|
|
|
Principles of Biology - Biology 101 Lake Tahoe Community College Fall Quarter Instructor: Sue Kloss _______________________________________________________________________________________________
Chapter 5: Organic Molecules _______________________________________________________________________________________________
Molecules of life small molecules have unique properties based on the orderly arrangement of their component atoms. Inside cells, small molecules are joined together to form larger molecules - 4 types: carbs, lipids, proteins, nucleic acids. Many organic molecules are huge. For example, proteins may consist of thousands of covalently bonded atoms. Such large molecules are termed macromolecules. The architecture (weaker chemical bonds) helps explain how the molecule works.
I. Macromolecules, polymers A. linked by covalent bonds 1. monomers B. Synthesis and breakdown of polymers 1. dehydration synthesis 2. a bond forms btn 2 monomers 3. this process is repeated 4. the process occurs w/ the help of enzymes and uses energy a. enzyme 5. Hydrolysis a. digestion, for example b. then, inside the cells, dehydration synthesis occurs to assemble monomers into new molecules C. Diversity of polymers 1. 40 - 50 common monomers, and a few others 2. the key is arrangement II. Carbohydrates A. Sugars = monosaccharides 1. monosaccharides a. glucose 2. trademarks of sugar 3. sugars can be either aldose or ketoses a. C skeleton b. hexose - c. triose - d. pentose - 4. arrangements of parts around C skeleton differs 5. simple sugars are hugely imp as fuel for cellular work. a. simple sugars are also used for their C skeletons b. monosaccaharides are the monomers that form polysaccharides or disaccharides c. disaccharides B. Polysaccharides 1. storage polysaccharides a. starch b. glycogen 2. structural polysaccharides a. cellulose 1. plants 2. structure of cellulose b. chitin – arthropods, fungi III. Lipids are diverse group of hydrophobic molecules A. Fats - not polymers 1. glycerol 2. fatty acid a. carboxyl group at end b. long chain of hydrocarbons - C-H bonds are nonpolar c. 3 fatty acids join to the carbon skeleton, making a triglyceride e. if there are no double bonds btn C- f. if double bonds occur- g. cis bonds vs. trans bonds in hydrogenated products h. fat is very useful - a gram of fat stores more energy B. Phospholipids - 2 fatty acids 1. head is hydrophilic, tail is hydrophobic a. in water, phospholipids self assemble into bilayers 2. cell membranes are made of this, semipermeable C. Steroids - lipids w/ 4 fused rings 1. functional groups vary 2. cholesterol
IV. Proteins have many structures resulting in a wide range of functions Proteins acct. for 50% of dry mass of most cells, instrumental in almost everything organisms do. Enzymes are catalysts - speed chemical reactions. Humans have 10s of thousands of difft proteins, difft functions and structure. Conformation of proteins is critical. Functions of proteins: 7 or 8 A. polypeptides – 1. amino acid monomers a. amino acids = b. another functional group is variable, symbolized by R, also called side chain c. there are 20 difft amino acids used as monomers d. side chains function 2. amino acid polymers a. carboxyl group of one amino acid adjacent to amine group of the other b. peptide bonds c. chains will have a free amino group at one end, free hydroxyl group at other B. protein conformation and structure – Shape determines everything; most proteins operate by interacting w/ other molecules 1. 4 levels of structure a. primary -amino acid sequence b. secondary - segments of polypeptide chains w/ local shapes c. tertiary - d. quarternary – 2. sickle cell anemia 3. What determines conformation? a. denaturation – 4. protein folding problem - very difficult to identify how they fold a. probably several intermediate stages b. chaperonin V. Nucleic acids store and transmit hereditary information A. roles of nucleic acids 1. DNA - 2. RNA - a. DNA -->RNA-->protein B. Structure of nucleic acids 1. nucleotide monomers – a. pyrimidines - b. purine - c. ribose and deoxyribose d. carbon atoms in sugar have ' (prime) after them to 2. nucleotide polymers a. sugar phosphate backbone, with N bases spanning the backbones b. each backbone has a 5' end and a 3' end c. Adenine bonds with thymine; Guanine bonds with cytosine d. one strand can serve as a template for the other in DNA synthesis C. DNA double helix - whole form is a double helix D. DNA and proteins help measure evolution - mutation changes DNA and protein sequence on a predictable time scale
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
