New Biology 2015

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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/ NH2and carboyl / !""H;

# $%group/ side chain & hydrogen;' $%group diers from one amino acid to another; Amino acids *oined by condensation;+ ,ond formed between NH2and !""H;

- .noles remoal of molecule of water;0 H from NH2and "H from !""H;

Explain how proteins are suitedfor their roles as receptormolecules.

Many dierent sorts of proteins;ierent primary structures/seuences of amino acids;3ertiary structure;

4hape; allowing formation of receptor/binding site/site into whichsubstance/substrate 5ts;

Explain how the structure of brous proteins is related to their functions.6ong chains of aa;7olding of chain into a coil / folds / heli / pleated sheet;Association of seeral polypeptide chains together;7ormation of 5bres / sheets eplained; 2H bonds / isulphide bonding (In context);7ibres proide strength (and 8eibility);4heets proide 8eibility;9ample e:g: eratin in hair< collagen in bone; (MUST be in context).nsoluble because eternal $%groups are non%polar;

Describe how you would use a biochemical test to show that a solutioncontained protein.

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,iuret / alali & copper sulphate;6ilac/purple/maue/iolet;

With reference to named parts of the diagram, explain thedierence between the termsTriglyceride andphospholipid;=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;

Describe a chemical test you could carry outto show that a piece of coconut contains lipids.!"#(!rush in) ethanol / alcohol;Add (to) water (Order of adding is critical for this point);9mulsion / white colour

Describe how you could use Benedict$s reagent to test a urine sample for thepresence of glucose.Add (,enedict?s) reagent (to urine sample) and heat / heat the miture;red/ brown/ orange/ green/ yellow;

Describe a further biochemical test to nd out if a substance is a non%reducingsugar.

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Heat with acid< then neutralise / hydrolyse using en@yme;

(heat) with ,enedict?s (solution);,ecause all amino acids hae dierent $? groupsthey hae dierent solubilities and dierent aBnities for solids: 7or this reasonthey can be separated by &'()*+)-(+'/:

A container is 5lled to a depth of 2 cm with a suitable chromatography

solent: 3he container is sealed and left to allow the solent to saturate theatmosphere: 3his is important because solent must not e0aporate from

the chromatogram as it is running: A strip of chromatography paper has a pencil line drawn on it slightly more

than 2 cm from the bottom and small crosses are drawn on it to indicatewhere to add the amino acids:

1t is important not to touch the paper as there are amino acids on your

ngers.

A spot of amino acid is applied to a cross on the line using a capillary tube 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 a dar region of chromatin< inoled

in maing ribosomes:

4ysosomes 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:

(ibosomes3hese 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

cellJs own use< or they are found attached to the

rough endoplasmic reticulum< where they maeproteins for eport from the cell: All euaryotic

K K

*itochondrion 3his is a sausage%shaped organelle

(0Lm long)< and is where aerobic respiration taes

place in all euaryotic cells (anaerobic respirationtaes 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 membrane

the outer membrane is simple and uite permeable coil up/spiralise/condense;(allo" shorter/contract/become 'isible)metaphase > moe to euator or centre of cell / attachto spindle;(re,ect if reference to pairing)anaphase > chromatids separate/centromeres diide;(re,ect chromosomes mo'e to poles "ithout further

explanation)telophase > uncoil; (allo" lengthen/becomes less'isible)

Describe two e0ents which occur during interphase..ncreased in olume of cell / amount of cytoplasm / increase in mass /cell bigger;.ncrease in number of organelles;=rotein synthesis / speci5c eample;NA replication / chromosomes become chromatids / chromosomes copy;1 references to G1< G2 and 4 phases).ncrease in olume of cell/olume of cytoplasm / increase in mass / cell bigger; increase innumber of organelles;synthesis of protein/named protein;

NA replication/increase / chromosomes copied;A3= synthesis / respiration;

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&omparing mitosisand meiosis

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Bacteria always reproduce asexually, using binary fission ("splitting

in two").

1 The DNA in a bacteriu is always circular (or rather a closedloop), and is often attached to an in!agination of the cell ebrane.

2 Before cell di!ision the DNA is replicated. nli#e eu#aryoticcells, there are no histone proteins, and the DNA is not coiled into

chroosoes.

