Module 2.2 Flashcards
(272 cards)
1
Q
Look at the sheet for the strcutre of water , rememeber it .
-What is cotnained in a molecule of water
A
-A moleucle of water contains on tom of oxygen , chemicallybonded to two toms of hydorgen . Bonds between o-hm covalnt bonds .
2
Q
Key about bonds in water moelcules
A
-In wter moelcules , the oxgen atom has a small NEGATIVE charge .
-The hydrogen atoms have a small POSITIVE chcagre .
-Because of these chagrers , scientists say that water is a POLAR molecule . And the oppoite charges means that the water moelcules are attracted to echother .
-these ofrces of ttraction are called HYDROGEN BONDS .
3
Q
Properties of hydorgen bonds
A
-Hydorgen bonds are quite weak bonds .
-However , even a smll volume of water contains a LARGE NUMBER of hydorgen bonds .
-so they have a LARGE efect on the propertieis of water .
4
Q
In liquid water …
A
water moleucles are not arranged neatly , instead , they aremoving ranodmly . HOwever , hydrogen bonds are sitll PRESENT .
5
Q
Check sheet to see hydrogen bonds in a water moelcule
A
…
6
Q
- propeties aND ROLE OF WATER
A
wATER H SA HIGH SPECIFIC CAPCAITY .
mening , WE HAVE TO PUT IN OR TAKE OUT A LARGE AMOUNT OF ENERGY OT CHANGE THE TEMPERATURE OF WATER.
7
Q
- properites and role of water pt2
A
-When we heat water , the heat energy goes towards weakening or breaking the hydorgen bonds .
-Rather than incresing the kinetic energyof the water moelcules .
-Becuase of this , water acts as BUFFER against rapid temperatrue changes aka temperature of water tends to not change rapidly.
ALLOWING water to ct as a habitt , for aquatic organsims . As awautic organisms would not be able to function if the temperture of water changed rapidly . E.g hot/cold days .
8
Q
If conditions are very cold ,
A
then water eventually freezes nd turns to ice .
KEY ; is ice is less dense than liquid water so ice flots and ice is also a habitat for a number of organsims .
-As well as this , ice also insualed the water below to prevnt it from freezin . This means that organisms can conintue to live int he water , udner hte ice .
9
Q
Another important property of water is that it has a very …
A
HIGH latent het of vaporisation .
-What this mean is that it takes a larger amount of heat energy to evaporae water .
-This allows orgnisms to cool themselevs without losign a great deal o water . We can see this with sweating /
10
Q
WHat hapens when you sweat
A
het enegry is used to evaporate water formt he surface of the skin .
-Ths transfer of heat energy allows the organisms to cool down .
11
Q
Another really improtnt role of water (4)
A
Solvent;
Water is an excellent solvent , in other words , lots of subsances can dissolve inw ater .
-Both eukaryotc +prokaryotic cells contain a large amount of dissolved susbtances .
EXAMPLES; the chemicals inovlved in metanlic reactions such as respiration . As well as the enzymes needed to carry out these reactions /
12
Q
Another really improtnt role of water (4) PT2
A
-Bodies of water such as ponds +river contrain dissolved oxygen + this is used by organisms living in the water to carry out respitation . Making wter an excellent habitiat for these organsims .
13
Q
As water is sucha GOOD SOLVENT …
A
it can be used to transport substances .
EXAMPLE , blood plasma .
-Blood plasma the liquid par of the blood , this contains a large number of dissolved substances .
-INC , Co2 , MINERAL IONS SUCH AS THE sodium ion + the chemical suchs as glucose + amino acids .
14
Q
Wter is a good solvent , how is this good in plants ?
A
-Water is also used to to tranposrt substancces int he xylem vessels of the plants , Water in the xylem contains dissolved mineral ions such s the magnesium ion .
15
Q
Water tranpsort in the xylem part 1
A
Water in the xylem contains a dissolved mineral ions , such s the magnesium ions .
16
Q
Water tranpsort in the xylem part 2
A
Magneism ions pass into the plant roots fromt he soil .
-They re transported in the xylm from the roots to the leaves.
17
Q
Water tranpsort in the xylem part 3
A
Once in the leaves , the mgnesium ions re used to make chlorphyl for photsynthesi .
-because water is such a good solvent , it amkes an excellent tranpsort medium .
18
Q
Another eally good PROPERTY of wter
A
-Water moelcules tend to STICK TOGETHER .
-Scientists call this COHESISION - this is due to the hydrogen bonds between water moeleucles .
-COHESION allows long columns of ter to travel in the xylem tube . Making water ideal s a transport medium in plants .
19
Q
Cohesions lso causes SURFACE TENSIONS
A
-Where wter mets air , surface tension is suefula s it allows hte surfce o wter to act as a habitait (for insects like pondskater0
20
Q
Final property of water !
A
-It is relaly improtnat in metabloic rections .
-E.g wate ris a reactant in amny differne trections .
These include hydrolissi rections and in photysntheis s.
-Water is also produced in certin metablolic reactions . These included condensation reactions aerobic respirations .
21
Q
strucutre of glucose
A
learnt it ish
-Glcuose has a RING SHAPE
-formula is C6H12O6
-All carbohydrates inclduing glcose contain only the elements carbon , hydorgen and oxygen .
22
Q
black underlines
A
–Shows glucose has SIX carbon atoms .
-Sugars with six carbon atoms we call HEXOSE SUGARS .
23
Q
The strcuture of glucos ei scomplicted , so scientists use a simpler version . (CHECK SHEET)
A
NEED TO LEARN THIS STRUCTURE AS CAN BE SKED IN EXAM .
24
Q
Glucose is a single sugar molecule
A
-Sciensits call single sugar moelcules MONOSACCHARIDES .
(mOno = one) (saccharide+suagr)
25
Examples of differen monosaccharides
-glucose
-galactose
-fructose
26
What is one property of monosaccharides ?
SOLUBLE IN WATERRR
-if we look again at the full strucutre of glucsoe we can see wh .
-Monosccharides , inclduing glucose hve aalrge umber of OH groups .
-Scientists call OH groups liek this hydroxyl groups.
27
soluble in water (2)
-hydroxyl groups can form hydorgen bonds with water molecules .
-Therefore monosaccharides are soluble in water .
-Scienitss cll moelcules like this hydrophilic .
-HYdrophillic mens water lvoign and hydrophilic moleucues ALL DISSOLVE IN WATER .
28
Some monosccharies contain five cabron atoms ;
-These are called PENTOSE monoscchrides .
-good exmpal e= RIBOSE .
CHECK SHEET AS WE NEED TO KNOW + LERN THE STRCUUTR OF RIBOSE /
29
Monosacchrides can be chemically joined to form larger crbohydrtes ;
scienitss cll these disacharides + polysacharides .
30
there are wo forms of glucose
-these two different forms are called isomers of glucose .
31
CHEK THE SHETT
-THE RIHT MOST CARBON ATOM IS NUMBER ONE.
