1 / 52

The Chemical Basis of Life

The Chemical Basis of Life. BASIC CHEMISTRY. ATOMIC STRUCTURE NUCLEUS PROTONS – ATOMIC MASS = 1 NEUTRONS – ATOMIC MASS = 1 ELECTRONS NOT ENOUGH MASS FOR US TO CONSIDER. Atomic Structure. (-). (+). Chemical Elements.

ocean
Download Presentation

The Chemical Basis of Life

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. The Chemical Basis of Life

  2. BASIC CHEMISTRY • ATOMIC STRUCTURE • NUCLEUS • PROTONS – ATOMIC MASS = 1 • NEUTRONS – ATOMIC MASS = 1 • ELECTRONS • NOT ENOUGH MASS FOR US TO CONSIDER.

  3. Atomic Structure (-) (+)

  4. Chemical Elements • All matter on Earth is composed of combinations of chemical elements. • Elements cannot be broken down by chemical processes into simpler substances. • There are over 90 naturally-occurring chemical elements. • The most common chemical elements in living things are: • S, P, O, N, C, H

  5. Periodic Table

  6. MOLECULES and COMPOUNDS • MADE OF MORE THAN ONE KIND OF ATOM HELD TOGETHER BY A CHEMICAL BOND. • FAMILIAR ONES INCLUDE WATER, SUGAR, FAT, PROTEIN, CARBOHYDRATE, SALT.

  7. WHY DO SOME ATOMS COMBINE TO FORM COMPOUNDS AND MOLECULES? • An Atom’s ability to combine with other atoms relies on its number of electrons in its outer shell (energy level): the outer shell needs to be full for the atom to become stable (stable atoms do not combine with other atoms). • For our purposes, the first shell contains 2 electrons, and each successive shell contains up to 8 electrons.

  8. Electron Energy Levels: First energy level holds up to 2 electrons Second energy level holds up to 8 electrons Third energy level holds up to 8 electrons

  9. Stable atoms: • Some atoms already have a full outer energy level. • These atoms do not react with other atoms to form molecules. • These include the inert or noble gases: helium, argon, neon, krypton, xenon, and radon.

  10. If an atom is not stable: • It will combine with other atoms • Some will give up or gain electrons. • These form ionic bonds • Each member is an ion • The opposite electrical charges attract each other • Some will share electrons between them. • The force holding them together is called a covalent bond.

  11. Ionic Bonds NaCl = salt

  12. POLAR MOLECULES • BECAUSE OF THE WAY SOME MOLECULES COMBINE, THEY CONTAIN DIFFERENT ELECTRICAL CHARGES AT OPPOSITE ENDS. • THIS CREATES ATTRACTION TO OPPOSITE CHARGES ON OTHER MOLECULES

  13. Polar Molecules Positive end

  14. HYDROGEN BONDS • HOLD TOGETHER MOLECULES THAT CONTAIN HYDROGEN. • IMPORTANT IN WATER MOLECULES AND MANY MOLECULES IN LIVING ORGANISMS. • WEAKER THAN IONIC OR COVALENT BONDS. • THESE HOLD DNA TOGETHER

  15. CHEMICAL REACTION • ONE OR MORE SUBSTANCES IS CHANGED INTO NEW SUBSTANCES BY BREAKING OR FORMING CHEMICAL BONDS. • EX: • 6CO2 + 6H20  C6H12O6 + 6O2 • WHAT IS THE ABOVE EQUATION AND WHAT DOES IT MEAN?

  16. ALL CHEMICAL REACTIONS INVOLVE ENERGY • WHEN BONDS FORM, ENERGY IS STORED • WHEN BONDS BREAK, ENERGY IS RELEASED ATP = energy carrier of a cell

  17. ORGANIC COMPOUNDS • COMPOUNDS THAT CONTAIN CARBON, HYDROGEN AND OXYGEN IN DEFINITE PROPORTIONS. • USUALLY ASSOCIATED WITH LIVING THINGS

  18. CARBOHYDRATES • BUILDING BLOCKS = SIMPLE SUGARS (MONOSACCHARIDES). • MONOSACCHARIDES INCLUDE • GLUCOSE • FRUCTOSE ISOMERS • GALACTOSE ALL THREE HAVE THE SAME MOLECULAR FORMULA, BUT DIFFERENT STRUCTURE: C6H1206 THESE MOLECULES ARE THE MOST COMMON SOURCE OF ENERGY FOR LIVING THINGS.

