unit_1_summary_notes_as_biology.doc

8/20/2019 unit_1_summary_notes_as_biology.doc

1/22

Biological molecules

Explain what is meant by a polymer.(Molecule) made up of many identical/similar molecules/monomers/subunits;

Describe the structure of an amino acid molecule and explain how amino acidslink together.1 Amino acid based on carbon with four groups attached;2 Amino/ NH2 and carboyl / !""H;

# $%group/ side chain & hydrogen;' $%group diers from one amino acid to another; Amino acids *oined by condensation;+ ,ond formed between NH

2 and !""H;

- .noles remoal of molecule of water;0 H from NH2 and "H from !""H;


2/22

6ilac/purple/maue/iolet;

With reference to named parts of

the diagram, explain thedierence between the termsTriglyceride and phospholipid;=hospholipid has (one) phosphate /=hosphoric acid;replacing fatty acid;

Saturated and unsaturated.4aturated > all alencies of ! 5lled / saturated withhydrogen / all (!>!)single bonds / no double bonds;fatty acid 1 is saturated/fatty acids 2 and # areunsaturated;


3/22

&rokaryotic cells 's Eukaryotic cells

(he structure of a cholera bacterium is dierent from the structure of anepithelial cell from the small intestine. Describe how the structure of a cholerabacterium is dierent.

1 !holera bacterium is proaryote;2 oes not hae a nucleus/nuclear enelope/ has NA free in cytoplasm/has loop of NA;# and ' Any two fromNo membrane%bound organelles/no mitochondria / no golgi/ no endoplasmicreticulum/etc; 4mall ribosomes only;+ and - Any two from!apsule/8agellum/plasmid / cell wall/etc;

)i*e + ways in which pathogens can cause disease when they enter thebody of their host.amage/destruction of cells/tissues =roduction of toins;

Describe the dierence between an endotoxin andan exotoxin.9ndotoins produced from the breadown of bacteria (cellwalls);(allow burst / lyse – do not allow decompose)

eotoins secreted / released (from liing cells) (not produced);endotoins are lipopolysaccharides;eotoins are protein;

ow '.cholerae causes Diarrhoea1: 3he cholera bacterium adheres to the epithelium andsecretes the cholera toin !3: !3 enters the epithelialcells and actiates a chloride ion channel in the cell

membrane


4/22

2ucleus. 3his is the largest organelle: .t is

surrounded by a nuclear enelope< which is

a double membrane with nuclear pores >

large holes containing proteins that control

the eit of substances from the nucleus: 3he

interior is called the nucleoplasm< which is

full of chromatin > the NA/protein comple

(see unit 2): uring cell diision the

chromatin becomes condensed into discrete

obserable chromosomes: 3he nucleolus is adar region of chromatin< inoled in maing

ribosomes:

3itochondrion 3his is a sausage%shaped

organelle (0Cm long)< and is where aerobic

respiration taes place in all euaryotic cells

(anaerobic respiration taes place in the

cytoplasm): Mitochondria release energy (in

the formA3=) from carbohydrates< lipids and

other energy rich molecules: !ells that use a

lot of energy (lie muscle cells) hae many

mitochondria:

Mitochondria are surrounded by a double

membraneB the outer membrane is simple

and uite permeable< while the inner

membrane is highly folded into cristae<

which gie it a large surface area: 3he space

enclosed by the inner membrane is called

the mitochondrial matri< and contains small

circular strands of NA: 3he inner

membrane is studded with staled particles<

which are the en@ymes that mae A3=:

ibosomes 3hese are the smallest and

most numerous of the cell organelles< and

are the sites of protein synthesis: $ibosomes

are either found free in the cytoplasm< where

they mae proteins for the cellDs own use< orthey are found attached to the rough

endoplasmic reticulum< where they mae

proteins for eport from the cell: All

euaryotic ribosomes are of the larger< E0F4E<

type:

9ndoplasmic $eticulum (9$): 3his is a series of

interconnected membrane channels inoled in

synthesising and transporting materials: $ough

9ndoplasmic $eticulum ($9$) is studded with

numerous ribosomes< which gie it its rough

appearance: 3he ribosomes synthesise proteins<

which are processed in the $9$ (e:g: by

en@ymatically modifying the polypeptide chain<

or adding carbohydrates)< before being

eported from the cell ia the Golgi ,ody:

