Chemistry Review Structure of an Atom are organized into shells or levels around the nucleus. Atoms are most stable when their outer or valence shell is. The six most abundant elements of life Types of chemical bonds 1
Let s Practice a. Draw five protons in the nucleus of the atom. Label them with their charge. b. Draw six neutrons in the nucleus of the atom. c. Draw two electrons in the first energy level and label them with their charge. d. Draw three electrons in the second energy level and label them with their charge. e. What element is represented by the diagram? Label the information provided in the periodic table. What does the atomic number represent? or What does the atomic mass represent? + The Biological Importance of Water Unique Bonding of Water Water is polar Polar: distribution of charge The in the covalent bonds are pulled toward the oxygen atom Oxygen is slightly Hydrogens are slightly Opposites! = Hydrogen bonds Nonpolar: No charges Polar and nonpolar don t like each other o Ex Hydrophilic Hydrophobic Amphipathic Molecules have both polar and nonpolar regions. Ex- cell membrane 2
Water is the Universal Solvent almost all substances (mostly polar) Solution: uniform mixture of two or more substances. o Solvent: Liquid in which solutes dissolve o Solute: substance that dissolves in the solvent. Some important solutes in the body:,,, Practice Questions 1. What are the three major types of bonds? 2. Which bond is the strongest? 3. Which bond is the weakest? 4. Which bond allows neighboring water molecules to attract to one another? 5. In water, is slightly positive, while is slightly negative. 6. List the six elements that are crucial for our biological survival. 7. Which molecule is considered the universal solvent? 8. Identify the solvent and solute in the table below. Urine Blood Solution Solvent Solute Properties of Water Water molecules. o Why? Cohesion creates : like a skin on the surface of the water. Examples: skipping rocks, rain drops beading up on a car, water droplets on a penny, and a spider walking on water. Examples: meniscus (graduated cylinder), wet microscope slides sticking together. 3
H 2O molecules up tubes of small diameter. Result of the of water molecules sticking to each other, and of water molecules sticking to another surface. Examples: o o Drinking straw Plants transporting water from roots to leaves Specific heat is the required to raise 1g of water by 1ºC. Water resists changes in temperature; therefore, water must absorb a lot of heat energy to increase temperature and vice versa. Very important because our cells release a lot of heat and water absorbs that heat, which allows us to regulate cell temperatures= Examples: oceans heat and cool slower than land due to the high specific heat of water. Vaporization = Evaporation produces a effect bonds must be broken before water can evaporate and this requires a lot of energy. Example: sweating (humans) or panting in dogs, dogs can t sweat through their skin, they pant to cool down= evaporative cooling. Frozen water has a crystalline structure maintained by bonding O o C / 32 o F = Freezing Ice is less dense than liquid water o hydrogen bonds are positioned in a way that pushes the molecules apart lowers density Protects aquatic ecosystems: o If ice filled an entire lake or ocean, from bottom to top, all the organisms would die. o Also allows turnover of nutrients o In the spring, the ice melts; cold water sinks and pushes up the nutrient rich water. 4
Property of Water Explanation of Property Drawing Cohesion Adhesion Surface Tension Capillary Action High Specific Heat High Heat of Vaporization Lower density when solid 5
