2.1 Basic Chemistry 1

Transcription

1 2.1 Basic Chemistry 1

2 A. Introduction 1. Matter anything that takes up space and has mass 2. States of matter a. Solid b. Liquid c. Gas 2

3 B. Elements and Atoms 1. Elements basic substances that make up matter; 92 naturally occurring elements a. Four elements that make up >90% of the human body 1) Carbon (C) 2) Nitrogen (N) 3) Oxygen (O) 4) Hydrogen (H) b. Represented by a symbol containing one or two letters 3

4 Common Elements in Living Things 4

5 2. Atoms a. Smallest unit of an element that has chemical and physical properties of that element b. Smallest unit to enter into chemical reactions c. Structure 1) Central nucleus containing protons and neutrons 2) Outer shells (energy levels) containing electrons 5

6 d. Subatomic particles 1) In the nucleus a) Protons positive charge b) Neutrons no charge 2) In shells a) Electrons negative charge b) Innermost shell (1 st energy level) can have 2 electrons c) Outer shells can have up to 8 electrons d) Number of electrons in the outer-most shell determines the chemical properties of an atom 6

7 Elements and Atoms 7

8 Atoms, cont e. Atomic number 1) Number of protons in the nucleus 2) Determines the identity of the element 3) Whole, consecutive numbers on the Periodic Table f. Mass number 1) Number of protons plus the number of neutrons 2) This number is NOT found on the Periodic Table 8

9 C. Isotopes 1. Isotopes are variations of one type of atom that differ in the number of neutrons; the number of protons does not change 2. Radioactive isotopes a. Unstable isotopes that break down over time b. Releases detectable energy c. Low levels of radiation can be used as tracers, X-rays, mammograms d. High levels of radiation can be harmful to cells, but can also be useful, such as for cancer treatment and sterilizing medical and dental equipment 9

10 D. Molecules and compounds 1. Molecules form when atoms bond to each other by covalent bonds 2. Compounds form when atoms of different elements bond 10

11 3. Ionic bonds Ions form when an atom gains or loses electrons in its outer energy level to become stable 1) Positive ion has lost electrons; indicated by superscript positive sign, as in Na + or Ca 2+ 2) Negative ion has gained electrons; indicated by superscript negative sign, as in Cl or O 2-11

12 Ionic Reaction 12

13 4. Covalent bonds a. Created when atoms share electrons b. Atoms can share one or more pairs of electrons 1) Single bonds atoms share one pair of electrons; ex H 2, H-H 2) Double bonds atoms share two pairs of electrons; ex O 2, O=O 3) Triple bonds atoms share three pairs of electrons between them; N 2, N N 13

14 c. Polar and nonpolar covalent bonds 1) Polar covalent bonds result when there is an unequal sharing of electrons between atoms a) Electrons spend more time closer to one atom than the other b) Get areas of partial positive and partial negative charges c) Molecules act like little magnets 2) Nonpolar covalent bonds result from equal attraction for shared electrons 14

15 Covalent Reactions 15

16 2.2 Water, Acids, and Bases 16

17 A. Water 1. Introduction a. Most abundant molecule in living organisms; 60-70% of body weight b. An inorganic molecule (does not contain carbon atoms) c. A polar molecule 1) Oxygen has a slight negative charge (δ - ) 2) Hydrogen atoms have a slight positive charge (δ + ) 3) Attraction between slightly positive hydrogen atoms and slightly positive oxygen atom results in hydrogen bonds 17

18 Polar water molecule 18

19 Hydrogen bonding between water molecules 19

20 2. Properties of water a. Water is a solvent (liquid into which particles are dissolved) 1) Facilitates chemical reactions 2) Molecules that dissolve in water are said to be hydrophilic (water-loving) 3) Molecules that do not dissolve easily in water are said to be hydrophobic (water fearing) 4) Ionic compounds and polar molecules tend to dissolve in water 5) Nonpolar molecules do not dissolve in water 20

