1.1: Chemical elements and biological compounds

Inorganic

Ions without carbon.

Micronutrients

Needed in minute (trace) concentrations.

Macronutrients

Needed in small concentrations.

Calcium

A main constituent in bones, teeth and shells.

Chlorine

Necessary to maintain electrical neutrality across membranes.

Iron

Necessary for healthy red blood cells.

Magnesium

Essential in photosynthesis.

Nitrate

Component of enzymes, amino acids, proteins, vitamins, etc.

Phosphate

Component of DNA, RNA, ATP, phospholipids, and nucleotides.

Potassium

A factor in protein synthesis and respiration.

Sodium

Needed to maintain active transport across cell membranes, and electrical balance.

Sulphate

Forms bridges between polypeptide chains.

Dipole

A molecule with one end having a partial negative charge and the other end having a partial positive charge; a polar molecule.

Polar

A molecule with different charges.

Delta

Symbol to show partial charge.

Hydrogen bonds

Weak attraction between a hydrogen atom and another atom.

Cohesion

Water molecules stick to each other, creating strong bonds.

Solvent

A liquid substance capable of dissolving other substances.

Hydrolysis

Breaking down a compound by the chemical addition of water.

Metabolite

Involved in chemical reactions in the body.

High latent heat capacity

The term for: 'a lot of heat energy is needed to change water between states'.

High surface tension

What allows insects to float on the surface of water.

Monosaccharide

A single sugar molecule such as glucose or fructose, the simplest type of sugar.

Disaccharide

Two monosaccharide molecules that join together - table sugar.

Polysaccharides

Carbohydrates that are made up of more than two monosaccharides.

Carbohydrates

Organic compounds composed of carbon, hydrogen, and oxygen.

Isomers

Two different molecules that have the same chemical formula.

Polymer

Large compound formed from combinations of many monomers.

Glycosidic

Bond formed by a condensation reaction between two monosaccharides.

Benedicts

Test for reducing sugars, done by heating the solution and adding an equal amount of the test solution.

Qualitative

Test that analyzes for the presence or absence of substances.

Sucrose

Table sugar.

Quantitative

Test that analyzes for numerical counts such as counting the number of blood cells.

Maltose

Glucose + glucose: used in germinating seeds.

Lactose

Glucose + galactose: in mammalian milk.

Starch

A storage polysaccharide in plants consisting entirely of glucose.

Amylopectin

Branched starch.

Amylose

Unbranched starch.

Glycogen

Storage form of glucose in animals - branched.

Cellulose

Carbohydrate component of plant cell walls, forms crosslinks between other layers.

Chitin

Polysaccharide found in arthropod exoskeletons and fungal cell walls, with amino acids added.

Microfibrils

Cellulose and chitin chains linked by hydrogen bonds form these strong fibres.

Fibres

Made of microfibrils held together in bundles by hydrogen bonding.

Heteropolysaccharide

A polymer made up of more than one type of monosaccharide.

Iodine-potassium iodine

Test that analyzes for presence of starch, done by adding the test solution.

Glucose

A simple sugar that is an important source of energy.

(CH2O)n

General formula for carbohydrates.

Proteins

Contain carbon, hydrogen, oxygen and nitrogen.

N-terminal

Amino end of a polypeptide.

C-terminal

Carboxyl end of a polypeptide.

R group

A functional group that defines a particular amino acid and gives it special properties.

Zwitterion

A molecule that contains charges, but is neutral overall. Can be used to describe amino acids.

Peptide

The chemical bond that forms between the carboxyl group of one amino acid and the amino group of another amino acid.

Primary

The first level of protein structure: sequence of amino acids.

Secondary

The second level of protein structure; beta pleated sheet or alpha helix.

B-pleated sheet

Two regions of the chain lie parallel to each other and are held together by hydrogen bonds, a form of the secondary structure.

A-helix

The chain is twisted into spirals, and is held by hydrogen bonds, a form of the secondary structure.

Tertiary

The third level of protein structure; the overall, three-dimensional shape of a polypeptide due to interactions of the R groups of the amino acids making up the chain.

Disulphide

Strong bonds between amino acids with sulphur, a covalent bond.

Hydrophobic interactions

Grouping of hydrophobic molecules grouping together to avoid water.

Quaternary

The fourth level of protein structure; the shape resulting from the association of two or more polypeptide subunits.

Fibrous

Long, insoluble, structural proteins.

Collagen

Fibrous protein that gives the skin form and strength.

Globular

A type of protein that is compact, folded into spherical molecules, soluble in water.

Biuret

Test used to detect for proteins.

Purple

Colour a solution turns if positive for proteins during a biuret test.

Salt bridge

An ionic bond in a protein, holds the polypeptide chain together.

Monounsaturated

One double bond in a lipid.

Polyunsaturated

Two or more double bonds in a lipid.

Emulsion

Test for lipids, by adding alcohol and checking for a milky white emulsion.

**Brick red**

Colour a solution turns if positive for reducing sugars during a Benedict’s test.

Blue-black

Colour a solution turns if positive for starch during an iodine-potassium iodine test.

HDL

Lipoprotein made by unsaturated fat.

Triglycerides

Lipid made from one glycerol and three fatty acids, which can vary. Used in energy reserves, thermal insulation and protection from physical damage.

Phospholipids

Lipids made of one phosphate and two fatty acids, with one hydrophobic and one hydrophilic end. Used in cell membranes and electrical insulation.