Ch3.Protein structure and function

• -They are large organic molecules
• -made of C,H,N,O,and S
• -perform various functions inside cells

The theory of chemical evolution tries to explain: In early oceans, larger organic molecules were formed from small molecules, using energy from sunlight, lightning, and geothermal heat.

• -Wanted to answer: Is it possible to re-create first steps of chemical evolution by stimulation ancient Earty conditions in the lab?
• -chemical evolution occurs when simple molecules are exposed to kinetic energy.
• -He boiled water by using big sphere (earth, ocean) and a smaller sphere.
• -It was supported

• -There are 20 different amino acids in proteins. While they are different, they also share a common structure. A central carbon atom (C) is surrounded by the following:
• -­an amino group (NH2)
• ‐a carboxyl group (COOH)
• ‐a Hydrogen atom(H)
• ‐a side chain denoted as an “R”group

By the process known as polymerization. Amino acids are the monomers, many of them join to form polymers called proteins. Such reactions are called as condensation or dehydration reactions too, because water is released. The bond formed between amino acids is called as a peptide bond.

• 1.act as enzymes to catalyze biological reactions,
• 2.form antibodies to defend against diseases,
• 3.work as motors to help move things inside cells and move cells around,
• 4.participate in signaling between cells and responding to signals,
• 5.act as structural enforcements ,and
• 6.form holes in the membranes to transport molecules through membranes

• 1. Primary structure–is the order in which different amino acids are joined
• 2. Secondary structure–is how this primary chain is folded into basic shapes
• 3. Tertiary structure–is how the complete protein looks as a whole
• 4. Quaternary structure–is how may individual protein molecules work together to perform a function

biological catalysts

-lower required activation energy making reaction happen easily.

• -active sites bind to substrate molecules
• -helps break old bonds to form different new bonds
• -can change shape to fit substrate better (induced fit)

• No.
• -have cofactors like:
• 1. metal ions like Mg, Z, Ferrous, Ferric
• 2. Organic molecules, coenzymes (vitamins are coenzymes)

Sometimes, another molecule that looks like an actual substrate could enter into the active site before substrate comes in. The inhibitor molecule competes with the substrate here.

• -another molecule could bind to the enzyme at a site other than the active site, and change the shape of the enzyme. This shape change could make:
• -Active site more receptive to the substrate (allosteric activation), or
• -Active site to reject the substrate (allosteric deactivation)