So, from memory (mostly), these are the things you need to know:
Macromolecule - a whole load of the same type of molecule (a micro molecule) joined up together to form one huge molecule - lots of things in biology are this way.
Cells - The basic building-block of an organism (a living creature). Your body contains between 50 and 100 Trillion cells (src). Some organisms are a single cell - like bacteria and the amoeba. Cells start off from unspecialised cells called "stem" cells and then they differentiate into specialised cells that have a specific function like White Blood Cells or Liver cells or whatever.
Proteins - The basic building block of cells and most of what is inside your body. Proteins are long chains of a small molecules called Amino Acids all connected up. Proteins can be globular - they curl up into a ball-like lump - or they can be structural - they have an organised shape which is essential to their joint function. Most proteins are enzymes and quite a number of them only function in pairs (dimer), triplets (trimer) or quadruplets (quatromer).
Enzymes - Proteins that have a special function: to reduce the energy required for a reaction to occur. They have an active site, which is like a gap on their surface, which docks onto a target that more or less fits its shape. When on the target they reduce the strength of a bond and then some other molecule, usually water, shoots in and breaks the bond. Now the target molecule is in two halves. The breaking molecule hit the target by chance alone - there was nothing, no special force, to draw it in to carry out the reaction. Enzymes are pH and heat sensitive.
Amino Acids - AAs are a special molecule which are the building blocks of proteins. There are 20 different types of Amino Acids - you MUST learn how to draw the basic structure of an amino acid to be a biologist or a bioinformatician and it is highly recommended you learn them all off by heart - I'll help you do this in a later post. Amino Acids are called 'acids' due to their hydroxylic chemical group - CO2H. But they are really amphipathic - they have both an acidic group (polar) and a basic (alkali - non-polar) group - NH2. In the presence of a particular enzyme the basic group hooks up to the acidic group to form a peptide bond (CO-NH) in a condensation reaction (H2O is released). Lots of these reactions form a chain - protein.
DNA - DeoxyriboNucleic Acid. Although you don't need to know how to draw its chemical structure it's fun to learn this off by heart. DNA is found in the nucleus of a cell. It carries all your genetic information (your genes) - the blue print of how to make proteins - how to build a whole organism. Almost all cells in your body have a full set of DNA. DNA is a very specific shape - a double helix. If you look at a picture of DNA (here) there is a small gap between the backbone and a bigger gap. These are called the minor and major grooves. DNA is wound into bundles called Chromosomes inside the nucleus. DNA has two strands that complement each other.
Chromosomes - Humans have 23 unique chromosomes. Different animals have varying numbers of chromosomes. A chromosome is a made of proteins called histones and the DNA threads are wound up on it like string is on a reel. Most human cells have 23 pairs of chromosomes (46) - they have the same DNA on both pairs. The first 22 chromosomes of the 23 individual chromosomes are numbered 1 to 22 while the other two are called X and/or Y. X and Y look like the letters X and Y hence their name and they are "sex chromosomes" - if you have an XX pair in your body you are female and if you have an XY pair you are male. The rest of the chromosomes are called "autosomes". The XY chromosomes form an odd couple - an unusual pairing which will be talked about in a future post.
Nucleotides - these are the building blocks of DNA. They are made up of a phosphate group, a pentose sugar and a base. The backbone is formed by the phosphate and the sugar. The important part is the base. There are 4 types of nucleotide bases Adenine, Thymine, Cytosine, Guanine (A, T, C, G). A ang G are Purines and T and C are Pyrimidines (don't ask). The bases point inwards from the backbone and they pair up with the other side specifically A-T and C-G. If you have one side having the code ATTCCGGA the other side will have TAAGGCCT.
RNA - RiboNucleic Acid. A lot like DNA except without that extra oxygen on the sugar backbone and that's why RNA doesn't form a double helix. RNA forms hydrogen bonds with the DNA bases in a complementary fashion except that instead of Thymine it has another base called Uracil - so A pairs up with U. DNA is used as a template in a copying process called transcription which involves RNA, now called mRNA (messenger RNA) carrying the code. mRNA is used to make proteins in a process called translation which involves another type of RNA called tRNA (transfer RNA). More about this in another post.
For more information read a textbook or wikipedia or just google it :)
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