BOT01 Lecture 1 PDF

9/18/24 Grading System The minimum requirement for a pas...

9/18/24 Grading System The minimum requirement for a passing grade is 60% of the total scores from the following: Performance Task Attendance, Assignments, Seatwork, Research / Critique Paper…….... 40% THE CHEMICAL COMPOSITION OF CELLS Recitation/Class Participation ………………………………………..…….…..... 15% Major Examination……………………………………………………...…...….… 30% Quizzes …………………..…………………………………….…….……………. 15% Total ………………….………………………………...…………………..…….… 100% BOT01 Lecture 1 JALindo 1 2 Cells are made from a few types of atoms The structure of atoms o Protons, neutrons, electrons etc. THE CHEMICAL COMPOSITION OF CELLS Atomic weight Mole Cells are made of only a small selection of these elements. BOT01 Lecture 1 JALindo 3 4 5 6 1  9/18/24 How atoms interact: atomic bonds Electrons are in continuous motion around the nucleus, following rules of quantum physics. o They occupy discrete states: electron shell An atom whose outermost shell is entirely filled with electrons is especially stable and therefore chemically unreactive. o Inert gases: Helium (2 electrons), neon (2 + 8), and argon (2 + 8 + 8) o Hydrogen: only one electron and only a half-filled shell, is highly reactive 7 8 Chemical bonds: covalent and ionic Ionic bonds formed between ions of opposite charges involve transfer of electron 9 10 Chemical bonds: covalent and ionic Polar Covalent / Non-polar Covalent / H Bonds Non-polar Covalent When covalently bonded atoms share electrons equally Covalent bonds Ex: CO2 atoms share electrons Polar Covalent more stable than ionic bond Electrons are shared unequally between atoms, creating a polar molecule Ex: H2O Hydrogen Bonds weak bonds important in the chemistry of life charged regions on water molecules are attracted to the oppositely charged regions on nearby molecules Ex: water to water (cohesion) 11 12 2  9/18/24 Non-covalent interactions help bring molecules together in cells Hydrogen bonds van der Waals attractions 13 14 Cells contain four major families of small organic Carbohydrates: Monomer = Monosaccharide molecules Carbohydrates provide an energy source for cells and are the Contain C, H, and O in a 1:2:1 ratio subunits of polysaccharides o sugar, starch, cellulose Most end with “ose” Lipids are components of cell membranes An animal’s main energy source o wax, fats, oil, steroids Carbs are burned first in the body Amino acids are the subunits of proteins o enzymes, hormones, muscles Nucleotides are the subunits of DNA and RNA. 15 16 Carbohydrates Monosaccharides: (C6H12O 6) Disaccharides: (C12H22O 11) glucose, fructose, galactose sucrose, lactose, maltose Disaccharides 17 18 3  9/18/24 glucose monomers connected by 1-4 linkages. Carbohydrates Polysaccharides: (complex carbohydrates) a. glycogen (carb storage animal liver) b. starch (carb storage in plants) c. cellulose (cell walls, cotton) “roughage” Structural d. chitin (exoskeletons of arthropods) polysaccharides monomers are connected by 1-4 linkages, additional 1-6 linkages occur periodically and result in branch points 19 20 Lipids: Monomer = Fatty Acids Mostly C and H atoms linked by nonpolar covalent bonds Reserve energy-storage molecules (burned after carbs are gone) Insoluble in water (polar) Soluble in nonpolar solvents (ether) More energy in lipids than in carbs 9 cal/g Lipid vs. 4 cal/g Carb Examples: triglycerides, phospholipids, steroids (cholesterol), waxes, oils, fats 21 22 Lipids: Monomer = Fatty Acids Triglyceride 3 fatty acids + 1 glycerol Saturated Fats all single bonds in chain solid at room temp (ex: butter, lard) Unsaturated fats one or more C=C bond in chain liquid at room temp (ex: all oils) 23 24 4  9/18/24 Proteins: Monomer = Amino Acid Proteins: Monomer = Amino Acid examples of groups of proteins: Essential to the structures and activities of life 1. enzymes (amylase, sucrase, maltase, lactase) –ase ending Contain C, H, O, N (S, P) 2. structural (collagen, elastin) 3. contractile (actin, myosin) 50% of your dry weight 4. transport (hemoglobin, protein channels) 5. hormones (insulin) 25 26 Amino Acids Each amino acid has: An amino group (-NH2) A carboxyl group (COOH) An R group, which distinguishes each of the 20 different amino acids Each amino acid has specific properties based on the R-group Peptide bonds link amino acids together à polypeptide (protein) 27 28 “sickled” cells Primary structure Primary structure 29 30 5  9/18/24 overall three-dimensional structure of a polypeptide Tertiary structure 31 32 33 34 6