-iN BOTH ISOMERS OF GLUCOSE of glucose , carbon 1 is bonded to a hydrogen atom .
-+ also to an OH gorup .
-remember sciensits call on Oh group a hydroxyl group .
32
Key differences between the two isomers
-is the potion of the hydroxyl group on cabron 1 .
33
chheck star one
-If the carbon 1 hydroxyl points BELOW the ring , then we call this isomer alpha glucose .
34
check star two
if the carbon 1 hydroxl point above the ring . Then we call this isomer beta glucose .
35
check disaccharide section ..
the two glucose molecule can rect together to form a disaccharide
Disacharides form when two mnosaccharides chemically react togehther .
36
-What happens when we react togthether two alpha glucose moelcules ,
the disaccharide we make is called maltose .
37
when we make a disacharide , we also produce a moleucle of wter .
-The water molecule is formed from a h yddrogen atom , from one of the monosaccharides + a hydroxyl group from the other . CIRICLED IN PURPLE ONT HE SHEET .
-when a r eactuib firs a water moleucl like this , scientiss call this A CONDENSATION reacton .
38
as we know two moleucles of alpha lglucose can rec togther to form the disaccharide maltose .
-In this reactionw e have formed a new chemicl bond between the to molecules of lpha glucose .
-This bond s called a glycosidicc bond . ( hve boxed the glcosidic bpnd in pink.)
39
-If we number , the carbon atoms , we can see , the glcosoidic bnd between carbon 1 one oe alpha glucose 1 and carbon 4 on the other (ciricled in pink0
SO WE CALL THIS A 1,4 glycosidic bond .
LEARN THE WHOLE DIAGRAM AS OUC OULD BE ASKED TO DRAW IN EXAM .
40
dISACCHARIDE ARE FORMED IN CODNENSATION REAXRIONS.
-A moeucle of water is produced .
-IF WE DD WATER TO A DIACCHARIDE , WE CAN BREAK THE GYLCOSIDIC BOND .
-This converts he disaccharide back to teh origional monosacharides . This ic alled a hhydrolysis reaction .
(normallyc rried out by enezymes ) .
41
s well as maltose , there are two other disccharides we need to learn .
sucrose = glucose +fructose
Lactose = glcuose +galactose .
42
-gLUCOSE IS EXTREMELY SOLUBLE INWATER.
-Contains a large number of hydroxyl groups .
-Hydorxyl groups re poalr due to the samall negatiive charge ont he oxygena otm + small posiitive charge on the hydorgen atom .
-Meaning hydroxyl groups can form hydrogn bonds with water moelecules .
43
However , due to its solubility ,t here is one BIG problem with glucose .
-If a cell congtains a large amount of dissolved glucose , this cna cause water to move into the cll by osmosiss .
44
How do we solve this prolem ;
plant cells store glcuose as starch .
STARCH: we find it starch grains .
-Strarch consists of two moleuvles called AMYLOSE AND AMYLOPECTIN .
45
Strucutre of amlose
DESCRIBE STRUCUTURE OF AMALAS - unbranched .
46
-Amlyose is a polymer of alpha glucose moleucles (tqo alpha glucose molecules molecules can join together disaccharide maltose .)
-glucose molecules joinbed by 1,4 glycosidic bond .
-condensationr ectoin s moelcule of wter is formed .
47
Key ; if we join togther a large number of alpha glucose moelcules , we make polysaccharides
(amylose canc ontain hundreds + thousnands or alpha glucse molecules , free sicl 1 .
alpha glcuose is joined by 1,4 glcosidic bonds , condnesation reacts bond is formed also porduces molecules of H20 .
-The amylose moleculle than twists into compct helix . With hydrgoen bonds forming between glcuose moelcues along the chain /
48
Starch is a store of glucsoe , so when the cell needs gluccose ,w ater is used to break down he glycosidi bonds .
check free scince videos this is a hydrolysis reaction .
49
Amlopectin is apolymer of alpha glucose . Joined by 1-4 glycosidic bonds .
UNLIKE amylsoe , amylopectin chains , have a branch , chery 25-30 glucose moelcules . 9Branchis just another chain of alpha glucose moelcules joined by 1,4 glcyosidic bonds .)
--The brnach is connected ot the mainc hain by glcysoicic bonds .(check statch part 2 free science lessons )
-
50
Amlopectin is apolymer of alpha glucose . Joined by 1-4 glycosidic bonds . part 2
-but in this cse , glycosidic bonds is inebtween carbon1 of one of the alpah glucos emoelcules + carbon 6 on the other alpha glcuos emoelcule .
-so it is claledd a 1,6 gylcosidic bond .
51
check shet fo simpified strucutre of AMYlopectin .
--can see it is a heavily branched molecule .
-Making amylopedtin differnt to AMYLOSE .]-As amylose is an unbranched polysacharide .
52
question asked in exam ?
HOW STRUCUTRE OF STARCH IS RELATED TO ITS FUNCITON ?
53
1. PORPERTY OF STARCH
AMYLSO forms a tight helic , makng starch compct .
-AK starch can store a large mount of glucose mollecues for its size
54
2. propertyof starch
starch is also insoulbe in wter .
-Meaning starch does not cause ater to enter the cell by osmosis .
-AS amylsoe and amlupoectin are polymers , they are too large to diffue throught he cell membrane and pass out of the cell .
55
what happens when a cell NEEDS GLCUOSE ?
-enzymes are sued to break the glycosidic bonds ins tarch . This is a hydrolysis reaction nd requires wter .
-Thr enzymes taht break downs tarch ac at the ends of the meolcule
-AS AMYLOPECITN HAS A LARGE NUMBER OF branches , IT EMANS IT HAS A LARGE NUMBER OF ENDS .
-tHEREFORE ,E NXYMES CAN BREAKDOWN STARCH RPIDLY /
56
What is the storage moleucle gluocse in animals
glycogen .
-glycogen is found in the liver and msnucle cells
57
What is glycogena polymer of ?
-*ALpha glucose ,
-mos of the alpah glucos emoelcues are joined by 1.4 glycosidic bonds .
-BUT ALSO CONTAIN BRANCHES - the glcuose moelcules at the branch are joined by a 1.y6 glcyosidic bonds .
58
glycogen seems to have the same trucutre as amylopecitn .
key differenc eis glycogen ahs more bbranches than amylopectin , making glycogen a very compact molecule .
59
As glycogen has a large number of branches i has a lot o free end .
Menain enzymes cn convert to gyclogen back to glucose very rapidly .
60
61
IMPORTANT ; as animals often hve a high rate of respitation , nd the energy needs of animals chan change rapildy .(animals may ave to move quicklybecuase of a predator)
-if that happened the rate of respiration woudl increase .
-Gyllcogen in the naimals msucls , could be rapidl converted ot flucose to be used in respiration ..
62
Glycogen is insoulbe in water
so glycogen does not draw water into cells by osmosis .
-Being a large moelcuels , glycoegn cnnot diuffse out of cell .
-All there featrues mke glycoegn an ideal glucose storga emeolcule in animal cells .
