biomolecules - summary

4
Raffles Junior College Core Syllabus - BioMolecules JC22008 EXAMPLES of CARBOHYDRATES 1. GLUCOSE 2. GALACTOSE 3. FRUCTOSE a-glucose i3-glucose s: 'CH,OH o :::J o (f) HOH2Q1C 0 ..... 8 '" 2 5 :::r Ci 3 4 6CHPH CD (f) H OH H OH H OH Fructose = C2 contains Glucose & Galactose = C1 contains aldo gp (making them aldehydes) keto gp (making it a ketone) 1. MALTOSE (0-1 ,4 glycosidic bond) a-glucose + a-glucose 'CH,OH 'CH,OH (ii' () () '" :::r Ci CD (f) 'I 'I H OH H OH maltose + 2. LACTOSE (13-1,4 glycosidic bond) f3-galactose + a-glucose 3. SUCROSE (0-1,2 glycosidic bond) a-glucose + f3-fructose 1. STARCH (plant) - a-glucose monomers Amylose Amylopectiin ·> ·9 ' branches of helices .til cfJ linked by 0-1,6 glycosidic !. ", d4 .. all monomers within helix V't ' all monomers within helix linked by 0-1,4 glycosidic bonds linked by 0-1,4 glycosidic bonds e, :X) ,.. 2. CELLULOSE (plant) - f3-glucose monomers "'0 o """ all monomers within chain linked by 13-1,4 glycosidic bonds, -< (f) making every altemate monomer/residue () '" () inverted in orientation :::r Ci CD . straight chains cross-linked by H bonds (interchain) (f) 3. GLYCOGEN (animal) - a-glucose monomers fI'!", ... '"ZL branches of helices .... linked by 0-1,6 glycosidic bonds ...... ".. .. "" ..... IltJ.. all monomers within helix '\J linked by 0-1,4 glycosidic bonds Last uodated by: Mrs Maodatene Tan & Mrs Jeanne Wan COMMON FEATURES 1. All are hexoses (6C) . 2. All carry one carbonyl gp (either aldo- or keto- gp) 3. Can exist as 6 or 5- membered ring 4. Ring structures exhibit a- and 13- isomerism (OH grp at C1: a - below, j3 - above) 5. Soluble, sweet, 6. All are reducing sugars 7. Basic unit of carbohydrates 1. Made up of 2 monomers 2. Monomers link to each other via condensation reaction to produce a disaccharide and a H 2 0 molecule via various types of glycosidic bonds 3. Splitting of a disaccharide into its component mono- saccharides via hydrolysis and uses 1 Hp 4. All are reducing sugars except sucrose 1. Made up of 1OOs - 1000s monomers 2. Monomers link to each other via condensation reaction to produce a polysaccharide and H20s via various types of glycosidic bonds 3. Splitting of a polysaccharide into its component mono- saccharides via hydrolysis and uses H 2 0s 4. Generally categorised based on function into (i) STORAGE Polysaccharide (starch: amylose & amylopectin; glycogen) & (ii) STRUCTURAL polysaccharides (cellulose) STRUCTURE FUNCTION 1. Small Mr/Small in size + many OH groups extending out of the ring readily soluble in water + easily transported in animal and plant transport systems 2. Carbonyl group possess a reducing property 3. Exhibits isomerism contributes to diversity of monomers diversity of polymers 1. Small Mr/Small in size + many OH groups extending out of the rings readily soluble in water + easily transported in transport systems (esp. in plants: sucrose) 2. Some possess a free carbonyl group possess a reducing property (except sucrose) STARCH (amylose) - Storage 1. Made up of many a-glucose residues large energy store insoluble/slightly soluble in water, 4J w of cells unaffected 2. Linear chains coiled into helices possibly more compact: more molecules per fixed voL 3. 0(1 glycosidic linkages between residues hydrolysis via specific enzymes when needed CELLULOSE - Structural 1. Made up of many f3-glucose residues large, insoluble and will not affect 4Jw of cells 2. glycosidic linkages hydrolytic enzymes limited to certain organisms, so not commonly hydrolysed source of our dietary fibre?) 3. Each residue is rotated 180·, making every altemate residue inverted in orientation OH groups project outwards in all directions H-bonds with adjacent parallel molecules H-bond cross-linking between cellulose molecules rigid structure with high stability 4. A structural hierarchy present (molecules microfibrils macrofibrils) reinforces structure to give high tensile strength fully permeable mesh of several layers free movement of water and solutes GLYCOGEN - similar to amvlose, but more highly branched

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Page 1: Biomolecules - SUMMARY

Raffles Junior College Core Syllabus - BioMolecules JC22008

EXAMPLES of CARBOHYDRATES

1 GLUCOSE 2 GALACTOSE 3 FRUCTOSE a-glucose i3-glucose

s CHOHo J o (f)

HOH2Q1C0 8

2 5r ~ Ci 3 4 6CHPHCD (f)

H OH H OH H OH Fructose = C2 contains

Glucose amp Galactose = C1 contains aldo gp (making them aldehydes) keto gp (making it a ketone)

1 MALTOSE (0-1 4 glycosidic bond) a-glucose + a-glucose ~

CHOH CHOH o middot (ii

() () r ~ Ci CD (f)

I I H OH H OH

maltose

-eH~H

+

2 LACTOSE (13-14 glycosidic bond) f3-galactose + a-glucose 3 SUCROSE (0-12 glycosidic bond) a-glucose + f3-fructose

1 STARCH (plant) - a-glucose monomers Amylose Amylopectiin

middotgt middot9 tJ+~ branches of helices tilcfJ linked by 0-16 glycosidic bon~s

d4 ~ middotNall monomers within helix Vt all monomers within helix

linked by 0-14 glycosidic bonds linked by 0-14 glycosidic bondseX) ~

2 CELLULOSE (plant) - f3-glucose monomers 0 o all monomers within chain linked by 13-14 glycosidic bonds-lt(f) ~ making every altemate monomerresidue

