Biochemistry: Important Macromolecules in the Human Body

Type / Category
of Macromolecule:

Specific Example(s):
.

Functions:
(... for the general case unless a specific example is stated)

Carbohydrates

Glucose

Glucose stores energy.

Glycogen

Glycogen stores energy.

Ribose

Ribose is important for the expression of hereditary information.

Lipids

Triglycerides

Many fats in the diet,
e.g. Butter, Olive oil

Triglycerides store energy.

Phospholipids

Lecithin, Cephalin

Phospholipids form cell membranes.

Steroids

Corticosteroids,
e.g. cortisol, cortisone, corticosterone

Steroids form cell membranes and synthesise hormones.

Prostaglandins

There are 9 classes of prostaglandins (PGA, PGB, PGC ... PGI) and individual prostaglandins denoted by subscripts e.g. PGE₁ .)

Prostaglandins have several functions, including:

• regulating the action of hormones
• helping the immune system
• influencing inflammatory responses
• causing contraction of smooth muscle e.g. of the uterus for labour
• contributing to production of mucus in the stomach

Proteins

Functional

Functional proteins regulate chemical reactions.

Structural

Structural proteins form part of tissues that provide mechanical support to the part of the body in which they are located.

Nucleic Acids

Deoxyribonucleic acid (DNA)

DNA is the genetic code from which all protein is synthesised.
It stores genetic information and ensures daughter cells inherit data from (hence receive the characteristics of) their parent cells.
Put simply, the purpose of DNA is to code the way proteins turn genes "on" or "off".
DNA is also needed to form 'Messenger RNA' (mRNA).

Ribonucleic acid (RNA)

RNA has many functions, including:

• carrying genetic information,
• catalysing certain biochemical reactions,
• acting as an adapter molecule in protein synthesis,
• acting as a structural molecule in cellular organelles.

This could be answered in even more detail by listing specific types of RNA with their functions, e.g.

• Messenger RNA (mRNA) - transfers genetic info from DNA to ribosomes
• Transfer RNA (tRNA) - translates genetic info from DNA to specific amino acids, i.e. specific tRNA for each amino acid.
• Ribosomal RNS (rRNA) - part of ribosome, catalytic function.
• Small Nuclear RNA (snRNA) - regulates & catalyses reactions involving mRNA
• Guide RNA (gRNA) - directs editing of RNA to specific locations.

Nucleotides - and related molecules

Adenosine triphosphate (ATP)

Important role in transferring energy from "fuel" molecules to working tissues in muscle actions (contraction and relaxation): ATP --> Adenosine diphosphate (ADP) + energy + inorganic Phosphate.

Creatine phosphate (CP)

Transfers energy from fuel molecules to ATP.

Nicotinic adenine dinucleotide (NAD)

Coenzyme for transfer of high-energy particles from one chemical process to another.

Examples of Combinations of the above

Glycoproteins

e.g. galactose, mannose

Glycoproteins regulate chemical reactions (i.e. they have similar functions to those of functional proteins).

Proteoglycans

Proteoglycans are a type of (heavily glycosylated) glycoprotein.
e.g. aggrecan

Proteoglycans are important for lubrication because they can increase the thickness of fluids.

Lipoproteins

Types of lipoproteins include:
low-density lipoproteins (LDLs), high-density lipoproteins (HDLs) and very low-density lipoproteins (VLDLs).

Lipoproteins transport lipids in blood.

Glycolipids

Cerebrosides (in the myelin sheaths of nerve fibres), e.g. glucocerebrosides and galactocerebrosides.

Glycolipids are component parts of the (non-rigid) phospholipid bilayer that forms cell membranes.

Ribonucleoproteins

e.g. ribosomes, small nuclear ribonucleoproteins (snRNPs), heterogeneous nuclear ribonucleoproteins (hnRNPs), and the enzyme telomerase.

Ribonucleoproteins have many enzyme-like functions, e.g. slicing mRNA.