level(PAL- kJ/unit time) is used, in the UK,this is an average of 1.4 (low), when multiplied by the BMR, EAR is given for different ages and lifestyles

Positive energy balance: when it is easy for people to eat above the Basal metabolic rate or recommended minimum daily intake Negative energy balance: when food is scarce and people barely cover their Basal metabolic rate or recommended minimum daily intake BMI-body mass index: now found not make allowance for the difference between fat and muscle and is not good at predicting likelihood of CVDs

o 18.5kg/m2-underweighto 18.5-25kg/m2-ideal rangeo 25-30kg/m2-overweighto 30-40kg/m2-obeseo 40kg/m2-morbidly obese

Risk: describes the probability that a particular event will happen and is calculated by diving the whole population by past events Multifactorial disease: .eg. dieases that show to correlate with several risk factors through genes or lifestyle, the study of this is epidemiology

Problems of Mal-overnutrition Problems of Mal-undernutrition

May lead to obesity that can reduce lifespan, increase risk of diabetes, coronary heart

disease and high blood pressure

Reduce resistance to disease and shorten lifespan, suffer deficiency diseases due to lack

of essential amino acids, minerals and vitamins, muscle wastage and heart damage

Weight in Kg

BMI= (Height in meters)2
http://www.google.co.uk/imgres?q=calorimeter&hl=en&biw=1366&bih=530&gbv=2&tbm=isch&tbnid=wP0a1pw8kZPWhM:&imgrefurl=http://m.eb.com/assembly/4705&docid=0tb-CmLSC79EsM&w=368&h=328&ei=7siMTvCDPc698gOkrvHRBg&zoom=1


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Retrospective: scientists look back at information on health and death rates collected years earlier Longitudinal studies: follow the same group of individuals over many years Metadata analysis: condensing large amounts of data Literature study: combines small and large studies in an area to give more reliable evidence than they do individually

Theory: 80% of the protein in milk is casein, which has the forms beta casein A1(unhealthy)and A2(healthy)with a single amino acid separating them Theory: when the amino acid homocysteine is not metabolised it causes atherosclerosis, this can be combated by taking folic acid and B vitamins Antihypertensives: drugs that reduce blood pressure they have side effects such as very low blood pressure, swelling, fatigue and constipation, e.g.

o Diuretics: lowers blood volume by increasing volume of urine to get rid of excess fluids and salts o Beta blockers: block hormones that may speed up rate or make the heart contact e.g. adrenalineo Sympathetic nerve inhibitors: inhibit the signals of the nerves to the arteries to constrict so that they dilate o ACE inhibitors: stops the manufacture of the hormone Angiotensin that constricts the arteries

Statins: drugs that reduce risk of atherosclerosis by balancing LDLs and HDLs and blocking the enzyme in the liver that makes cholesterol, rare side-effect: liver or muscle damage Plant stanols and sterols have a similar structure to cholesterol but reduce the amount absorbed from the gut to the blood and reduces LDL thus if

the recommended 2g is taken daily, it can lower risk of heart disease by 25%, however less tested than drugs as evidence is weak

Thrombosis treatment involves anticoagulants that blocks blood-clotting prothrombin and loosens blood (warfarin which needs careful dosage)and platelet inhibitor drugs which make platelets less sticky (painkiller aspirin or clopidogrel which could cause stomach or brain bleeding).

High salt intake has proven to be a factor in the risk of CVDs but people have many personal reasons they chose to have lifestyles with health risks


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Genetic code is all the instructions for making cells whether by mitosis or meiosis it is found in nucleic acids stored in the chromosomes of thenucleus, it is used to made DNA, RNA and other proteins

DNA and RNA are polymers and have similar monomer units, nucleotides, which have three parts (below)

Nucleotides are linked by a condensation reaction producing a covalentphosphodiesterbridge between the sugar and acidto make the spine ofpolynucleotide

The two DNA stands known as 5 prime and 3 prime for carbon atoms are held by hydrogen bonds between complementarybase pairs (10 per twist).

In 1865 Mendel posed the concept of inherited particles, scientist then looked at the behaviour of chromosomestransferring this, in 1945, MacLeod and McCarty found DNA was the genetic code carrier, in 1951, Chargaff found equal

proportions of bases in DNA, Pauling lead the study of DNAs structure and proves hydrogen bonds could be broken by

heating, Wilkins and Franklin were observing x-ray crystallography with difficulty that ensued rivalry, Wilkins then secretly

gave Franklins measurements to Watson and Crick whom had a breakthrough of understanding the double helix and thus

the role of DNA in reproduction.

where the enzyme helicase unzips the coil and new base bonds are joined to make stands by polymerase and ligase There are two types of DNA replication, conservative where the double helix remains completely intact and an entirely new double helix is formed

without destroying the original copy and semiconservative where the bonds between the bases are broken and the DNA molecule "unzips" into

two strands. Alongside each of the two strands forms a new strand, thus the final copies are half original DNA and half new DNA.

