Biological Molecules

Carbon, Hydrogen and oxygen. They are 'hydrated carbon' meaning for every carbon there are two hydrogen atoms and one oxygen atom.

They are three-fold. They act as a source of energy ( glucose) , a store of energy (starch and glycogen) and as structural units (cellulose)

Monosaccharides , disaccharides and polysaccharides.

They are the simplest carbohydrates, they are a source of energy. They are sugars.

Monosaccharides are soluble in water, and are insoluble non-polar solvents.

They have a backbone of single bonded carbon atoms, with one double-bonded oxygen- carbonyl group.

6 carbon atoms and exist in rings

5 carbon atoms exist in rings

3 carbon atoms and exist in straight chain

Glucose is a monosaccharide hexose sugar, they are monomers that can bond to form disaccharides and polysaccharides.

-They are when two monosaccharides join together. When they join a condensation reaction occurs to form a glycosidic bond.

• A glycosidic bond is when a water molecule is removed leaving an oxygen acting as a link between the two monosaccharides.

They are broken by hydrolysis , the addition of water. The water provides the hydroxyl group and a hydrogen , which helps the glycosidic bond to break.

maltose

sucrose

lactose

-a-glucose: energy source and component of starch and glycogen acting as energy stores -b-glucose component of cellulose for structural support in plants.

Ribose : component of ribonucleic acid (RNA) ,ATP and NAD. Chemical formula: C5H10O5

They are polymers of monosaccharides

-Joining lots of glucose molecules together into polysaccharides can create a store of energy. -Examples of energy stores: starch in plants in chloroplast. Glycogen in cells of liver and muscle cells.

Amylose and amylopectin

-They have a larger size,the amylose may form a double helix structure which is hydrophobic. -Furthermore, if many water molecules did dissolve in cytoplasm , the water potential would decrease and excess water would diffuse in.

-Amylose (plants)- forms long chains of a-glucose and have glycosidic bonds between carbon 1-4. -Amylopectin (plants) - forms a-glucose with glycosidic carbon bonds 1-4. But has branches between carbon 1-6. -Glycogen (in animals) : like amylopectin , it has carbon 1-4 bonds and branches formed by glycosidic bo

It's a homopolysaccharide made from long chains made from long chains of up to 15000 b-glucose molecules bonded together through a condensation reaction to form glycosidic bonds

It's formed by the removal of water , a condensation reaction.

-Cellulose chains are straight and lie side by side. -The hydrogen and hydroxyl groups on carbon 1 are inverted compared to a-glucose -The hydrogen bond is rotated - gives additional strength and stops spiralling -Hydroxyl groups on carbon 2 sticks out , enabling hydrogen bonds to be formed between them

The microfibrils are embedded in pectins to form the wall Macrofibrils run in all directions criss-crossing the wall for extra strength

-microfibrils and Macrofibrils have very high tensile strength due to glycosidic bonds and hydrogen bonds -Microfibrils run in all directions cross-crossing the wall for extra strength -It is difficult to digest cellulose - due to its glycosidic bonds

-each cell provides strength as plants don't have a rigid skeleton -There is a space between Macrofibrils for water and mineral ions to pass into and out of the cell. Making cell fully permeable -Cell had high tensile strength , prevents cell from bursting when turgid -Macrofibril reinforced with other substances , eg lignin, makes cell wall waterproof

The cell wall is not made of cellulose but peptidoglycan, lie in parallel , cross linked by short peptide chains

-lipids contain C,H,O -They are insoluble in water as they aren't polar -They dissolve in alcohol -The three most important lipids are : triglycerides, steroids and phospholipids -They are examples of macromolecules

1 glycerol backbone with 3 fatty acid tails.

Glycerol has 3 carbon atoms. It is an alcohol so it has 3-OH , which are important to the structure of triglycerides

They have a carboxyl group (-COOH) on one end, attached to a hydrocarbon tail. The carbon chains can be up to 2-20 carbons long. The carboxyl group ionises into H+ and COO- groups. Therefore this is an acid due to free H+ ions.

-no C=C Bonds in molecule -Forms straight chains -solid at room temperature , high melting point

monounsaturated

polyunsaturated

-Forms a kink in the chain where double bond is -These kinks push the molecules apart slightly, making them more fluid. -more unsaturated fatty acids , the lower the melting point

-Condensation reaction happens between the -COOH group of fatty acids and the -OH group of the glycerol. -Due to the 3 -OH group, three fatty acids will bond. A water molecule is produced and the covalent bond, the ester bond

-Energy source - Triglycerides are broken down in respiration to release energy and generate ATP. -The ester bonds are hydrolysed and then glycerol and fatty acids can be broken down completely -Triglycerides are insoluble in water- so can be stored without affecting the water potential -Insulation - Adipose in whales (blubber), lipid in nerve cells act as an electrical insulator, animals prepare for hibernation -Buoyancy - fat is less dense than water so used by aquatic molecules to help them float Protection - protect vital organs .

-glycerol, two fatty acids, and a phosphate group -One of the three -OH groups on the glycerol forms an ester bond by a condensation reaction -2 hydrophobic tails and hydrphilic head (due to the charged phosphate making it polar)

-Testosterone, oestrogen, vitamin D are all made from cholesterol -They are small and hydrophobic so they can pass through the cell membrane and any other membrane inside the cell. -Steroid hormones are abundant in plants and in ingestion and absorption some can be converted into animal hormones.

Liver

hydrolysis reaction

Amine group (-NH2) at one end and a carboxyl (-COOH) group at the other end

H

When dissolved in water , the amine group and carboxyl group can ionise.

The amine group can accept an H+ ion to change from NH2 to NH3+ . The carboxyl group can give up an H+ ion to change from COOH to COO-

Enzymes catalyse the reaction of peptide bonds.

For example protease enzymes break peptide bonds during digestion. They also break down protein hormones so their effects are not permanent.

Dipeptides

The sequence of amino acids found in a molecule

The overall 3D shape of a protein molecule. Its shape arises due to interactions including hydrogen bonding, disulfide bridges,ionic bonds, and hydrophobic interactions

There are 20¹⁰⁰ possible ways of ordering amino acids

Secondary, tertiary and quaternary structure