Biological Molecules

Calcium ions

Muscle contraction and nerve impulse transmission

Sodium ions

Co transport, reabsortoption of water in kidney, and nerve impulse transmission

Potassium ions

Stomata opening and nerve impulse transmission

Hydrogen ions

PH determination and catalyses reaction

Ammonium ions

Nitrogen cycle —> bacteria convert ammonium ions into nitrate ions

Nítrate ions (NO3-)

Mineral ion absorbed by plants to provide a source of nitrogen to make amino acids

Hydrogencarbonate (HCO3-)

Maintain the pH of the blood

Chloride ions CL-

Negative charge to balance positive sodium ion and potassium ions in cells

Phosphate ions (pO43-)

Formation of phospholipids for cell membranes, nuclei acid ad ATP formation

describe the bonds in water

Polar molecule due to uneven charge —> H bonds form between oxygen and hydrogen as positive and negative regions interact with eachother

Individual H bonds weak, but together are strong

The four key properties of water

Solvent in reactions

Transport medium

Coolant

Provides habitats

Describe the role of water as a solvent

Polar (hydrophilic) molecules dissolve in water as water is polar

Slight positive charge on hydrogen atoms attract negative solutes and slight negative charge on oxygen attracts positive solutes

Non polar (hydrophobic) molecules cannot dissolve in water - repelled

Describe the role of water as a transport medium

In blood, or in xylem of plants - polar substances dissolve and are transported

Cohesion = water molecule s stick together via H bonds

Water moves up xylem in plants due to transpiration, it is a continuous stream due to cohesion

Advantage = easier to draw up column than individual

Describe the role of water as a coolant

High specific heat capacity = due to energy required to break hydrogen bonds between water molecules

Advantage = Internal temp or plants / animals stay constant (enzymes dont denature reduce activity levels)

Large latent heat of vaporisation = due to energy required to break H bonds between water molecules to turn into a gas

Advantage = sígnica t cooling effect

Describe the role of water as a habitat

Water buffers temperature, provide a stable environment

Cohesion = surface tension in water, allow small insects to live on surface Away from predators

Ice is less dense than liquid water (due to hydrogen bonds) = so ice floats on top of water, provide a surface habitat for animals, and insulate water below for aquatic organisms

Define monomer and polymer

Monomer = smaller units that create larger molecules

Polymer = made from lots of monomers bonded together

Give examples of three monomers and their polymers

Glucose = starch, cellulose, glycogen

Amino acids = protein

Nucleotide = DNA and RNA

What do carbohydrates split into?

Monomers = single unit (glucose)

Diners = 2 sugars unit

Polymers = many sugar units

Structure of alpha glucose

C6H12O6

Structure of beta glucose

Carbon 1 has OH group at the top

Isomers of glucose - same molecular formula different sturtal formula

Describe ribose

Monosaccharide

Pentose sugar, has 5 carbons

Describe a disaccharide

Made of two monosaccharides

Joined by a glycosidic bond

Formed via condensation reaction

Name examples of disaccharides forming

Glucose + glucose —> maltose + water

Glucose + galactose —> lactose + water

glucose + fructose —> sucrose + water

Name the isomers to make each disaccharide

Alpha g + alpaca G = maltose

Beta g + Galactose = lactose

Alpha G + fructose = sucrose

What is a condensation reaction

Joining two molecules together, by removing water

Chemical bond is formed

What is a hydrolysis reaction?

Splitting apart of molecules through addition of water molecule

Chemical bond is broken

Descibe how condensation reactions and hydrolysis happens in disaccharides

On carbon 1 and carbon 4, water is eliminated from hydroxyl groups

1-4 glycosidic bond

Water added back too hydroxyl group for hydrolysis to make 2 monosaccharides

Describe the location of starch and its monomers

Plant cells (e.g chloroplast)

Alpha glucose

Bonds = 1,4 glycosidic bonds in amylose

1,4 and 1,6 in amylopectin

What is the function and suture of starch?

Stores glucose

Amylose = un branched helix, can compact to fit a lot of glucose in small space

Amylopectin = branched molecule, increases surface area for rapid hydrolysis back to glucose

Insoluble = doesn’t affect water potential

Descibe the location and monomers of cellulose

Location = Plants, cell wall

Monomers = beta glucose, 1-4 glycosidic bonds

Descibe the structure and function of cellulose

Structure strength for cell wall

Polymer forms long straight chains that are held in parallel by hydrogen bonds —> make fibrils

Macrofirbirls combine to make cellulose fibre

Insoluble - doesn’t affect water potential

Hydrogen bonds provide collective strength

Describe the location and monomers of glycogen

Alpha glucose

1-4 and 1-6 glycosidic bonds

Animal = muscle / liver cells

Descibe the structure and function of glycogen

Store of glucose

Highly branched molecule - increases surface area for rapid hydrolysis back to glucose

Insoluble

Define features of lipids

Macromolecules, dont make polymers

Non polar

Insoluble in water

Dissolve in organic solvents (ethanol)

Hydrophobic

Made up of fatty acids and glycerol

Describe the structure oftwo lipids: triglycerides and phospholipids

T = glycerol molecule and 3 fatty acids

P = glycerol backbone + phosphate group + 2 fatty acids

How are triglycerides made?

Formed via condensation reactions between one molecule of glycerol and three fatty acids

Ester bond formed from this (3, one for each fatty acid that bonded )

R group = fatty acids, what does it mean if they are saturated / unsaturated?

Saturated fatty acids = hydrocarbon chain has only single bonds between carbons

Unsaturated fatty acids = hydrocarbon chain has at least one double bond between carbons

Describe the properties of triglycerides

Can transfer energy = large ratio of energy storing carbon hydrogen bonds to carbon atoms

Metabolic water source = high ratio of hydrogen to oxygen atoms, because they release water if they are oxidised

Insoluble = wont affect water potential and osmosis

Low in mass = a lot can be stored in animal without preventing movement

Describe properties of phospholipids

Hydrophilic head = attract water as it is charged

Phosphate is charged, so repels other fts

Hydrophobic tail = repels with water, mixes with fats as the fatty acid chain is not charged

Descibe the phospholipid bilayer

Have 2 charged regions, so are polar

\in water they position so heads are exposed to water and tails are not

Makes up plasma membrane in cells

Describe cholesterol structure and function

Sterol = 4 carbon rings and hydroxyl group at one end, have hydrophobic and hydrophilic regions

Cholesterol embedded within cell membranes to reduce fluidity of membrane at high temperature, and increase fluidity at low temps

Draw amino acid general structure

Amine group = H N H

Carboxyl group = COOH

Hydrogen

R group - variable group

Define the four levels of structure in a protein

Primary

Secondary

Tertiary

Quaternary

Primary structure:

Order of amino acids in polypeptide chain (polymer)

Secondary structure

Sequence of amino acids cause parts of protein molecule to behind into alpha helix or beta pleated sheets

These are held by hydrogen bonds (that form between the C=O of carboxyl and H of amine group)

Tertiary structure

The secondary structure is bent and folded to form a precise 3D shape, held by:

Hydrophobic and hydrophilic interactions (weak)

Hydrogen bonds (weak)

Ionic bonds (stronger, form between R groups)

Disulfide bonds = (strong covalent bonds between R groups of amino acids that contain sulcus)

Quaternary structure + example of conjugated protein

Protein made up of more than one polypeptide chain

Example:

Haemoglobin made of four polypeptide chains

Has prosthetic group (containing iron) attached to polypeptide chain = conjugated protein, which men’s has a non protein group added rto it