Biology PDF - Notes

BIOLOGY  Copyright © 2021 by Workman Publishing, Co., Inc. By purchasing this workbook the buyer is permitted to reproduce pages for classroom use only but not for commercial resale. Please contact the publisher for permission to reproduce pages for an entire school or school di...

BIOLOGY  Copyright © 2021 by Workman Publishing, Co., Inc. By purchasing this workbook the buyer is permitted to reproduce pages for classroom use only but not for commercial resale. Please contact the publisher for permission to reproduce pages for an entire school or school district. With the exception of the above, no portion of this book may be reproduced-mechanically, electronically, or by any other means, including photocopying-without written permission of the publisher. Library of Congress Cataloging-in-Publication Data is available. ISBN : 978-1-5235-0436-7 Writer: Matthew Brown Reviewer: Keyla Soto Hidalgo Illustrator: Chris Pearce Designer: Jessie Gang Editor: Karen Edwards Production Editor: Kim Daly Production Manager: Julie Primavera Workman books are available at special discounts when purchased in bulk for premiums and sales promotions as well as for fundraising or educational use. Special editions or book excerpts can also be created to specification. For details, contact the Special Sales Director at [email protected]. Workman Publishing Co., Inc. 225 Varick Street New York, NY 10014-4381 workman.com WORKMAN, BRAIN QUEST, and BIG FAT NOTE-BOOK are registered trademarks of Workman Publishing Co., Inc. Printed in Thailand First printing March 2021 10 9 8 7 6 5 4 3 2 1  de the complete high school study gui BIOLOGY WO R K M A N P U BL I S HI N G N EW YO R K  BIOLOGY EVERYTHING YOU NEED TO ACE Hi! Welcome to Biology ! This notebook is designed to support you as you work through the major areas of biology. Consider these the notes taken by the smartest person in your biology class- the one who seems to “get” everything and who takes clear, understandable, accurate notes. Within these chapters you’ll find important concepts presented in an accessible, relatable way. Cell theory, how bacteria and viruses work, the world of fungi, the animal kingdom, the human body systems, and more are all presented in a language you can easily understand. Notes are presented in an organized way : Important vocabulary words are highlighted in YELLOW. All vocabulary words are clearly defined. Related terms and concepts are writ ten in BLUE PEN. PEN Key concepts are clearly explained and supported by diagrams, illustrations, and charts. If you want a fun, easy-to-understand resource to use as a companion to your textbook, and you’re not so great at taking notes in class, this notebook will help. It hits all the really important stuff you need to ace biology.  CONTENTS UNIT 1: BASICS OF BIOLOGY 1 1. Introduction to Biology 2 2. Critical Thinking in Biology 11 3. Characteristics of Life 19 4. Biological Classification 29 UNIT 2: THE CHEMISTRY OF LIFE 43 5. Atoms and Molecules 44 6. The Importance of Water 61 7. Organic Compounds 69 8. Chemical Reactions and Enzymes 75 UNIT 3: CELL THEORY 83 9. Cell Structure and Function 84 10. Chemical Energy and ATP 97 11. Photosynthesis 103 12. Cellular Respiration 109 13. Mitosis 119 14. Meiosis 131 UNIT 4: BACTERIA, VIRUSES, PRIONS, AND VIROIDS 141 15. Bacteria 142 16. Viruses 153 17. Prions and Viroids 163 18. Disease 169 UNIT 5: PROTISTS 177 19. The Protist Kingdom 178 20. Protozoa 185 21. Algae 193 22. Molds 201 UNIT 6: FUNGI 207 23. The Fungi Kingdom 208 24. Fungi Reproduction 216 25. Ecology of Fungi 223 UNIT 7: PLANTS 229 26. The Plant Kingdom 230 27. Plant Structure and Function 241 28. Plant Reproduction 248 29. Plant Adaptation 257 UNIT 8: ANIMALS 267 30. The Animal Kingdom 268 31. Invertebrates 275 32. Arthropods 285 33. Chordates 293 34. Vertebrates: Anamniotes 303 35. Vertebrates: Amniotes 311 UNIT 9: THE HUMAN BODY 325 36. Body Systems and Homeostasis 326 37. The Integumentary System 334 38. The Muscular and Skeletal Systems 341 39. The Nervous and Endocrine Systems 353 40. The Respiratory and Circulatory Systems 367 41. The Digestive and Excretory Systems 380 42. The Immune System 389 43. The Reproductive System 401 UNIT 10: GENETICS 413 44. Introduction to Genetics 414 45. DNA and RNA 429 46. Genetic Engineering 445 UNIT 11: LIFE ON EARTH 451 47. Evolution 452 48. The History of Life 469 UNIT 12: ECOSYSTEMS AND HABITATS 483 49. The Ecosystem 484 50. Populations 499 Index 509 Unit 1 Basics of Biology 1  Chapter 1 INTRODUCTION TO BIOLOGY WHAT IS BIOLOGY? BIOLOGY is the study of life and BIOLOGY living things. BIOLOGISTS refer The study of life and to living things as ORGANISMS. living things. Organisms, like humans, animals, and plants, all rely on one another to live. BIOLOGISTS Scientists who study biology. Many organisms grow, change, reproduce, and die. The series of changes that an organism can go through are called the ORGANISM A living thing. LIFE CYCLE. 