4mooth 9ndoplasmic $eticulum (49$) does not

hae ribosomes and is used to process

materials< mainly lipids< needed by the cell:

Golgi ,ody (or Golgi Apparatus): Another series of

8attened stacs of membrane esicles< formed

from the endoplasmic reticulum: .ts *ob is to

transport proteins from the $9$ to the cell

membrane for eport: =arts of the $9$ containing

proteins fuse with one side of the Golgi body

membranes< and are modi5ed (carbohydrate is

added to form glycoproteins)< while at the other

side small esicles bud o and moe towards thecell membrane< where they fuse< releasing their

contents by eocytosis:

4ysosomesB 3hese are small membrane%bound

esicles formed from the $9$ containing a coctail of

hydrolytic en@ymes: 3hey are used to brea down

unwanted chemicals< toins< organelles or een whole

cells< so that the materials may be recycled: 3hey can

also fuse with a feeding acuole to digest its contents:

5hloroplast

Membranes arrangement and disc shape

proides large surface for light absorption;

layering of membrane allows a lot of pigment;

=ermeable membrane allows diusion of

gases /carbon dioide;

membranes proide surface for attachment of

electron / hydrogen acceptors;

!ontains chlorophyll for light absorption;

!ontains dierent pigments to absorb

dierent waelengths;

4tacing / arrangement of grana/thylaoids

maimises light catchment;

4troma contains en@ymes for photosynthesis;

"uter membrane eeps en@ymes in


5/22

3icroscopes

What is resolution and why is it better in Electron 63icroscopes than in lightAbility to distinguish points (close together)< 9lectrons hae a shorter waelength;

/cientists use optical microscopes and transmission electron microscopes!(E3s# to in*estigate cell structure. Explain the ad*antages and the limitationsof using a (E3 to in*estigate cell structure.AdantagesB1 4mall ob*ect can be seen;2 39M has high resolution;# aelength of electrons shorter;

6imitationsB

' !annot loo at liing cells; Must be in a acuum;+ Must cut section / thin specimen;- =reparation may create artefact0 oes not produce colour image;

3easuring the si7e of an ob8ect under a microscopeMeasure with an eyepiece graticule!alibrate with the stage mcirometer (an ob*ect of a nown si@e)

$epeat and calculate an aerage

5ell fractionation/tarting with some lettuce lea*es, describe how you would obtain a sample ofundamaged chloroplasts. 9se your knowledge of cell fractionation andultracentrifugation to answer this :uestion.1: !hop up (accept any reference to crude breaing up);2: !old; (reduces en@yme actiity)#: ,uered solution; (preents pH aecting en@ymes)

' .sotonic / same water potential; (preents osmosis and possible lysis or shrinage of

4ta

pho

$ib

syn

4ha

for


6/22

3embranes and mo*ement/uggest why the model of the membrane is described as afuid mosaic.Molecules within the membrane able to moe;miture of phospholipid and protein / arrangement of protein;

Describe the structure of a phospholipid molecule and explainhow phospholipids are arranged in a plasma membrane.1 =hosholipid consists of glycerol;2 (3o which are *oined) two fatty acids;# And phosphate;' ,y condensation/elimination of water molecules; Arranged as bilayer in membrane;+ Head/phosphate hydrophilic/polar and tail/fatty acid

hydrophobic/non%polar;- Heads outside and tails attracted to each other/inside;

Describe the structure of a cell membrane. !1#ouble layer of phospholipid molecules;etail of arrangement of phospholipids;.ntrinsic proteins/protein molecules passing right through;4ome with channels/pores;9trinsic proteins/proteins only in one layer/on surface;

Molecules can moe in membrane/dynamic/membranecontainscholesterol;Glycocaly/carbohydrates attached to lipids/proteins;

;


7/22

ierent cells hae dierent proteins;

!orrect reference to cytosis


8/22

9n@ymes3any reactions take place in li*ing cells at temperatures far lower than those re:uired forthe same reactions in a laboratory. Explain how en7ymes enable this to happen.lowers actiation energy;releant mechanism e. g. brings molecules close together / reaction in smaller

steps / change in charge distribution / proton donation or acceptance / inducedt ensuring substrates brought in correct se!uence"including releant reference to actie site;