  19. Isomers – can you tell the difference? glucose C6H12O6

  20. MORE COMPLEX CARBS • DISACCHARIDES • MADE UP OF TWO MONOSACCHARIDES CHEMICALLY COMBINED. • GLUCOSE + GLUCOSE = MALTOSE • GLUCOSE + GALACTOSE = LACTOSE • THIS IS MILK SUGAR • GLUCOSE + FRUCTOSE = SUCROSE • THIS IS TABLE SUGAR • These molecules store energy for later use

  21. THE MOST COMPLEX CARBS • STARCH – MADE UP OF MANY GLUCOSE UNITS COMBINED. • PLANT LONG-TERM FOOD STORAGE • GLYCOGEN – MADE OF MANY GLUCOSE UNITS COMBINED • ANIMAL STORAGE IN LIVER AND MUSCLES • CELLULOSE – MADE OF MANY GLUCOSE UNITS COMBINED. • PLANT CELL WALLS; FIBER • CHITIN – PROTECTIVE COVERINGS IN INSECTS AND OTHER ARTHROPODS; ALSO IN FUNGUS CELL WALLS

  22. DEHYDRATION SYNTHESIS • In order for two molecules to join together, each molecule must break off atoms to provide a bonding place. • Most organic molecules do this by losing a hydrogen atom from one molecule and a hydroxyl group from the other. • These two join to form water, and allow the molecules to make a bond.

  23. Dehydration Synthesis C6H12O6 + C6H12O6 C12H22O11+ H2O disaccharide

  24. Hydrolysis • In order to break down a large molecule to make smaller molecules, a molecule of water has to be added. • This fills in the spots where the bond broke – one molecule gets a hydrogen atom, the other gets the hydroxyl group.

  25. Hydrolysis ADD WATER TO A POLYSACCHARIDE AND FORM MANY MONOSACCHARIDES

  26. Dehydration Synthesis and Hydrolysis store and release energy • Dehydration synthesis stores energy by forming bonds. • As in the formation of polysaccharides from monosacharides • Hydrolysis releases energy by breaking bonds.

  27. Lipids: fats, oils, waxes, phospholipids, steroids • Used for longer-term storage of energy • Fats – in animals • Oils – in plants • Waxes – water repellent (In your ears, beeswax, coat plant leaves), waterproof bird feathers. • Steroids – in animal cell membranes and some hormones. • Phospholipids – make up parts of cell membranes

  28. A common fat = Triglyceride • Composed of one glycerol and three fatty acids, joined together by dehydration synthesis: 3 F A T T Y A C I D S G L Y C E R O L

  29. Saturated and unsaturated fats: • Saturated fats have no C=C bonds within the fatty acids • These are considered unhealthy – they clog up the coronary (heart) arteries. • These are solid at room temperature. • From animals. • Unsaturated fats have at least one C=C bond in one of its fatty acids • These are considered healthier. • Plant oils are usually unsaturated. • Liquid at room temperature.

  30. PROTEINS • Important for movement, structure, regulation, transport, nutrition, and defense. • Composed of building blocks called amino acids • Humans cannot make these from scratch – we must eat foods with proteins, then use the amino acids to make our own proteins.

  31. Amino Acids • There are 20 different aa’s • They are combined in various numbers and orders to produce a great number of different proteins. • Each aa has an amino group, an acid group (carboxyl), and a variable group (there are 20 different variable groups). • Amino acids attach to each other by dehydration synthesis forming a peptide bond between the amino group of one aa and the acid group of the other aa. • Change the number or arrangement of the aa’s and the protein ischanged.

  32. Amino acids Acid group Three different R groups: Amino group

  33. Dipeptide – two aa’s joined by a peptide bond.

  34. Polypeptide

  35. Enzymes – Special Proteins • Change the rate of chemical reactions without being used up themselves (biological catalyst). • Can be used over and over. • Action is very specific – each enzyme will only work on one particular substance (the substrate).

  36. LOCK AND KEY MODEL INDUCED FIT MODEL HOW DOES AN ENZYME WORK?

  37. Nucleic Acids • Molecules of heredity. • DNA – deoxyribonucleic acid • makes up chromosomes (GENES) • Contains the genetic code • Determines the organism’s traits • Contains the code for making proteins Which control the cell’s activities • RNA– ribonucleic acid • Helps DNA make proteins

  38. Metabolism • All the chemical reactions that take place in the organism • These reactions need to be balanced to keep the organism alive • The balance is called homeostasis

  39. Water and Solutions • H2O • Forms solutions easily – all life’s chemical reactions take place in solutions. • Solution – two or more substances are mixed together that they cannot be distinguished. • Ex- sugar + water or salt + water • Sugar or salt is the solute • Water is the solvent

  40. Salt + Water Solution:

  41. Acids and Bases • Form when an ionic compound is mixed with water to form a solution. • Acid – releases H+ (hydrogen) ions (like HCl = hydrochloric acid) • Base – releases OH- (hydroxide) ions (like NaOH = sodium hydroxide)

  42. pH scale • Standard measurement of the H+ ions in a solution • Ranges from 0 – 14 • 7 is neutral • Water has an equal number of H+ and OH- ions, so there is no excess of either ion.

  43. pH scale • Acids are less than 7 • Bases are more than 7 • The further away from 7, the stronger the acid or base • Most chemical reactions in humans take place between 6+8 • However, stomach acid is 2-3 • Enzymes are pH specific

  44. the end

More Related