Introduction to Proteins in Human Cells
Basics of Amino Acids and Transcription & Translation
Mar 17, 2009
Proteins are molecules essential to living, for they tell the body’s cells how to run. Genes are the instructions for making these proteins. This process, made up of two steps called transcription and translation, is quite complex. The information in the DNA is actually moved to a similar molecule before being turned into a protein.
What are Proteins?
Proteins are molecules composed of chemical units. These units are amino acids. There are twenty standard amino acids in total, split into two groups:
- Nonessential amino acids, that the body can synthesize itself.
- Essential amino acids, that the body cannot synthesize. These are sourced from food and drink intake.
The human body is made up of trillions of cells. Individual cells in the body contain thousands of proteins, each working to keep the cell functioning. For example, proteins called antibodies help to protect the body against infection, and proteins called enzymes help ensure that food is being properly digested.
A good analogy for understanding how proteins work can be found in the Genetic Learning Centre’s What is a protein? article. It says, “You can think of proteins as part of a car engine – each part looks different, and they all do separate jobs to make the engine run”.
Making Proteins – Transcription and Translation
Transcription happens in the cell’s nucleus, when the information from the DNA is read and copied into another molecule called ribonucleic acid (RNA). RNA and DNA are very similar. RNA contains ribose (rather than deoxyribose), and a base called uracil in place of thymine. It usually has one strand, whereas DNA has two.
The type of RNA referred to in the context of transcription is called messenger RNA (mRNA). This is because it leaves the cell nucleus. Translation occurs in the cell’s cytoplasm, where a complex called a ribosome reads the information in the mRNA and assembles the protein.
Read Basic Cell Biology for Understanding Genetics to learn more about what happens inside cells. For more information on proteins, read the National Institute of General Medical Sciences website section Structures of Life, which includes details of protein structure and function.
Sources
How do genes direct the production of proteins?, Genetics Home Reference website, published: March 6th 2009, accessed: 15th March 2009, no author specified.
What is a genome?, National Center for Biotechnology Information website, accessed: 15th March 2009, no author specified.
The Structures of Life, National Institute of General Medical Sciences website, accessed: 15th March 2009, no author specified.
 |
