Module 2.2 Biological Molecules Flashcards
Water
Properties of water
High specific heat capacity: water acts as a buffer for temperature, so it’s acts of a habit for fish
Ice: the hydrogen bonds are frozen in place ice insulated water, acts as a habitat,
Latent heat of vaporisation: heat energy evaporated from skin for cooling mechanism like sweating
Solvent: good solvent, can be used to transport substances (blood plasma, xylem vessels)
Cohesive properties: water molecules stick together, causes surface tension acts of surface of water to act as habiats (pond skaters)
Carbohydrates
What elements are carbohydrates made up of?
give the properties of monosaccharides?
Give examples of monosaccharides
All carbohydrates contain carbon hydrogen and oxygen
Glucose is a hexose sugar
Soluble because of hydroxyl groups, small
Examples: Galactose, glucose, fructose
What is a disaccaride
Two monosaccharides joined together by a 1,4 glycosidic bond
What type of reaction produces disaccharides
Condensation reaction
Produces water
Carbohydrates
Give examples of disaccharides
Sucrose: glucose and fructose
Maltose: glucose and glucose
Lactose: glucose and galactose
Carbohydrates
What is the structure of amylose
Structure of amoylose
- polymer of alpha glucose
- joined by (1,4 glycosidic bonds)
- twists into a compact helix
- unbranched
- forms hydrogen molecules with glucose molecules along the chain
Carbohydrates
What is the structure of amylopectin
Structure
- polymer of alpha glucose
- has a branch every 25/30 glucose molecules
- forms a 1,6 glycosidic bonds
Carbohydrates
How does the structure of starch relate to its function
- compact- store a large amount of gocuose molecules for its size
- insoluble: so does not change water potential of cells
- amylopectin has many ends so it’s easier for enzymes to break starch down
70% amylose and 30% amylopectin
What is the structure of glycogen
Structure
- polymer of alpha glucose
- many branches
- has 1,4 glycosidic bonds and 1,6 bonds
How does the structure of glycogen relate to its function
Properties
- large: so it can’t diffuse into cells
- insoluble: so it can’t change water potential of cell
- many branches: enzymes can break down glycogen quicker as animals have a higher metabolic
Carbohydrates
What is the structure of cellulose
Structure
- polymer of beta glucose
- every other carbon ring is rotated 180
- forms 1,4 glycosidic bonds
- unbranched
- forms a straight chain, which allows hydrogen bonds to form between chains
- huge numbers means cellulose strong
- forms microfibrils which forms macro-fibrils
How does the function of cellulose relate to its function?
- strong due to high tensile strength provided through hydrogen bonds
- prevents cell from bursting
- impermeable to water, still doesn’t burst when contents of cell is pushing against it
What is the general structure of amino acids
Amino acids contains carbon, hydrogen, oxygen, nitrogen and sometimes sulphur
-contains an amine group and a carboxyl group
Amino acids can have different r groups
What is the difference between a polypeptide and protein
Polypeptide: a large number of amino acids joined together
-protein: polypeptide folded into a shape that can carry out a function
What are the levels of protein structure
Primary structure- a sequence of amino acids joined by a peptide bond. Helps determine final 3D shape. This is determined by DNA sequence
Secondary structure: hydrogen bonds form causing an alpha helix and beta pleated sheet
Tertiary structure: overall 3D shape of chain, folding depends on the Interactions of r groups (Hydrogne bonding, ionic bonding, hydrophilic and phobic interactions, disulphides bridges)
Quaternary structure: polypeptides interact with other polypeptide chains
What are the features of globular proteins
-spherical
-soluble in water: due to r groups that are attracted to water on their surface
Hydrophobic amino acids in centre of protein
Proteins
Haemoglobin
- made up of 4 polypeptide subunits
- two alpha and two subunits
- contains prosthetic group haem
- so it’s a conjugated protein
- when oxygen attaches to haemoglobin changes quaternary structure making it easier for other oxygen molecules to bind onto haemoglobin
Proteins
Insulin
- two polypeptide chains
- linked by disulphides bonds
- globular protein
- hormone
- shape of insulin molecule means that it complimentary to target cells
Proteins
Enzymes
- only react with specific substrates
- the active site is complimentary to the substrate
Proteins
What is the general structure of fibrous proteins
- play a structural role
- form linear chains
- insoluble in water due to hydrophobic r groups
Proteins
Collagen
- found in tendons
- strong molecule due to structure
- forms a triple helix
- joined together by cross links, these form microfibrils
- the molecule is staggered so there are no weak spots
- third amino acid is glycine which alleos collagen to wrap tightly making it strong
Keratin
Found in hair nails
Strong
Long stranded
Contains cysteine which forms disulphides brides increases strength of kertain molecules
Elastin
- Found in artery walls and skin
- long strands which are cross linked
- hydrophobic strands associate
- when stretched they remain attached to crosslinks
- making molecule stretchy
Lipids
What is the functions of lipids
- source of energy
- store energy
- cushioning around organs
- waterproofing
- electrical insulation around neurone
- thermal insulation
- can make vitamins and steroid hormones
- buoyancy
Triglycerides
Formed from 1 molecule of glycerol and 3 fatty acids
The fatty acids can be unsaturated (has a double bond)
Or saturated (no double bond)
-form an ester bond
-called estérification
-form through condensation reaction
-non polar
-large number of carbon carbon bonds means lost of energy can be released
What is the structure of a phospholipid
Structure
Glycerol molecule bonded to a phosphate and two fatty acids
Part hydrophilic and part hydrophobic
Can form a phospholipid bilayer
Cholesterol
- hydroxyl group is hydrophilic
- rest is hydrophobic
- insert it’s self in membranes
- controls fluidity
- starting point for steroid hormones like oestrogen, can pass through cell membranes
- vitamin D
- used in liver for bile
Tests for biological molecules
Starch
Process
- grind up food
- add water
- filter out water
Test for starch
- add 1 cm3 of iodine and potassium iodide
- positive result should turn blue black
Tests for biological molecules
Proteins
Process
- grind up food
- add water
- filter out water
Using filtrate
Add 3cm3 of NAOH and mix
Then add 10 drops of copper two sulfate
Detects for peptide bonds
Tests for biological molecules
Lipids
Food should not be filtered as lipids could stick to filter paper
Add 3cm3 of food soutien
Add 3cm3 of ethanol and water
If lipids of present a white cloudy emulation will form
Should not do this near a naked flame
Tests for biological molecules
Reducing and non reducing sugars
A reducing sugar can donate electrons to another molecule
Reducing sugars
- grind up food
- add water
- filter out water
- add 3cm3 of filtrate and Bénédicts to a test tube
- positive test from blue to yellow, orange, red
Benedicts test is semi quantitive, gives is an idea of amount of sugar, people can perceive colours differently
Non reducing sugars
-we need to break glycosidic bond of sucrose
-get unknown solution and add 3cm3 of HCL, then place in boiling tube for 5 minutes (hydrolyses glycosidic bonds)
-then add 3cm3 add NAOH
-check if solution is alkaline
Then do the Benedicts tests
What are the other ways of testing for biological molecules that aren’t food tests
- Colorimeter
- bio sensor