() () inverted in orientationr ~ Ci CD straight chains cross-linked by H bonds (interchain)(f)

3 GLYCOGEN (animal) - a-glucose monomers fI ZL branches of helices ~W~~

linked by 0-16 glycosidic bonds ~ ~~~ IltJ all monomers within helixJ linked by 0-14 glycosidic bonds

Last uodated by Mrs Maodatene Tan amp Mrs Jeanne Wan

COMMON FEATURES

1 All are hexoses (6C) 2 All carry one carbonyl gp

(either aldo- or keto- gp) 3 Can exist as 6 or 5shy

membered ring 4 Ring structures exhibit

a- and 13- isomerism (OH grp at C1 a - below

j3 - above) 5 Soluble sweet 6 All are reducing sugars 7 Basic unit of carbohydrates

1 Made up of 2 monomers 2 Monomers link to each other

via condensation reaction to produce a disaccharide and a H20 molecule ~ via various types of glycosidic bonds

3 Splitting of a disaccharide into its component monoshysaccharides via hydrolysis and uses 1 Hp

4 All are reducing sugars except sucrose

1 Made up of 1OOs - 1000s monomers

2 Monomers link to each other via condensation reaction to produce a polysaccharide and H20s ~ via various types of glycosidic bonds

3 Splitting of a polysaccharide into its component monoshysaccharides via hydrolysis and uses H20s

4 Generally categorised based on function into (i) STORAGE Polysaccharide (starch amylose amp amylopectin glycogen) amp (ii) STRUCTURAL polysaccharides (cellulose)

STRUCTURE ~ FUNCTION

1 Small MrSmall in size + many OH groups extending out of the ring ~ readily soluble in water + easily transported in animal and

plant transport systems 2 Carbonyl group ~ possess a reducing property

3 Exhibits isomerism ~ contributes to diversity of monomers ~ diversity of

polymers

1 Small MrSmall in size + many OH groups extending out of the rings ~ readily soluble in water + easily transported in transport

systems (esp in plants sucrose) 2 Some possess a free carbonyl group ~ possess a reducing property (except sucrose)

STARCH (amylose) - Storage 1 Made up of many a-glucose residues ~ large energy store ~ insolubleslightly soluble in water 4J w of cells unaffected

2 Linear chains coiled into helices ~ possibly more compact more molecules per fixed voL

3 0(1 ~4) glycosidic linkages between residues ~ hydrolysis via specific enzymes when needed

CELLULOSE - Structural 1 Made up of many f3-glucose residues ~ large insoluble and will not affect 4Jw of cells

2 i3(1~4) glycosidic linkages ~ hydrolytic enzymes limited to certain organisms so not

commonly hydrolysed (~ source of our dietary fibre) 3 Each residue is rotated 180middot making every altemate

residue inverted in orientation ~ OH groups project outwards in all directions ~

H-bonds with adjacent parallel molecules ~ H-bond cross-linking between cellulose molecules ~ rigid structure with high stability

4 A structural hierarchy present (molecules ~ microfibrils ~ macrofibrils) ~ reinforces structure to give high tensile strength ~ fully permeable mesh of several layers ~

free movement of water and solutes GLYCOGEN - similar to amvlose but more highly branched

AMINO ACIDS AMINO ACIDS (MONOMERS) -7 POlYPEPTIDES (POLYMERS) -7 PROTEINS EXAMPLES OF PROTEINSSTRUCT -7 FN

Properties of amino acids -0 1 Unique sequence and number of amino acids Hierarchy of protein structure 1 Form long chains 1 Basic unit of proteins sect in a polypeptide 2 Stable regular structure

ltQ PGbull lt Primary structure2 20 different aa in cells III 2 Linked by covalent peptide bonds 3 Insoluble in water 3 All possess 1 a carbon atom bonded to -lt 3 Eg of a portion of a primary structure 0 rl r 4 Secondary structure important M)Pdy ~ H H

- 1 carboxyl group ~ - gly - ser - his - val - gly - ala - 1 t~ 1 i V S Usually play structural role - 1 amino group 1i 4 The secondary tertiary and quaternary I)LI ~ ri - 1 H atom ~ structures are hence direct consequences of COLLAGEN ~~7 C=~ - 1 R group varies with different aa and (I) the primary structure t V

can be a hydrophobic hydrophilic

0 5acidic alkaline side group) 1 Intramolecular hydrogen bonds formed at secondary structuret_ 1 Each polypeptide chain is a helix with -1000 o H regular intervals along polypeptide backbonecopy I residues-7 triple helix structure ~l VI I 0 ~ 0 (called tropocollagen) -7 large

N f- C ~ 2

backbone (CO-NH) Bonds only involve atoms

Le atoms of R groups of polypeptide H O

Hence function insoluble in water amino H R OH carboxyl W not involved ~ 2 H bonds between the 3 polypeptides -7 group group 8 4 2 types ALPHA HELIX (fj

l tropocollagen -7 covalent bonds between

R-group a -7H bonds form between Hand 0 staggered tropocollagen molecules -7 l 4 Soluble ampexists as zwitterions (have ~ atoms 4 aa apart (ie H belongs to collagen fibril -7 collagen fibre ~

f3 pleated sheetboth basic and acidic properties) ~ NH of aa1 0 belongs to C=O of aaS) Hence function no weak spot runn ing through in solution 2 -7 H-bonds 11 to longitudinal axis fibril + large bundle produce a rope-like

l of helix structure of great tensile strength ~ -73D helical structure

S Hence act as buffers -7Structure supports its STRUCTURAL function

BETA PLEATED SHEET(resists small changes in

to give firmness and to skinH I -7 H bonds form between segments of

tertiaryH~ the polypeptide which are parallel to structureH R 1 Form spherical compact shapeseach other -7 3D accordion-like sheet (Note secondary