2  fertilization infancy A human life cycle childhood adulthood adolescence An important part of biology is studying how organisms interact and the laws that apply to their life cycles. Biology is called a LIFE SCIENCE, SCIENCE or NATURAL SCIENCE because it is the study of life-forms in nature. SCIENCE, Biology comes from the Greek words bios, meaning “life,” and logia, meaning “the study of.” Biology translates to “the study of life.” Aristotle (384- (384-322 BC) is said to be the first biologist. He developed the first organized study of the natural world. 3 TYPES OF BIOLOGY Biology is divided into many branches, or DISCIPLINES. The main disciplines are: BRANCH THE STUDY OF… Anatomy... the bodily structure of organisms. Botany... plants. Ecology... the relationships between various organisms. Microbiology... tiny organisms. Pathology... the causes and effects of diseases. Pharmacology... the uses and effects of drugs. Physiology... the functions of living organisms and their parts. Taxonomy... the classification of organisms. Toxicology... the nature and effects of poisons. Zoology... animals. 4 Biologists use their specialized knowledge in various ways. There are biologists who work as researchers on food products, medicines, or analyzing diseases. Others use their knowledge to advance agriculture or provide solutions to environmental issues. THE TOOLS OF THE BIOLOGIST Specialized tools are sometimes used to study organisms in specific branches of biology. For example, a botanist may need tools like a trowel and shears to collect specimens, while an anatomist might work with tweezers and scalpels. Microscopes Most biologists, regardless of their branch, rely on some type of imaging tool. The MICROSCOPE was the first imaging tool invented. A microscope is a tool that provides an enlarged image of an object. The most basic concept in biology- that organisms are made up of cells-would not have been discovered without microscopes. There are two general types of microscopes: COMPOUND microscopes use visible light as a source of illumination and have multiple lenses (usually two) that can MAGNIFY specimens up to 1,500 times their actual size. You can change the magnification by rotating make larger to a different lens that is closer to the slide. 5  ELECTRON microscopes use electron beams as a source of illumination and electron lenses to help magnify specimens up to 100,000 times their actual size. All scientists begin their experiments with observation. A microscope helps scientists see tiny organisms and understand the fine details of cells, fibers, and other structures invisible to the naked eye. There are various types of compound and electron microscopes. These microscopes can be specialized to fit biologists’ fields of study. However, they all have the same basic function: to show details in objects that cannot be seen by the naked human eye. In a school lab, we usually use a compound (light) microscope. microscope It has two lenses: the Ocular lens OCULAR LENS that we look through and the two OBJECTIVE LENSES that are closer to the SLIDE. The larger the Objective lenses magnification, the longer the objective lens is. Be careful not Slide to crush the slide when you Light focus at a high magnification! source ELECTRON MICROSCOPES are similar to compound light SLIDE A thin piece of glass microscopes, except they use really used to hold a specimen. 6 tiny particles called ELECTRONS instead of light to show the SPECIMEN. SPECIMEN A sample that There are two main types of electron is studied. microscopes: TRANSMISSION ELECTRON and SCANNING ELECTRON. ELECTRON Other Imaging Tools X-RAY is another imaging tool used in biology. It’s most commonly used in research and in the practice of medicine. X-rays are a type of RADIATION that are absorbed by various things. RADIATION When a human, or animal, The transmission of energy in the form of undergoes an X-ray, the image waves through an object. taken of their body reveals the structures that absorbed the most radiation. In the picture, bones appear white because the calcium in them absorbs the most radiation. Everything else in the body absorbs less radiation, causing the color of the organs to look gray or black. There are many types of X-ray machines, but they all work in the same way: by sending X-ray radiation and displaying an image. 