Chapter 2 Chemistry for Life.pdf

Campbell Essential Biology and Campbell Essential Biology with Physiology Sixth Edition Chapter 2 Essential Chemistry for Biology Copyright © 2021 Pearson Educat...

Campbell Essential Biology and Campbell Essential Biology with Physiology Sixth Edition Chapter 2 Essential Chemistry for Biology Copyright © 2021 Pearson Education, Inc. All Rights Reserved The Exhaust Released by a Car in Boston Contributes to the Death of Coral in the Great Barrier Reef of Australia Copyright © 2021 Pearson Education, Inc. All Rights Reserved Biology and Society: Nuclear Medicine Radioactivity, the emission of high-energy particles, can kill cells by damaging DNA. Radiation can also be medically beneficial, helping to treat cancer. Radiation therapy exposes only a small part of the body to a precise dosage of radiation. Knowledge of chemistry is essential to understanding biology. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Radioactive Vision. This Pet Scan of a Human Liver Highlights Areas of Diseased Tissue Chapter Thread: Radioactive vision Copyright © 2021 Pearson Education, Inc. All Rights Reserved Matter: Elements and Compounds (1 of 2) Take any biological system apart, and you eventually end up at the chemical level. – Matter is anything that occupies space and has mass. – Mass is a measure of the amount of material in an object. – An element is a substance that cannot be broken down into other substances by chemical reactions. – All matter is composed of chemical elements. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Abbreviated Periodic Table of the Elements Copyright © 2021 Pearson Education, Inc. All Rights Reserved Matter: Elements and Compounds (2 of 2) Of the 92 naturally occurring elements, 25 are essential to people. – Four of these elements make up about 96% of the weight of the body. – Trace elements are required in only very small amounts and are essential for life. – Elements can combine to form compounds, substances that contain two or more elements in a fixed ratio. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Chemical Composition of the Human Body Copyright © 2021 Pearson Education, Inc. All Rights Reserved Diet and Goiter Copyright © 2021 Pearson Education, Inc. All Rights Reserved Atoms (1 of 2) Each element consists of one kind of atom. An atom is the smallest unit of matter that still retains the properties of an element. Atoms are composed of subatomic particles. – A proton is positively charged. – An electron is negatively charged. – A neutron is electrically neutral. Copyright © 2021 Pearson Education, Inc. All Rights Reserved A Simplified Model of a Helium Atom Copyright © 2021 Pearson Education, Inc. All Rights Reserved Atoms (2 of 2) All atoms of a particular element have the same unique number of protons. This number is the element’s atomic number. An atom’s mass number is the sum of the number of protons and neutrons in its nucleus. – Isotopes have the same number of protons and behave identically in chemical reactions, but they have different numbers of neutrons. – A radioactive isotope is one in which the nucleus decays spontaneously. Copyright © 2021 Pearson Education, Inc. All Rights Reserved The Process of Science: How Effective Is Radiation in Treating Prostate Cancer? Among American men, prostate cancer is the most frequently diagnosed cancer. Common treatments are surgery and radiation. Studies of the effectiveness of different methods, such as surgery and external radiation, are problematic, because the groups of patients are not controlled for all characteristics. It would be unethical to withhold treatment from cancer patients. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Treatment of Prostate Cancer With Radiation (a) Radioactive seeds (c) Comparing outcomes after three types of (b) Radioactive seed implantation prostate treatment Copyright © 2021 Pearson Education, Inc. All Rights Reserved Chemical Bonding and Molecules (1 of 2) Only electrons are directly involved in chemical reactions. – The number of electrons in an atom determines the chemical properties of that atom. – Chemical reactions enable atoms to transfer or share electrons. – These interactions usually result in atoms staying close together, held by attractions called chemical bonds. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Ionic Bonds When an atom loses or gains electrons, it becomes electrically charged. – Ions are atoms or molecules that are electrically charged as a result of gaining or losing electrons. – Ionic bonds are formed between oppositely charged ions. – Compounds, such as table salt, that are held together by ionic bonds are called ionic compounds. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Animation: Ionic Bonds https://mediaplayer.pearsoncmg.com/assets/secs-campbell- ionic-bonds Copyright © 2021 Pearson Education, Inc. All Rights Reserved Electron Transfer and Ionic Bonding Copyright © 2021 Pearson Education, Inc. All Rights Reserved Covalent Bonds A covalent bond forms when two atoms share one or more pairs of electrons. Covalent bonds – are the strongest of the various bonds and – hold atoms together in a molecule. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Animation: Covalent Bonds https://mediaplayer.pearsoncmg.com/assets/secs-campbell- covalent-bonds Copyright © 2021 Pearson Education, Inc. All Rights Reserved Alternative Ways to Represent a Molecule Copyright © 2021 Pearson Education, Inc. All Rights Reserved Hydrogen Bonds A molecule of water (H2O) consists of two hydrogen atoms joined to one oxygen atom by covalent bonds. But the electrons are not shared equally between the oxygen and hydrogen atoms. This causes water to be a polar molecule, one with an uneven distribution of charge. The polarity of water results in weak electrical attractions, called hydrogen bonds, between neighboring water molecules. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Hydrogen Bonding in Water Copyright © 2021 Pearson Education, Inc. All Rights Reserved Animation: Water Structure https://mediaplayer.pearsoncmg.com/assets/secs-campbell- polarity-water-v2 Copyright © 2021 Pearson Education, Inc. All Rights Reserved  Chemical Bonding and Molecules (2 of 2) Checkpoint: When a lithium ion (Li + ) joins a bromide ion (Br − ) to form lithium bromide, the resulting bond is a(n) fill in the blank bond. