Symbols Symbols Atomic Number No of protons Atomic
Symbols
Symbols Atomic Number- No. of protons Atomic Mass – No. of protons and neutrons (electron mass negligible) Chemical symbols found on Periodic table
Definitions • Element- Substance consisting of one type of atom. • Isotope – Atom of an element with different number of neutrons. • Molecule – Smallest unit of substance. Retains chemical & physical properties of substance. Compose of 2 atoms held together by a bond. Atoms may be of same/different elements. • Compound- Substance composed by chemical combination of two or more elements in definite proportions.
Relationships • Work in groups of 4 and respond to the following questions. • Are N 2, H 2, and O 2 elements or compounds? • Are N 2, H 2, and O 2 atoms or elements? • Is C an atom or element? • Is H 20 a molecule or a compound?
Elements of Life
Organic Compounds • Carbohydrates (sugars) : Carbon, Oxygen, Hydrogen • Lipids (fats): Carbon, Oxygen, Hydrogen, and Phosphorus • Proteins: Carbon, Oxygen, Hydrogen, Nitrogen, and Sulfur • Nucleic Acids (DNA, RNA): Carbon, Oxygen, Hydrogen, Nitrogen, Phosphorus
Isotopes have a different # of neutrons. Isotopes have the same number of electrons and behave the same way chemically.
Radioisotopes • Valuable research tools. • Unstable nucleus; over time gives off subatomic particles & energy; results in stable nucleus. • Decay of radioisotopes occurs at constant rate called half life. • Use carbon isotopes to date fossils and minerals. • Use other radioisotopes in medical tests.
Isotopes Why is the atomic mass not exactly double the atomic number?
Periodic Table
Bonding • Atoms – held together by chemical bonds. • Two types – Ionic bond and covalent bond. • Ionic bond – one or more electrons transferred from one atom to another. • Covalent bond – electrons shared between atoms. • Van der Waals Forces – Weak attractive force between molecules.
Bonding • • Compounds are held together by chemical bonds. Electrons are involved in chemical bonding. The outer shell (orbital) of atom is called valence shell. Electrons in this shell are valence electrons.
Bonding • Atoms with unfilled valence shells are chemically reactive. • Atoms seek to fill valence shell. • Bonding fills valence shell with electrons.
Ionic Bond
Covalent Bond
Bond Strength • Covalent bonds are strongest bond. Takes more energy to break bond. • Ionic bonds are weaker than covalent. • Van der Waals forces are weak attractions. Assignment: Create a graphic organizer. Compare and contrast ionic and covalent bonds. Work with a partner.
Properties of Water • Only substance on Earth found as solid, liquid, and gas. Solid less dense than liquid state. • Polarity • Cohesion • Adhesion • Capillary Action
Polarity Water is polar- uneven distribution of electrons between hydrogen and oxygen atoms. Hydrogen bonds- Attraction between + charged H and – charged O. One atom forms multiple H bonds give water special properties.
Cohesion • Attraction between molecules of the same substance. • Surface tension – tension at surface of water is related to cohesion
Adhesion • Attraction between molecules of different substances.
Capillary Action Capillary action is responsible for water moving through a plant. Adhesion- water is attracted to roots, stems, and leaves. Cohesion – water column is held together as it rises.
Review 1. What do the numbers 11 and 23 near the sodium symbol represent? 2. Use the Bohr model on the right. How many a. How many valence electrons are available? b. What is the atomic mass of this element? c. Is this element an isotope? Why? 3. What elements are present in a protein? 4. What type of bond is occurring between the Mg and Cl? a. Which of the two elements has a higher electro-negativity? b. What would happen to this compound in an aqueous solution? 5. On the left is a drop of water. Why does water make drops?
Mixture/Solutions/Suspensions • Mixture: Two or more elements/compounds physically mixed but not chemically mixed. • Solution: Homogeneous mixture in which one substance is dissolved (solute) in another (solvent) usually water. • Suspension: Mixture of water and non dissolved substance.
Solution • Na. Cl dissolves in water. • Na. Cl is the solute; water is the solvent. • Water surrounds the Na + and Cl-.
Suspensions • Blood is an example of a suspension. • Red blood cells are suspended in a liquid called plasma.
p. H • A molecule of water can form ions • 1 molecule in 550 million will react to form ions. • Water has the same number of H+ and OH-; it is neutral. • Solutions that have a higher concentration of H+ than water are acidic. • Solutions that have a lower concentration of H+ that water are basic (or greater OH -)
p. H Scale 7 = Neutral p. H Below 7 = acidic p. H Above 7 = basic p. H Each p. H change represents a 10 fold change in the level of H+. EX: p. H of 4 has 10 x more H+ than p. H of 5 EX: p. H of 5 has 10 x less H+ than p. H of 4
Organic Molecules • Are made of carbon. • Can be very small like CO 2 to very large like a protein. • Living organisms are made of and use organic molecules.
