2.2 Biological Molecules Flashcards
Examples of reducing sugars
Maltose and lactose
Examples of non reducing sugars
Sucrose
What elements make up lipids and carbohydrates?
C
H
O
Which elements make up proteins?
C H O N S
Which elements make up nucleic acids?
C H O N P
Alpha-glucose + alpha-glucose
Maltose
A-glucose + fructose
Sucrose
Beta-glucose + alpha-glucose
Lactose
Beta + beta-glucose
Cellobiose
Difference between glycogen and amylopectin
1-4 chains are smaller
Less tendency to coil
More branches
More compact
Why are polysaccharides less soluble than monosaccharides?
Their size
Regions that could hydrogen bond are hidden away
Why is cellulose a good material for plant cell walls?
High tensile strength due to different bonds
Macrofibrils criss cross
Can be reinforced by other substances
Examples of macromolecules
Triglycerides and Phospholipids
Fibrous proteins
Insoluble
Metabolically inactive
Globular proteins
Soluble
Metabolically active
Structure of insulin
Two polypeptide chains
Chain A starts with a a helix and chain B ends with a b pleat
Joined by disulfide links
Soluble
Two types of computer modelling for protein structure
Ab initio
Comparative.
Summarise ab initio protein modelling
Based on physical and electrical properties of atom
Multiple solutions to the same amino acid sequence
Other methods needed to reduce solutions
Summarise comparative protein modelling
Protein threading
scans amino acid sequence against a database of solves structures and produces a set of possible models
Cations 2.2
Ca2+ Na+ K+ H+ NH4+
Anions 2.2
NO3- HCO3- Cl- PO43- OH-
Colour change Benedicts
Blue to green to yellow to orange red with reducing sugars
How do you use test strips for reducing sugars?
Commercially manufactured test strips
Dip strip in solution
Compare colour with calibration card
Used as test for glucose in urine of diabetic patients
Test for non-reducing sugars
Test sample for reducing Boil with HCl Cool Add sodium hydrogencarbonate to neutralise Do Benedicts
Emulsion test
Mix with ethanol
Filter
Pour into water in clean test tube
Cloudy white emulsion
Biuret test
1) Biuret A = sodium hydroxide solution
2) Biuret B = copper (II) sulfate solution
Protein present = changes to purple/lilac
Protein absent = stays blue
How do you use a colorimeter?
Shining light through a sample
Put supernatant in curvette
Use coloured filter red
Percentage transmission
How do you use a calibration curve?
Do Benedicts on know concentrations of sugar
Find percentage transmission
Plot curve
Find Unknown samples to find original sample
Describe biosensors
devices that use biological molecules to detect chemicals which are converted into electrical signals by transducers
How to see animo acids on chromatography
Spray with ninhydrin
Binds to amino acids
Brown or purple spots
What to do if chromatography is colourless?
UV light
Ninhydrin
Iodine crystals that form a gas
How does chromatography work?
exposed OH make it very polar and allow hydrogen bonds to form with the molecules
Highly polar the reform moves more slowly
What to do in chromatography if solvents travel at the same speed?
Different solvent
Change pH
Define condensation reaction
reaction that occurs when two molecules are joined together with the removal of water
Define hydrogen bond
a weak interaction that can occur wherever molecules contain a slightly negatively charged atom bonded to a slightly positively charged hydrogen atom
Define hydrolysis reaction
reaction that occurs when a molecule is split into two smaller molecules with the addition of water
Define monomer
a small molecule which binds to many other identical molecules to form a polymer
Define polymer
A large molecule made from many smaller molecules called monomers
List of properties of water
- Liquid at room temp
- density
- solvent
- cohesion and surface tension
- high specific heat capacity
- high latent heat of vaporisation
- reactant
Why is density of water important?
aquatic organisms stable environment in winter
insulation against extreme cold
Why is it important that a water can act as a solvent?
- medium for metabolic reactions
- allows ionic compounds to separate
- transport (eg transpiration pathways and tissue fluid)
- ability to dilute toxic substances
Why is surface tension good?
