Ch. 3.2 - Proteins

• polymers made from various combinations of 20 amino acids • most diverse type of biomolecule • all enzymes that catalyze reactions • each has a carboxyl group (COOH) and amino group (NH3), that tend to be ionized at cellular pH

primary, secondary, tertiary, quaternary

• building blocks of proteins • linked via dehydration synthesis between the carbon of the carboxyl group of one molecule and the amino group of another -> forms peptide bond

central carbon=alpha C is bonded to an amino group on one side, a carboxyl group on another side, a H on the 3rd side, and a functional R group on the 4th side

• only difference between the 20 a2 is the R group - can be hydrophobic (more insoluble) or hydrophilic (soluble)

• enzymes (catalyze/regulate chemical reactions) • transport (embedded molecules transport across CM) • defensive (antibodies) • signal (hormone and other chemical messengers that help coordinate activities and reactions in the body) • receptor (built into CM and help transmit and receive signals between different body cells) • contractile (muscle cells) • structural (fibrous proteins found in hair and collagen that make up connective tissue)

• involves 2+ 3D tertiary proteins and “sticking” them together to form a larger protein • many enzymes and transport proteins have 2+ parts

• becomes denatured when they lose their 3D shape and their function • denaturation can be caused by acids, salts, or heat and may be reversible

• found in nucleus • responsible for gene transfer • ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) • monomers • nucleotide

nucleotides, joined by dehydration synthesis

5C sugar (ribose or deoxyribose), PO4 group, nitrogen containing base

• DS joins the sugar of one nucleotide to the phosphate group of the next monomer • nitrogenous bases are not part of the backbone • RNA tends to be single stranded • DNA is a double stranded helix • because DNA cannot get out of the nucleus, its information is transcribed to RNA • RNA can then leave the nucleus and interact with the “protein making machinery” of the cell where DNA code is translated into proteins

• codes for everything the cell makes and does - responsible for the primary structure of proteins

• cytosine, guanine, adenine, thymine • strands are joined by H-bonds between the bases • in RNA thymine is replaced with uracil, so A pairs with U

• made from glycerol (3C alcohol) and 3 long chain fatty acids • fatty acids • function: long term energy storage • carboxyl end of one fatty acid joins with OH group of the glycerol via DS to form an ester bond

COOH and a HC chain ~16-18C (non polar)

0 double bonds = max. H = mostly animal fats, pack tightly, tend to be solid at room temp

• one or more double bonds = may be kinked, pack more loosely, tend to be liquid at room temp • cis double bond causes bending

• similar to triglycerides but only 2 HC tails and add one more PO4 group • structure very important for cell membrane structure and transport of fats in the body • sensitive to temp changes - alter membrane fluidity

• lipids with C skeleton of 4-fused rings - cholesterol is an important building block of cell membranes and steroids, including hormones, etc

• packaged for transport in lipoproteins • HDL: more protein than fat and cholesterol • LDL: more fat and cholesterol than protein (leaves more sticky cholesterol build up in arteries)