Carbon • Is tetravalent; can form 4 bonds. • Bonds with many types of elements: H, N, O, P, S • Can form many types of structures.
Macromolecules • Macromolecule – Giant molecule made from smaller molecules. • Polymer- Large molecule consisting of similar or identical molecules linked together. • Monomer – Subunit of polymer. • Polymerization - Process of polymer creation
Polymerization
Figure 5. 2 The synthesis and breakdown of polymers
Organic Molecules • Carbohydrates, proteins, and nucleic acids are polymers (and macromolecules). • Lipids are macromolecules (but not polymers) • All are biomolecules.
Carbohydrates • Made of C, H, O in 1: 2: 1 ratio; (CH 2 O) • Used for energy by all organisms, plants & some animals use them for structures. • Monosaccharides- single sugar (monomer) • Glucose is a monosaccharide used for energy.
Carbohydrates • Disaccharides - Two sugars • Table sugar sucrose is a disaccharide composed of two monosaccharides glucose and fructose (fruit sugar).
Carbohydrates • Polysaccharides are polymers made of many monosaccharides. • Examples: - Plant starch – used to store energy - Glycogen (animal starch) – used to strore energy. - Cellulose – used by plants for structure. Cellulose
Lipids • Made from C, H mostly. • Used to store energy, for cell membranes, water proof coverings, some hormones. • Three types of lipids - Triglycerides - Phospholipids - Cholesterol
Triglycerides • Made of 2 components - glycerol - fatty acid chains (3) • Used to store energy (2 x energy in a polysaccharide)
Saturated vs. Unsaturated Saturated Lipid • Single bonds between Cs in carbon skeleton. • Each C single bonded to H. (i. e. saturated with H) • Chain straight / pack tightly /solids at RT. Unsaturated Lipid – • Some Cs double bonded • Makes kink in chain • Chains can’t pack as tightly/ oils at RT.
Figure 5. 11 Examples of saturated and unsaturated fats and fatty acids
Saturated vs. Unsaturated • Saturated fats - Animal fats - Raise LDL or bad cholesterol levels. • Unsaturated fats -Vegetable fats - either help to raise HDL or good cholesterol levels or decrease LDL levels.
Phospholipids • Phospholipids- glycerol, 2 fatty acid chains, & phosphate group. • Function – to make up cell membranes.
Cholesterol Steroids- lipids with 4 fused carbon rings. Cholesterol is a steroid. Function- component of animal cell membranes. Precursor from which other steroids are made including hormones. High levels contribute to atherosclerosis
Nucleic Acids • Made of C, H, O, N, P • Used to store and transmit genetic information. • Two types: DNA & RNA • Monomer: Nucleotide
Nucleotides -Nitrogenous base -Pentose (5 C) sugar/ Deoxyribose in DNA Ribose in RNA -Phosphate group
DNA (polymer) is made by bonding nucleotides together. Phosphate of one nucleotide is bonded to sugar of the next nucleotide.
Proteins • Made of C, H, O, N • Have many functions: - Control chemical reaction rates – Enzymes - Form bones and muscles – Structural - Hemoglobin carries oxygen – Transport - Fight disease - Antibodies
Proteins • Are structurally diverse consistent with their many functions.
Proteins • Amino Acids – Monomer • There are 20 amino acids. • Proteins are made by the bonding of some configuration of the 20 amino acids
Figure 5. 16 Making a polypeptide chain
• There are 4 levels of protein structure: • Primary • Secondary • Tertiary • Quaternary
Chemical Reaction • Changes one set of chemicals into another set of chemicals. • Reactants- enter into chemical reaction • Products – produced by chemical reaction • Involves breaking and making of chemical bonds.
Energy • Energy is released when chemical bonds are broken; reactions occur spontaneously. • Energy is absorbed when chemical bonds are formed; reactions require additional energy. • Living organisms carry out both types of chemical reactions to sustain life ; metabolism.
Enzymes • Are catalysts; speed up rate of chemical reaction. • Are proteins; biological catalysts. • Speed up reaction rates by lowering activation energy. • Activation energy; the amount of energy needed to get a chemical reaction started. • Lowering activation energy makes the reaction happen faster.
Enzymes
Enzymes • Enzymes provide site where reactants are brought together. • Reactants = substrate • Substrate binds to active site of enzyme; enzyme substrate complex • Reaction occurs. • Product released; enzyme freed for another reaction.
