Water is made up of 2 hydrogen atoms and one oxygen atom.
The oxygen part of water has a slighly negative charge, whereas the hydrogen has a slightly positive charge. This causes the a covalent bond to form between the oxgen and the two hydrogens to make a water molecule.
These charges also mean that water is a polar molecule.
Since water is polar, it binds to other water molecules - hydrogen bonds form between the oxygen atom of one molecule, and one hydrogen atom of another water molecule.
A monomer is a small repeating molecule.
A polymer is a large molecule made from many monomers joined together.
For example, an amino acid is a monomer, but when many amino acids are joined together, they made the polymer protein.
A condensation reaction forms polymers by joining monomers together, forming covalent bonds and releasing water in the process.
Hydrolysis breaks the bonds in polymers, using water.
Carbohydrates are made up of Carbon, Hydrogen and Oxygen.
Sugars are an example of a carbohydrate.
A monosaccharide refers to a single sugar molecule.
A hexose monosaccharide is a sugar that has 6 carbons.
A pentose monosaccharide is a sugar that has 5 carbons.
Glucose is an example of a hexose monosaccharide.
Glucose has the chemical formula C6H12O6.
An isomer is a molecule that contains the exact same chemical formul, but arranges its atoms in a differnt way.
Glucose has two isomers: alpha and beta.
In alpha glucose, the -OH group on carbon 1 points down.
In beta glucose, the -OH group on carbon 1 points up.
Ribose is an example of a pentose monosaccharide.
Ribose has the chemical formula C5H10O5.
Ribose is found in RNA and ATP.
A disaccharide refers to two monosaccharides that are joined together.
A polysaccharide refers to many monosaccharides that are joined together.
When monosaccharides join to form a disaccharide or a polysaccharide, in a condensation reaction, glycocidic bonds form between the monosaccharides.
Glycocidic bonds are broken by hydrolysis.
Examples of disaccharides:
Maltose = glucose + glucose
Sucrose = glucose + fructose
Lactose = glucose + galactose
Examples of polysaccharides:
Amylose
Amylopectin
Glycogen
Cellulose
Amylose, amylopectin and glycogen are all made up of alpha glucose whereas cellulose is made up of beta glucose.
Amylose and cellulose are unbranched chains, whereas amylopectin and glycogen are branched chains.
They all have 1,4 glycocidic bonds, 1,6 glycocidic bonds are present at the branch points for amylopectin and glycogen.
Amylose forms a helix.
Glycogen is compact and can be rapidly hydrolysed for energy release.
Cellulose forms hydrogen bonds between its chains, making it very strong.
Properties of carbohydrates:
Glucose is small and soluble which means it is easiy transported and used in respiration.
Glucose is a monosaccharide so it has a simple structure making it easy to break down for respiration.
Starch is the energy storage molecule in plants
Starch is insoluble, so it doesn't have an effect on water potential.
Starch is a large molecule, so it cannot diffuse out of cells.
Starch is compact and coiled which makes it effective for storage.
Starch is comprised of amylose and amylopectin. Amylopectin is branched, which provides a large surface area for enzymes to attach and break down glucose.
Glycogen is the energy storage molecule in animals and fungi.
Glycogen is insoluble and compact, which makes it effective for storage.
Glycogen is branched which provides a large surface area for enzymes to attach and breakdown glucose.
Cellulose is the main substance of plant cell walls.
Cellulose is comprised of straight chains, with hydorgen bonds between the molecules on the different chains.
Cellulose is insoluble and chemically stable.
Cellulose has a high tensile strength which strengthens the cell walls and prevents bursting.
Lipids are insoluble fatty compounds.
Lipids are made up of Carbon, Hydrogen, and Oxygen.
Lipids have a much lower proportion of oxygen than carbohydrates.
Examples of lipids:
Phospholipids are made of one phosphate group, two fatty acids, and glycerol.
Phospholipids are found in plasma membranes
Phospholipids have a hydrophillic phosphate head, and a hydrophobic fatty acid tail.
Triglyicerides are the most common type fat in animals.
Triglyicerides are made up of one glycerol and three fatty acids.
