Proteins are multipurpose molecules. 2006-2007

Proteins Examples muscle skin, hair, fingernails, claws pepsin insulin collagen, keratin pepsin digestive enzyme in stomach insulin hormone that controls blood sugar levels pepsin collagen (skin)

Proteins Function: many, many functions hormones movement signals from one body system to another insulin movement muscle immune system protect against germs enzymes help chemical reactions

Proteins —N— H | —C— C—OH || O Building block = – 20 different amino acid – 20 different There’s 20 of us… like 20 different letters in an alphabet! Can make lots of different words —N— H | —C— C—OH || O variable group

20 DIFFERENT AMINO ACIDS How many words are there in the English language? How many letters are there in the modern English alphabet?

APPLE 20 DIFFERENT AMINO ACIDS How many different three letter words can you make using the letters from the word above?

Proteins are similar. The order of letters determines the meaning of a word. (Example: pal vs. lap) The order of amino acids determines the type of protein and its function.

For proteins: SHAPE matters! Proteins fold & twist into 3-D shape that’s what happens in the cell! Different shapes = growth hormone hemoglobin pepsin collagen

It’s SHAPE that matters! Proteins do their jobs, because of their shape Unfolding a protein destroys its shape wrong shape = can’t do its job unfolding proteins = “denature” temperature pH (acidity) unfolded “denatured” folded

Enzymes Enzymes are proteins that ______________(speed up) biochemical reactions, which otherwise would not take place. These enzymes are essential for chemical processes like digestion and cellular metabolism. Without enzymes, most physiological processes would proceed so slowly (or not at all) that life could not exist.

What the heck does this sentence mean? Enzymes Because form determines function, each enzyme is specific to its substrates. The substrates are the reactants that undergo the chemical reaction catalyzed by the enzyme. The location where substrates bind to or interact with the enzyme is known as the active site, because that is the site where the chemistry occurs. When the substrate binds to its active site at the enzyme, the enzyme may help in its breakdown, rearrangement, or synthesis . By placing the substrate into a specific shape and microenvironment in the active site, the enzyme encourages the chemical reaction to occur. What the heck does this sentence mean?

Enzymes

Hormones Some proteins function as chemical-signaling molecules called hormones. These proteins are secreted by endocrine cells that act to control or regulate specific physiological processes, which include growth, development, metabolism, and reproduction. For example, insulin is a protein hormone that helps to regulate blood glucose levels. Other proteins act as receptors to detect the concentrations of chemicals and send signals to respond. Other hormones, such as estrogen and testosterone, are lipid steroids, not proteins.

Other protein functions Proteins perform essential functions throughout the systems of the human body. In the respiratory system, hemoglobin (composed of four protein subunits) transports oxygen for use in cellular metabolism. The proteins actin and tubulin form cellular structures , while keratin forms the structural support for the dead cells that become fingernails and hair. Antibodies help recognize and destroy foreign pathogens in the immune system. Actin and myosin allow muscles to contract, while albumin nourishes the early development of an embryo or a seedling.