Deoxyribonucleic acid pentose sugar (deoxyribose)+nitrogen base(purines=adenine and guanine=pyrimidines=cytosine and thymine)+phosphoric acid

Ribonucleic acid pentose sugar (ribose)+nitrogen base(purines=adenine and guanine=pyrimidines=cytosine and uracil)+phosphoric acid (in cytoplasm)


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In 1958, Meselson and Stahl carried out this experiment:

A triplet code is used to form the many combinations of amino acids, where TAC codes for the start of a gene and methionine if within a gene Gene: a sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain. mRNA has an antisense stand of DNA and is engulfed by a ribosome, tRNA is found in the cytoplasm and deliver amino acids to make peptide bonds Mutation: changes in the arrangement of bases in an individual gene or in the structure of the chromosome, which changes genes in chromosome Point mutations: miscopying of one nucleotide, causing a frame shift or reshaped active site, where Met bonds with Phe, making an unhealthy

phenotype protein

Chromosomal mutations:changes in the positions of genes in the chromosomes either by point, deletion, duplication, inversion or translocation whole-chromosome mutation: when a whole chromosome is lost or duplicated during meiosis, like many mutations, they can be inherited mutagens:ionising radiation, x-rays and some chemicals that can increase rate of mutations occurring


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Q10= rate of reaction at (x+10)oc

rate of reaction at xoc

Thalassemia is when blood proteins are faulty made; cystic fibrosisis when a membrane function cant function and Downs syndrome occurs bywhole-chromosome duplication of chromosome 21, skin cancers is mutations in somatic (body) cells.

Metabolism: combinations ofanabolic (build-up of bonds)and catabolic (break-up of bonds)reactions, can form a metabolic chain or pathway Specificity: enzyme that works in a specific group because of the specific shape of the active site, small depression on the surface of a 3-D molecule Complex: formed by enzymes and substrates locking , lowering activation energy in anabolic reaction by bringing stuffs closer and catabolic

reactions by the active affecting the bonds in the substrates making bonds easier to break, thereafter it may break or become inactive

Induced-fit hypothesis: new model where the more flexible enzyme is modified to allow substrates Molecular activity: measures number of substrate molecules transformed per minute by a single enzyme, catalase being the fastest Enzymes can become statured by the concentration of substrates, this means all of the active site are full of substrates Temperature co-efficient: effect of temperature on reactions, (expressed aside) the typical range being every

10oc

rise=doubling of rate, outside the range enzymes can become denatured similarly with the affect PH has on its

weak bondage, there are exceptions for thermophilic (heat loving) enzymes

Enzymes, used in diagnostic testing e.g. urine-glucose test, enzyme-linked immunosorbent assays are useful in detecting antibodies and infections the history of enzymes include the realisation of how to extract them and the discovery of them being globular proteins enzymes that work inside the cells are intracellular and those that are secreted by cells are extracellular, enzymes can be named according to what

it does, what it works on or by a classification number.

Phenotype: chemical and physical characteristics of an organism Genotype: inherited genetic information from parents Karyotype: the assortment chromosomes in the genotype of an organism organised in homologous pairs which have similar genes(except gametes) Locus: the position of a gene Alleles: different versions of genes that produce characteristic variations Homozygote or true breed: organism with the same alleles (homozygous), desirable for farmers Heterozygous: organism with different alleles (heterozygous) Monohybrid cross: when one gene is considered at a time in a genetic cross First filial generationF1 is the first cross round,Second filial generation F2 is the second cross round(characteristics can be hidden in either round) Test cross: crossing organisms to deduce if they are homo or heterozygous These traits make organisms like fast plants, insects, fungi and bacteria suitable for experimentation:

cheap and easy to raise in bulk have distinguished features have large offspring with short life cycles


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Sampling error when find theoretical ratios,because the joining of gametes is a random affair and predictions are never precise,decreases with s-size Gregor Mendel investigated peas meticulously by predicting the results of their crosses, he made these laws but his findings were ignored due to

the perfect evidence that proved others wrong through statistics, Thomas Morgan later found Mendels laws was correct and they still apply today

o Law of segregation: in a diploid, one allele for each trait is inherited from each parent to give two allele for each trait (segregated gametes)o Law of independent assortment: different traits are inherited independently, gene linkage and polygenic inheritance contradicts this

