Biological Molecules: Carbohydrates Flashcards
Why is water a polar molecule?
due to uneven distribution of charge
- hydrogen atoms are more positive than O2 atoms so one end is more + than the other
Why is water an important molecule?
- It is a metabolite - for hydrolysis and condensation
- solvent where metabolic reactions occur
Properties of water?
solvents - allows substances needed for body to dissolve/be transported around body e.g glucose
- high heat specific capacity - more energy needed to warm up water so less temp fluctuations
- provide stable habitat/optimum temp for enzyme activity
- large latent heat of vaporisation - cooling effect with Iittle water loss
- strong cohesion - molecules ‘stick tgt’ by hydrogen bonds - effective transport of water in tube like transport cells (surface tension at the air-water boundary is high)/ allows pond skate to float
- max density is at 4 degrees - ice will be less dense/float creating insulating layer , so prevents organisms from freezing
How does water act as a solvent?
- water is polar, so positive parts of water molecule will be attracted to negative parts of solute and vice versa
- water molecule then surrounds the charged parts of solute/ion —> leads to solute dissolving
What are monomers and polymers?
Monomers - smaller units from which larger molecules are made
Polymers - molecules made from a large number of monomers joined together in a chain
What are macromolecules?
Very large molecules
- contain 1000 or more atoms /have high molecular mass
What is a condensation reaction?
- occurs when monomers combine together by covalent bonds to form polymers or macromolecules (lipids) / water is removed
What is hydrolysis?
-covalent bonds are broken when water is added.
Covalent bond for carbohydrates/proteins and lipids?
Glycosidic
Peptides
Ester
Covalent bond for nucleic acids
Phosphodiester
What do carbs, lipids, proteins and nucleic acids contain?
Carbon and hydrogen
→carbon can form 4 covalent bonds - make compound very stable
Why are carbon atoms key to organic compounds ?
→carbon can form 4 covalent bonds - make compound very stable
→ carbon atoms can form covalent bonds with oxygen, nitrogen and sulfur
→ carbon atoms can form straight chains , branched chains and rings
Carbs functions?what elements do they contain?
Source of energy - glucose used for energy release in respiration
store of energy - glycogen stored in muscles/liver
structurally important - cellulose in cell walls of plants
Contains C, H, O
→ H and O Are present in 2:1 ratio
What are Monosaccharides, give an example and function ?
Single sugar monomer, all are reducing sugars
E.g : glyceraldehyde (3C)
Ribose (5C)
Glucose (6C)
Function : source of energy in respiration / building blocks of polymers
What are disaccharides , example and functions ?
A sugar formed from 2 monosaccharides joined by a glycosidic bond in a condensation reaction
E.g maltose : alpha glucose + alpha glucose
Sucrose : alpha glucose+ fructose
Lactose : alpha glucose + beta galactose
Function : - sugar found in germinating seeds (maltose)
- mammal milk sugar (lactose)
- sugar in sugar canes (sucrose)
Polysaccharides definition, eg. And function?
Polymer formed by many monosaccharides joined by glycosidic bonds in a condensation reaction.
Examples: cellulose: beta glucose
Starch: alpha glucose ( amylose and amylopectin)
glycogen: alpha glucose
Function: energy storage ( plant-starch and
Animals - glycogen)
→ structural -cell wall
What do proteins contain and function?
C, H, N ,O and some proteins have sulphur
Functions: → cell growth and Repair
→ structural
→ carrier molecules in cell membranes , antibodies, enzymes and hormones
Nucleic acids contain and Function?
C, H, O, N AND P (phosphorus )
Functions:→ carry genetic code in organisms
→ control cellular processes
What are reducing sugars?
→ can donate elections
→ reducing agent
→ can be detected by Benedict’s test
What are non reducing sugars?
→ cannot donate electrons → cannot be oxidised.
→ detected by hydrolysis to break into monosaccharides then Benedict’s test
3 types of monosaccharides?
Trisoses (3C)
Pentoses (5C)
Hexoses (6C)
Function of glucose?
→ energy source
→ soluble, so transported is water
What is an ISOMER?
Molecules that have the same molecular formula but different structures —> different properties
Why is ribose and deoxyribose important?
- Pentose sugars found in nucleotides that make up RNA and DNA
How are glycosidic bonds formed?
Two hydroxyl (-OH) groups interact to form strong covalent bond called glycosidic bond to form disaccharides/polysaccharides
- water is removed
How are glycosidic bonds broken?
HYDROLYSIS
—> Disaccharides and polysaccharides are broken down
- catalysed by enzymes/ water is added
Examples of polysaccharides/what bonds do they contain?