2 less stable less regular structureH structuresH~ 1 4 key intramolecular bonds formed along can be found 3 Soluble in water wl

H

(OH ----J polypeptide (ie bonds formed within the within) 4 Tertiary structure important09OH~ ~ 09Jo- same polypeptide) -7 hydrophobic interaction S Common eg enzymes blood proteins~ ~ ltH bondsltionic bonds ltdisulphide bridges6 Each aa will have its own isoelectric iij

2 Formed at irregular intervals HIV Proteasepoint (pH at which each aa is electrically -lt 3 Bonds involve atoms of R groups only (Le the quaternaryneutral) due to unique R groups ~

hydrophobic R group of (eg ) aa1 will interact structure7 Amino acids undergo condensation 1i with the hydrophobic R group of eg aa 78 and (Note thereaction to form polypeptides The ~ hence pull the 2 aa close together) polypeptide is

Ggtreverse occurs via hydrolysis (I) just one of the subunits)-7 3D irregular contortions of the polypeptide 0 cshyAmlnoAcld NnlnoAdd l 1 Consist of two identical polypeptides (99aa)Bonds making up the tertiarv structure

H 0 H 0 ~ -7 homodimerI II I 11 o Two Arn IhQ H-N-Q--C--QH I 1 Intermolecular bonds formed between 2 orH--N--C-C--OH 0 2 Terminal domain impt for stabilising active

AddS I I III oI I more polypeptides (ie between subunits) HIVenzymeH H R2 CD

l 2 Maintained by 4 key bonds H bonds ---I~vl~pTtt~kshy 5 3 At interface of 2 domains is the active site with III tKkbr~ I1~

Condensation ionic bonds disulphide bonds hydrophobic VI specific 3D conformation - compriSing of 2gtOH -lt-er reverse hydrolysis) VI interactions others (not in your syllabus) lIydwsvn groups of three amino acids (asp-thr-gly) md ) -7 involve in catalysisPeptide bond H 0 i HO I

o I 1 I1 1 Ill -7 allows entry of water and viral polyprotein

~kkB(ltKl eshyH--H--C-+-C-- H-i-C-o--OH Un~a1J for hydrolysis of peptide bondI I i I i I

H RI H R2 -7 enzyme specificityt 3D shape of a protein may be changed by 4 2 flexible flaps guard active sites -7 excludei

a

1 Heat C~tenrnnusHmiddottermIOlS more incoming water molecules -7 this allows ~-- 3 Inorganic chemicals eg heavy metals

2 AcidsAlkalis (pH) catalytic reaction to occur

S ENZYMATIC function to cleave polyproteinsPolyptftld~ H~-~AAI-Mt~AAr-AA~ AA2--AA--AAn- ~t~ 4 Organic chemicals eg ether alcohol into functional viral proteinsS Mechanical forces

2

EXAMPLES OF LlPIDS

1 Each is made up of glycerol and fatty acids 1 glycerol + 3 fatty acids ~ 1 triglyceride (via condensation of components)

H HtOH

I Il- middotCmiddot- Oll

I H MCOIl

I-l H to -lt n lttl

1 glycerol +

~ HmiddotmiddotCmiddotmiddot OH

i r Ile OHtl

o Il If C OH

C Ir Hg Ca

ester linkagesHO M O ~

n bullbull~~ An exan1p~ orj trigyccrkle o o Iii A

HO ~O M ~ -S) v middot V 1I o

HO wO-llI i ltshy6 hydrocarbon tail

a 2 Hence a triglyceride molecule has a hydrophilic headand a hydrophobic tail lttl Il 3 Insoluble in water (exists as micelles) soluble in organic solvent

4 2 types Saturated Fat Unsaturated fat 1 lacks C=C in hydrophobic tails 1 possess 1 or gt1 C=C ~ kinks in tails 2 quite closely packed ~ solid at room temp 2 kinks prevent close packing ~ liquid at room temp 3 usually found in animals 3 usually found in plants and fish 4 eg bacon grease lard butter 4 eg vegetable oil cod liver oil

cc middotCC Cmiddot CJC O C c~O~O~cdeg OC cmiddotCcmiddotcmiddot J~9Jc ~cmiddot~c~cP ~H

1 Each is made up of glycerol fatty acids and phosphate groups 2 fatty acids + 1 phosphate grp

1l0 -OM 1I OH tI I 0 OH- P-OH

1I HO-O ~ 0

clI

phosphoester link 1-

bH

~ 1 phospholipid + 3H20

CH COO~1 ~

lHCOO OH IHJ~P-OH

Il 2 Hence it has a hydrophilic phosphate head (also cos of -ve charge) and a hydrophobic hydrocarbon tail 3 Such a property makes it an amphipathic molecule 4 Insoluble in water (exists as micelles) soluble in organic solvent 5 Exist as a phospholipid bilayer at the cellorganelle surface ie cell membrane 6 May have small variable molecules attached to the phosphate head eg choline

1 Insoluble in water soluble in organic compounds Some reproductive hormones 2 Possess 4 interconnected C rings

progesterone3 Structurally little in common with other lipids (J) 4 eg cholesterol vitamin D steroid hormones Omiddotfcen Q Cl 0 CH

y H)

cmiddotmiddoto ~ ~~~

CH 1 I t~J )