21 Properties of water, cont b. Water molecules are cohesive and adhesive 1) Cohesion - water molecules cling together because of hydrogen bonding 2) Adhesion - water molecules cling to other substances due to hydrogen bonds 3) Water flows freely, allowing it to distribute evenly 4) Allows for transport 21

22 Properties of water, cont c. Water has a high specific heat capacity and a high heat of vaporization 1) Specific heat capacity is the amount of energy needed to change an object s temperature by 1 C 2) Water can absorb large amounts of heat without changing its temperature 3) Heat of vaporization is the amount of energy needed to turn water into steam which allows for release of heat 4) Both processes are necessary for thermoregulation of body temperature 22

23 B. Acids and Bases 1. Acids and Bases a. When water molecules break up, an equal number of hydrogen ions (H + ) and hydroxide ions (OH - ) are released H + + OH - H 2 0 b. Acids are substances that release hydrogen ions (H + ); also called protons c. Bases are substances that release hydroxide ions (OH - ) or accept hydrogen ions (protons) d. Acids and bases can be strong or weak depending on the number of H + or OH - 23

24 Acids and Bases, cont 3. ph Scale a. Used to indicate the acidity and basicity (alkalinity) of a solution b. ph 7 is neutral (an equal number of hydrogen ions and hydroxide ions are released) c. ph above 7 is a base (more hydroxide ions are released than hydrogen ions) d. ph below 7 is an acid (more hydrogen ions are released than hydroxide ions) 24

25 ph Scale 25

26 4. ph of body fluids a. Normal ph of blood is 7.4 b. Acidosis blood ph less than 7.35 c. Alkalosis blood ph greater than 7.45 d. Blood ph needs to be maintained within a narrow range 1) Respiratory and urinary systems work to maintain ph balance 2) Buffers (chemicals that take up excess hydrogen or hydroxide ions) to prevent rapid, drastic ph changes 26

27 2.3 Molecules of Life 27

28 A. Four categories of molecules are unique to cells (called macromolecules or polymers) 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids 28

29 2.4 Carbohydrates 29

30 A. Introduction 1. Carbohydrates contain carbon, hydrogen, and oxygen 2. The ratio of hydrogen (H) atoms to oxygen (O) atoms is approximately 2:1 3. This group is made up of sugars and starches 4. Function for quick, short-term cellular energy 30

31 B. Simple Carbohydrates 1. Low number of carbon atoms (3-7) 2. Monosaccharides or simple sugars a. Glucose main carbohydrate building block b. Fructose found in fruits c. Galactose found in milk 3. Disaccharides a. Two monosaccharides joined together by dehydration reaction b. Sucrose (table sugar) glucose + fructose c. Lactose (milk sugar) glucose + galactose d. Maltose (grain sugar) glucose + glucose 31

32 Glucose and maltose Glucose, C 6 H 12 O 6 32

33 C. Complex Carbohydrates (polysaccarides) 1. Contain many glucose (monosaccharide) units 2. Starch storage form of glucose in plants 3. Glycogen storage form of glucose in animals 4. Cellulose a. Found in plant cell walls b. Humans are unable to digest (passes through digestive tract as fiber) 33

34 Starch Structure and Function 34

35 Glycogen Structure and Function 35

36 2.5 Lipids 36

37 A. Introduction 1. Contain more energy per gram than other biological molecules 2. Some function as long-term energy storage in organisms 3. Do not dissolve in water 4. Consist mostly of carbon and hydrogen atoms; contain few oxygen atoms 37

38 B. Fats and Oils 1. Also called triglycerides or neutral fats 2. Formed when one glycerol molecule reacts with three fatty acid molecules 3. Fats a. Usually of animal origin b. Solid at room temperature c. Used for long-term energy storage, insulation, and cushioning 4. Oils a. Usually of plant origin b. Liquid at room temperature 38

39 Fats and Oils, cont 5. Emulsification a. Emulsifiers are molecules with a polar end and a nonpolar end that can surround fats so they can mix with water b. Examples soaps, detergents, bile 39

40 C. Phospholipids 1. Contain a phosphate group 2. Have a hydrophilic head and hydrophobic tails 3. Form backbone of cellular membranes 40

