2.1.2 Biological Molecules Flashcards
Water structure
H20 - Two delta positive hydrogen atoms and one delta negative oxygen atom joined by covalent bonds. Makes hydrogen bonds with other molecules of water.
Cohesion and Adhesion
Because water is slightly negative its polar (charged).
Cohesive - the attraction of molecules of the same type, water molecules form hydrogen bonds to each other, helps water to be transported up stems in the transpiration stream.
Adhesive - the attraction of molecules of one type to another, allows it to flow up the transpiration stream.
Solvent
Because water is slightly negative its polar (charged). This means that the positive end and the negative end will be attracted to different ions which will dissolve the ions. Therefore water can be used as a solvent to transport ions in the blood. Most biological reactions take place in solution.
Less dense when solid
At low temperatures water freezes, the extra H bonds when frozen increase the space between molecules. Therefore it floats as ice. This enables a habitat for animals that live on ice and insulation for fish.
High Specific Heat Capacity
The energy needed to raise the temperature of 1 gram by 1°C. H bonds absorb a lot of energy. Doesn’t undergo rapid temperature changes and so it’s a good habitat.
High Latent Heat of Evaporation
Lots of energy to break H bonds. Good for cooling, sweating cools the skin.
Carbohydrates
Made up of CHO.
Ribose
Pentose monosaccharide. C5H10O5
Alpha and Beta Glucose
Hexose monosaccharide. C6H12O6. In alpha glucose the carboxyl group points below the plane of the ring, In beta glucose the carboxyl group points above the plane of the ring.
Glucose
Soluble due to polar hydroxyl groups so can be transported. The chemical bonds contain lots of energy.
Monosaccharides to Disaccharides
Joined by condensation reactions and glycosidic bonds (removing H2O), broken by hydroxyl bonds (adding H2O).
Disaccharides
a Glucose + a Glucose = Maltose
a Glucose + Fructose = Sucrose
a/b Glucose + Galactose = Lactose
Starch
Plant store of glucose. Insoluble in water so it doesn’t cause water to enter and stays compact.
Starch Structure - Amylose
Long unbranched chain of a glucose, 1.4. Coiled and compact.
Starch Structure - Amylopectin
Long branches chain of a glucose,1.4 and 1.6. Side branches allow it to be quickly broken down for quick releases of glucose.
Glycogen
Animal store of glucose. Compact.
Glycogen Structure
Very branched, a glucose 1.4 and 1.6.
Cellulose
Plant cell wall material. Strong.
Cellulose Structure
Unbranched, b glucose 1.4. Straight cellulose chains bond by hydrogen bonds to from strong microfibrils.
Triglycerides
Store energy in plants and animals. Lots of chemical energy stored in hydrocarbon chains which is released when broken down. Insoluble so no water enters by osmosis.
Triglycerides Structure
1 glycerol, 3 fatty acid/hydrocarbon (CH) molecules. Hydrophilic tails so insoluble in water. Ester bonds join, condensation and hydrolysis.
Saturated vs Unsaturated
Saturated contain single bonds. CₙH(2 ₙ+1)COOH
Unsaturated contain double bonds.
Phospholipids
Plasma membrane. Hydrophilic head, hydrophobic tail.