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Chemical Reactions (1 of 2) Cells constantly rearrange molecules. Such changes in the chemical composition of matter are called chemical reactions, and include – reactants, the starting materials, and – products, the end materials. Chemical reactions can rearrange matter but cannot create or destroy matter. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Chemical Reactions (2 of 2) Checkpoint: Predict the formula for the compound that results when a molecule of sulfur trioxide (SO3 ) combines with a molecule of water to produce a single molecule of product. (Hint: In chemical reactions, no atoms are gained or lost.) Copyright © 2021 Pearson Education, Inc. All Rights Reserved Identifying Major Themes (1 of 3) Cells constantly rearrange molecules by breaking existing chemical bonds and forming new ones. Which major theme is illustrated by this action? 1. The relationship of structure to function 2. Information flow 3. Pathways that transform energy and matter 4. Interactions within biological systems 5. Evolution Copyright © 2021 Pearson Education, Inc. All Rights Reserved Water and Life Life on Earth began in water and evolved there for 3 billion years before spreading onto land. – Modern life is still tied to water. – Your cells are composed of 70–95% water. The abundance of water is a major reason that Earth is habitable. The polarity of water molecules and the hydrogen bonding that results explain most of water’s life- supporting properties. Copyright © 2021 Pearson Education, Inc. All Rights Reserved A Watery World Copyright © 2021 Pearson Education, Inc. All Rights Reserved The Cohesion of Water Water molecules stick together as a result of hydrogen bonding. This tendency of molecules of the same kind to stick together is called cohesion and is much stronger for water than for most other liquids. – Trees depend on cohesion to help transport water from their roots to their leaves. – Surface tension is a measure of how difficult it is to stretch or break the surface of a liquid. Hydrogen bonds give water unusually high surface tension. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Animation: Water Transport https://mediaplayer.pearsoncmg.com/assets/secs-campbell- cohesion-water Copyright © 2021 Pearson Education, Inc. All Rights Reserved Cohesion and Water Transport in Plants Copyright © 2021 Pearson Education, Inc. All Rights Reserved A Raft Spider Walking on Water Copyright © 2021 Pearson Education, Inc. All Rights Reserved How Water Moderates Temperature Because of hydrogen bonding, water has a stronger resistance to temperature change than most other substances. – Because heat is first used to break hydrogen bonds, water absorbs and stores a large amount of heat while warming up only a few degrees. – Conversely, when water cools, hydrogen bonds form, a process that releases heat. – Evaporative cooling occurs when a substance evaporates and the surface of the liquid remaining behind cools down. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Sweating as a Mechanism of Evaporative Cooling Copyright © 2021 Pearson Education, Inc. All Rights Reserved The Biological Significance of Ice Floating When water molecules get cold enough, they move apart, forming ice. A chunk of ice floats because it is less dense than the liquid water in which it is floating. – Floating ice acts as an insulating “blanket” over liquid water, allowing life to persist under the frozen surface. – If ice did not float, ponds, lakes, and even the oceans would freeze solid. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Why Ice Floats Copyright © 2021 Pearson Education, Inc. All Rights Reserved Water as the Solvent of Life A solution is a liquid consisting of a homogeneous mixture of two or more substances. – The dissolving agent is the solvent. – The dissolved substance is the solute. When water is the solvent, the result is an aqueous solution. Checkpoint: Explain why ice floats. Copyright © 2021 Pearson Education, Inc. All Rights Reserved A Crystal of Table Salt (NaCl) Dissolving in Water Copyright © 2021 Pearson Education, Inc. All Rights Reserved Identifying Major Themes (2 of 3) The polarity of water molecules helps explain water’s ability to support life. Which major theme is illustrated by this action? 1. The relationship of structure to function 2. Information flow 3. Pathways that transform energy and matter 4. Interactions within biological systems 5. Evolution Copyright © 2021 Pearson Education, Inc. All Rights Reserved Acids, Bases, and pH (1 of 2) A chemical compound that releases H+ to a solution is an acid. A compound that accepts H+ and removes them from solution is a base. To describe the acidity of a solution, chemists use the pH scale, a measure of the hydrogen ion H+ concentration in a solution Buffers minimize changes in pH. Copyright © 2021 Pearson Education, Inc. All Rights Reserved The pH Scale Copyright © 2021 Pearson Education, Inc. All Rights Reserved Ocean Acidification by Atmospheric CO2 C O sub 2 Copyright © 2021 Pearson Education, Inc. All Rights Reserved Acids, Bases, and pH (2 of 2) Checkpoint: Compared with a solution of pH 8, the same volume of a solution at pH 5 has fill in the blank times more hydrogen ions (H+ ). This second solution is considered a(n) fill in the blank. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Identifying Major Themes (3 of 3) The release of CO2 from a factory in one region can cause ocean acidification that affects coral reefs in another region. Which major theme is illustrated by this action? 1. The relationship of structure to function 2. Information flow 3. Pathways that transform energy and matter 4. Interactions within biological systems 5. Evolution Copyright © 2021 Pearson Education, Inc. All Rights Reserved Evolution Connection: Radioactivity as an Evolutionary Clock Radioactive decay can be used to obtain important data about the evolutionary history of life on Earth. Fossils are reliable chronological records of life. A fossil’s age can be estimated by measuring the ratio of the two isotopes to learn how many half-life reductions have occurred since it died. Using such techniques, scientists can estimate the ages of fossils and place them in an ordered sequence called the fossil record. Copyright © 2021 Pearson Education, Inc. All Rights Reserved Radiometric Dating Copyright © 2021 Pearson Education, Inc. All Rights Reserved