Biochemistry Chapter 2 1

Atoms and their interactions 2

Elements Substances that cannot be broken down into simpler chemical substances 92 naturally occurring  25 essential to life 3

4

5

Carbon (C), hydrogen (H), oxygen (O), and nitrogen (N)  96% of human body Trace elements  present in small amounts Iron, magnesium, iodine 6

7

Atoms Smallest particle of an element that has the characteristics of that element Nucleus  central portion Protons  positive charge Neutrons  no charge 8

Atoms cont. Electron cloud surrounds the nucleus Negative charge Travel in energy levels 1 st level  2e- 2 nd level  8e- 3 rd level  8e- (18e- total) Most atoms have equal numbers of protons and electrons  no net charge 9

10

Isotopes Atoms of the same element containing different numbers of neutrons Effects mass only (not charge) Some are unstable  radioactive 11

Carbon 12  6p and 6n Carbon 14  6 p and 8n 12

Compounds and bonding 13

Compound Composed of atoms of 2 or more different elements that are chemically combined Water  H 2 O Bonding occurs between atoms to reach stability Stability = outermost energy level is full 14

Covalent bonding  sharing e- H 2 O: O  6e- in 2 nd level H  1e- in 1 st level Most compounds in living organisms have covalent bonds  strong 15

Hydrogen gas covalent bond 16

17

Ionic bonding  gaining or losing e- Produces ions  charged particles NaCl: Na  1e- in 3 rd level Cl  7e- in 3 rd level 18

19

How an ionic bond forms 20

Chemical reactions Breaking and forming bonds Atoms are rearranged to form new substances Metabolism  all the chemical reactions in an organism 21

Chemical reactions cont. Represented by chemical equations 2H 2 + O 2  2H 2 O 2H 2 + O 2 are the reactants 2H 2 O is the product The numbers of each atom must be = on each side of the equation 22

Mixtures and solutions 23

Mixture Combination of substances that each retain their own properties Can easily be separated Salt and iron 24

Solution 1 or more substances (solutes) are distributed equally in another (solvent) Cannot easily be separated Kool-Aid  sugar dissolved in water 25

Acids and bases The pH scale 26

27

Water and diffusion 28

The importance of water Essential for most life processes Universal solvent Means of transport 29

Polarity  unequal distribution of charge e- not shared equally  positive and negative ends to a molecule Polar molecules attract other polar molecules and ions (opposites attract) 30

Polarity continued Form weak hydrogen bonds 31

Cohesion  water molecules stick together 32

Surface Tension 33

Adhesion  water sticks to other molecules 34

Capillary action  water creeps up thin tubes 35

Water resists temperature changes Requires a lot of heat to increase water temperature Insulator  helps maintain homeostasis Expands when freezes  ice is less dense than water and floats 36

37

Diffusion Movement of particles from an area of high concentration to an area of lower concentration 38

Diffusion continued Due to random movement of all molecules  slow Continues until equilibrium is reached  equal concentration on each side 39

40

Diffusion cont. Concentration gradient  difference in concentration No energy required to move with the gradient 41

Rate is affected by Concentration  higher concentration of molecules = faster diffusion Temperature  higher temperatures = faster diffusion Pressure  higher pressure = faster diffusion 42

Life substances 43

Role of carbon  organic compounds (C-H bonds) Can form 4 different bonds  versatile Straight chains, branched chains, rings Any number of C atoms  infinite number of structures 44

Isomer same formula, different structures C 6 H 12 O 6 45

Role of carbon cont. Polymers  long chains of repeating units 46

Polymer production Made from smaller molecules bonded together by the removal of water  dehydration synthesis Hydrolysis  breaking apart polymers by adding water 47

Opposite Reactions Dehydration SynthesisHydrolysis 48

Carbohydrates  C:H:O in a 1:2:1 ratio Used to store and release energy Monosaccharides  simple sugars Building blocks of carbs Glucose  C 6 H 12 O 6 49

Forms of glucose Linear (dry) formRing (dissolved) form 50

Disaccharides  2 monosaccharides linked together Glucose + glucose  maltose 51

Carbs cont. Polysaccharides  polymers of monosaccharides Used for food storage Starch (plants), glycogen (animals), and cellulose 52

53

Lipids  CHO Less O than carbs Used for energy storage, insulation, protection, cell membrane components 54

Nonpolar  insoluble in water Building blocks  3 fatty acids and 1 glycerol molecule Fats, oils, and waxes 55

56

Lipids cont. Saturated fats  C-C bonds are single Maximum amount of H Solid at room temperature Increase cholesterol levels  cardiovascular disease 57

A saturated fat  no C=C in tails 58

Unsaturated fats  some C-C double bonds Liquid at room temperature Plant products Hydrogenation  converting unsaturated to saturated by adding hydrogen 59

An unsaturated fat  at least 1 C=C in tails 60

Proteins  CHON Used for tissue structure and cell metabolism Building blocks  amino acids Humans need 20 different amino acids Held together by peptide bonds 61

62

Proteins cont. Number and order of amino acids determines the protein Each protein has a specific 3-D shape Shape determines function Denaturation  changing the shape of a protein impairs it’s function 63

64

Proteins cont. Enzymes  protein catalysts that change the rates of chemical reactions, but are not changed themselves Most reactions will occur without enzymes, but at a slower rate 65

Highly specific  1 enzyme per substrate Lock and key model  enzyme and substrate fit together precisely to form an enzyme-substrate complex 66

67

Factors affecting enzyme action: Concentrations of enzyme and substrate Temperature  37 o C (human body temp.) pH of environment Homeostasis must be maintained in order for enzymes to function 68

Nucleic acids  DNA and RNA Store cellular information in code form Building blocks  nucleotides 5-C sugar Nitrogenous base Phosphate group 69

DNA  deoxyribonucleic acid Double helix structure  Watson and Crick Sugar is deoxyribose Bases: cytosine, guanine, adenine, thymine 70

RNA  ribonucleic acid Single strand Sugar is ribose Bases: cytosine, guanine, adenine, uracil 71

72

73

The End!! 74