Module 2: Biological molecules Flashcards
Importance of water having a high latent heat of vaporisation
Large amount of energy required to change from liquid to gas. Therefore when water evaporates it can help cool living things and keep temperature stable.
Importance of water having a high specific heat capacity
Large amount if energy required to change temperature therefore:
Thermally Stable environment for aquatic organisms
Aquatic organisms use less energy on temperature control
Living things have a stable temperature for enzyme controlled reactions
Structure of glycogen
a-glucose molecules joined by 1,4 and 1,6 glycosidic bonds
Large side branches
Compact
Importance of ice being less dense than water
Aquatic organisms have stable environment to live in during water
Provides insulation for ponds against extreme cold
Starch: Structure related to function
Compact so doesn’t occupy a large amount of space
Insoluble so has no osmotic effect
Can be hydrolysed quickly
Cellulose: Structure related to function
Microfibrils and macro-fibrils have high tensile strength
Macro-fibrils criss-cross for extra strength
Insoluble
Structure and Function of Insulin
Structure:
2 polypeptide chains- A chain begins with a-helix B chain ends with b-pleated sheet
R group on the outside of molecule - makes it soluble in water
Function:
Binds to glycoprotein receptors on muscle and fat cells to increase uptake of glucose
Tertiary Structure
a-helices and b-pleated sheets along with areas of straight chains of amino acids fold further to form a 3D structure
Held together by: hydrogen bonds ionic bonds Disulfide bridges Hydrophobic and hydrophilic interactions
Importance of water having cohesion and surface tension
Collums of water in plant vascular tissue are pulled up the xylem tissue together from the roots.
Insects like pond-skaters can walk on water
Test for non-reducing sugars
Boil a sample with hydrochloric acid to hydrolyse sucrose into glucose and fructose
Cool solution and neutralise with sodium hydrogen carbonate
Test for reducing sugars again
Green,yellow orange and red indicate presence of sugar
Structure of Haemoglobin
Made of 4 polypeptides- 2 a-chains and 2 b-chains
1 haem group per polypeptide- 4 haem groups per molecule
Haem is prosthetic group which contains iron (Fe2+)
Primary structure
Sequence of amino acids in a protein chain
General structure of an amino acid
One central carbon atom bonded to: Hydrogen atom carboxyl group amino group R group
Test for lipids
Mix sample with ethanol
Filter it and pour solution into water
Cloudy white emulsion indicates presence of lipids
Importance of water being a solvent
Medium for metabolic reactions
Molecules and ions can be transported around living things
Able to dilute toxic substances
Function and properties of collagen
Provides mechanical strength:
- Artery walls prevent it from bursting
- Tendons made from collagen connects muscle to bone
- cartilage and connective tissue made from collagen
Structure of Amylopectin
a-glucose molecules joined by 1,4 glycosidic and 1,6 glycosidic bonds
Branched and coiled
Compact
Iodine test for starch
Add iodine solution to sample
If starch is present colour will change form yellow brown to blue-black
Function of phospholipid
Help form plasma membranes of cells
Form a bilayer with fatty acid stains facing into each other and polar heads facing outwards
Structure of a Triglyceride molecule
1 glycerol
3 fatty acids
bonded by ester bonds
Function of Haemoglobin
Carry oxygen from lungs to tissues
Structure and function of pepsin
Structure:
- Single polypeptide chain of 327 amino acids folded into a symmetrical tertiary structure
-Held together by hydrogen bonds and 2 disulphide bridges
Function:
Digests protein in stomach
Structure of a phospholipid molecule
1 glycerol
2 fatty acids
a phosphate group
Bonded by ester bonds
Quaternary structure
Interaction between two or more polypeptides
Secondary structure
Chain of amino acids
Some coil into a-helices some fold into b-pleated sheets
Both held together by hydrogen bonds
Bonds form between amino group and carboxyl group
Properties and function of elastin
Cross-linking and coiling make it strong and extensible
Skin can stretch around bones and muscles
allows lungs to inflate and deflate
helps bladder expand to hold urine
Structure of cellulose
long, unbranched aims of b-glucose
Joined by 1,4 glycosidic bonds
every other b-glucose molecule in chain is rotated 180º to stop spiralling
Many cellulose chains form microfibrils which form macro-fibrils
Structure of Amylose
unbranched chain of a-glucose molecules joined by 1,4 glycosidic bonds
coiled
very compact
Formation of hydrogen bonds between two water molecules and how water forms these bonds
Bond between O and H of adjacent molecules
Bond between electropositive Hydrogen and electronegative oxygen.
Water forms these bonds because it is polar
Test for reducing sugar
Add Benedict’s reagent to sample and heat in a water bath at 80ºC for 3 mins
Orange-red precipitate indicates reducing sugar is present
Function of cholesterol
Sits in the middle of hydrophobic part of bilayer to regulate fluidity of membrane so its not too fluid or stiff
Test for proteins
Add Biuret reagent
Colour changes from blue to lilac
Properties and function of keratin
Rich in cysteine so lots of disulphide bridges waterproof Found in: Finger nails Hair Claws Fur