3 The cell elongates fro the iddle, separating the two DNAolecules, which are attached to different parts of the ebrane.

4 A new cell wall, or septu, is fored down the iddle of theelongated cell.

5 $!entually the septu eets, di!iding the cell in two.

Although this loo#s a bit li#e itosis in eu#aryotic cells, it isn%t.

There is no nucleus, no chroatids, no centrioles and no spindle.

Binary fission is !ery fast and bacteria can double e!ery &' in

under optiu conditions, though the doubling tie is usually

slower.

Bacterial Sporesany bacteria can produce spores. These are specialised dorant cells fored in response to ad!erse

conditions, and they can sur!i!e long periods of high teperatures (e!en boiling), desiccation, low nutrients,

radiation and cheicals. hen conditions return to noral the spores "gerinate" and de!elop into noral

cells. Although spores are a little li#e plant seed they are not used for reproduction. Because they are so

difficult to #ill, spores can cause probles for sterilisation.

*iruses can only reproduce inside host cells. The general strategy is to use the host cell en+yes to replicate

and translate !iral DNA, a#ing ore !irus particles, which then burst out of the cell.

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1E

The !irus attaches to

the host cell

ebrane, which

stiulates

endocytosis.

The NA is now used

to synthesise ore !iral

NA and capsid

proteins.

The NA and proteins

are assebled into new

!irus particles (without

en!elopes). The

glycoproteinsigrate to the cell

ebrane.

The NA enters the

nucleus, where it isreplicated to for

NA, using the !iral

NA polyerase

en+ye.

The !irus particles are

released by exocytosis,

collecting the lipiden!elope fro the cell

ebrane. This #ills the

host cell

The !iral en!elope

fuses with the !esicle

ebrane, releasing

the nucleocapsid intothe cytoplas.

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*embranes and mo0ement3uggest 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. !?#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;

Describe the part played by cell surface membranesin regulating the mo0ement of substances into and out of cells. !>#Non%polar/lipid soluble molecules moe through phospholipid layer/bilayer;

4mall molecules/water/gases moe through phospholipid layer/bilayer;.ons/water soluble substances moe through channels in proteins;4ome proteins are gated;$eference to diusion;!arriers identi5ed as proteins;!arriers associated with facilitated diusion;!arriers associated with actie transport/transport with A3=/pumps;ierent cells hae dierent proteins;!orrect reference to cytosis;

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Explain how three features of a plasma membrane adapt it for its functions.1: =hospholipid bilayer (as a barrier);2: 7orms a barrier to water soluble / charged substances / allows non%polar substances to pass"$

Maintains a dierent enironment on each side / compartmentalisation;#: ,ilayer is 8uid;': !an bend to tae up dierent shapes for phagocytosis / form esicles / self%repair;: !hannel proteins (through the bilayer)/intrinsic protein;+: 6et water soluble/charged substances through / facilitated diusion;-: !arrier proteins (through the bilayer);0: Allow facilitated diusion / actie transport;E surface proteins / etrinsic proteins< glycoproteins / glycolipids;1I cell recognition / act as antigens / receptors;11cholesterol;12 regulate 8uidity / increases stability;

Describe how the distribution of cell membranes in a prokaryotic cell such as a bacterium

diers from that in a cell from a plant leaf. !#Absence of nuclear enelope/membrane;Membrane bounded organelles;4uch as mitochondria/chloroplast/acuole/lysosome;and membrane systems/endoplasmic reticulum/Golgi;Mesosomes in proaryotes;

.mmunity

hagocytes and lysosomes are in0ol0ed in destroying microorganisms. Describe how.

=hagocytes engulf pathogens/microorganisms;9nclosed in a acuole / esicle/ phagosome;7uses with lysomsome to for a phagolysosome

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6ysosomes hae en@ymes;3hat digest/hydrolyse molecules/proteins/lipids/microorganism;

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

What is an antibody!2#=rotein/immunoglobulin;speci5c to antigen;idea of 5t?/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;

5accines protect people against disease. Explain how.!?#1: Laccines 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;-: Herd eect / fewer people to pass on disease;

What is 0accination.n*ection of antigens/tooids;(Antigen from) attenuated microorganism/non%irulent microorganisms/deadMicroorganisms/isolated from microorganism;4timulates the formation of memory cells;

