The Basics...
Proteins are the major workers in the body. They perform a variety of functions important for life. To remember these functions you can use the acronym "He's Smart".
| H | hormones | travel through blood stream to regulate body |
| E | enzymes | speed up chemical reactions |
| S | structure | proteins make up most body structures |
| S | signals | proteins such as neurotransmitters can signal other cells |
| M | movement | muscles, cilia and flagella all work via proteins |
| A | antibodies | fight infections (bacteria & virus) |
| R | receptors | receive signals (like hormones) to help direct cell activity |
| T | transport | protein channels in the cell membrane transport items in and out |
Proteins are made in cells through two processes called transcription and translation. The amino acid sequence of the proteins is coded within the DNA of the cell. In fact, this is DNA's main function - to code for proteins.
In transcription, a section of DNA, or gene, is read and a messenger RNA (mRNA) is created. This mRNA leaves the nucleus and goes to the cytoplasm.
In translation, the mRNA docks on a ribosome and a particular sequence of amino acids is strung together to make the desired protein. A typical protein is around 300 amino acids long, although they could be much shorter or much longer. The protein titin is around 34,000 amino acids long and found in muscle fibers.
Links...
Protein Molecular Modeling Activity
The Structures of Life - use this excellent book published by NIGMS to see how proteins are made, and why it is important to know about proteins and their structure.
Protein Synthesis - step through this animation to see an overview of transcription and translation in action.
Translation 1 - view this animation to see more details of translation.
Translation 2 - another quick animation of translation that is worth viewing.
- Each of the translation animations above gives details that the other leaves out. Each one is short and you should view them both.
Firefly Glow - go to this page to see how proteins make a firefly glow.
Practice Quiz - go to this site to practice answering questions about transcribing and translating DNA to proteins.
Interactive Practice - a second site to practice showing off your transcription and translation abilities by actually doing it.
Protein Denaturing - watch this video to understand how proteins denature at high temperatures.
Protein Modification
Watch this NOVA video to see a simplified but cute version of RNA interference. For a more detailed experience, see the Nature video below.
Watch this video on RNA interference from Nature.com to learn about two ways mRNA strands are destroyed before they can be translated into a protein. The video is embedded below but the original site can play full-screen and has a slideshow you can watch to learn more.