CHH

CH

testosterone (PCrt~J cJ 0-

+ 3HzO

(STRUCTURE~) FUNCTION

1 Higher HO ratlq compared to carbohydrates ~ good energy store (2x that of carbohydrates) ~ Hence animals store more energy with less

weight than plants ~ enables animals to travel around with less

weight 2 Good insulator of heat ~ used by animals to retain body heat

eg blubber subcutaneous fat 3 Good barrier of ions ~ allows saltatory conduction of nerve

impulses ~ hence increase transmission of impulse greatly

4 Protection Able to absorb impact ~ cushions vital organs for protection

5 Less dense than water ~ aquatic animals can stay buoyant in water

6 Releases water as a by-product when oxidised ~ metabolic water is a useful source of water for

desert animals or for dev of avian and retile eggs

1 Bilayers form continuous sheets ~ serve as membranes that enclose

cellorganelles allows compartmentalisation 2 Hydrophobic core selectively permeable membrane ~ allows lipid-soluble molecules to pass through

readily ~ although water is polar it can pass through

occasionally because it is small and weak in charge

~ regulates movement of ions polar molecules into and out of cell

3 Hydrophobic interactions between the molecules ~ self-sealing will reseal quickly if they are

punctured or disrupted

4-ring structure of cholesterol (within membrane) ~ regulatesmodulates membrane fluidity ~ At low temperature prevent phospholipids

from getting too close together and therefore prevents solidification of membrane

~ at high temperature prevent the membrane from being excessively fluid and unstable at higher temperatures through their interaction with phospholipids

1 Structurally similar to fats and oils only that the long-chained fatty acids are linked to long-chained alcohols Insoluble ~ 2 Insoluble in water ~ cutin coats surface of leaves to reduce water lossgtlt lttl 3 Chemically inert ~ similar concept with insectsIl

3

Il

PROCEDURE

1 Place 2 cm3 of test solution in a test tube og (l) J 2 Add equal volume of Benedicts reagent c(l) c c 3 Shake the mixture Q omiddot J ~ 4 Heat it by immersing the tube in boiling water bath for 2 minutes

lt0 ( 5 Observe the contents of the tube (J)-I c (l)

lt0 (JgtIII ~

en Q

z 1 If a negative result for Benedicts test is obtained for test solution o 2 Boil equal volume of test solution with dilute HCI for about 1 minute

to hydrolyse disaccharide to monosaccharides ~-I c (l) 3 Cool the contents of the tube Q ~ J 4 Neutralise the contents with sodium hydrogencarbonate solution

lt0 0 (J) because Benedicts regent only works in alkaline conditions c

lt0 5 Carry out Benedicts test for reducing sugar III 6 Record observations in the same format as that for Benedicts test Ul

1 Add a few drops of potassium iodide solution to 1 cm 3 of 0[ test solution (or a piece of the test specimen) S2 ~ 2 Observe any colour change III -I (l)g~

1 Place 2cm3 of test solution in a test-tube 2 Add equal volume of 5 NaOH solution OOJ cmiddot 3 Shake the mixture well

-0 (l)o ~ 4 Add 1 copper sulphate solution drop by drop shaking well (ii-l_ (l) after each drop J (Jgt(Jgt ~ 5 Observe any colour change

m 1 Place 2cm3 of absolute ethanol in a test-tuibe s III 2 Add 2cm3 of test solution to this test-tube J

0 2 Dissolve the contents by shaking vigorously o shy m 3 Add equal volume (ie 4cm3) of cold water C3 u c 4 Observe any colour change CiiJi omiddot

J

-I (l) ~

OBSERVATIONS

1 The contents of the test-tube remains a blue solution 2 A green ppt forms in the contents of the test-tube

3 A yellow ppt forms in the contents of the test-tube

4 A brown ppt forms in the contents of the test-tube

5 A brick-red ppt forms in the contents of the test-tube

1 The contents of the test-tube remains a blue solution 2 A green ppt forms in the contents of the test-tube

3 A yellow ppt forms in the contents of the test-tube

4 A brown ppt forms in the contents of the test-tube

5 A brick-red ppt forms in the contents of the test-tube

1 The mixture turns blue-black in colour 2 The mixture remains yellowish-brown in colour

1 The mixture turns from blue to purpleviolet 2 The mixture remains blue in colour (because of the

copper sulphate solution)

1 The mixture turns a clear solution 2 The mixture turns a cloudy white suspensionan emulsion

is formed

CONCLUSIONS

1 No reducing sugars present in the test solution 2 A small amount of reducing sugars is present in the a

~ test solution

3 A moderate amount of reducing sugars is present in the test solution

4 A moderately large amount of reducing sugars is present in the test solution

5 A large amount of reducing sugars are present in the test solution

1 Non reducing sugars absent in the test solution 2 A small amount of non-reducing sugars is present in the

test solution 3 A moderate amount of non-reducing sugars is present in

the test solution 4 A moderately large amount of non-reducing sugars is

present in the test solution 5 A large amount of non-reducing sugars are present in the

test solution

1 Starch is present in the test solution 2 Starch is absent in the test solution

1 Proteins are present in the test solution 2 Proteins are absent in the test solution

1 Lipids are absent in the test solution 2 Lipids are present in the test solution

Page 2: Biomolecules - SUMMARY

AMINO ACIDS AMINO ACIDS (MONOMERS) -7 POlYPEPTIDES (POLYMERS) -7 PROTEINS EXAMPLES OF PROTEINSSTRUCT -7 FN

Properties of amino acids -0 1 Unique sequence and number of amino acids Hierarchy of protein structure 1 Form long chains 1 Basic unit of proteins sect in a polypeptide 2 Stable regular structure

ltQ PGbull lt Primary structure2 20 different aa in cells III 2 Linked by covalent peptide bonds 3 Insoluble in water 3 All possess 1 a carbon atom bonded to -lt 3 Eg of a portion of a primary structure 0 rl r 4 Secondary structure important M)Pdy ~ H H