63
where is celluose a mjor part of
-the cell wl foudn in plant cells .
-struucture cellulose poluyer of beta glucose .
64
Key; Hydroxyl on carbon1 , points above the plane of the ring .
probelem ; if we needed to form a glysocosiidc bond betwen two crbon 1+4 .
-The hydroxyl groups are pointing in different reaction
65
problem witht he cellulose
if we need to form a glydcosidic bond between two carbon 1+ .
-yhr hydgroegn groups are pointing in different reaction .
66
-so when a moelcule of cellulose is formed .
-eevyr second beta glucose flip .
-now a glycosisic bond fan form etwen carbon 1+4 (don't need to flip 3rd lpha beta) , any second .
-cellulose is an unbranched polysaccharide ..
67
-Cellulose forms a straight chain , without any branches allowing cellulos emoleucles to get close together .
-hydrogen bonds , can now from between neighbourign cjains .
-because a huge numebr of hydrognb bond form , it makes cellulose EXTREMELY STRONG .
68
when cellulose chins group together , scienits call this is a micorgibril .
micrfibrils then group together to form larger strcutres called macrofirills .
-Finally macrofibrils dan group together tof orm a celluloe fibre .
69
these cellulose fibres form a palnt cell wall .
key feature of celllsoe is strenfrh .
-stnregth allows cellulose wcell wall to cry out its unctions .
-the cellulose cell wall is also permeebale to moelcules good examples is wate r.
70
-the cellulose cell wall is also permebale ot moelcules good example is water .
-under nromalc onditiosn , plant cells containg a gret del of warer .
-as water moves in by osmosiis ,t he plan cells contenrs push outward agasint the cellulose cell wall.
-means it cn resist the outwall pressure due to cell contins ,
-Prebenting the plant cell from bursitn g.
71
part two LAST CARD ON CELLULOSE
-WHEN a cell is full of t , like this i becomes rigid , scientists say the plant cell is turgid .
-These turgid planrt cels helpt og ive the plant is urpgpiht trcure ,
FOR ALL THIS CHEKC IVDEO ON FREE SCIENCE OR STRCUTREU .
72
-Proteins are among the most important molecules in biology .
-proteins carryo ut a visit number of functions in lviing organsims.
-All proteins are formed aminoa cids ,
-20 diffeent amino acids found in biology .
73
-structure o aino acid .
-general strcuture
-three parts to an aminoa cid
-maine group
-cabroxyl group
-these two gorups are the same for any aminocid .
-R giryo --? differrent fo reach of the 20 aminoa cid .
74
two differen aminoa ccid are
r gorup for first si hydorgen
-r group fo rthe second one is a carbon atom onded to three hydrogen aotms .
75
-In the xam YOU COULD E ASKED TO TNAME TE ELEMNTS PRESEN TIN PROTIENS .
-THEY CONTRAIN thre rlrmrnyd
csarbon , hdyorgen , nitrogen + oxygen .
-Some amino acids also contrian the elemnt suflur .
76
Two amino acids forming aa peptide bond
-tehse two amino acid can react togyher + form a chemical bond .
-peptide bodn formed . Do need to know this .
-THIs is an exmpale of a CONDENSASTION rection ,.
77
The mioelcule that ws formed is clled a DIPEPTIDE , AS IT CONTAINS TWO MINO AICDS , BONDED TOGETHER.
+-this rectiont akes palce in riosomes , wich s where porteins are synthesised inc ells .
-This reaction is catlaysed ba specific nzyme .
78
-If we join three or mor eaminoa cids we make a POLYPEPTIDE .
-One meolcule of water is amde for every peptide bond ,we're bond .
-I shouldpopojt out polypeitded often consits of hundres of minoa cids togher ,
79
-We can also REVERSE , the reaction + break the peptide bond , tod o that ,w e add bac a moelcule of wate r.
-This is called a hydrolysis of a rection .
-This rection is carreid out by portease enzymes int he digesitve styems .
80
difference between a polypeptide and portein
-in ordered to be calesed as a porien , a polypepetide has to fold into a comples 3 dimnsional shape .
-Once tje [pu[eotde js fpded omtp tje cprrec sj[ae . It cn carry out its fucions foe xample as an enzyme or a hormoene .
-At this point , we would rfer to it as a protien moelcule .
81
-Many proteins actull conits of several different poypetides .
-Forming a alrge + compex moeclule .
-+Proteins of concerins other moelcule s, helpign them to crry out there functions .
82
Lipids is the scienitc name for moelcules ofund in FATS AND OILS .
...
83
One fucniton of lipids
-Lipdis are a major source of energy in the human dier .
-We dinf lipids in oils sucha s olive oil + in solid fats such as butter both sources rich in eenegry .
84
Second funciton of lipids
-lIpids are also used to store enegry ,f or exmpale adipose tissue in huans .
-Aidpose tissue is found udner the skin . As well as acting as an energy store .
-The adipsoe tissue also heps to insulae the body reducing heatloss to the environemnt .
-AAlso can find adpiose itssue around itnernal organs sucha s the kidneys .
-Helping to portect the organs form injuryt .
85
third fucniton of lipids
Lipids are also sued as waterproofing ,f or exampel the oils which caot the fetaher of awuatic birds .
86
foruth function of lipids
lipdis are also a major part of the surface of memrbane ssuch as hose which surround cell s+ mitochodnira .
87
What are the two main categories of lipids
-triglycerides
-phospholiipds
88
check heet , what do triglyceridies cosnit of ?
a moleucle of glcyerol with three fatty acids .
89
check sheet for strcuture of a fatty acid moelcule .
-there are two key parts to the fatty acid moelcule .
-At the end there is a CRBOXYLIC GROUP , this plays n improtnat role when we form triglycerides .
-The rest of the moelecule consits of a long hcian of crbona toms bonded to hydrogen .
-This is ruroudned by fattya cids .
-saturated fattya icds contain a single covlent bond between the carbon aoms .
-CEHCK SEE TTO SEE .
90
check sheet to see an unstaturated fatty acid .
-As youc an see , unsaturated fatty acids have one double covalent bond beteen the carbon atoms .
-tHIS IS A MONTONOUS SATURATED FATTYA CID AS THERE IS ONLY ONE DOULE COVALENT BOND IN THE CARBON ATOM .
-This fatty acid has two doule covalent bonds in the carbon chain . So , this fatty acid is polyunsaturated .
91
Formation of triglycerides (check sheet for strucuture(
As you cn see , trigluceries re formed from a moelcule of glycerol and three fatty acids .
-underlinded is the thre hydroxyl gorups .
92
check hseet and video
-a moleucle of glycerol and three fattya cids can react togther to form a bond
-an esterbond is also formed .
This process is called esterificiton and wate ris also formed in the porcess so is an exmpale of CONDENATION REACTION .
93
-we can carry out this reaction with two or more fatty acids .
this is the strucuture of a triglcueride moelcule .
94
HOw ar dats + oils a mojor spource of energy in the huamnd die t?