The glycerol and fatty acids a joined by an ester bond in a condensation reaction.
Cholesterol is found in eukaryotic cell membranes.
Cholesterol regulates the fluidity of the membrane.
Cholesterol is hydrophobic and reduces permeability to water and ions.
There are two types of fatty acids: saturated and unsaturated.
Saturated fatty acids are straight chains that don't contain any C=C double bonds.
Unsaturated fatty acids are kinked chains that contain one or more C=C double bonds.
Amino acids are the building blocks of protein.
Many amino acids joined together creates a protein.
Amino acids join in a condensation reaction that forms peptide bonds between the amino acids.
A dipeptide refers to two amino acids that are joined together.
A polypeptide refers to many amino acids that are joined together.
The structure of amino acids consists of an amino group (-NH3), a carboxyl group (-COOH), a hydrogen atom, an R group, and a central carbon atom to which all others attach to.
The R group differs between amino acids and it determines their properties.
There are four levels of protein structure: primary, secondary, tertiary, and quaternary.
The primary structure of a protein is the linear sequence of amino acids joined by peptide bonds.
The secondary structure of a protein is the folding pattern of the polypeptide backbone into beta-pleated sheets or alpha helices which are formed by hydrogen bonds between parts of the polypeptide chain.
The tertiary structure of a protein is the overall 3D shape of a polpeptide chain which forms by hydrogen, ionic, and disulfide bonds as well as hydrophobic and hydrophylic interactions between the R groups.
The quaternary structure of a protein is the of two or more polypeptide chains into a single protein complex.
There are two types of protein, globular and fibrous.
Globular proteins are soluble in water.
Globular proteins are spherical in shape.
Globular proteins have metabolic roles. Eg: transport, hormones, enzymes.
Examples of globular proteins:
Haemoglobin is a globular protein.
Haemoglobin transports oxygen in the blood.
Haemoglobin is made of four polypeptide chains (quaternary structure).
Haemoglobin is a conjugated protein meaning it has a non-protein chemical component, such as a prosthetic group.
Haemoglobin contains a haem prosthetic group with Fe2+
Insluin is a globular protein.
Insulin is a hormone that works to lower blood glucose.
Insulin is made up of two polypeptide chains.
In addition to globular proteins, the other type of proteins are fibrous proteins.
Fibrous proteins are insoluble in water.
Fibrous proteins have a long and thin shape.
Fibrous proteins have structural roles.
Examples of fibrous proteins:
Collagen is a fibrous protein.
Collagen is strong with high tensile strength.
Collagen provides strength and support.
Collagen is found in connective tissues like tendons, ligaments, skin and blood vessels.
Keratin is a fibrous protein.
Keratin is tough and waterproof.
Keratin provides protection.
Keratin is found in hair, nails, horns, antlers, hooves, beaks, claws and feathers.
Elastin is a fibrous protein.
Elastin is stretchy and elastic.
Elastin allows tissues to stretch and recoil.
Elastin is found in the skin, lungs and arteries.
Inorganic ions are charged atoms or molecules that do not contain carbon-hydrogen bonds.
In biology, they are essential for a wide range of cellular and physiological processes, including muscle contractions, nerve impulses, pH regulation, and enzyme activity.
Examples of inorganic ions:
Calcium ions (Ca2+) are essential for muscle contraction, nerve transmission, blood clotting, and bone formation.
Potassium ions (K+) are crucial for maintaining the resting membrane potential of neurons, and muscle contractions.
Sodium ions (Na+) are used in nerve impulses, co-transport, and water balance.
Hydrogen ions (H+) determine pH.
Ammonium ions (NH4+) contain a source of nitrogen for amino aid synthesis in plants.
Nitrate ions (NO3-) are used to make amino acids in plants.
Hydrogencarbonate ions (HCO3-) help to maintain blood pH and transport CO2 in the blood.
Chloride ions (Cl-) are invloved in the chloride shift to maintain charge balance.
Phosphate ions (PO43+) are found in ATP, DNA, RNA and phospholipids.
Hydroxide ions (OH-) affect pH.