Insects walk on water and water can go up xylem
Why is high specific heat capacity of water good?
water does not heat up or cool down easily
stable temp in body and habitats
Why is high latent heat of vaporisation good?
a lot of energy needed to evaporate
sweating
Define glycosidic bond
bond formed between two monosaccharides by a hydrolysis reaction
Does alpha glucose have same or opposite?
same
What polysaccharide is a storage molecule in animals?
glycogen
What polysaccharide is a storage molecule in plant?
Amylose and amylopectin
Difference between amylose and amylopectin?
amylopectin has branches between carbons 1 and 6 as eel as glycosidic bonds between carbons 1 and 4
What type of glucoses makes amylose amylopectin and glycogen?
alpha glucose
What type of glucose is cellulose made from?
beta glucose
How do the properties of cellulose relate to its function?
- high tensile strength to support the plant
- there is space between macrofibrils for water and mineral ions to pass
- structure can be reinforced
Define lipids
a group of substances that are soluble in alcohol rather than water. They include triglycerides, phospholipids and cholesterol
Define macromolecule
A very large, organic molecule
Define phospholipid
molecules consisting of glycerol, two fatty acids and one phosphate group
Examples of macromolecules
triglyceride
phospholipid
Functions of triglycerides
energy source - broken down for ATP energy store (insoluble in water and so can be stored without affecting the water potential of the cell) insulation buoyancy protection (around organs)
Properties of cholesterol
small and hydrophobic, prevents cell from becoming too fluid
Define peptide bond
a bond formed when two amino acids are joined by a condensation reaction .
Which amino acid has an R group with sulphur in it?
cysteine, strong covalent bonds
Define fibrous protein
- has a relatively long, thin structure
- is insoluble in water and metabolically inactive
- often having a structural role within an organism
Define globular protein
- has molecules of a relatively spherical shape
- which are soluble in water
- have metabollic roles within an organism
Define prosthetic group
a non-protein component that forms a permanent part of a functioning protein molecule
Structure of haemoglobin
two alpha-globin chains and two beta-globin chains
each chain has haem prosthetic group
Structure of pepsin
Enzyme that digests protein
single polypeptide chain of 327 amino acids
very few amino acids with basic R groups but a lot with acidic
What type of protein are most enzymes?
globular
Properties and functions of collagen
- providing mechanical strength
- tough
- insoluble
Properties and functions of keratin
- parts of the body that need to be hard and strong
- mechanical protection
- impermeable barrier to infection
- waterproof
Properties and functions of elastin
Where things need to stretch their shape
eg skin can stretch around bones
Examples of reducing sugars
glucose maltose lactose
How much benedicts reagent do you add?
always EXCESS
What do different colours of benedicts test indicate?
Different concentrations of sugar
Describe iodine test for starch
add iodine dissolved in potassium iodide
if starch is present, goes from orange brown to blue black
Describe glucose biosensors
used to determine conc of glucose
uses the enzyme glucose oxidase and electrodes
the oxidation of glucose at the electrodes creates an electrical signal
Whats chromatography used to separate?
proteins, carbohydrates, vitamins or nucleic acids
properties of cellulose that make it suitable for cell walls
- high tensile strength
- H bonds between adjacent fibrils
- insoluble
Functions of cholesterol
Regulating fluidity of membranes Converted to steroid Waterproofing skin Making vitamin d Making bile
Why is glycogen a good storage molecule?
Insoluble Doesn’t affect water potential of cell Can be broken down and built up quickly Lots of branches for enzymes to attach Compact High energy content for mass
What makes a glucose molecule suitable?
- soluble for easy transport
- small molecule goes across membranes
- easily broken down
- join to produce polysaccharides
How is the tertiary structure of proteins affected by increases in temperature?
- increased kinetic energy
- molecule vibrates
- hydrophobic/hydrophilic/hydrogen/ionic bonds break
- change in 3D shape
- denatures
Properties of collagen
strong
flexible
not elastic
insoluble
Structural similarities between maltose and lactose
- both have 2 6-membered rings
- both have 1-4 glycosidic bonds
- both have 2 CH2OH groups
- both have rings that contain oxygen
Are all monosaccharides reducing or non-reducing sugars?
reducing
Examples of monosaccharides
galactose, glucose, fructose, ribose, and maltose
Example of non reducing sugar
sucrose
Is maltose monosaccharide or disaccharide?
di
Is sucrose a monosaccharide or a disaccharide?
di
