Presentation on theme: "UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of life"— Presentation transcript:
1 UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of life
2 UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of LifeI. Atoms, Ions, and Molecules (2.1)A. Living things consist of atoms of different elements
3 1. An atom is the smallest basic unit of matter 2. An element is one type of atom3. An atom has a nucleus and electrons
4 a. The nucleus has protons and neutrons b. Electrons are in energy levels outside the nucleus
5 4. A compound is made of atoms of different elements bonded together a. Water (H20)b. Carbon dioxide (CO2)c. Many other carbon-based compounds in living things.
6 B. Ions form when atoms gain or lose electrons 1. An ion is an atom that has gained or lost one or more electronsa. Positive ions -lost electron(s)b. Negative ions -gain electron(s)2. Ionic bonds form between oppositely charged ions
7 1. A covalent bond forms when atoms share a pair of electrons a. Multiple covalent bondsb. Diatomic molecules
8 2. A molecule is two or more atoms held together by covalent bonds
9 A. Life depends on hydrogen bonds in water II. Properties of WaterA. Life depends on hydrogen bonds in water1. Water is a polar moleculea. Polar molecules have slightly charged regions
10 b. Nonpolar molecules do not have charged regions
11 c. Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms.
12 2. Hydrogen bonds are responsible for three important properties of water. a. High specific heatb. Cohesion- attraction between molecules of the same substance (because of hydrogen bonds, water is very cohesive)
13 c. Adhesion- attraction between different substances c. Adhesion- attraction between different substances. Adhesion between water and other charged or polar substances very important force. (responsible for capillary action)
14 B. Many compounds dissolve in water 1. A solution is formed when one substance dissolves in anothera. A solution is a homogeneous mixture
15 b. Solvents dissolve other substances c. Solutes dissolve in a solvent c. Solutes dissolve in a solvent
16 a. Polar solvents dissolve polar solutes 2. “Like dissolves like”a. Polar solvents dissolve polar solutesb. Nonpolar solvents dissolve nonpolar solutesc. Polar substances and nonpolar substances generally remain separate
22 III. Carbon-Based Molecules (2.3) A. Carbon atoms have unique bonding properties1. Carbon forms covalent bonds with up to four other atoms, including other carbon atoms.
23 2. Carbon-based molecules have three general types of structures a. Straight chainb. Branched chainc. Ring
24 1. Monomers are the individual subunits B. Many carbon based molecules are made of many small subunits bonded together1. Monomers are the individual subunits 2. Polymers are made of many monomers
25 1. Carbohydrates are made of carbon, hydrogen, and oxygen B. Four main types of carbon-based molecules are found in living things.1. Carbohydrates are made of carbon, hydrogen, and oxygena. Carbohydrates include sugars and starchesb.Monosaccharides are simple sugars
26 c. Polysaccharides include starches, cellulose, and glycogen d. Carbohydrates can be broken down to provide energy for cellse. Some carbohydrates are part of cell structure
27 a. Many contain carbon chains called fatty acids 2. Lipids are nonpolar molecules that include fats, oils, and cholesterola. Many contain carbon chains called fatty acidsb. Fats and oils contain fatty acids bonded to glycerol.
28 c. Lipids have several different functions 1). Broken down as a source of energy2). Make up cell membranes3). Used to make hormones
29 d. Fats and oils have different types of fatty acids 1). Saturated fatty acids2). Unsaturated fatty acids
30 e. Phospholipids make up all cell membranes 1). Polar phosphate “head” 1). Polar phosphate “head”2). Nonpolar fatty acid “tails”
31 3. Proteins are polymers of amino acid monomers a. Twenty different amino acids are used to build proteins in organisms
32 b. Amino acids differ in side groups, or R groups c. Amino acids are linked by peptide bonds
33 d. Proteins differ in the number and order of amino acids 1). Amino acids interact to give a protein its shape 2). Incorrect amino acids change a proteins structure and function
34 4. Nucleic acids are polymers of monomers called nucleotides a. Nucleotides are made of sugar, phosphate group, and a nitrogen base.
35 b. DNA stores genetic information c. RNA builds proteins c. RNA builds proteins
36 C6H12O6 + O2 CO2 + H2O IV. Chemical Reactions (2.4) A. Bonds break and form during chemical reactions.1. Reactants are changed during a chemical reaction2. Products are made by a chemical reactions.C6H12O6 + O CO2 + H2Oreactantsproducts
37 B. Bond energy is the amount of energy that breaks a bond 1. Energy is added To break bonds2. Energy is released when bonds form
38 C. A reaction is at equilibrium when reactants and products form at the same rate. CO2 + H2O H2CO3
39 D. Chemical reactions release or absorb energy 1. Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction.
40 2. Exothermic reactions release more energy than they absorb. a. Reactants have higher bond energy than productsb. Excess energy is released by the reaction
41 3. Endothermic reactions absorb more energy than they release. a. Reactants have lower bond energy than products a. Energy is absorbed by the reaction to make up the difference.
42 A. A catalysts lowers activation energy V. Enzymes (2.5)A. A catalysts lowers activation energy1. Catalysts are substances that speed up chemical reactionsa. Decrease activation energyb. Increase reaction rate
43 1. Enzymes are catalysts in living things B. Enzymes allow chemical reactions to occur under tightly controlled conditions.1. Enzymes are catalysts in living thingsa. Enzymes are needed for almost all processesb. Most enzymes are proteins
44 C. Disruptions in homeostasis can prevent enzymes from functioning. 1. Enzymes function best in a small range of conditions2. Changes in temperature and pH can break hydrogen bonds.3. An enzyme’s function depends on its structure
45 D. An enzyme’s structure allows only D. An enzyme’s structure allows only certain reactants to bind to the enzyme1. Substrates2. Active Site
46 E. The lock-and-key model helps illustrate how enzymes function 1. Substrates brought together2. bonds in substrates weakened