Explain how a substrate is broken down by the en7yme.4ubstrate enters actie site;!omplimentary shapes / 6oc and Iey;(,inding) to form en@yme%substrate comple;6owering of actiation energy;

!onformational / shape change;,reaing of bonds in substrate;=roducts no longer 5t actie site and so are released;

Describe howthe condensation reaction can be catalysed by an en7yme.

en me has an acti e site


9/22

,y breaing speci5ed bonds (not peptide bond);Actie site altered/substrate cannot bind/5t/Explain how inhibitors aect the rate of en7yme%controlled reactions.1 4tatement about two types< competitie and

non%competitie;#ote. $ward points % –& only in context of competiti'e andnon(competiti'e inhibition!ompetitie2 4imilarity of shape of inhibitor and substrate;# .nhibitor can enter/bind with actie site (of en@yme);Non%competitie

' Aect/bind to en@yme other than at actie site; istorts shape of actie site;.nhibitors+ =reent entry of/binding of substrate to actie site;- 3herefore fewer/no en@yme%substrate complees formed;


10/22

igetsion

Describe the role of the en7ymes of the digesti*e

system in the complete breakdown of starch.

Amylase;(saliary/pancreatic)(4tarch) to maltoseBMaltase;(built into the membrane of the small intestine)Maltose to glucose;Hydrolysis;("f) glycosidic bond;

Explain how the small intestine is adapted to its function in the absorption of theproducts of digestion.

6arge surface area proided by illi /microilli;long / folds increase surface area / timefor absorption;thin epithelium;short diusion pathway;capillary networ absorbs amino acids /sugars;lacteal for absorption of digested fats;

Maintains a steep concentrationgradientmitochondria supply A3= / energy foractie transport;carrier proteins (in membranes);

Describe the processes in*ol*ed in the absorption of the products of starch digestion.Glucose moes in with sodium (into epithelial cell);

Ci ( i / h l) t i / t


11/22

reference to co%diusion e:g: glucose and Na!l;monosaccharide?s or named / amino acids moe into blood;


12/22

1: Mouth (,uccal caity): 3he teeth and tongue physically brea up the

food into small pieces with a larger surface area< and form it into a ball or

bolus: 3he saliary glands secrete salia< which contains water to

dissole soluble substances< mucus for lubrication< lyso@ymes to ill

bacteria and saliary amylase to digest starch: 3he food bolus is

swallowed by an inoluntary re8e action through the pharyn (the bac

of the mouth): uring swallowing the trachea is bloced o by theepiglottis to stop food entering the lungs:

2: "esophagus (gullet): 3his is a simple tube through the thora< which

connects the mouth to the rest of the gut: No digestion taes place here:

3here is a epithelium< no illi< a few glands secreting mucus< and a thic

layer of circular and longitudinal muscle to propel the food by peristalsis:

=eristalsis is a wae of circular muscle contraction< which passes down

the gut and is completely inoluntary: 3he oesophagus is a soft tube that

can be closed< unlie the trachea< which is a hard tube< held open by

rings of cartilage:

3he mucosa< which secretes digestie *uices and absorbs digested food: .t is

often folded to increase its surface area: 3here is a layer of columnar epithelial

cells lining the mucosa: 3hese epithelial cells contain microilli< membrane

proteins for facilitated diusion and actie transport< mitochondria< and

membrane%bound en@ymes: 9pithelial cells are constantly worn away by

friction with food moing through the gut< so are constantly being replaced:

K 3he submucosa< which contains blood essels< lymph essels and neres to

control the muscles: .t may also contain secretory glands:

K 3he muscle layer< which is made of smooth muscle< under inoluntary

control: .t can be subdiided into circular muscle (which suee@es the gut

when it contracts) and longitudinal muscle (which shortens the gut when it

contracts): 3hese two muscles therefore hae opposite eects and so are

antagonistic: 3he combination of these two muscles allows food to be pushed

along the gut by peristalsis:

K 3he serosa< which is a thin< tough layer of connectie tissue that holds the

gut together< and attaches it to the abdomen:

#: 4tomach: 3his is an epandable bag where the food is stored for up to a few

hours: 3here are three layers of muscle to churn the food into a liuid called

chyme: 3his chime is gradually released in to the small intestine by a sphincter<

a region of thic circular muscle that acts as a ale: 3he mucosa of the

stomach wall has no illi< but does hae numerous gastric pits (1F' cm%2)

leading to gastric glands in the mucosa layer: 3hese glands secrete gastric *uice<

which containsB hydrochloric acid (pH 1) to ill bacteria (the acid does not help

digestion< in fact it hinders it by denaturing most en@ymes); mucus to lubricate

the food and to line the epithelium to protect it from the acid; and some

protease en@ymes: No other digestion taes place in the stomach:

': 4mall .ntestine: 3he 5rst #Fcm of the small intestine is called the duodenum:

Although this is short< almost all the digestion taes place here< due to two

secretionsB pancreatic *uice and bile: =ancreatic *uice is secreted by the pancreas

into the duodenum through the pancreatic duct: =ancreatic *uice contains

numerous amylase< protease and lipase en@ymes: ,ile is secreted by the lier<

stored in the gall bladder< and released into the duodenum through the bileduct: ,ile doesn?t contain any en@ymes< but it does contain bile salts to aid lipid

digestion< and the alali sodium hydrogen carbonate to neutralise the stomach

acid: 3his alali gies chyme in the duodenum a pH of around -:< so the

pancreatic en@ymes can wor at their optimum pH: 3he mucosa of the

duodenum has few illi< since there is no absorption< but the submucosa

contains glands secreting mucus and sodium hydrogen carbonate: 3he rest of

the small intestine is called the .leum: 3his is the site of 5nal digestion and

absorption: 3o maimise the rate of absorption the ileum has the three features

dictated by 7ic?s lawB large surface area< short diusion distance and a steep

cponcentrtain gradient sustained by moement of 8uids on both sides of

echange surface (see sheet aboe for detail)


13/22

6ungs and 6ung disease

Describe how muscles in the thorax !chest# cause air to enter the lungsduring breathing.iaphragm/intercostal muscles contract;

.ncreases olume of thora/chest/lungs;Negatie/lower pressure in lungs;

>n normal breathing, describe the part played by the intercostal muscles!ontract;ribs moe upwards/out;increasing olume/decreasing pressure in chest/thora/lungs

Describe the dierence in the composition of gases in inhaled and exhaled

air. Explain how these dierences are caused.1 inhaled air contains more oygen than ehaled air;2 inhaled air contains less carbon dioide than ehaled air;# inhaled air contains less water (apour);' relatie amount/percentage of nitrogen also changes; respiration results in lower blood oygen / higher blood carbon dioide;+ oygen enters blood / carbon dioide leaes blood in aleoli;- by diusion;0 water apour diuses from moist surface;

Describe how the structure of the lungs and the red blood cells enablee?cient diusion and transport of oxygen.1 6arge surface area produced by many aleoli;2 4ingle layer of epithelial cells / ery thin epithelium / suamous / paement;# !apillary walls one cell thic;' Giing short diusion pathway; $,! thin / 8attened / disc%shaped so large surface area;+ No nucleus / mitochondria;

- H l bi f t t f

: 6arge .ntestine: 3he large intesti

and rectum: 7ood can

spend #+ hours in the large intestin

faeces: 3he mucosa contains illi bu

glands secreting mucus: 7aeces is

cholesterol< bile< mucus< mucosa ceand water< and is released by the a

inoluntary muscle that we can lea


14/22

&ulmonary brosisB when scars form on the epithelia that are damaged< increasing the

diusion pathway< loss of elasticity in lung tissue< which reduces the concentration

gradient< narrowing of essels< reducing air 8ow and concentration gradient: $esults in

shortness of breath< dry cough< tiredness (insuLcient oygen for respiration)

@sthma is caused by physical factors called allergens in the enironment: 3hese

allergens include pollen< dust mites faeces and fur:

3hese allergens trigger an in8ammatory response by the immune system:

hite blood cells called mast cells release histamines< which cause the smooth circular

muscles of the bronchioles to contract< narrowing the airways (bronchoconstriction):