ph Scale ph = potential of Hydrogen Measures how acidic (more H + ) or how basic/alkaline (more OH - ) a solution is H + + OH - H 2O acid + base neutral How is ph regulated in our bodies? Through - compounds that can bind H + ions when the H + concentration increases and can release an H + ion when the H + ion concentration decreases. Normal ph of blood is 7.35-7.45 (slightly basic). Any small change could disrupt cells and could potentially be fatal. Practice Questions 1. A student mixes strawberry koolaid and water. The ph was taken using an indicator; the ph was 5.4. What kind of solution is strawberry Koolaid? 2. In the Kool-Aid mixture, what must there be more of, hydrogen ions or hydroxide ions? 3. A student adds an alka-seltzer tablet to the koolaid and stirs. The ph is now 8.3. What was released by the alkaseltzer tablet to cause this change? 4. Bromothymol blue is a chemical indicator that turns blue in basic and neutral solutions, and turns greenish and then yellow as the solution becomes increasingly acidic. Fill in what color you think bromthymol blue would be in each of the situations in the chart. Situation Ph Indicator Color Water directly out of tap ph =7.2 ph after exhaled air is blown through a straw into water for 5 min. ph=5.1 ph after a snail has lived in water for three day ph=5.8 ph with 2mL of bleach added to the water ph=9.4 ph with instant coffee added to the water ph=5.0 ph after an aquatic plant is grown in water for three days in bright sunlight ph=7.7 6
Chemical Reactions 7
Photosynthesis Cellular Respiration U n i t 2 - B i o c h e m i s t r y 8
Macromolecules (Polymers) Making and Breaking Polymers 1. How do we make a polymer from a monomer? 2. How do we break down a polymer? 3. : a chemical process where two smaller molecules are combined to make a larger molecule. Water is released and energy is stored in the newly formed chemical bonds. 4. : A chemical process where a large molecule is broken down into smaller molecules. Water is required and energy is released. Digestion is a series of hydrolytic reactions. 9
Four Types of Macromolecules 10
DIRECTIONS LABEL EVERYTHING! Color the A s- green Color the T s- Orange Color the C s- Yellow Color the G s- Purple Color the U s- Brown Color the phosphates- pink Color deoxyribose- dark blue Color ribose- light blue Color the hydrogen bondsgray Label the covalent bonds. 11
Practice! Enzymes Match the Monomer on the left to the macromolecules on the right. Fatty acids and glycerol A. Protein Monosaccharide B. Lipid Nucleotide C. Nucleic acid Amino acid D. Carbohydrate Match the Polymer on the left to the macromolecules on the right. DNA A. Protein Enzyme B. Lipid Triglyceride C. Nucleic acid Polysaccharide D. Carbohydrate Act as catalysts: Proteins that speed up chemical reactions Lowers activation energy so that the product can form faster. Step 1 Substrate binds to active site of enzyme Step 2 Enzyme changes shape causing substrate to break apart (or bond) Step 3 Products are released and enzyme can be used again 12
Enzyme names often end in -ase o Sucrase breaks down sucrose (sugar) o Lipase breaks down lipids o Catalase breaks down hydrogen peroxide (H 2O 2) in cells o Starch synthase makes starch in plants Factors that affect enzyme reaction rates o Too hot: protein structure, enzyme falls apart o Too cold: lowers kinetic energy, enzyme slows down o Optimal temp in humans: o Too acidic or too basic can denature the protein structure, changes shape of active site o Enzymes have an optimal ph depending on where they function As the enzyme concentration increases, the rate of reaction increases. As the substrate increases, the reaction increases up to a certain point (enzyme is limited). ATP ATP: Main Function: Third bond is very weak. When phosphate is removed, energy is released and ATP becomes ADP, Adenosine Diphosphate. 13
Differences: ATP vs. ADP ATP 3 phosphates energy ADP 2 phosphates energy phosphate removed Macromolecules and ATP Lipids o o Store 80% of body s energy 1 triglyceride 148 ATP Carbohydrates o o 1 glucose 36 ATP Proteins o Not likely to be used for energy Practice Questions 1. The substrate is also known as the in a chemical reaction. 2. List three ways in which enzymes can be altered. 3. Some organisms live in very hot or very acidic environments. Would their enzymes function in a person s cells? Why or why not? 4. Suppose that the amino acids that make up an enzyme s active site are changed; how might this change affect the enzyme? 5. What is the main function of ATP? 6. How do we obtain ATP? 7. Which organic molecule is used by the body as a good source of long term energy storage? 8. Proteins are composed of a chain of. 9. Label the diagram. 14