- 1 carboxyl group ~ - gly - ser - his - val - gly - ala - 1 t~ 1 i V S Usually play structural role - 1 amino group 1i 4 The secondary tertiary and quaternary I)LI ~ ri - 1 H atom ~ structures are hence direct consequences of COLLAGEN ~~7 C=~ - 1 R group varies with different aa and (I) the primary structure t V

can be a hydrophobic hydrophilic

0 5acidic alkaline side group) 1 Intramolecular hydrogen bonds formed at secondary structuret_ 1 Each polypeptide chain is a helix with -1000 o H regular intervals along polypeptide backbonecopy I residues-7 triple helix structure ~l VI I 0 ~ 0 (called tropocollagen) -7 large

N f- C ~ 2

backbone (CO-NH) Bonds only involve atoms

Le atoms of R groups of polypeptide H O

Hence function insoluble in water amino H R OH carboxyl W not involved ~ 2 H bonds between the 3 polypeptides -7 group group 8 4 2 types ALPHA HELIX (fj

l tropocollagen -7 covalent bonds between

R-group a -7H bonds form between Hand 0 staggered tropocollagen molecules -7 l 4 Soluble ampexists as zwitterions (have ~ atoms 4 aa apart (ie H belongs to collagen fibril -7 collagen fibre ~

f3 pleated sheetboth basic and acidic properties) ~ NH of aa1 0 belongs to C=O of aaS) Hence function no weak spot runn ing through in solution 2 -7 H-bonds 11 to longitudinal axis fibril + large bundle produce a rope-like

l of helix structure of great tensile strength ~ -73D helical structure

S Hence act as buffers -7Structure supports its STRUCTURAL function

BETA PLEATED SHEET(resists small changes in

to give firmness and to skinH I -7 H bonds form between segments of

tertiaryH~ the polypeptide which are parallel to structureH R 1 Form spherical compact shapeseach other -7 3D accordion-like sheet (Note secondary

2 less stable less regular structureH structuresH~ 1 4 key intramolecular bonds formed along can be found 3 Soluble in water wl

H

(OH ----J polypeptide (ie bonds formed within the within) 4 Tertiary structure important09OH~ ~ 09Jo- same polypeptide) -7 hydrophobic interaction S Common eg enzymes blood proteins~ ~ ltH bondsltionic bonds ltdisulphide bridges6 Each aa will have its own isoelectric iij

2 Formed at irregular intervals HIV Proteasepoint (pH at which each aa is electrically -lt 3 Bonds involve atoms of R groups only (Le the quaternaryneutral) due to unique R groups ~

hydrophobic R group of (eg ) aa1 will interact structure7 Amino acids undergo condensation 1i with the hydrophobic R group of eg aa 78 and (Note thereaction to form polypeptides The ~ hence pull the 2 aa close together) polypeptide is

Ggtreverse occurs via hydrolysis (I) just one of the subunits)-7 3D irregular contortions of the polypeptide 0 cshyAmlnoAcld NnlnoAdd l 1 Consist of two identical polypeptides (99aa)Bonds making up the tertiarv structure

H 0 H 0 ~ -7 homodimerI II I 11 o Two Arn IhQ H-N-Q--C--QH I 1 Intermolecular bonds formed between 2 orH--N--C-C--OH 0 2 Terminal domain impt for stabilising active

AddS I I III oI I more polypeptides (ie between subunits) HIVenzymeH H R2 CD

l 2 Maintained by 4 key bonds H bonds ---I~vl~pTtt~kshy 5 3 At interface of 2 domains is the active site with III tKkbr~ I1~

Condensation ionic bonds disulphide bonds hydrophobic VI specific 3D conformation - compriSing of 2gtOH -lt-er reverse hydrolysis) VI interactions others (not in your syllabus) lIydwsvn groups of three amino acids (asp-thr-gly) md ) -7 involve in catalysisPeptide bond H 0 i HO I

o I 1 I1 1 Ill -7 allows entry of water and viral polyprotein

~kkB(ltKl eshyH--H--C-+-C-- H-i-C-o--OH Un~a1J for hydrolysis of peptide bondI I i I i I

H RI H R2 -7 enzyme specificityt 3D shape of a protein may be changed by 4 2 flexible flaps guard active sites -7 excludei

a

1 Heat C~tenrnnusHmiddottermIOlS more incoming water molecules -7 this allows ~-- 3 Inorganic chemicals eg heavy metals

2 AcidsAlkalis (pH) catalytic reaction to occur

S ENZYMATIC function to cleave polyproteinsPolyptftld~ H~-~AAI-Mt~AAr-AA~ AA2--AA--AAn- ~t~ 4 Organic chemicals eg ether alcohol into functional viral proteinsS Mechanical forces

2

EXAMPLES OF LlPIDS

1 Each is made up of glycerol and fatty acids 1 glycerol + 3 fatty acids ~ 1 triglyceride (via condensation of components)

H HtOH

I Il- middotCmiddot- Oll

I H MCOIl

I-l H to -lt n lttl

1 glycerol +

~ HmiddotmiddotCmiddotmiddot OH

i r Ile OHtl

o Il If C OH

C Ir Hg Ca

ester linkagesHO M O ~

n bullbull~~ An exan1p~ orj trigyccrkle o o Iii A

HO ~O M ~ -S) v middot V 1I o

HO wO-llI i ltshy6 hydrocarbon tail

a 2 Hence a triglyceride molecule has a hydrophilic headand a hydrophobic tail lttl Il 3 Insoluble in water (exists as micelles) soluble in organic solvent

4 2 types Saturated Fat Unsaturated fat 1 lacks C=C in hydrophobic tails 1 possess 1 or gt1 C=C ~ kinks in tails 2 quite closely packed ~ solid at room temp 2 kinks prevent close packing ~ liquid at room temp 3 usually found in animals 3 usually found in plants and fish 4 eg bacon grease lard butter 4 eg vegetable oil cod liver oil

cc middotCC Cmiddot CJC O C c~O~O~cdeg OC cmiddotCcmiddotcmiddot J~9Jc ~cmiddot~c~cP ~H