3he epithelial cells also secrete more mucus< which further blocs the airways:

3he constricted bronchioles stimulate whee@ing and coughing as the lungs try to loosen

the mucus: 3he constrictions reduce the tidal olume< so aleolar air is only replaced

slowly: 3he oygen concentration gradient across the aleolar epithelium is reduced< so

the rate of diusion in the aleoli is reduced by 7ic?s law: 6ess oygen diuses into the

blood< so less oygen is aailable for cellular respiration throughout the body:

eart and heart Disease

1) $ight atria receiing deoygenated blood from

the ena caa

2) $ight entricle: 4eparated from the atria (1)

by the tricuspid ale: 3his wall is thinner than

the left entricle as it pumps blood only to the

lungs (pulmonary circulation)


15/22

1 6

1 2

8

4

0

– 2

P r e s s u r e /

k P a

0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 0

T i m e / s

A o r t a

L e f t

v e n t r i ! e

" u r v e X

!ure is the right entricle< this is clear as the pattern is the same as that of the leftentricle< but the pressure is lower as a result of the smaller muscle content of the wall:hen the left entricle pressure crosses the pressure line representing the aorta theblood 8ows through the semi%lunar ales: hen entricular pressure drops below theaorta pressure then the ales shut: 3his causes the second sound you can hear on aheart beat (dub):


16/22

Describe the parts played by the sinoatrial node!/@2# and the atrio*entricular node !@'2# incontrolling the heartbeat.14AN initiates / sends heart beat;

2Myogenic / beats spontaneously / does not reuire nereimpulse;#$ate of beating in8uenced by neresB'ae of electrical actiity / impulses / ecitation passesoer atrium;3riggers contraction of atrium;+9lectrical actiity can only pass to entricles / alongbundle of His by way of ACN-7ibrous tissue preents passage elsewhere;

0 elay at ACN; Allows blood to empty into entricles / atria to empty;

5ardiac -utput!ardiac "utput is the amount of blood 8owing through the heart each minute: .tis calculated as the product of the heart rate and the stroe olumeB

!ardiac output O heart rate stroe olume

K 3he heart rate can be calculated from the pressure graph by measuring thetime taen for one cardiac cycle and using the formulaB

Heart rate (beats per minute) O+F Pcycle time (s)

K 3he stroe olume is the olume of blood pumped in each beat:,oth the heart rate and the stroe olume can be aried by the body: hen the


17/22

5igarette smoking and a diet high in saturated fat increase the risk ofmyocardial infarction. Explain how.!


18/22

isease is a general term meaning a disorder of the body:iseases can be caused by many dierent factorsBK >nfectious Diseases are caused by pathogenic organisms(usually microbes) liing in or on the body and so causing harm(e:g: cold< 3,< A.4):K Dietary Deciency Diseases are caused by a lac ofspeci5c nutrients in the diet< e:g: washioror (protein)< scury(itamin !)< and ricets (itamin ):K En*ironmental Diseases are caused by non%liing factorsin the enironment: 3hey include sin cancer (caused byradiation)< lung cancer (caused by smoing)< asthma (caused

by dust)< pulmonary 5brosis (caused by dust or pollution)< and!reut@feldt%Raob disease (caused by prions):K /ocial Diseases are caused by human actiities andlifestyle: 3hey include alcoholism< emphysema< coronary heartdisease< anoreia< drug addiction and een accidents:K @geing Diseases are caused by degeneration of bodytissues and include arthritis< arteriosclerosis and cataracts:K )enetic Diseases are caused by genes inherited fromparents: 3hese are really characteristics that are unusual in thepopulation and are life%threatening (e:g: muscular dystrophy<cystic 5brosis< haemophilia):.n fact all diseases are aected by genetics< but these Ssinglegene disordersT are goerned entirely by the action of a single

allele and are not in8uenced by any other factor:

7or a pathogen to cause a disease these steps must tae placeB1: 3he pathogen must be transmitted to the human host (through drining water<eating food< breathing aerosol droplets< animal bites< or direct contact)2: 3he pathogen must gain entry inside the human body: 3he human body isprotected by a tough layer of endodermis (sin)< but pathogens can enter ia cuts inthe sin (e:g: malaria); or the thinner epithelium echange interfaces< such as thedigestie system (e:g: cholera) or lungs (e:g: tuberculosis):#: 3he pathogen must eade the defences of the host: Humans hae a range ofdefences< such as stomach acid< lyso@yme en@ymes and the immune system< andthese defences are usually ery eectie at preenting disease: ,ut it only taes a

few pathogen cells resisting the defences to multiply and cause a disease:': 3he pathogen must harm the host: =athogens harm their hosts in two ways:K 7irst< by reproducing inside host cells< using up cellular resources and preentingthe cell from carrying out its normal reactions: 3he microbes then usually burst outof the host cell< rupturing the cell membrane and illing the cell in the process:K 4econd< by producing toins > chemicals that interfere with the bodyDs reactions: 3hese chemicals may inhibit en@ymes< bind to receptors< bind to NA causingmutations< interfere with synapses and so on:

A person?s lifestyle aects their chances of sueringfrom diseases (ecept the single gene disorders):6ifestyle factors can include diet< eercise< worenironment< seual habits< smoing< drining anddrug%taing: 4ome of these factors hae obiousassociation with disease (lie smoing)< while othersare less obious (lie occupation)< but all the factorshae an associated ris:

ierent disease hae speci5c ris factors< i:e:factors that speci5cally increase the ris of gettingthat disease: A few eamples areB

Disease isk actors6ung cancerB smoing and cleanliness of theenironment:4in cancerB eposure to sunlight and colourof sin:!HB diet< age< genetics andeercise:iabetesB genetics diet and eercise:A.sB seual habits< drug habits andgenetics:

4ome of these ris factors are beyond our control<e:g: genes and age: ,ut the others are lifestyle

1) 3his graphshows there is

no patternbetweenincome andincidence oflung cancer

2) 3his graphshows acorrelationbetweensmoing and

cancer: ,ut itdoes not proecausation asother factorscan in8uenceresults< age<diet< andgenetics

#) 3o show causalitycontrolledeperiments areneeded: Here

arsenic (componentof cigarette smoe)inhibits NA ligasewhich repairsdamaged NA: 3husin cells this couldlead to cancer< nowwe hae amechanism toeplain graph 2< andwe hae eidencefor a causalrelationshipbetween smoing

and cancer:

') 3here is acorrelation between

alcohol and cancer:6ab studies hae notfound a causal linbetween the two< soalcohol is not a risfactor: 3he correlationis indirect< whereheay driners< tendto be heay smoers


19/22

.mmunity

&hagocytes and lysosomes are in*ol*ed in destroying microorganisms. Describe how.=hagocytes engulf pathogens/microorganisms;9nclosed in a acuole / esicle/ phagosome;

7uses with lysomsome to for a phagolysosome6ysosomes hae en@ymes; 3hat digest/hydrolyse molecules/proteins/lipids/microorganism;

What is an antigen0Molecule/part of molecule/protein/glycoprotein;4timulates immune response;

What is an antibody0!+#

=rotein/immunoglobulin;speci5c to antigen;idea of S5t?/complementary shape;

@ntibodies are protein molecules. Explain why protein molecules are particularly wellsuited to carry out the role of antibodies.6arge ariety of dierent molecules;range of shapes; 3ertiary shape;

locs onto / complements speci5c antigen;

'accines protect people against disease. Explain how.!1#1: Caccines contain antigens / antigens are in*ected;2: ead pathogens / weaened pathogens;#: Memory cells made;': "n second eposure memory cells produce antibodies / become actie / recognise pathogens;: $apidly produce antibodies / produces more antibodies;+: Antibodies destroy pathogens;

- H d t / f l t di


20/22

>mmunisation programmes may use either attenuated or dead microorganisms./uggest why there might be problems for the patient when using these *accines:=rocess of illing organisms might not be 1FFU eLcient;lie organisms might gie rise to full%blown disease;attenuated organisms are non%irulent;

but might mutate to irulent forms;immunity can decline % booster in*ections reuired;named side eects< eg allergies;less eectie due to changed antigens;

/uggest two reasons why parents may decide against *accination for their children.consider accines to be unsafe / hae side eects / damage immune system;consider natural immunity to be more eectie; allow in (a) if not herereligious / ethical ob*ections :ualied e:g: ob*ections to use of fetal /

animal tissue;consider low ris of disease when high percentage of population alreadyaccinated/$ef: to VHead 9ect?

