Biological molecules Flashcards
what is an isomer
They have the same number of atoms but in a different arrangement
How are polysaccharides formed
Condensation reaction of two monosaccharides
STARCH
It is polysaccharide
Amylose - Straight chain of alpha glucose with alpha 1-4 glycosidic bonds - unbranched and is wound and wound into a helix due to hydrogen bonding
Amylopectin - Branched molecule - held togather by 1-4 glycosidic bonds and every 25th glucose molecule it has a alpha 1-6 glycosidic bond.
Describe the structure of a cellulose molecule and explain how cellulose is adapted
for its function in cells.
- made from β-glucose;
- joined by condensation / removing molecule of water / glycosidic bond;
- 1 : 4 link specified or described;
- “flipping over” of alternate molecules;
- hydrogen bonds linking chains / long straight chains;
- cellulose makes cell walls strong / cellulose fibres are strong;
- can resist turgor pressure / osmotic pressure / pulling forces;
- bond difficult to break;
- resists digestion / action of microorganisms / enzymes;
GLYCOGEN
It is a storage polysaccharide
Found mostly in the muscle and the liver
Branches more frequent than amylopectin
Polymer of alpha glucose
Properties of polymer
- Insoluble in water
- Osmotically inert
- Compact
( Not sweet and not crystallisation)
Lipids
Glycerol and three fatty acids
esterification
There are saturated and unsaturated fatty acids
Phospholipids
One of the fatty acids of the triglyceride is substituted by a phosphate containing group
functions of lipids
source of energy-
Insulation - poor conductors of heat and are stored in adipose tissue
Saltore connection- Speeds it up and is found in the mylein sheeth around axon and it is an electrical
indicator
Protection- surrounds our organs
Waterproofing- wax cuticle -lipids are insoluble in water and useful for waterproofing
Structure of Triglycerides
High ratio of energy storing carbon-hydrogen bonds to carbon atoms and excellent source of energy.
Have low mass to energy ratio, good storage molecules and stored in small volume - reduced mass for animals for movement
non-polar osmotically inert
Releases water when oxidised therefore prevent desiccation
Structure of Phospholipids
bi-layer due to hydophillic and hydrophobic end
Phospholipid structure and allows glycoprotiens to form by combing with carbohydrates and glycoprotiens are v.important in cell recognition.
Protiens
General structure L-R
Amine group, carbon hydrogen with r group, carboxyl group.
If the :
R=H - glycine
R= CH3 - alanine
R= CH2SH - cysteine
dipeptide - 2 amino acid and forms a peptide bond
Lipid TEST
- Dissolve in alcohol, then add water;
2. White emulsion shows presence of lipid.
The movement of the woodlice in low relative humidity is an advantage to their survival.
Explain how.
1.Low humidity results in more woodlice moving;
So increased movement increased chance of leaving dry / unfavourable
environment so reduce water loss / reduce evaporation;
Complete the table to show two ways in which the structure of a hemicellulose
molecule differs from the structure of a cellulose molecule.
hemicellulose shorter / smaller than cellulose / fewer carbons;
hemicellulose from pentose / five-carbon sugars and cellulose from
hexose / glucose / six-carbon sugars;