Enzymes
Enzymes • Enzymes are specific; enter into one type of reaction. • Enzymes are biological molecules; can be damaged by changes in p. H and temperature
Figure 6. 11 Example of an enzyme-catalyzed reaction: Hydrolysis of sucrose
Figure 6. 12 Energy profile of an exergonic reaction
Figure 6. 13 Enzymes lower the barrier of activation energy
Figure 6. 14 The induced fit between an enzyme and its substrate
Figure 6. 15 The catalytic cycle of an enzyme
Figure 6. 16 Environmental factors affecting enzyme activity
Figure 6. 17 Inhibition of enzyme activity
Digestion • Nutrient – substance that supplies energy and raw material for growth, maintenance, and repair. - water for all of life’s activities -carbohydrates for energy - fats (lipids) for cell membranes, hormones - proteins for enzymes, structures, transport - vitamins for working with enzymes to regulate body processes - minerals such as calcium/bones, iron/hemoglobin, sodium & potassium/nerve function
Calorie • When food is burned, energy is converted to heat. • Calorie= amt. of heat to raise the temperature of 1 g of H 2 O 1 degree Celsius • c = 1 calorie C= 1, 000 calories = kilocalorie
Digestion • To break down food into simple molecules that can be used by body. • Two types of digestion: - Physical digestion: Breaking down of food into smaller pieces. - Chemical digestion: Breaking down of macromolecules, polymers into smaller molecules.
Figure 41. 9 Bulk-feeding: a python
Figure 41. 10 Intracellular digestion in Paramecium
Figure 41. 11 Extracellular digestion in a gastrovascular cavity
Figure 41. 12 Alimentary canals
Figure 41. 21 The digestive tracts of a carnivore (coyote) and a herbivore (koala) compared
Figure 41. 22 Ruminant digestion
Digestion-Anatomy
Identify
Digestion • Mouth - Teeth tear apart food (physical digestion) - Saliva has an enzyme amylase to break down starches to complex sugars. (chemical digestion)
Digestion • Esophagus moves food from mouth to stomach. • Smooth muscles contract to swallow food. • Contractions known as peristalsis.
Digestion • Stomach continues mechanical and chemical digestion. • Mechanical – Stomach muscles contract; mix & churn food; produce chyme. • Chemical – HCl and pepsin (enzyme) work together to break down proteins into polypeptides.
Digestion Accessory Digestive Structures • Pancreas- produces hormones to regulate blood sugar; produces enzymes to breakdown carbohydrates, lipids, proteins. (chemical) • Liver produces bile which breaks down lipids (fats) to smaller molecules. • Gallbladder stores bile.
Digestion • Small Intestine – 2 functions: complete chemical digestion and absorption of food molecules. • Has 3 parts: duodenum, jejunum, ileum • Chemical digestion: All molecules broken down to smallest component glucose, amino acids, fatty acids, glycerol
Figure 41. 16 The duodenum
Figure 41. 17 Enzymatic digestion in the human digestive system
Complete Mechanical Digestion Mouth Esophagus Stomach Small Intestine Chemical Digestion
Digestion Absorption of glucose and amino acids occurs at the villi (finger like projections). Absorbed by blood. Absorption of fats occurs at the villi; absorbed into lymph system.
Figure 41. 19 The structure of the small intestine
Digestion • Large intestine functions: Remove water from undigested material; make vitamin K; expel waste from body.
Enzyme Lab • • • Investigating Enzyme Activity Introduction: Enzymes are Biological catalysts (usually proteins) that speed up the rates of chemical reactions that take place within cells. In this investigation, you and your group will study how temperature or p. H affects the activity of enzymes. The specific enzyme you will use is catalase, which is present in most cells and found in large concentrations in liver and blood cells. You will use liver homogenate as the source of catalase. Catalase promotes the decomposition of hydrogen peroxide (H 2 O 2) in the following reaction: 2 H 2 O 2 2 H 2 O + O 2 Hydrogen peroxide is formed as a by-product of chemical reactions in cells. It is toxic and soon would kill cells if not immediately removed or broken down. (Hydrogen peroxide is also used as an antiseptic. It is not a good antiseptic for open wounds, however, as it is quickly broken down by the enzyme catalase, which is present in human cells. )
Enzyme Lab Your assignment is to design an experiment which tests the affect of temperature/p. H on the action of catalase. There are pieces of equipment available in the classroom. In the course of designing the experiment decide which of the equipment/ glassware you will use and how many. Write this down. 1. State the purpose of the lab. 2. What is the experimental hypothesis? (remember to use an “If…. , then…” statement) 3. Write out in detail, and sketch out if necessary, the final procedure (method) your group will follow to test your above hypothesis. 3. Have your procedure approved by the teacher.
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