STARCH - glycosidic bonds between alpha glucose molecules (1,4 and 1,6 - depends if amylose or amylopectin)
GLYCOGEN- glycosidic bonds between alpha glucose molecules ( 1,4 and 1,6 BONDS = BRANCHED)
CELLULOSE - glycosidic bonds between beta glucose molecules (1,4 Glycosidic bonds )
- beta glucose is an ISOMER of alpha glucose, so is rotated 180 degrees to form glycosidic bonds
What is starch constructed of and what are their differences ?
AMYLOSE - unbranded chain with 1,4 glycosidic bonds
- helix shape is more compact so resistant to digestion
AMYLOPECTIN - branched chain with 1,4 and 1,6 glycosidic bonds
Function of starch, glycogen and cellulose?
STARCH - storage polysaccharide in plants
- stored as granules in plastids
Amylose NOT BRANCHED - no need to rapid release of glucose in plants
- amylopectin has branches so can be easily hydrolysed for use in cell respiration
GLYCOGEN - storage polysaccharide of animals/fungi
- more branched than amylopectin so more compact so animals can store more/take up less space
- easily condensed/hydrolysed - release glucose quickly
- insoluble - won’t affect WP
CELLULOSE - main structural component of cell walls due to high strength due to hydrogen bonds between chains
Structural differences between lactose and maltose?
LACTOSE: glucose + galactose monomer
Contains alpha glucose
Beta glycosidic bond
Sugars are in opposing orientation
MALTOSE : both monomers are glucose
Alpha glucose
Alpha glycosidic bond
Both monomers are in same direction
How does the structure if galactose allow it to be used a respiratory substrate?
- bonds within molecule contain energy
- bonds are broken by enzymes
- galactose is soluble so can move within cell
Properties of cellulose?
Insoluble
High tensile strength
Form hydrogen bonds with neighbouring chains
Describe method to measure concentration of lactose in unknown sample?
Zero the colorimeter
Use red filter in colorimeter
Use a series of known concentrations of lactose - prepare a serial dilution, add reagent to test (eg Benedict’s )/test in colorimeter
Use results from known concs to produce calibration curve
Test unknown sample/use graph to determine concentration
Test for reducing/non reducing sugars?
REDUCING : add Benedict’s reagent (contains copper II sulphate ions)
- heat sample in water bath
- if reducing sugar is present , a coloured precipitate will form as copper (II) sulfate (2+) is reduced to copper (I) oxide (1+) which is insoluble in water
(colour changes from BLUE to green, yellow,orange to brown/brick red depending on conc of reducing sugar
NON REDUCING : add dilute HCl (hydrolysis) /heat in water bath
- neutralise solution with sodium hydrogen carbonate (use indicator to see when it’s neutralised) /add a little more to create alkaline conditions
- carry out above process to test (if colour changes, reducing sugars are present)
Test for starch?
Add iodine dissolved in potassium iodide solution
If starch is present goes brown/orange —> blue/black
Test for glucose?
Use test strips coated in reagent /dip in solution you’re testing
- change colour if glucose is present
Colour change compared to chart to show concentration of glucose present
What is the mobile and stationary phase in chromatography?
Mobile - where molecules can move
- normally liquid solvents is mobile phase
Stationary : where molecules can’t move
Stationary phase is the chromatography paper /layer of gel,glass or plate
Using paper chromatography to identify unknown amino acids?
- Draw pencil line near bottom of chromatography paper /put concentrated spot of mixture of amino acids on it
- Add small amount of solvent to beaker /dip bottom of paper into it (BUTAN-1-OL , GLACIAL ETHANOIC ACID /WATER used for amino acids)
DO IN FUME CUPBOARD/cover with lid to stop solvent evaporating - As solvent spreads up paper, different amino acids move with it - at different rates so separate out
- Mark solvent front once solvent nearly reached top /leave paper to dry
- Spray paper with ninhydrin solution to turn amino acids purple otherwise can’t see tem - FUME CUPBOARD/GLOVES
- Use Rf vales to identify amino acids - compare values to database/table to identify amino acids
What is a biosensor ?
Device that uses a biological molecule such as an enzyme to detect a chemical
- biological molecule produces a signal which is converted to electrical signal by transducer
Electrical signal is processed
How do glucose biosensors work?
Used to determine conc of glucose in solution
- uses enzyme GLUCOSE OXIDASE/ELECTRODES
Enzyme catalyses oxidation of glucose at electrodes - creates a charge which is converted to electrical signal by electrodes
- electrical signal is processed to work out initial glucose conc