41 D. Steroids 1. Structure consists of four fused carbon rings with attached functional groups 2. Cholesterol a. Structural component of animal cell membrane b. Precursor of several other steroids including testosterone and estradiol 41

42 Steroids 42

43 2.6 Proteins 43

44 A. Functions of proteins 1. Fibrous structural proteins collagen and keratin 2. Hormones chemical messengers; growth hormone, insulin 3. Muscle contraction actin and myosin 4. Transport - hemoglobin 5. Protection antibodies, clotting proteins 6. Enzymes globular proteins 44

45 B. Structure of proteins 1. Made of amino acid subunits a. Amino group b. Acid group c. R (Remainder) group differentiates the 20 amino acids 45

46 4. Denaturation a. The final three-dimensional shape of the protein determines its function b. If a protein loses its shape, it becomes nonfunctional c. Denaturation irreversible change in the normal shape of a protein due to extremes in heat and ph 46

47 C. Enzymatic reactions 1. Metabolism - sum of all chemical reactions that occur in a cell 2. Enzymes - protein catalysts that enable metabolic reactions at the body s normal temperature a. Named for their substrate or type of reaction b. Lower the activation energy needed to start a reaction c. The shape of the active site and its chemical composition determines specificity of enzyme d. The reactant the enzyme catalyzes is the substrate 47

48 3. Enzyme catalyzed reactions a. Enzyme and substrate(s) fit together like pieces of a puzzle b. Forms the enzyme-substrate complex c. The active site catalyzes the reaction d. The enzyme is released to be used again 48

49 Enzymatic Action 49

50 4. Cofactors and coenzymes a. Some enzymes require nonprotein components to become an active enzyme b. Cofactor inorganic metal; ex Cu, Zn, Fe c. Coenzyme organic, nonproteins molecule like the B-vitamins 50

51 D. Types of reactions 1. Synthesis Reactions a. Two or more reactants combine bonds form b. Require energy c. Dehydration is a synthesis reaction 2. Degradation (Decomposition) Reactions a. Larger, more complex molecule breaks down into smaller, simpler products b. Hydrolysis is a degradation reaction 3. Replacement (Exchange) Reactions involve both degradation and synthesis 51

52 2.7 Nucleic Acids 52

53 A. Introduction 1. Huge macromolecules composed of nucleotides 2. Nucleotides composed of 3 subunit molecules: a. A phosphate b. A pentose sugar c. A nitrogen-containing base 3. Two classes of nucleic acids a. DNA b. RNA 53

54 Nucleotide Structure 54

55 B. DNA 1. Deoxyribonucleic acid a. Contain pentose sugar deoxyribose b. Nitrogen-containing bases 1) Adenine (A) 2) Thymine (T) 3) Guanine (G) 4) Cytosine (C) 2. Usually double stranded double helix 3. Makes up the genes that contain hereditary information that determines the proteins a cell makes 55

56 DNA, cont 4. DNA is like a twisted ladder with alternating sugar phosphate on the sides and complementary nitrogenous base pairs as the rungs a. Adenine thymine b. Cytosine guanine 5. The sequence of groups of three bases codes for an amino acid 56

57 Overview of DNA structure 57

58 C. RNA 1. Ribonucleic acid a. Contain pentose sugar ribose b. The nitrogen-containing base uracil (U) replaces thymine c. Usually single stranded 2. Carries the instructions from DNA for making a protein 58

59 Comparison of DNA and RNA 59

60 D. ATP adenosine triphosphate 1. A modified nucleic acid 2. Primary energy currency of cells 3. Cells break down glucose and convert released energy into ATP and heat 4. Used when cellular reactions require energy 5. Breakdown of ATP results in one molecule of ADP (adenosine diphosphate) and one molecule of inorganic phosphate 6. ATP is rebuilt by the addition of inorganic phosphate to ADP 7. One glucose molecule can build 36 to 40 ATP molecules 60

61 Breakdown and formation of ATP 61

62 Summary of macromolecules and monomer 62