-IOn the digestive sytem , ipase nezymes break up the esterbond , releasing the glycerol + datty acid moelcules .
-This reaction requries three water meolcuels and is an exmaple of a hdyrolsyis reaciton .
95
Trigclycerides are NON-POLR moelcules .
-Menain that they ar hydrophobic , in other words , they do not dissolve in water .
-Expalining why trigolycerides are used as waterporofing in aquatic birds .
96
As triglcyerides contrain a large amount of carbon + hdyrogen atoms...
A greta deal of enegry can be releaeed from tirglycerides .
97
Phodpholipids strcuture similr to triglcyerides.
-Phospholipids have a strucutre which is simialr to triglcyeirdies but is differen tin one key wy .
-this differenc ehas a major effect ont he way phospholipds behave .
98
strucutrue of phospholpids
-A glcyerol moelcule bonded to two fstty acid moleucles .
-The glcyerol moelcule is also onded to phosphate . DONT need to know the strucutre of phospahte , just know i is negaitvily charged (check sheet) 9AKA THIS PART OF THE MEOLECULE IS POLAR) .
-Becaus eof this , the pshosphate gorup is hdyophillic (it attracts water aka) .
99
Inrl phospholipd sare more compliacted , however ,w e can draw phospholipids ina simpliefied wyz (check sheet)
-Head is the polar hydrophillic part of the meolcule .
-The tail is meant to represent the TWO FATTYA CID MOELCULES , remembrer htese are non-polar +hydrophobic .
100
Phospholipdis contain both a hydrophillic +hydorphobic region .
-Meaning phospholids behave very differnelty in water compred to triglycerides .
101
In wter , phospholipd molecules , position themsleves so that the hydorphillic head gorups can itneract with the water moelcules .
-While hte hydrophobic tails clsuter together ,w ell away form water moelcuels . SCIENITSTS CALL THIS STRUCUTRE A PHOSPHOLIPID BILAYER .
-This property of phospholipds is extreemley sueful . As it allwos phospholids to form memeranes that we find oth around cells ++ within cells .
102
Cholestrol - need to be able to describe the properties + fucntion of cholestrol .
-Choelstrol is part of a famil of lipdis called STEROIDS .
-does not looka ntyhign like triglycerides/phospholips and do not need ot know the strcutre .
103
Check sheet - what are they key fetures of cholestrol
-the hydroxyl group (HO0 is hydrophillic .
-Howevefattty acid tails . r , the rest of the molecule is hydrophobic .
THIS MEANS , that cholestorl can insenrt into cell memebranes .
-The hydrophillic hydroxyl gorup on the hcolestrol moelcule cn interact iwth the head groups of phospholipds . While the rest of the choelsreol moelcule can intreacys with the hdyrophobic
104
one role of choelstrol
-choelstrol plays a key role in controlling the fludiiuty of cel memrbanes .
105
Cholestrl plays a number of critical roles in living organisms (1)
-It is the starting point for a range of HORMNES . (including oestrogen and tesoserone).
-As they are base don cholestrol m these hromones can pass through cell memebrans + interact with other receptors inside he cell .
106
Cholestrl plays a number of critical roles in living organisms (2)
-Cholestrol is used int he body to amke vitamin D .
-This takses place in the skin in resposne to UV LIGHT .
-Vitamin D is needed for for the proper development of bones .
107
Cholestrl plays a number of critical roles in living organisms (3)
-Cholestrol is used in the liver to produce Bile .
-the fucniton of bile is o increase the rate ofdigestion of lipids by the enzyme liapise .
108
Why do we test for biological moelcules ?
-We oftn carry out these tests to see which chemicls are present in foods .
-As WELL S OTHE RPORCESSES --> WE CAN TEST FOR STRATCH IN PLANS TO SEE IF THEY HAVE CARRIED OUT PHOTOSYNTHESIS .
--> WE CAN TEST URINE FOR POTEIN , TO DIAGNOSE KIDNEY PROBLEMS .
--> TEST URIEN FOR HYLUCOS ETO CHECK FOR DIABETES .
109
Testring different foods
All of these tests are potenitally harmful chemicals , so safety googles should be warn and ans pills should be cleane dupasap .
110
s1 for tsting for biological moelcules .
grind our food with a small amount of distilled water ina motar and pestle .
111
ss2 or tsting for biological moelcules .
once w ehave turned hte food into a paste ,a dd more distille dwate r+stir the micutre .
112
problem wiht the mixture
the mixture igs going otbe full of solid food particles ---> these could make the est results difficult to see .
113
To avoid this problem s3 or tsting for biological moelcules .
-Filter out mixture to remove the solid food particles .
-We can cary out tests ont he fitrate AKA food soultionw hich passes htoruh the filte r.
114
SATGE ONE test for starch
-Place 3 cn3 if fiid siktui ibti a test tube
115
stage two test for starch
then add one cm3 of solution containing iodine + potassium iodidie .
116
stage three test for starch
-on the presencre fo starch ,t he iodine soultion turns a blue-black olour .
-in the absence o starh , idoine remains orange .
117
stage one testring for porteins
-add 3 cm of our food solution into a testube .
118
stage two testing for porteins
af 3 cm3 dilute sodium hydroxide solution i=+ mic .
119
stage three testing for poteins
add ten drops of dilue copper(ii) sulfate solution + mix again .
120
stage four testing for poteins
-if protein is present , the solution will turn purple or lilac .
-if portein is absent , then the solution will remian blue .
121
points aout the prtoien test that you need to remeber
-sodium hydroxide solution and copper (ii) sulfate solutiona re premixed .
-this is called BIURET SOLUTION .
122
points about the protein test that you need to remember (2)
-Tgus test actyally detects peptide bonds .
-So you cna get a postivi test reuslts with porteins as these contain peptide bodns .
-HOWEVER , a solution of amino acids would give you a negative result as they do not contin peptide onds .
123
key thing about lipids in our test for poteins .
-the food micutre hsould not be filtered as lipids will stick to the filter paper .
124
stage one of the lipid test
-Leave the food solution for a hwile to let the particles to settle .
-*add 3 cm3 of food solution to the testube .
125
stage two of the lipid test
add ecm3 of ethanol and 3cm3 o water and shake the odlution .
126
stage three of he lipid test
-if lipids ar epresne t,w hite cloudy emulsion forms .
-if solution stays clear , the lipids are not present . HAZARD ; ethaol highly flammable , don't expote it to an falems .
127
What are monosaccharides ?
-Single suagr molecules (e.g glcuose)
128
What re disaccharides
-Two sugr moelcules joined bya glycosidic bond )mltose and sucrose)
129
All sugars can be separated into two grpups .
-Reducing suagrs
-non-reducing usagrs
130
reducing suagrs
-reducing suagrs , can donate an electron to another moelcule .
-All monosacharides are reducing suagrs .
-Some discchairdes are also recing sugr (maltose)
131
some disacchairdes are also non-reducing surgars
e.g sucorse .
132
GOGGLES NEED OT BE WARN
Testing different foods to test for reudcing sugars (1)
Start by grinding up the food with distilled water up the food wih distilled wate r.