where traits are controlled by several interacting genes

Enzyme chains: to make proteins enzymes need a lot of energy, aided by genes involved an example of polygenic inheritance Incomplete dominance: neither allele is completely dominant or recessive thus both affect the phenotype polygenetichaemoglobin is made up of 574 amino acids arranged in 4 polypeptide chains either from alpha or beta chains, Thalassemia stops these

forming thus stopping oxygen transport, there are varied types but common symptoms are fatigue, anaemia or death, it can be caused by gene

deletion ( c-16)or mutation( recessive c-11), those with Thalassemia have high resistance to malaria, Thalassemia major or Cooleys anaemia is

severest where chains cannot be made and Thalassemia is incurable but treated by blood transfusions or screening with side effects, moral issues

genetic pedigree diagrams:shows how a trait can be inherited theoretically,it includes all family members and useful when predict human diseasesproband is the person being studied( ),identical twins( )

Albinism: when natural melanin pigment of the skin, eyes and hair cannot form(not fatal),caused by either a recessive mutant allele which stopsenzyme tyrosinase form, (active in melanocytes that reacts to make melanin) or the breakdown of amino acid phenylalanine by mutant enzymes

Some people find learning they have an incurable fatal disease e.g.Huntingtons disease unbearable and would rather not be tested by others whomwant to start a family with them think they have the right to know or insurance companies, as no one has a set of perfect genes. Some biotech

companies take advantage of the free human Gerome project and develop to sell, causing drugs to be too expensive for the developing world.

Apart from the outer cell one, there are many membranes within a cell, these control fluid compositions for suitable reaction conditions, it is alsoflexible to adjust to cell water levels changes, they are made from polar lipids, some phospholipids and proteins, some glycoproteins.

Vesicles: sacks of cell secretion which fuses with membrane Each polar lipid is joined to a polar group while the fatty acids have the structure of a hydrophilic head and a hydrophobic tail, when tightly packed

either form a monolayer (heads in water and tails in air) or a micelle (heads pointing outwards and tails hidden). When there is water on each side a monolayer may rarely form at the surface and a bilayer is formed (heads in the water and tails hidden)making

the unit membrane which allows fat-soluble organic molecule into the cell

Fluid mosaic model: Proteins float in a lipid sea, the proportion of phospholipids containing unsaturated fatty acids in the bilayer affects how freelythe proteins float, even some penetrate all the way through the lipid (having hydrophobic part in lipid bilayer)


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proteins have gated channels or pores, some allowing ionics in or active carrier systems which provides energy for molecule to move proteins can be a specific receptor molecules, enzymes or glycoproteins with a carbohydrate part added to the molecule allows cells be recognised at the end of the nineteenth century Overton found lipid-soluble matter passed through membrane well, in 1917 Langmuir demonstrated the

monolayer,in 1925 Gorter and Grendel measure the size of membrane components with error, in 1935 Davson and Danielli found proteins and lipid

gases water and lipid-soluble substances can pass into membrane via diffusion where after the particles reach a uniform distribution=net change facilitated diffusion can be passive transport through protein lined pores occurs when channel proteins are allowing types of molecule through

which is specified by its shape or triggered to open by an electrical impulse. Or depending on protein carriers on the outside surface of the

membrane passing through a substance or on the inside when a substance moves out, the carrier rotates with the molecule by diffusion the

membrane with a renewed shape e.g. RBC carrying oxygen

water enters by osmosis thus avoiding the hydrophobic centre, glycocalyx found on the outer side is used for cell recognition within tissues osmosis is the net movement of solvent molecules from a region of dilute solution of solute to a more concentrated solution of solute through a

partial permeable membrane, in living organisms the solvent is always water, osmotic concentration describes how solutes usually in plant cells are

effected, there is hypotonic (higher c. water), hypertonic (higher c. solute) or isotonic solution (equal c.), osmosis can be investigated by benedicts

solution. Isotonic sport drinks help give equal levels of body fluid. If the surrounding cell solution is hypotonic, the osmotic c. of solutes is lower

than that in the cytoplasm of cells, the reverse if hypertonic. in animals water does not move continuously into cells due to overfill, so the net movement is kept at a minimum, if water is deficient ,the

concentrated cytoplasm loses structure and reactions stop, cellulose cell wall prevents cells bursting by halting water influx after cell is rigid, turgor

cells can metabolise substances by chemically changing it or by active transport involving a whole membrane carrier protein that uses energy fromthe breakdown ofATP (produced during cellular respiration)assisted by ATPase removing a phosphate group to form ADP. AT is faster and one-way,

it relies on temperature and oxygen c. and cells contain lots of mitochondria-the site of aerobic cellular respiration, cyanide poisons ATP and stops it

sodium pump: actively moves potassium ions into the cell and sodium ions out, vital for the CNS, each nerve impulse depends on the influx ofsodium ions through the axon membrane, these ions have to be actively pumped out the neuron after to let the next impulse pass.