7  MAGNETIC RESONANCE IMAGING SCANS (MRIs) (MRI ) are another form of imaging used in medicine. MRIs use a magnet and radio waves to produce detailed images of internal organs and muscles that might not show up in an X-ray. Many microscopes and radiation-based imaging tools are linked to computer programs to create and visualize the images in a more efficient manner. 8 w 1. What is biology? 2. Biology is also known as a science. 3. What is the life cycle? Name the stages of the human life cycle. 4. What is the purpose of having different disciplines of biology? 5. Anatomy is a discipline that studies. 6. What is the function of tools for scientists? 7. What is the purpose of a microscope? 8. How can you magnify a specimen using a compound microscope? 9. Why do bones show up on an X-ray image? 10. What does magnetic resonance imaging show in a body? answers 9  1. Biology is the study of life. 2. natural or life 3. The life cycle is the changes that an organism goes through. The human life cycle includes infancy, childhood, adolescence, adulthood, and reproduction. 4. Disciplines help scientists focus on specific parts of biology. 5. the structure of the body 6. Tools help scientists study their discipline. 7. A microscope shows details that cannot be seen by ordinary human vision. 8. You can magnify a specimen by rotating to a lens that is closer to the slide. 9. Bones absorb the X-ray radiation. 10. Organs and muscles 10  Chapter 2 CRITICAL THINKING IN BIOLOGY SCIENTIFIC INQUIRY Scientists use evidence from observations and experiments to create an explanation of an event. This process is called SCIENTIFIC INQUIRY. Scientific inquiry begins with the observation of something unknown, which leads the scientist to ask questions. Scientists follow an organized system to conduct their research of this unknown factor. This system is called the SCIENTIFIC METHOD. SCIENTIFIC METHOD The use of a system of experimentation and analysis to explore observations and answer questions. 11 Scientists use the scientific method to help them find evidence, make observations, and organize new information. This system includes several steps that help scientists conduct their experiments. The scientific method starts with a single question. The type of question asked creates the boundaries for the experiment. The more specific the question is, the more focused the experiment will be. Using the scientific method is like building a house. The initial question could be thought of as the foundation of the house. Just as a shaky foundation can cause a house to fall apart, not having a clear, specific question can prevent an experiment from having a direction and then failing. Once a question has been posed, scientists conduct background research to gather information about the experiment they need to perform. Scientists use the information they’ve found to make an assumption about the answer to their question. 12 A HYPOTHESIS is a possible explanation for an observation or problem that can further be tested by experimentation. There can be many various hypotheses proposed to answer a single question; however, there should be only one experiment for each hypothesis. HYPOTHESIS plural: hypotheses The proposed answer to a scientific question. Biologists use EXPERIMENTS to test hypotheses. During the experiments, they study VARIABLES VARIABLES, factors that can change an experiment’s results. There are two different variables: An INDEPENDENT VARIABLE is a condition that has been changed before an experiment. A DEPENDENT VARIABLE is the factor that is influenced EXPERIMENT by the independent variable. It A procedure used to test a hypothesis. is what is affected during the experiment. Dependent variable Independent variable The result showing A change is made the effect of the to a condition. change made. 13 Any data from the experiment, even if that data proves the hypothesis wrong, is collected and analyzed in a RESULTS step. This analysis can be done by the team performing the experiment or by other scientists. After results are gathered and analyzed, conclusions can be made. These conclusions are important, and may result in the need for a brand-new experiment, which is why collecting all the results is important. After the analysis scientists compare the conclusion and the original hypothesis. They ask: Does the conclusion confirm or support the hypothesis? If it does, then the experiment is complete and the results are considered the answer to the question. When a hypothesis is supported by the results of an experiment, the hypothesis becomes a THEORY THEORY. If the hypothesis is not supported, a new hypothesis must be made and tested. In these cases, the scientific method begins the cycle again; from the conclusion that proved the hypothesis wrong, to a new hypothesis, to more experimentation. You have a theory! YES Does the conclusion support the hypothesis? Back to the NO drawing board with a new hypothesis! 