-Then filtering away he solid food particles .
133
Testing different foods to test for reudcing sugars (2)
-We then place 3cm3 of our food solution into a boiling utbe + add 3cm3 of benedicts solution .
-Beneidcts solution contains copperions CU2+w hich amks the solutoin BLUE .
134
Testing different foods to test for reudcing sugars (3)
-We then place the boiling tube into beaker of boling water .
-Leave this of rfive minutes .
135
If the solution remains blue ...
there is no reudcing suagr present .
136
However if a reducing suagr is present ...
-then this addsa ne electrol to the copper 2+ ion .
-this ow forms the copper 1+ ion and ghis forms a red ppt .
137
if there i onlya very samll amount of reducing suagr (then only a smal amount of red ppt form)
-causing the benedicits solution o appea rgreen , iF MROE REDUCING SURGAR PRESNE COLOUR URNS YELLOW .
138
A higher level of reducing suagr
oeageg colour
139
A highhh level of reducing suagr
rick red .
140
Key about bedndicts test
-It gives a very apporximate idea od the amount o reducin ssuagr .
-As the bednicts onlhs hows a NARROW RANGE of colour changes + all humans precieve colours slightly differnely , Scinits say hat he Bendeict;s test is semiquanittaitev e.
141
Testring of rnon-reduing sugars (sucrose)
-REMEMBER that sucorse contaisn the monosaccharides glucose + fructose . JOined by a clhycoisidc bonds .
142
How do we test for non-reducing sugars ?
-We cannot test fo rnon-reducing suagrs direclt .
-Instead we need to BREAK the glcosidic bonds releasing the monosacchairdes .
-As ALL monosaccharides are reducing usgars we can now est fr them using BENEIDCITS OSLTUOn /
143
non-reudicng suagr solution
int he solution , we wont see if it contains a non-reudcing suagr (sucorse).
1.check to see if the oslution contains any reducing usrgars , if i does , this iwll e taken itno accoutn later .
144
Stage one of the non-reducing surgar test .
-First tkae a small amount of our unknown solution + carry ot Benedicts tes . Note down any colour change that takes palce .
145
Stage two of the non-reducing sugar test.
-Take a fresh boiling tube and add 3cm3 of our unkwnon solution .
146
stage three of our no-reducing suagr test .
-tenadd 3cm3 of dilute hcl + gentl boil the solution ina waterbath for mintues .
147
stage four of our non-reducing suagr tes t.
id a nonreducing duagr is presnet , then the acid HYDROLYSES the glcysoidic bonds , releaesign hte monosacchardies .
148
Stage 5 of the nonreducing surgr test .
-Next , dd 3cm3 o dilude alkali like sodium hydrocid soltuion and then use ph paper to chekc our solution is alkaline . -As the bendicts tst CANNOT WORK under acidic conditions .
149
Stage 6 of the non-reducing sugar tes t.
-Fianlly , add 3cm3 od Bendidicts oslutoin , an heat in boing waye rfo r5 mINTUES + NOTE DOWN COLOUR CHANGE
150
example results first test reducing usgar second test non-reducing
FIRST BEENDICTS TEST IS NGATIVE AKA COLOUR REMAINS BLUE .
-This tells us that our solution , does not contain a reducing suagr .
151
test porduced an oragne colour
-ths tells us that he solution contin a non-reducing sugar .
152
different solution
first benedicts test is produced a green colour
telling us a evry small amount of reducing suagr is present.
153
different solution
second test porduced a red colour
telling us a non-reducing suagr is also present .
154
final solution
-first test is porduced RED COLOUR
-telling us the solution contaisn a LARGE AMOUNT of reducing sugr .
-In this case , we cnnog test for a non-reducing suagr .
-as even if a non-reducing suagr was present , we would not be bale to see a olour change beyond RED .
155
--Therefore ! we cn any test for a non-reducing suagr , iof there is either no reducing suagr present or a very small amount .
...
156
-how we can use the benedics test , to determne when we can ck c eratjk kfareducing suagr mroe accuratle .
-RECAP SCIECNE FOR BEHIND BENEDICTS ?-Benedicts reafent a blue solution , this blue colour is caused by the presence of the copper ion cu2+.
-reducing suhars --? glcuose --> done an elexron .
-reducing hre cu2+ ion to the cu+ in . This formed a red ppt .
-the red ppt + blue of the Benedictsl solution led to the colour chnges we have lrey sene .
157
-If we left out test tube , for several hours , the red pp twould settle t the bottom .
-this would allow us to see the blue Benedict;s solution above it .
158
KEY; this Benedict;s oslution will be LESS B ue then it was before the tests .
as some of the cu2+ ions he reacted are areno longer in solution .
159
RECAP ; with the Bnenedict's test , the greater the concenrration of glcuose , to less nlue the enedicts solution will be att the end .
...
160
These changes in the blueness of the olution may be ttoo sublte to dectect by eye .
-So we wusnity the bluenss of the solution , by using a amchine called a COLORIMETER .
161
Beofre we use the coloritmeter we need to filter out the red ppt .
Leeving just the blue Benedicct's soltuoin .
162
HOw a colorimeter works .
LAMP; emitting white light ,
Rememeber that white light consints of all the different coours of the spectrum .
163
-If we shine white light thourgh a sample of Benedictls solution , all the colours of white light willbe BOSRBED prt from blue .
- s the Benedict's solution llows the Blue light to pss thorugh .
-hence why Benedicits oslution , lue colour .
-This SBROPRTION of light cn be used to qunitfy the level of bluenss .
164
-As Benedicts solution llows blue light to pas horugh .
Hence ,w hy Benedictls soltuion , blue colour ,.
-This absorption of light cn be used to quity the level of beluenss .
165
Ratheer thn using white light , RED , is used as .
-Benedeicts solution abosrbs red the msot out of ll the different colours .
-As red is on the opposte end of the spectrum toblue .
-Red is the complemenatary of the colour to blue .
166
Now we plac a red filter infront of a lamp . Thsi red filter only llows red to pass thorugh .
(Benedictls oslution less blue before e.g enediccts solutio thaat has reacted with glcuose + los its bluec olor .
-As he solution is elss blue ,t han before less of the red will be now absorbed . mening hat some of the red light will be transmitted .
-This light can be cetected by the photocentric cells (type of light detector )
167
sample of benedicts oslution tht is a very pale blue
--> this samle ould hve been reactrd with a very LARGE amount of glucose .
-In this cas e, even less red ligt s absorbed by the solution .
168
-AS youcan see --> the less red light is absorbed , the rgeater amount of glcusoe that msu have reacted with our Benedict;s oslution .
now when we su ebendiedcis test iwth colorimwter we can now more accuratleyd etermine the glcose cocnnetration of glcuose in a ample .
169
In this practical , we need to determine the cocnentration of glcuse in a sample .
...
170
pROBLEM ; COLORIMETER CANNOT tell us the actual concentration of glucose .
