As we mentioned in the last article on proteins and amino acids, the shape of a protein is very important to its function. To understand how a protein gets its final shape or conformation, we need to …

The formation of a functional protein from amino acids occurs in several stages, referred to as primary, secondary, tertiary, and quaternary structures. Each stage represents a progressively complex level …

Now, any protein that's made up of a single polypeptide is only going to have primary structure, secondary structure and tertiary structure, but if we're dealing with something like hemoglobin, that's …

Thus, during expression of a protein-coding gene, information flows from DNA → RNA → protein. This directional flow of information is known as the central dogma of molecular biology.

As a protein is made, it passes step by step through a shipping "decision tree." At each stage, the protein is checked for molecular tags to see if it needs to be re-routed to a different pathway or …

A protein consists of a unique combination of amino acids drawn from this 20-member library. The amino acids that make up a protein are linked together into long linear chains, like a train made up of …

These sequences, often found close to the N- or C-terminus, can be thought of as the protein’s “train ticket” to its final destination. For more about how this works, see the article on protein targeting.

To see how cells make proteins, let's divide translation into three stages: initiation (starting off), elongation (adding on to the protein chain), and termination (finishing up).

This diagram shows a G protein-coupled receptor (GPCR), a type of receptor we'll examine in more detail later in the article. GPCRs have seven membrane-spanning domains, as shown by the seven …

The fluid mosaic model of the plasma membrane. Protein, lipid, and carbohydrate components of the membrane.