1 Each is made up of glycerol fatty acids and phosphate groups 2 fatty acids + 1 phosphate grp

1l0 -OM 1I OH tI I 0 OH- P-OH

1I HO-O ~ 0

clI

phosphoester link 1-

bH

~ 1 phospholipid + 3H20

CH COO~1 ~

lHCOO OH IHJ~P-OH

Il 2 Hence it has a hydrophilic phosphate head (also cos of -ve charge) and a hydrophobic hydrocarbon tail 3 Such a property makes it an amphipathic molecule 4 Insoluble in water (exists as micelles) soluble in organic solvent 5 Exist as a phospholipid bilayer at the cellorganelle surface ie cell membrane 6 May have small variable molecules attached to the phosphate head eg choline

1 Insoluble in water soluble in organic compounds Some reproductive hormones 2 Possess 4 interconnected C rings

progesterone3 Structurally little in common with other lipids (J) 4 eg cholesterol vitamin D steroid hormones Omiddotfcen Q Cl 0 CH

y H)

cmiddotmiddoto ~ ~~~

CH 1 I t~J )

CHH

CH

testosterone (PCrt~J cJ 0-

+ 3HzO

(STRUCTURE~) FUNCTION

1 Higher HO ratlq compared to carbohydrates ~ good energy store (2x that of carbohydrates) ~ Hence animals store more energy with less

weight than plants ~ enables animals to travel around with less

weight 2 Good insulator of heat ~ used by animals to retain body heat

eg blubber subcutaneous fat 3 Good barrier of ions ~ allows saltatory conduction of nerve

impulses ~ hence increase transmission of impulse greatly

4 Protection Able to absorb impact ~ cushions vital organs for protection

5 Less dense than water ~ aquatic animals can stay buoyant in water

6 Releases water as a by-product when oxidised ~ metabolic water is a useful source of water for

desert animals or for dev of avian and retile eggs

1 Bilayers form continuous sheets ~ serve as membranes that enclose

cellorganelles allows compartmentalisation 2 Hydrophobic core selectively permeable membrane ~ allows lipid-soluble molecules to pass through

readily ~ although water is polar it can pass through

occasionally because it is small and weak in charge

~ regulates movement of ions polar molecules into and out of cell

3 Hydrophobic interactions between the molecules ~ self-sealing will reseal quickly if they are

punctured or disrupted

4-ring structure of cholesterol (within membrane) ~ regulatesmodulates membrane fluidity ~ At low temperature prevent phospholipids

from getting too close together and therefore prevents solidification of membrane

~ at high temperature prevent the membrane from being excessively fluid and unstable at higher temperatures through their interaction with phospholipids

1 Structurally similar to fats and oils only that the long-chained fatty acids are linked to long-chained alcohols Insoluble ~ 2 Insoluble in water ~ cutin coats surface of leaves to reduce water lossgtlt lttl 3 Chemically inert ~ similar concept with insectsIl

3

Il

PROCEDURE

1 Place 2 cm3 of test solution in a test tube og (l) J 2 Add equal volume of Benedicts reagent c(l) c c 3 Shake the mixture Q omiddot J ~ 4 Heat it by immersing the tube in boiling water bath for 2 minutes

lt0 ( 5 Observe the contents of the tube (J)-I c (l)

lt0 (JgtIII ~

en Q

z 1 If a negative result for Benedicts test is obtained for test solution o 2 Boil equal volume of test solution with dilute HCI for about 1 minute

to hydrolyse disaccharide to monosaccharides ~-I c (l) 3 Cool the contents of the tube Q ~ J 4 Neutralise the contents with sodium hydrogencarbonate solution

lt0 0 (J) because Benedicts regent only works in alkaline conditions c

lt0 5 Carry out Benedicts test for reducing sugar III 6 Record observations in the same format as that for Benedicts test Ul

1 Add a few drops of potassium iodide solution to 1 cm 3 of 0[ test solution (or a piece of the test specimen) S2 ~ 2 Observe any colour change III -I (l)g~

1 Place 2cm3 of test solution in a test-tube 2 Add equal volume of 5 NaOH solution OOJ cmiddot 3 Shake the mixture well

-0 (l)o ~ 4 Add 1 copper sulphate solution drop by drop shaking well (ii-l_ (l) after each drop J (Jgt(Jgt ~ 5 Observe any colour change

m 1 Place 2cm3 of absolute ethanol in a test-tuibe s III 2 Add 2cm3 of test solution to this test-tube J

0 2 Dissolve the contents by shaking vigorously o shy m 3 Add equal volume (ie 4cm3) of cold water C3 u c 4 Observe any colour change CiiJi omiddot

J

-I (l) ~

OBSERVATIONS

1 The contents of the test-tube remains a blue solution 2 A green ppt forms in the contents of the test-tube

3 A yellow ppt forms in the contents of the test-tube

4 A brown ppt forms in the contents of the test-tube

5 A brick-red ppt forms in the contents of the test-tube

1 The contents of the test-tube remains a blue solution 2 A green ppt forms in the contents of the test-tube

3 A yellow ppt forms in the contents of the test-tube

4 A brown ppt forms in the contents of the test-tube

5 A brick-red ppt forms in the contents of the test-tube

1 The mixture turns blue-black in colour 2 The mixture remains yellowish-brown in colour

1 The mixture turns from blue to purpleviolet 2 The mixture remains blue in colour (because of the

copper sulphate solution)