-To adress that , we need ot prpepapre a whole range of known glucose concnentraitons .
-we then need to react each o those solutions with Benedict's + filter off the red ppt .
-We then sue a colirmter to see hwo muchr ed light is absorbed bye ach solution.
-carry out the sam porcedure with ou r unknown solution .
-BY comparing our unknons olutions with our known solutions ,w e cand etrmine the cocnentrations of glucose in our unknown solutons .
-Scienitsts call this a caliration curve .
171
stge 1 determinign the cocnentration o glcuose
-Set un six tes ttuebs .
-start with a known concenntration of glucose eg mmol/]dm3 + creat range of dilutions form tha t.
-We call our known concnentration our STOCK SOLUTIONS .
172
STAGE 2 determinign the cocnentration o glcuose
Using a syringe , we place cm3 of our sotck solution in tes tube 1 .
-So this text tube has lucose solution of mmol/dm3.
173
stage 3 determinign the cocnentration o glcuose
test tube 2 , ad cm3 of our sotck solution + 1 cm3 of disitlled wte --> glucose osolutoin cocnentration 4mmol/dm3
174
stage 4 determinign the cocnentration o glcuose
test tube 3 cm3 of sotck solution , 2cm3 of distilled water --> cocnentration of glucose solution concentration3 mmol.dm3
175
stage 5 determinign the cocnentration o glcuose
test tube 4--> 2cm3 stock solution and 3cm3 distilled water -> cocnenntration of glucose osltuion 2mmol.dm3
176
stage 6determinign the cocnentration o glcuose
test tube 5 1 cm3 of stock solution and 4c3 of distilled water --> cocnentration of glucose solution 1mmol/dm3
177
stage 7 determinign the cocnentration o glcuose
test tube 6 5 cm3 of disitlled water and no glucose oslutoin .
178
stage 8 determinign the cocnentration o glcuose
-Next we set up a tst tube containign 5cm4 of our unkwnon cocnnetration of glcuose .
-at THIS STAGE we need to ad 5 cm3 o Benedict's solutin tie ach tes ttube + mix thoruguhly .
179
stage 9 determinign the cocnentration o glcuose
Then palce ll the trst tubes in ab oiling water bath for 5 mingues .
-During this time ,, the Benedicts solution can eacts with the glcuose porducing a red pp t.
180
stage ten determinign the cocnentration o glcuose
Fianly ,w e filter each solution on a fresh tes ttube .
This removes the ppt leaving the remainign benedicts oslution .
181
Alternativley
-iNSTED OF FILTERIGN COLUD US A CENITRGUE , TO SEAPRTE THE OSLUTION FORM THE PPT .
182
How to use a coloirmeter (1)
-some colorimter you can place ts tutbed riecl yinto the coloiremer .
-In otehr you need to tranfer LAL YOUR SOLUTIONS INTO SMAL PLSTIC CONTIANS COULD CURBETTES .
183
CURVETTES - HAVE TWO CLR TRANPSARENT SIDES + TWO SIDES WHICH E TRANSLUCENT ..
....
183
Awkas place hre curvettes into the colorimeter o tha the lgiht pses htroguh the trnapsrnet sides.
...
184
How to use a coloirmeter (1)
-Set colorimeter to red iflter .
-as red is the compelmematry colour to blue AKA - red will be the colour msot absored by the blue solution .
185
How to use a coloirmeter (2)
Then set the colroimete rto measure absorotion aka how much red light is abrosrbed by the soloution .
186
How to use a colorimeter (3)
-Then palce a curvetter containing just distilled wer , into the coloritmer and set the coloriemter to zero .
-Esenitallyw e are telling the oloritmeter to cosnider distilled wter to absor zeero red lgiht .
187
How to use a colorimeter (4)
-No w w euse the colroitmer to read the absorbeanes of all our soltuions .
188
How to use a coloritmeer (5)
-At this stage ,w e plot the absorbances of our dilution series ona graph like this .
-We cn use the calibration curve to detect the cocnentration of clusosue ofour unknwon ample .
LOOK AT EMPAL EON SHEET .
189
iF THE ABSORBANCE O THE UNKWNON SMPLE IS too gret TO READ OFF OF THE CALIBRATION CUVE .
-tHEN YOU NEED TO DILUE THE SOLUTION AND READ THEE ABSORANC WAGAIN .
rememebr TO TKE INO ACOUNT DILUTION FACTORS when determining the ocnentration of glcuose .
190
Proteins are among the most important molecules in biology
Proteins carry out a vast number of functions in living organisms
191
All proteins are formed from amino acids
There are 20 different amino acids found in biology
192
General structure of amino acid (need to know )
-Check sheet
-Three parts of an amino acid
-Amkne group
-carboxylate group
And the R GROUP
Key : r group is DIFFERENT for each 20 amino acids
193
Two groups of amino acids on the sheet
-R group is a carbon atom bonded to three hydrogen atoms
- in one d groip
Is hydrogen
In the other r froup is carbon atom bonded to three hydrogen atoms
194
In the exam , you could be asked to name the ELEMENTS present in proteins
- They contain the elements carbo. , hydrogen , nitrogen +ozygen
-some amino acids also contain the element sulfur
195
The peptide bond
- check sheet to see two
Amino acids side by side
- In this case both amino acids are glycine
-these two amino acids can react together + form a chemical
Bond .
- A peptide bond is formed Xo need to learn this son heck structure
- As you can see , a molecule of water is also formed , so this is an example of a condensation reaction .
196
Peptide bond (2)
-The molecule that we have formed is called a dope price , as it contains two amino acids bonded together .
-this reaction takes place on
The
Ribosomes which is where proteins are synthesises in cell , this reaction is also CATALYSED by a specific enzyme
197
If we join three or more amino acids …
Then we make a polypeptide
-one molecule of water is
Made for
One peptide bond we,ve formed
(Polypeptides usually contain hundreds of amino acids joined together )
198
We can also reverse the reaction + break the peptide bond , to do that we add a molecule of water
-This is called a hydrolysis reaction
-this reaction is carried out by PROTEASE enzymes in the digestive system
199
Difference between a polypeptide and a protein (1)
-In order to be classed as a protein , a polypeptide has to fold
Inflation complex three dimensional
Shape .
Once the polypeptide has folded into the correct shape . It can then carry out its functions for example as an enzyme or hromones .
- At this point , we wouldn’t refer to it as a PROTEIN molecule
200
Many proteins acutely consists of several different polypeptides
- Forming a large + complex lole ikr .
- proteins often contain other molecules helping them to carry out their function
201
Levels of protein structures
…
202
First level of protein structure is the primary structure
- the specific order of AMINO ACIDS in a polypeptide
-improtant to a protein as it helps to determine the final 3 dimensions shape of the protein molecule .
- The shape of a protein is critics for its function . Even changing a SINGLE amino acids int he primary shape , can change the final shape of the protein .
- Thi can prevent the protein from carrying out its fun if on properly
203
Primary structure (2)
The primary structure of a polypeptide is determined by the DNA sequence of the gene which encodes the polypeptide .
