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Transcript
Matter: anything that has mass & occupies space Atoms: The basic unit of matter Protons (+) and neutrons (0) in nucleus Electrons (-) in orbits around nucleus Atomic number = number of protons Atomic mass = mass of protons + neutrons Charge: Neutral atoms: electron # = proton # Ions: # of electrons & protons differ Periodic Table Atomic number is shown for each element. Arrangement of the electrons: First shell: Can hold 2 electrons Every other shell can hold up to 8 electrons. Chemical Bonds : How elements “hook up” with eachother a. Covalent bond: two atoms share one or more pairs of valence electrons Example: diatomic hydrogen These atoms are sharing! b. Ionic bond: atoms donate or receive electrons from other atoms Example: sodium chloride Sodium needs to lose an electron, and chlorine needs to gain one these two atoms are a very compatible pair! There is no sharing of electrons, sodium gives away one electron to chlorine. However, this introduces something new. Sodium now has 11 protons, but only 10 electrons (because it has given one away). Chlorine has 17 protons, but now has 18 electrons (as it has taken an extra one from Sodium). The effect of this is easy to calculate - it leaves the atoms with a charge - they are no longer neutral. The Na+ (Sodium) with one more positive proton than negative electrons is positively charged, and the Cl- (Chlorine) with one extra negative electron is negatively charged. However as a pair, they are still neutral (the sodium is "+1" and the chlorine is "-1"). Any atom that carries a charge is called an ION and ions can be positive or negative. The ions in this example would be written as Na+ and Cl-.. They are bonded by ionic attraction. This type of bonding, where atoms give away or accept electrons to form a pair of charged ions, is called IONIC bonding. http://chemistry.about.com/library/weekly/blatomquiz.htm http://chemistry.about.com/library/weekly/blatomquiz.htm Elements Cannot be decomposed into simpler substances (by any chemical reaction). Are made up of only one kind of atom (i.e. atoms having the same atomic number). Compounds Can be decomposed into its elements by chemical means only. Are made up of two or more elements EX. H2O Vocabulary • • • • • Organic compounds Acids Carbohydrates Lipids Proteins • • • • • Nucleic Acids Monosaccaride Polysaccharide Glycogen Dehydration Synthesis ACID: A solution that has an excess of H+ ions. It comes from the Latin word "acidus" which means "sharp". BASE: A solution that has an excess of OH- ions. Another word for base is ALKALI. NEUTRAL: A solution which has a pH of 7. It is neither acidic nor basic. That pH scale we talked about is actually a measure of the number of H+ ions in a solution. If there are a lot of H+ ions, the pH is very low. If there are a lot of OH- ions, that means the number of H+ ions is very low, so the pH is high. pH Scale: Acids have pH values under 7 Bases have pH values over 7 What is the pH of normal rain? Normal rain has a pH of about 5.6. It is slightly acidic because naturally present carbon dioxide from the Earth's atmosphere dissolves in the rain drops to form carbonic acid. pH Testing: Use pH paper to test the following substances. Predict which household products (ammonia, vinegar, lemon juice, tap water, snapple,) would fall on the pH scale. Procedure: 1. Pipette a 5 mL of the flavin extract from the red cabbage in each test tube 2. Take a dropper of each sample to be tested and place it in the test tubes ONE AT A TIME. 3. Record your color change and indicate the pH number associated with it. 4. Take the pH paper and dip it into each sample to test. 5. Observe the color. Match it with the scale provided on the tube. iNOrganiC • Substances can contain either carbon or hydrogen, but NOT TOGETHER • Examples: H2O, CO2, vitamins, minerals There are 6 elements critical in the survival of living organisms: 1. 2. 3. 4. 5. 6. CARBON (C) HYDROGEN (H) OXYGEN (O) NITROGEN (N) PHOSPHOROUS (P) SULFUR (S) These elements combine to form key organic compounds critical to living organisms. Organic compounds: Carbon based and contain Hydrogen at the same time. 4 groups of organic compounds which are critical: 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic Acids What is the biological importance of organic compounds? Carbohydrates • Organic compounds,Contain C, H, O arranged in a ring. Ex: sugars and starches • Primary source of energy • Can be single units of C6H12O6- called monosaccharides or chains of these units called Polysaccharides. • Anything ending in “ose” is a sugar • Ex: fructose, sucrose, glucose, galacatose • Cellulose- common starch made by plants • Glycogen- common starch made by animals Structural Formula of Glucose: C6H12O6 CH OH H C C H OH H C C C H H OH HO O OH Starch is many repeating units of monosaccharides. Sources of Carbs • Sugars are found in honey, fruit (both fresh and dried) soft drinks, milk and sugar. • Starches are found in cereals, pasta, flour, bread, potatoes, root and pulse vegetables. • Cellulose or Dietary Fiber is found in whole cereals, whole meal bread, outer skins of fruit and vegetables, brown rice and oatmeal How do these units “get together” when there isn’t any “space” for a bond to be formed? Construct a glucose molecule and examine its bonds. See if you can devise a way to connect 2 monosaccharides. Do you have anything left over? Dehydration Synthesis: Loss of water Act of creating By releasing one water molecule, 2 sugars can be added together for form a larger molecule. Hydrolysis: The insertion of a water molecule to split apart a molecule. The Pros and Cons of Lipids: •Extremely large molecules •Release lots of energy when broken down •Used for long term food storage •Used as an insulator •Used to cushion vital organs •Waterproof covering of fruits and leaves •Incorporated into structures like the cell membrane Structure of lipid(fats, oils, waxes) 3 fatty acids Consist of long chains of carbons 1 glycerol molecule acts