Skip main navigation

Week 3 Overview 1

Watch John Cohen introduce week three
Welcome to Week 3! Time to go seriously cellular and molecular. Most human cells are in the range of 5 to 20 micrometers across, so we have to use special technology to see what they look like. There are all sorts of amazing new microscopes; we’ll see the results they get this week, and then in Course 2
of this Program.We try to define life: Whatever it is, it can’t exist below -50C, where the water in cells turns into a glass, or above 140C, where DNA spontaneously falls apart. Along the way we’ll meet a greedy amoeba who bites off more than it can chew. When biologists became able to look at the anatomy of cells, they found they had their own internal structures, called organelles–little organs. The cell even has a skeleton (and since cyto- means cell, it’s called the cytoskeleton.) The cell’s membrane keeps the good stuff in and the bad stuff out, but we have channels and pumps in the membrane to get the right things where they need to be.
Add a nucleus and protein-making factories and we have a tiny space that’s crammed full of goodies! Proteins are long polymers made up of about 20 different building blocks called amino acids–here’s a protein now!–each of which has different chemical properties, so a typical protein with about 200 amino acids in its chain
can do a very specific job: Hemoglobin carries oxygen, myosin contracts muscles, and so on.
Enzymes are the spice of life (or I think I mean splice?): all sorts of chemical reactions go on in the body, which wouldn’t work in the absence of these excellent catalysts. Molecular biology–transcription, translation… is it impossible to understand? Not with the power of analogy! DNA is the precious book that the library won’t lend, but RNA is the photocopy they allow us to make. And proteins are the useful machines we build, reading our photocopied RNA instructions. And we begin to find out why scientists made such a fuss when it was found that DNA comes in the form of a double helix.

Overview of the first 4 activities in your last week of MiniMed Course 1: Life and the Size of Things, Cell anatomy, Proteins, and DNA-RNA-Protein.

This article is from the free online

Mini Medical School: Introduction to Medical Science

Created by
FutureLearn - Learning For Life

Our purpose is to transform access to education.

We offer a diverse selection of courses from leading universities and cultural institutions from around the world. These are delivered one step at a time, and are accessible on mobile, tablet and desktop, so you can fit learning around your life.

We believe learning should be an enjoyable, social experience, so our courses offer the opportunity to discuss what you’re learning with others as you go, helping you make fresh discoveries and form new ideas.
You can unlock new opportunities with unlimited access to hundreds of online short courses for a year by subscribing to our Unlimited package. Build your knowledge with top universities and organisations.

Learn more about how FutureLearn is transforming access to education