14 The final step in the scientific method is the SHARING OF RESULTS. RESULTS Publishing results enables the scientific and medical communities to evaluate the findings themselves. It also provides instructions so that other researchers can repeat the experiment, build on it, and verify and/or confirm the results. Results should also be shared with other scientists who may be able to use those results in their own experiments in the future. Results are often shared in scientific journals, which are written by the scientists who performed the experiment. In the case of clinical studies, published results can help make informed decisions about a person’s health or behaviors. 15  Scientific Method 1 A SK A Q UE STION 2 CON D UCT OR I D E NTIFY A BACKG RO UN D PROBL E M R E S E ARCH 3 CR E ATE A H Y POTH E SI S 4 TE ST TH E HY POTH E SIS W ITH AN E X P E R IM E NT 5 M AK E OBS E R VATIONS AN D COL L ECT DATA 6 ANAL YZ E R E SULTS/ DR AW CONCLUSIONS IF CONCLUSIONS AR E FAL S E, CHANG E VAR I ABL E AN D B EG IN AGA IN 7 S HAR E R E SULTS! 16 w 1. What is the purpose of the scientific method? 2. A(n) must be created before the scientific method can be used. 3. What helps with focusing the scope of the experiment? 4. What is the purpose of doing background research? 5. How do scientists conduct experimentation? 6. What happens to the dependent variable when a change is made to the independent variable? 7. What is the purpose of the sharing results step? 8. What is the purpose of the analysis step? 9. If the conclusion proved the hypothesis wrong, what is the next step? 10. The process of scientific inquiry can be a. answers 17  1. The scientific method helps scientists structure their research. 2. inquiry/question 3. A specific question 4. Background research is used to make an assumption about the answer to the question. 5. By using scientific tools and observation 6. The dependent variable will also change. 7. The sharing results step exists for scientists to share their results with the public and with fellow scientists. 8. The analysis step allows you to examine your results to see if your hypothesis is supported. 9. The next step would be to restart the scientific method with a new hypothesis. 10. cycle 18  Chapter 3 CHARACTERISTICS OF LIFE All living things share the same characteristics of life: They are made up of one or CELLS more CELLS. The basic units of life. They need energy to live. They respond to STIMULI - STIMULUS they react to their environment (pl. stimuli) (for instance, light, temperature, Anything that and touch). causes a response. 19 LIFE FUNCTIONS All ORGANISMS (living things) must have the potential to carry out certain behaviors, known as LIFE FUNCTIONS. Life functions are processes that an organism takes on to help it survive. The life functions are: 1. Growth : an increase in the number of cells. Some organisms, in order to live bet ter in an environment, need more cells. As more cells are made, the organism goes through the process of growth. Adults are larger in size than babies because they have more cells. The growth in cells helps them live better in their environment. parent 2. Reproduction : the creation of a offspring new organism with its own cells. A new organism is created from parent organisms. The new organism is referred to as OFFSPRING OFFSPRING. Some offspring are born looking like their 20 parents (for example, human babies); other offspring are born in one form and then change as they grow to another (like tadpoles changing into frogs). Reproduction can happen with either one- or two-parent organisms. When one parent organism reproduces by itself, the process is called ASEXUAL REPRODUCTION. REPRODUCTION The offspring looks like the parent. Bacteria usually reproduce asexually. When two parents reproduce, it’s called SEXUAL REPRODUCTION. Many plants and animals are sexual REPRODUCTION reproducers. 3. Nutrition : the taking in of food (nutrients). All living things need NUTRIENTS to survive. Nutrients keep an organism healthy. NUTRIENT Any substance that promotes life and Organisms can be categorized provides energy. according to how they get their nutrition: 21  AUTOTROPHS , organisms that can make their own food, such as plants. HETEROTROPHS , organisms that cannot make their own food, such as animals. Auto comes from the Greek word autos, meaning “self.” Hetero comes from the Greek word heteros, meaning “other.” -troph comes from the Greek word trophos, meaning “one who is nourished.” Autotrophs are nourished by themselves, and heterotrophs are nourished by others. 