as a backbone Lipids in Cell Membrane Saturated versus Unsaturated fats A saturated fat is a fat or fatty acid in which there are no double bonds between the carbon atoms of the fatty acid chain. Saturated fats tend to be solid at room temperature •Diets high in saturated fat correlate in some studies with an increased incidence of atherosclerosis and coronary heart disease •Saturated fat is found in dairy products, especially cream and cheese and in meat as well as in many prepared foods. Clogged Artery Unsaturated Fats: They are called unsaturated because they could hold more hydrogen atoms than they do. Unsaturated Fats • Come mainly from plant and fish sources such as peas, beans, and lentils, whole cereals, nuts, cooking oils, margarine, and oily fish • These fats are better for you Protein: Structure and function •Contain C,H,O,N •Most abundant organic compound •Made from different assortments of amino acids •Below is a single amino acid H H N C O C OH H R R is a radical group that changes with every different amino acid. Function of Proteins: •Transporters in the cell membrane •Major component of muscle cells •Hormones : control growth and development •Antibodies: function in immunity •Enzymes: Control reactions Proteins in Cell Membrane Sources of Proteins • High Biological Value Proteins come mainly from animal foods such as meat, fish, eggs, cheese and milk. However some plant foods provide this type of protein e.g. soy bean. • Low Biological Value Proteins come mainly from plant foods such as peas, beans and lentils (pulse vegetables), whole cereals and nuts. These foods also contain fiber and are low in fat. Levels of Protein Structure “Structural features of proteins are usually described at four levels of complexity: Primary Structure: the linear arrangEment of amino acids in a protein and the location of covalent bonds between amino acids. Secondary Structure: areas of folding or coiling within a protein; helix or a sheet. Tertiary Structure: the final three-dimensional structure of a protein, which results from a large number of non-covalent interactions between amino acids A PROTEIN’S FUNCTION IS DETERMINED BY ITS SHAPE!! Nucleic Acids • Organic compounds • Ex: DNA, RNA • Deoxyribose Nucleic Acid • Found in EVERY living cell • Function: Store hereditary information What are Nucleotides? • DNA is a long chain made up of nucleotides • Nucleotides consist of: 1. Deoxyribose (a sugar) 2. Phosphoric Acid 3. Nitrogen (organic) Base What are the Nitrogen Bases? • There are 2 types of Nitrogen Bases: 1. Purines - Large • Adenine (A) • Guanine (G) 2. Pyrimidines - small • Thymine (T) (DNA) • Cytosine (C) (DNA) • Uracil (U) (RNA) Base Pairing • In a DNA double helix, one strand is made up of a purine (either A or G) • The other strand is made up of a pyrimidine (T or C) • When the 2 separate strands are bonded together, A bonds with T • And G bonds with C • Think: AT Garden City • RNA is different (instead of A bonding with T, it bonds with U) DNA Double Strand • Notice that the sugar and the phosphate are on the outside of the helix and the base pairs are parallel to each other and on the inside of the helix • The 2 strands are held together by hydrogen bonds Enzymes: Enzymes are the organizers and orchestrators of all chemical reactions. Their presence determines how fast a reaction will occur and under what conditions a reaction will occur. Characteristics of an enzyme: 1. They are proteins which have a definite shape which determines who they will link up with. 2. Enzymes link up with specific molecules called substrate. (the material acted upon by enzymes) The substrate molecules are smaller than the enzyme & fit into specific places on the surface called active sites. Enzyme-substrate complex Enzymes lock in to an enzyme substrate complex and “unlock” when the reaction is over. 3. Enzymes are affected by temperature. Most do not function above 60o C. 4. Enzymes work best under certain pH conditions. 5. Enzymes are needed in very small quantities. A single enzyme molecule may be used over and over because it is not used up. 6. Enzymes are specific Saturation levels: Lock and Key Model-Why is this a good choice of a model? Which is the enzyme? Which is the active site? Which is the substrate? Enzymes denature at high temperatures. Their shape changes and they no longer fit. Enzymatic Reactions CO2 + H2O X H2CO3 Carbon dioxide combines with water to form carbonic acid which is then transported to the lings and disassociated to form carbon dioxide and water which is exhaled. The “X” represents the enzyme which controls the reaction. Catalase reactions The body produces H2O2 (hydrogen peroxide) which is toxic in large amounts. The body cells have an enzyme to break it down called catalase. This enzyme is present in liver. + Liver H2O4 This reaction produces water and oxygen. Design an experiment to investigate how a variable will affect the rate of reaction of the enzyme catalase. Independent variable: Temperature, pH, Amount of enzyme, amount of substrate. Dependent variable: the way you measure the rate of reaction. Can be: 1. The time it takes for the disk to rise in the beaker 2. The amount of time the disk continues to bubble. How are you going to conduct the experiment? Procedure: The exact steps you will take. Includes: 1. The number of trials 2. The experimental group and the control group 3. The data table you will use Results: Average the data obtained over several trials Organize it into the data table and come up with a general trend or observation. Note any additional comments (sources of error) Graph your results Analyze and Conclude Does you data support you hypotheses? Why or why not? What did you learn about enzyme reactions when doing this experiment? X 2H2O2 ----> 2H2O + O2 1. In the above reaction, what does the “X” represent? 2. In your experiment, how did you show that enzymes are reusable? 3. What was the gas that was causing the bubbles? 4. What did you predict would happen to the reaction when the liver was heated? Why?