Explain how the defence mechanisms of the body reduce the chance of entry by apathogen.9pidermis of sin is dead / eratinised so pathogens cannot penetrate;mucus in respiratory system is trapping sticy pathogens;cilia moe 8uid / mucus remoing pathogens;

tears / salia / mucus contain lyso@yme breaing down bacterial cell wall;stomach contains hydrochloric acid which destroys bacteria;blood clot preents entry;8uid nature of tears wash away bacteria;aginal acid destroys bacteria;commensal bacteria on sin compete with pathogen;sebum (fatty acid) inhibits bacterial growth;

Explain how the body responds both generally and specically to pathogens that enter

h bl d


21/22


22/22

3onoclonal @ntibodies 3he uniue tertiary structure of each antibody protein allows it to bindspeci5cally and tightly to one particular antigen: 4cientists uicly realisedthat the remarable speci5c binding property of antibody proteins in iowould mae them ery useful tools in medicine and research in itro: W.n iomeans Sin lifeT< i:e: in a liing organism; and in itro means Sin glassT< i:e: ina test tube:X Monoclonal antibodies are antibodies of one particular shapemade by a clone of a single ,%lymphocyte:

3aking 3onoclonal @ntibodies

Antibody proteins are far too complicated to be synthesised chemically initroB they hae to be made by liing cells: .n 1- Iohler and Milsteindeeloped a method to mae monoclonal antibody proteins using mice:

1: .n*ect a mouse with the antigen protein that you want antibodies for: 3hemouse will show a primary immune response and mae a clone army of ,%lymphocytes with antibodies speci5c for that antigen:

2: After a few days< etract ,%lymphocyte cells from the rabbit?s blood: 3heblood contains a miture of thousands of dierent ,%cells< each maing theirown speci5c antibodies< so we need to isolate the ,%cell we want: ilute theblood cells into hundreds of wells in an immunoassay plate< so that there is *ust one cell per well: 3he cells multiply in their wells and secrete antibodies

> a dierent antibody in each well:

#: 3est each well for production of the antibody reuired and row the ,%cellsfrom that well in a culture 8as< where they multiply by mitosis< maingmillions of identical cloned cells< each secreting identical antibodies >monoclonal antibodies:

9sing 3onoclonal @ntibodiesMonoclonal antibodies hae many uses< but they are all based on thesame principle: .f monoclonal antibodies are mied with a samplecontaining a miture of proteins< the antibodies will bind speci5callyand tightly to only one protein in the sample:

3he monoclonal antibodies can hae another molecule chemicallyattached to the constant region< which can mae the antibodycoloured< or 8uorescent< or attach it to a surface: 3his allows thetarget protein to be isualised:4ome uses of monoclonal antibodies includeB

K Antibodies can be used as a Smagic bulletT to target drugs to onespeci5c cell type in the body: Monoclonal antibodies are made to anantigen only found on the target cell< and the drug is bound to theconstant region of the antibody: 3he antibody/drug comple is thenbe in*ected into the patient and the antibody will ensure that theagent is carried only to the target cells and nowhere else:

K Antibodies can be made to target a toic agent (e:g: a radioactie

substance) to cancer cells and nowhere else in the body:

K Antibodies to the protein hormone h!G< produced in pregnancy< arebound to a test strip and used to detect the presence of h!G in urinein a pregnancy test strip:

K Antibodies are used to detect the presence of speci5c proteins inery low concentrations in the 96.4A assay:

K 7luorescent antibodies are used to stain particular cell organelles inmicroscope slides:

K Antibodies can be used directly in passie immunity to help the

bodyDs normal immune response to a serious infection

What is a monoclonalantibodyA hybrid cell from tumour(cancerous< myeloma) and ,%lymphocyte called a hybridomait produces the same antibodiesas it is deried from one type ofplasma cell;this means the antibodies arespeci5c (complementary) to 5ts

unit_1_summary_notes_as_biology.doc

Documents