Endocytosis: when materials are taken in by vesicles e.g. phagocytosis(cell eating) or pinocytosis(cell drinking)

Exocytosis: the emptying of the vesicles at the surface e.g. hormones The rate of diffusion across a membrane has these factors and can be calculated by this:

increasing surface area- maintaining the c. gradient decreasing the distance

Ficks Law: surface area*c. difference

Rate of diffusion __________________________

Thickness of membrane


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Gases that need to be supplied more quickly than diffusion need a respiratory system, the nasal passages have large moist surface area to increasethe air water vapour, a good blood supply for air temperature and the lining secretes mucus and is covered in cilia which removes dust breathed in

Alveoli are tiny air sacs made of squamous epithelial cells, one-cell-thick capillaries run close, separated by elastic tissue that performs elastic recoil Alveoli naturally tend to collapse,phospholipid lung surfactant coating prevents this while phagocytic WBC in macrophage kept it free from bacteria Inhalation: more chest cavity volume, intercostal muscles contract, diaphragm flattens, air pressure lung pressure, air goes out (forced exhalation) Exhalation: less chest cavity volume, intercostal muscles relax, diaphragm domes, elastic fibres return, air pressure lung pressure, air goes in Stomach acid and enzymes digest mucus and is kept runny by this process:

o Chorine pump allows Chlorine ions in e. cells (maintains gradient)o Chlorine ATP-activated gated channels in lumen made from CFTR protein pass ions (diffusion), also sodium channels for sodium ionso High c. of Na and Cl in fluid of cytoplasm of e. cells causes water osmosis, so water can dilute mucus

Cystic fibrosis is caused by a recessive mutation on chromosome 7 coding for CFTR,DC508,thus chlorine and water does not move out&mucus sticks Symptoms: salty sweat, blocked bronchioles, breathlessness, bacteria growth in mucus, dehydrated antibodies, infertility and gut and pancreas

indigestion as mucus blocks the pancreatic duct passing enzymes from pancreas to duodenum (top of s. intestine), villi absorbs enzymes into lining,

as a result, less nutrients gained and trapped enzymes may digest pancreas cells e.g. insulin-risk of diabetes or blocked villi=malnutrition

Excess mucus can block a womans cervix and oviducts stopping sperm or block a mans vas deferens so sperm is not carried from testis to semen Usually CFTR keeps Na and Cl ions at a gradient so that it can be reabsorbed as it is passes by gland ducts,salty sweat indicates CF or heart problems No real cure for CF but there are the following aids:

o Physiotherapy exercises out mucus twice day e.g.flutter, thAIRapy, or Positive Expiatory Pressure valveo Diet: due to digestive issues, CF sufferers need to eat more, high-fat, carb and energy food and twice as much proteino Drugs and enzymes: antibiotics via inhalers for lung infections, vaccines against flu and pneumonia, DNAase mucolytics dilute mucus,

salbutamol and steroids to open airways and reduce inflammation, missing pancreatic enzymes and insulin

o Heart or lung transplant surgery: on that organ is cured, body needs immunosuppressant drugs to prevent rejection(less immune)o Genetic modification: restriction endonucleases enzymes cut DNA, perhaps at a sticky end (more base pairs on one stand than the other-

easier to attach new pieces, healthy genes made by mRNA-DNA using reverse transcriptase to make cDNA, DNA ligases acts as genetic glue

o Vectors:adenovirus or retrovirus or plasmids (naked DNA gun)or liposome combine with recombinant DNA in the host nucleus(transfection)o Somatic cell gene therapy: gene therapy may not work because of these barriers:

sodium ion move out less easily than chlorine ions epithelial cells are always being shed enhanced gene not inherited look at germline

difficult lung blockage- looking at blood medium low permanent vector success rate- looking at stem cells


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It is now possible to perform gene therapy on early stage embryos but this may lead to designer babies or invasive intervention Screening babies for faulty genes has been introduced to give early treatment, balancing the finance, prenatal screening may raise traumatic

decisions for abortion, most parents would rather not know if their child is a carrier, genetic counselling is used in these cases , foetuses are tested:

o Amniocentesis: removes 20cm3 of amniotic fluid surrounding fetus with syringe, cells are spun in centrifuge and are cultured/analysed-late stage fetus abortion more traumatic -1% risk of miscarriage -results take a while

o Chorionic villus sampling: small sample of embryotic tissue taken from developing placenta, earlier in pregnancy, faster results-4.8% risk of miscarriage -faults on inactivated X chromosome undetected

o Preimplantation genetic diagnosis: involves IVF where on faulty gene-free embryos are implanted thus removing the gene from the pool

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Biology Notes Unit One