204
Secondary structure
Looking at the diagram , we can see that all along the polypeptide chain there are c=o groups and n-h groups .
KEY : oxygen atoms in the c=o groip has a small negaitve charge .
-And the hydrogen atoms in the n=h groups have a small positive charge
205
Secondary structure (2)
- This means that these positive + negative charges can attract eachtoher .
- When this e , hydrogen bonds form between amino acids , which along the polypeptide chain
-these HYDROGEN BONDS. , cause the polypeptide chain got WIST and fold into shapes .
Scientists cal these twists and folds the secondary structure .
206
Secondary structures (3)
One type of secondary structure is asphalt helix
-very common secondary structure found in proteins .
-as you can see (check sheet) , the polypeptide chains twisted into a helical shape and is held in place by HYDROGEN BONDS .
207
Secondary structures (4)
-Another type of secondary structure is called the beta pleated sheet .
-in this case , the polypeptide chain folds into a flatter , sheet-like structure .
- Again hydrogen bonds between the amino acid hold the shape in place .
- Many proteins have regions with alpha helixes and regions with beta eared sheets .
the TYPE OF SECONDARY STRUCTURE FORMED DEPENDS ON THE PRIMARY STRUCTURE IN THAG REGION .
- certain amino acids tend to be found in alpha helices , and others tend to be found in beta pleated sheets ,
208
Tertiary structure
- The tertiary structure did the overall 3 dimensional shape of the polypeptide chain ,
-unfolded polypeptide chain as you can see on the sheet it hasn’t folded her .
- the chain folds into regions of secondary structure
- once the regions of secondary structure form , the chain now continues folding , forming the final tertiary structure .
209
Tertiary structure (2)
Tertiary structure is criticsl for now a portion functions .
E.g active site of an enzyme depends on the protein forming w very specific tertiary stuctute .
- if we change the tertiary structure of an enzyme (by hearing it ) then the shape of active site has changed and the enzyme can no longer function properly - it has denatured .
210
Quaternary structures
- A large number of proteins consist of several polypeptide chains eorking togeyher as a large protein example haemoglobin
211
Haemoglonin
- hamelglonin coneite kf four polypeptide chains forming a large molecule .
scientists thee polypeptides “subunits”
- two shown in red and two in blue
212
- the quaternary structure hows how the individual subunits are arranged to form a larger three dimensional structure
- quatnernady studicres allies to proteins with wt least two subunits .
213
Another point about quaternary structures is that some proteins contain other non protein molecules forming part of the structure
These are called PROSTHETICS GrOUPs and they help the protein to carry out its role
- haemoglobin contains the orthotic groip when which binds to oxygen (shown In pic )
214
Proteins with a prosthetic group is called conjugated proteins
- so as well as showing us how subunits are are ages , quaternary structures show us THE POSITION OF ANY prosthetic groups .
215
The bonds we are looking at now , are in tertiary and quaternary structures !!
- these bonds form between the R groups of amino acids of a polypeptide chain .
MEANING The Type of hormone depends on the SPECIFIC AMINO ACIDS PRESENT IN THE POLYPEPTIDE .
216
First type of bonding
Hydrogen Bonding
- Showing in diagram polypeptide chain .
- Those polypeptide chain had two amino acids with r groups containing a hydroxyl .
- due to the slight positive and negaitve charges present on the hydroxyl , a HYDROGEN BOND FORMS 9’ the polypeptide chains .
217
What are hydrogen bonds easily broken by ?
High temperatures and Ph changes
218
The second file of bonding is called hydrophobic and hydrophilic interactions
-several amino acids have uncharged at groups , we xall thsr , non-polar amino acids , these are NOT attracted to water . They are hydrophobic
- Amino acids with hydrophobic r groups tend to CLUSTER TOGYEJER AAND HY DLKNG TJOE RHEH BAN ESFLUDE WATER MOLEFULES .
Scientists call thsr hydrophobic kntrtscgilnd
219
Hydrophobic interactions (2)
Hydrophobic interactions tend to be found in the VENTER of proteins . Well away from any water mellcules .
-Hydrophilic amino acids tend to be found on the SURFACE of proteins where they can interact with water molecules .
220
- like hydrogen bonding hydrophilic and hydrophobic interactions are also weak bonds
…
221
Third type of bonding
- Ionic bonding
- found inbetween amino acids with CHARGED r groups .
- in diagram can two amino acid onw. Polypeptide chains .
- one of the amino acids has a positively charged r group other has a negatively charged r group .
222
Ionic bonding (2)
- thsr opposite charges attract eachother + form an ionic bond .
-This ionic bond holds different parts of the polypeptide chain together and again , contributes to the structure of the protein .
223
Key : ionic bonds are broken by changes in Ph
One reason why enzymes DENAUREE when under acidic or also r fone irons
224
Last type of bonding
- showing polypeptide and it contains two molecules of amino acid called cysteine .
-
- the r group of cysteine contains a sulfur atom and the sulfur atoms in the two cysteine molecules can form a covalent bond like SHEIN .
- scientists cal fhis a DISULFIDE BOND .
-DISULFIDE bonds are relatively strong + are NOT broken by high temperatures or pH changes ,
225
These are the four bonds important for protein structure
🤑🤑🤑
226
If these bonds form between amino acids in the SAME polypeptide chain
-Then , they are involved in the tertiary structure
227
However if they form between DIFFERENT SUBUNITS
Then they are involved in the quaternary structure
228
Key : structure of any protein is critical to its function
Scientists divide proteins into two very broad groups , based on their structure . Called globular and fibrous proteins .
229
Globular proteins : structure , they tend to have an approximately spherical shape
Key : globular proteins are soluble in water . Need to be able to explain why . Some amino acids have R groups which are attracted to water . Called hydrophilic amino acids .
-
230
- Globular proteins have got hydrophilic amino acids on their surface .
- Fhis means that the hydrophilic at groups can interact with water molecules making globular proteins soluble in water .
-Other amino acids have R groups which are not attracted to water .These are called hydrophobic amino acids .
231
- Globular proteins have got hydrophilic amino acids on their surface .
- Fhis means that the hydrophilic at groups can interact with water molecules making globular proteins soluble in water .
-Other amino acids have R groups which are not attracted to water .These are called hydrophobic amino acids .
232
In globular proteins , we find the hydrophobic amino acids deep in the center of the protein as well as away from any water molecules .
…
233
Haemoglobin OCR SPEC
- need to be able to describe how the structures of THREE globular proteins link to their functions .
234
Haemoglobin is a globular protein with four polypeptide subunits .
….
235
-Two are called alpha subunits + two are called beta subunits
- We find Haemoglobin in red blood cells and the function of Haemoglobin is to hinge reversely to oxygen .
-Haemoglobin binds to oxygen in the lungs and then releases the oxygen in the body tissues .
236
Key of Haemoglobin :
Js fhat each subunits contains a prosthetic group haem.
-Tjis means that Haemoglobin is an example of a CONJUGATED protein .
