Science at a Distance

Biological Information

Lecture notes - Part 1 Lecture notes - Part 3

This Bio-Module requires the use of the text book " Exploring Life" by Professor John Blamire.

Lecture Notes

a check up

Use this department to check up on the accuracy of your lecture notes. Make sure that you have written down the following definitions, explanations and important concepts in your notes.

Biological Information - Part Two

The Flow of Biological Information

Biological information is read, followed and expressed in a series of well defined stages. At each stage a new type of molecule is made, or used, as the instructions are copied and interpreted.

The Genetic Code

The language of the genetic code is written as a linear sequence of nucleotide bases along a single strand of DNA.


In the cytoplasm of the cell, the mRNA encounters the machinery needed to decode the linear sequence of codons and produce the polypeptide chain. Ribosomes are where most of the decoding events take place.

Transfer RNA

Transfer RNA, or tRNA, molecules deliver the amino acids to the ribosome and are also involved in decoding the codons on the messenger RNA.

Translation: Getting started

Protein synthesis, the linking together of amino acids to form a polypeptide chain, begins with the bringing together of the components of the system.

Translation: Elongating the polypeptide

Once the intact 70S ribosome has been formed the process of creating and elongating the polypeptide can begin. This process takes the form of a cycle in which a series of actions are repeated over and over again.

Translation: The end

The elongation cycle is repeated over and over again until the ribosome complex arrives at a stop signal (stop codon) on the mRNA. This is where the polypeptide synthesis halts and the complete molecule is released.

Completing the Protein

A newly translated polypeptide is not necessarily a functioning protein. Polypeptides must be folded and often altered or modified before they can carry out their assigned roles within the cell or organism.


Mutations are alterations to the base sequence of a DNA molecule that are both permanent and inheritable. They not only alter the DNA, but if they occur in structural genes (those coding for proteins) they also cause alterations in proteins that can have serious consequences for the cell or organism.


Mutations on the DNA molecules can be brought about by a variety of agents and mechanisms.

Test Yourself with Quick Check Number BI-2025
Lecture Notes - Part 1 Lecture Notes - Part 3
Biological Information - Topic Outline

Science at a Distance
© 1997, 1998, 1999, 2000 Professor John Blamire