-i0e two other methods used to prepare 0accines.Dilled microorganism;modi5ed toin;attenuated/heat treated/FL treated microorganism;genetically engineered antigens;isolated antigen;

5accines protect against disease by stimulating the production of memory cells.Describe how memory cells protect the body from disease."n further eposure to same microorganism;Antigen recognised;7aster response;Greater production of antibodies;

What is a monoclonal antibody !2#$eference to hybrid cell from tumour / cancer and,%lymphocyte/hybridoma;antibodies all the same / from one type of plasma cell;speci5c to / complementary to / 5ts only one antigen

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1mmunisation programmes may use either attenuated or dead microorganisms.3uggest why there might be problems for the patient when using these 0accines:=rocess of illing organisms might not be 1II eBcient;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;

3uggest two reasons why parents may decide against 0accination 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 Head 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 enterthe blood.action of phagocytes;

.nterferon production;body temperature increased;ref to , or 3 lymphocytes;actiated by non%self%antigen;either clone / diide by mitosis;3 helper cells role;, plasma cells produced;which produces antibodies;any speci5c eect (e:g: immobilise /agglutinate / lysis /coat for recognition /neutralise toins);3 iller / cytotoic cell;perform produced;memory cell produced;

Explain the role of B%lymphocytes and %lymphocytes in the defence of the bodyagainst a 0irus infection., lymphocytes produce antibodies/inoled in humoral response;3 lymphocytes inoled in cell mediated immunity;Macrophages present antigens;(speci5c) , lymphocytes recognise/bind to antigen;increase in numbers by mitosis;produce plasma cells (which mae antibodies);antibodies bind to and clump/ agglutinate irus;

memory cells produced by 1st

eposure/cloned on 2nd

eposure;3 lymphocytes(helpers) produce lymphoines/chemicals;

which aid , lymphocyte cloning;encourages phagocytes to engulf clumped irus;iller 3 cells ill irus infected cells;

2#

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2'

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onoclonal +ntibodies

he uniue tertiary structure of each antibody protein allows it to bind speci5cally and tightly to one partic

aking *onoclonal +ntibodies

ntibody proteins are far too complicated to be synthesised chemically in itro they hae to be made by l

.n*ect a mouse with the antigen protein that you want antibodies for: 3he mouse will show a primary im

After a few days< etract ,%lymphocyte cells from the rabbit?s blood: 3he blood contains a miture of th

3est each well for production of the antibody reuired and row the ,%cells from that well in a culture 8a

3he

4ome

R Anti

R Anti

R Anti

R Anti

R 7luo

R Anti

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ransmission hrough infected semen or 0aginalsecretions during seual actiity< or through infect

3igns and 3ymptoms

6ie other retroiruses< H.L has a long latency of 0%1I y

H.L does not become A.4 immediately; time between

2+

H.L (human immunode5ciency irus)

A.4 (Acuired .mmune de5ciency syndrome)

3he human immunode5ciency irus (H.L) is a lipidmembrane eneloped retroirus: 3he membranenot made by the irus itself< but deried from ahost cell membrane:

.t comprises 2 copies of single%stranded $NAtogether with some en@ymes< surrounded by anicosahedral capsid< which is in turn surrounded bya sphere of matri proteins attached to a lipidenelope:

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ELISA (enzyme-linked

immunosorbent assay)

This technique is performed to detect

the presence and/or amount of a target

protein/antigen of interest. Or it can be

used to detect if a person contains

antibodies for a certain antigen.

This process can be used to detect for

allergies or infection.

An antibody is used which has an

en@yme attached to it; this will

catalyse the conersion of a

substrate to a coloured product:

3he intensity of the colour can be

an indicator of the uantity of

*echanism of the direct E413+ testAntibody is bound inside the tray (complementary to theantigen under inestigation),lood sample is added that may or may not contain theantigenA detection antibody is added that is (complementary tothe antigen in uestion): 3his antibody contains anattached en@yme:

3he tray is washed to remoe any unbound antibodiesand samples< particularly the antibody attached to theen@yme

.f the antigen was present it will be bound to theimmobilised antibody and the detection antibody willalso bind to it:7inall a substrate solution is added and an en@ me

3he antibodies are oftengenerated using animals; clearly

this raises some ethical issues