1 The mixture turns a clear solution 2 The mixture turns a cloudy white suspensionan emulsion

is formed

CONCLUSIONS

1 No reducing sugars present in the test solution 2 A small amount of reducing sugars is present in the a

~ test solution

3 A moderate amount of reducing sugars is present in the test solution

4 A moderately large amount of reducing sugars is present in the test solution

5 A large amount of reducing sugars are present in the test solution

1 Non reducing sugars absent in the test solution 2 A small amount of non-reducing sugars is present in the

test solution 3 A moderate amount of non-reducing sugars is present in

the test solution 4 A moderately large amount of non-reducing sugars is

present in the test solution 5 A large amount of non-reducing sugars are present in the

test solution

1 Starch is present in the test solution 2 Starch is absent in the test solution

1 Proteins are present in the test solution 2 Proteins are absent in the test solution

1 Lipids are absent in the test solution 2 Lipids are present in the test solution

Page 3: Biomolecules - SUMMARY

EXAMPLES OF LlPIDS

1 Each is made up of glycerol and fatty acids 1 glycerol + 3 fatty acids ~ 1 triglyceride (via condensation of components)

H HtOH

I Il- middotCmiddot- Oll

I H MCOIl

I-l H to -lt n lttl

1 glycerol +

~ HmiddotmiddotCmiddotmiddot OH

i r Ile OHtl

o Il If C OH

C Ir Hg Ca

ester linkagesHO M O ~

n bullbull~~ An exan1p~ orj trigyccrkle o o Iii A

HO ~O M ~ -S) v middot V 1I o

HO wO-llI i ltshy6 hydrocarbon tail

a 2 Hence a triglyceride molecule has a hydrophilic headand a hydrophobic tail lttl Il 3 Insoluble in water (exists as micelles) soluble in organic solvent

4 2 types Saturated Fat Unsaturated fat 1 lacks C=C in hydrophobic tails 1 possess 1 or gt1 C=C ~ kinks in tails 2 quite closely packed ~ solid at room temp 2 kinks prevent close packing ~ liquid at room temp 3 usually found in animals 3 usually found in plants and fish 4 eg bacon grease lard butter 4 eg vegetable oil cod liver oil

cc middotCC Cmiddot CJC O C c~O~O~cdeg OC cmiddotCcmiddotcmiddot J~9Jc ~cmiddot~c~cP ~H

1 Each is made up of glycerol fatty acids and phosphate groups 2 fatty acids + 1 phosphate grp

1l0 -OM 1I OH tI I 0 OH- P-OH

1I HO-O ~ 0

clI

phosphoester link 1-

bH

~ 1 phospholipid + 3H20

CH COO~1 ~

lHCOO OH IHJ~P-OH

Il 2 Hence it has a hydrophilic phosphate head (also cos of -ve charge) and a hydrophobic hydrocarbon tail 3 Such a property makes it an amphipathic molecule 4 Insoluble in water (exists as micelles) soluble in organic solvent 5 Exist as a phospholipid bilayer at the cellorganelle surface ie cell membrane 6 May have small variable molecules attached to the phosphate head eg choline

1 Insoluble in water soluble in organic compounds Some reproductive hormones 2 Possess 4 interconnected C rings

progesterone3 Structurally little in common with other lipids (J) 4 eg cholesterol vitamin D steroid hormones Omiddotfcen Q Cl 0 CH

y H)

cmiddotmiddoto ~ ~~~

CH 1 I t~J )

CHH

CH

testosterone (PCrt~J cJ 0-

+ 3HzO

(STRUCTURE~) FUNCTION

1 Higher HO ratlq compared to carbohydrates ~ good energy store (2x that of carbohydrates) ~ Hence animals store more energy with less

weight than plants ~ enables animals to travel around with less

weight 2 Good insulator of heat ~ used by animals to retain body heat

eg blubber subcutaneous fat 3 Good barrier of ions ~ allows saltatory conduction of nerve

impulses ~ hence increase transmission of impulse greatly

4 Protection Able to absorb impact ~ cushions vital organs for protection

5 Less dense than water ~ aquatic animals can stay buoyant in water

6 Releases water as a by-product when oxidised ~ metabolic water is a useful source of water for

desert animals or for dev of avian and retile eggs

1 Bilayers form continuous sheets ~ serve as membranes that enclose

cellorganelles allows compartmentalisation 2 Hydrophobic core selectively permeable membrane ~ allows lipid-soluble molecules to pass through

readily ~ although water is polar it can pass through

occasionally because it is small and weak in charge

~ regulates movement of ions polar molecules into and out of cell

3 Hydrophobic interactions between the molecules ~ self-sealing will reseal quickly if they are

punctured or disrupted

4-ring structure of cholesterol (within membrane) ~ regulatesmodulates membrane fluidity ~ At low temperature prevent phospholipids

from getting too close together and therefore prevents solidification of membrane

~ at high temperature prevent the membrane from being excessively fluid and unstable at higher temperatures through their interaction with phospholipids

1 Structurally similar to fats and oils only that the long-chained fatty acids are linked to long-chained alcohols Insoluble ~ 2 Insoluble in water ~ cutin coats surface of leaves to reduce water lossgtlt lttl 3 Chemically inert ~ similar concept with insectsIl

3

Il

PROCEDURE

1 Place 2 cm3 of test solution in a test tube og (l) J 2 Add equal volume of Benedicts reagent c(l) c c 3 Shake the mixture Q omiddot J ~ 4 Heat it by immersing the tube in boiling water bath for 2 minutes

lt0 ( 5 Observe the contents of the tube (J)-I c (l)

lt0 (JgtIII ~

en Q

z 1 If a negative result for Benedicts test is obtained for test solution o 2 Boil equal volume of test solution with dilute HCI for about 1 minute

to hydrolyse disaccharide to monosaccharides ~-I c (l) 3 Cool the contents of the tube Q ~ J 4 Neutralise the contents with sodium hydrogencarbonate solution

lt0 0 (J) because Benedicts regent only works in alkaline conditions c

lt0 5 Carry out Benedicts test for reducing sugar III 6 Record observations in the same format as that for Benedicts test Ul

1 Add a few drops of potassium iodide solution to 1 cm 3 of 0[ test solution (or a piece of the test specimen) S2 ~ 2 Observe any colour change III -I (l)g~