-Eavh haem group contains an Fe2+ ion where oxygen binds .
-Meaning one Haemoglobin molecule can bind to four oxygen molecules .
237
Haemoglobin has an interesting feature
-When oxygen attaches to Haemoglobin , the quaternary structure of the protein changes sogjtlt .
-making it easier for MORE oxygen to attach to
238
Insp lin is a another globular protein
It’s a hormone that is carried in the blood stream .
-Insulon plays a role in blood glucose regulation .
-Insulin consists of two polypeptide chains (shown in orange and green)
The two chains are linked by disulphide bonds and these are shown in yellow
239
-Hormones like insulin carry out their functions by binding to specific receptor molecules .
- These proteins are proteins found on the cell membrane of target cells .
the shape of the insulin molecules means that it fits perfectly inrl the receptor .
-Even slight changes tk the shape of the insulin molecule could prevent it from burning effectively .
240
You need to remember that the shapes of protein hormones such as insulin are critical for how they bind to their receptors and caddy out their effects
…
241
Third globular protein. ENZYME lysosome
lysozyme is found in saliva + YWASS + it’s ion is to catalyse the breakdown of a molecule in the bacterial cell wall and dhis helps to defend the body against bacteria .
Key: if any enzyme , including lysozyme , is that they only reach with a specific substrate molecule .
-This speficag is due to the structure of the enzyme
242
Pic of lysozyme check sheet
Lysozyme contains a SINGLE polypeptide chain .
-The chain folds to form a groove along the surface and this groove is called the active site .
—shape of the active site means that it fits perfectly to the substrate molecule in the bacterial cell wa .
243
Regions in blue show the
location of the amino acids which hold the SUBSTRATE IN PLACE .
…
244
-Regions in red show the locations of the amino acids which catalyse the reaction .
-as the active site is perfectly shaped to fit the substrate , this makes the e lysozyme extremely specific .
245
Fibrous proteins often play a structural role
For example in bones / tendons or in the walls of blood vessels such as arteries .
246
Unlike globular proteins , fibrous proteins tend to form long rope like molecules shown here
Fibrous proteins are also have a large proportion of Iv hydrophobic t groups , meaning unlike globular proteins fibrous proteins wre insoluble in water
247
Collagen
Found in tendons which connect to muscles to bones and in ligaments which connedf bones to eachother
-also find collagen in the skin .
KEY: collagen is a strong molecule due to its structure
248
Structure of collagen
Polypeptide chains in collagen wrap tightly together to form a triple helix
/in the collagen polypeptide every third amino acid is glycine wnd the r groip for glycine is a HYDROGEN atom .
249
-This means that glycine has the smallest r group of any amino acid . This allows the collagen polypeptide to warp very tightly around eachother.
As the polypeptide wrap
Around eachotehr ? A large number of hydrogen bonds form between the polypeptide chains .
-these hydrogen bonds help to stablise the quart energy structure of the proteins .
-The polypeptide chains are Wlso joined to eachother by strong cross links
250
A large number of these triple helical molecules join together to form alevel structure called microfibrils and
-as you can see these molecules are staggeees , This means there are no weak spots .
If the model idle was arranged like this , then the weak spots would run across the structure , reducing the strength of collagen .
-By staggering the moleucules like this ? The weak spots are avoided .
251
Collagen is further strengthen by …
Cross lining between different helical molecules
252
Keratin
W for pure protein found in hair and fingernails wmd the outer surface of the skin
-keratin is extremely strong and insoluble in water .
253
The structure of keratin
Like a lot of fibrous proteins , keratin consist of two long stranded molecules .
However , keratin contains w very high proportion of the amino acid cysteine
254
Cysteine is used to form disulphide bonds .
Remember , disulphide bonds are strong covalent bonds , so as if contains a high proportion of cystine , keratin molecules contain a large number of disulphide molecules contributing to the strength of the keratin molecules
255
Elastin
Skin contains a large almond of elastin Forbes
These help to make the skin supple and elastic
- we also find elastin in the walls of arteries
-elastin fibres stretch when blood passes through the after then RECOIL in between pluses ( helping the artery return to its normal shape .
256
Elastin molecules are long strands containing hydrophobic regions .
Strands aww doess linked to eaxhother .
-normally the hydrophobix region of different strands associate causing the elastin molecules to group together .
- however when they are stretched the strands move apart, but remain attached at the cross links .
 After stretching the elastin molecule soemthing g sprinting back into togeyher tjis lakes elastic a very elastic molecule .
257
258
Consolidation property of microfibrils
Microfibrils and macrofinrils have a very high tensile strength both heavier fly he etr nth or the tlyfoeirifnhonre but wlepnbefwiee or the hydrogen bonds between the chains mwfeoronirle wre stronger then steel wire bro
259
Consolidation property of microfibrils
Microfibrils and macrofinrils have a very high tensile strength both heavier fly he etr nth or the tlyfoeirifnhonre but wlepnbefwiee or the hydrogen bonds between the chains mwfeoronirle wre stronger then steel wire bro
260
Consolidstiojnwhybcelluloseb
Felliloeendifesting hefwise the glyfoeidifnhonre hereeen the glucose molecules are less easy to break indeed , most chemicals do not even haves n enzyme toncatsyulse the reaction
261
Consolidation functions kf triglycerides
Buoyancy - bevwuse fat is less dense than water it is shed HH aquatic mammals tk help them stay afloat
262
What is the derivative of cholesterol in plants consolidation
Stigmasterol
263
Proteins
Membranes have poroteins constituents thay afte we carriers and pores for active transports across the membrane and facilitated diffusion
264
Consolidation amino acids can act as buffers
When dissolved in water the amino group and csrbodulngroip cwknionose .
Nh2 and nh3 the dwejdoult rooptniheenilnhrijnfirflmpwhe page 65
265
Consolidation of ionic bonds
Between carbonyl and amomo groups
266
Consolidation of hydrophobic and hydrophilic interactions
Hydrophobic and hydrophilic interactions cause twisting of amino acid chains which changes the shape of protein .
- ;£3 interactions can be w very important infleunce given that most proteins are to be found surrounded by water in living organisms .
267
Consolidation prediction of tertiary structure
Check page 71
268
Consolidation testing for starch
When dissolved in lylssdoum iodide the iodine forms a triiododie which slips into the middle of the amylose helix causing the colour change
269
Consolidation reducing sugars what happened when the Benedictus solution in excess
The intensity of the reencolpurbidnproportionslntonthebconcrntrsrioknofbduhsrbthebrecsrionnkoxneillnsppesrbgreennifnonlynsnlittlenpprnodnformefnsjdnorwjgebrednifnwnlotnofnpptnidnforkedn.
270
What is the use of hiodjesjors
They take a holofifwl hsir wlr which cannot he kewdured and convert it into an electrical signal
271
How do biosneskodrs SOELL
Biosensors have many other applications for edmamole they can be sued to detect contaminants in water and park grams sm godsons for food tjeu can be used to drrrcf airborne bacteria for example in counter bioterorrism programmes .