1 Place 2cm3 of test solution in a test-tube 2 Add equal volume of 5 NaOH solution OOJ cmiddot 3 Shake the mixture well

-0 (l)o ~ 4 Add 1 copper sulphate solution drop by drop shaking well (ii-l_ (l) after each drop J (Jgt(Jgt ~ 5 Observe any colour change

m 1 Place 2cm3 of absolute ethanol in a test-tuibe s III 2 Add 2cm3 of test solution to this test-tube J

0 2 Dissolve the contents by shaking vigorously o shy m 3 Add equal volume (ie 4cm3) of cold water C3 u c 4 Observe any colour change CiiJi omiddot

J

-I (l) ~

OBSERVATIONS

1 The contents of the test-tube remains a blue solution 2 A green ppt forms in the contents of the test-tube

3 A yellow ppt forms in the contents of the test-tube

4 A brown ppt forms in the contents of the test-tube

5 A brick-red ppt forms in the contents of the test-tube

1 The contents of the test-tube remains a blue solution 2 A green ppt forms in the contents of the test-tube

3 A yellow ppt forms in the contents of the test-tube

4 A brown ppt forms in the contents of the test-tube

5 A brick-red ppt forms in the contents of the test-tube

1 The mixture turns blue-black in colour 2 The mixture remains yellowish-brown in colour

1 The mixture turns from blue to purpleviolet 2 The mixture remains blue in colour (because of the

copper sulphate solution)

1 The mixture turns a clear solution 2 The mixture turns a cloudy white suspensionan emulsion

is formed

CONCLUSIONS

1 No reducing sugars present in the test solution 2 A small amount of reducing sugars is present in the a

~ test solution

3 A moderate amount of reducing sugars is present in the test solution

4 A moderately large amount of reducing sugars is present in the test solution

5 A large amount of reducing sugars are present in the test solution

1 Non reducing sugars absent in the test solution 2 A small amount of non-reducing sugars is present in the

test solution 3 A moderate amount of non-reducing sugars is present in

the test solution 4 A moderately large amount of non-reducing sugars is

present in the test solution 5 A large amount of non-reducing sugars are present in the

test solution

1 Starch is present in the test solution 2 Starch is absent in the test solution

1 Proteins are present in the test solution 2 Proteins are absent in the test solution

1 Lipids are absent in the test solution 2 Lipids are present in the test solution

Page 4: Biomolecules - SUMMARY

PROCEDURE

1 Place 2 cm3 of test solution in a test tube og (l) J 2 Add equal volume of Benedicts reagent c(l) c c 3 Shake the mixture Q omiddot J ~ 4 Heat it by immersing the tube in boiling water bath for 2 minutes

lt0 ( 5 Observe the contents of the tube (J)-I c (l)

lt0 (JgtIII ~

en Q

z 1 If a negative result for Benedicts test is obtained for test solution o 2 Boil equal volume of test solution with dilute HCI for about 1 minute

to hydrolyse disaccharide to monosaccharides ~-I c (l) 3 Cool the contents of the tube Q ~ J 4 Neutralise the contents with sodium hydrogencarbonate solution

lt0 0 (J) because Benedicts regent only works in alkaline conditions c

lt0 5 Carry out Benedicts test for reducing sugar III 6 Record observations in the same format as that for Benedicts test Ul

1 Add a few drops of potassium iodide solution to 1 cm 3 of 0[ test solution (or a piece of the test specimen) S2 ~ 2 Observe any colour change III -I (l)g~

1 Place 2cm3 of test solution in a test-tube 2 Add equal volume of 5 NaOH solution OOJ cmiddot 3 Shake the mixture well

-0 (l)o ~ 4 Add 1 copper sulphate solution drop by drop shaking well (ii-l_ (l) after each drop J (Jgt(Jgt ~ 5 Observe any colour change

m 1 Place 2cm3 of absolute ethanol in a test-tuibe s III 2 Add 2cm3 of test solution to this test-tube J

0 2 Dissolve the contents by shaking vigorously o shy m 3 Add equal volume (ie 4cm3) of cold water C3 u c 4 Observe any colour change CiiJi omiddot

J

-I (l) ~

OBSERVATIONS

1 The contents of the test-tube remains a blue solution 2 A green ppt forms in the contents of the test-tube

3 A yellow ppt forms in the contents of the test-tube

4 A brown ppt forms in the contents of the test-tube

5 A brick-red ppt forms in the contents of the test-tube

1 The contents of the test-tube remains a blue solution 2 A green ppt forms in the contents of the test-tube

3 A yellow ppt forms in the contents of the test-tube

4 A brown ppt forms in the contents of the test-tube

5 A brick-red ppt forms in the contents of the test-tube

1 The mixture turns blue-black in colour 2 The mixture remains yellowish-brown in colour

1 The mixture turns from blue to purpleviolet 2 The mixture remains blue in colour (because of the

copper sulphate solution)

1 The mixture turns a clear solution 2 The mixture turns a cloudy white suspensionan emulsion

is formed

CONCLUSIONS

1 No reducing sugars present in the test solution 2 A small amount of reducing sugars is present in the a

~ test solution

3 A moderate amount of reducing sugars is present in the test solution

4 A moderately large amount of reducing sugars is present in the test solution

5 A large amount of reducing sugars are present in the test solution

1 Non reducing sugars absent in the test solution 2 A small amount of non-reducing sugars is present in the

test solution 3 A moderate amount of non-reducing sugars is present in

the test solution 4 A moderately large amount of non-reducing sugars is

present in the test solution 5 A large amount of non-reducing sugars are present in the

test solution

1 Starch is present in the test solution 2 Starch is absent in the test solution

1 Proteins are present in the test solution 2 Proteins are absent in the test solution

1 Lipids are absent in the test solution 2 Lipids are present in the test solution