4. Respiration : the breakdown of nutrients to get energy. After nutrients are ingested, METABOLISM begins. There are two metabolic processes: DIGESTION , where nutrients METABOLISM are broken down into simpler The set of chemical forms that are easier for the reactions that maintain organism to use. the life of an organism. 22  CELLULAR RESPIRATION , using glucose and oxygen along with chemical reactions to produce energy from nutrients. 5. Transport : In humans, it involves, for example, the movement of nutrients from the stomach to the cells. Before simple nutrients can be used by cells, they must first be CIRCULATION transported from the stomach The movement of throughout the body in a process something through called CIRCULATION. Once the the body of an organism. nutrients reach the cell, they are absorbed and become part of the process of respiration. 6. Synthesis: the use of energy to build more complex chemicals within the body, such as carbohydrates and proteins. 23 When an organism gets the energy it needs, it can create complex chemicals that perform various tasks. For example, it can create proteins, which help support the structure and function of the body. 7. Excretion : Removes waste products from the body. Not all substances ingested are nutrients. Some of these substances are not useful to an organism. In these cases, the organism excretes the substance. There are some substances that act as both a nutrient and a waste product. After the organism excretes it, they must replace the product by ingesting or creating more of it. Water is an example of a material that humans ingest that is also a waste product. We drink it, and also excrete it, for example, as sweat. 8. Regulation : Organisms survive in changing environments by changing the conditions within their bodies. 24 Organisms sense what is happening in their environment and adapt to any changes in order to maintain HOMEOSTASIS. HOMEOSTASIS A state of steady internal physical and chemical conditions set by the body. Homeostasis keeps an organism alive despite a changing external environment. Homeostasis comes from the Greek words homeo, meaning “same,” and stasis, meaning “state.” Homeostasis describes a state in which something remains the same. An example of homeostasis in humans: When it’s hot, we sweat to cool down our bodies. When it’s cold, we shiver, which helps warm up our bodies. An organism’s body can also change over time to bet ter fit a ADAPTION new environment. This process A behavior or physical characteristic that allows is called ADAPTION. Some an organism to survive evolving creatures may gain new or reproduce in its traits that help them survive in environment. their environment. 25 Adaptations are changes in a species that occur over many generations due to environmental pressures. The organisms do not make a conscious choice to adapt. Adaptations can be behavioral or physiological. Camels have adapted to NO THANK S, living in the desert. They are I’M FIN E. known to be able to survive without drinking water for six or seven months. 26 w 1. What are three characteristics of all living things? 2. What are life functions? 3. Growth is the increase in the amount of within an organism. 4. What is the outcome of reproduction? 5. What form of reproduction do bacteria usually undergo? 6. Why are nutrients important? 7. What are the methods by which nutrients can be gained? 8. When a substance is not useful to the body, it is. 9. What is the purpose of homeostasis? 10. How does adaption impact an organism’s ability to survive in their environment? answers 27  11.. They are made of cells, need energy to survive, and respond to stimuli. 2. The processes that an organism takes on that help it survive 3. cells 4. The creation of a new organism 5. Asexual reproduction 6. Nutrients are substances that promote life and provide energy. 7. Nutrients can either be created by the organism or ingested. 8. excreted 9. Homeostasis maintains the stability of the body’s internal environment. 10. An organism may gain new traits that can either help it survive in its environment or prevent its survival. 28  Chapter 4 BIOLOGICAL CLASSIFICATION CLASSIFICATION The process of organizing living things is called CLASSIFICATION. Scientists classify organisms by their structure and how closely related they are. They arrange them into groups and categories based on the features they have in common. Classification Hierarchy TAXONOMISTS, scientists who classify organisms, developed TAXONOMISTS categories to organize every discovered organism. The categories are DOMAIN DOMAIN, KINGDOM KINGDOM, PHYLUM PHYLUM, CLASS CLASS, ORDER ORDER, FAMILY, GENUS FAMILY GENUS, and SPECIES SPECIES. 29 The order of categories from the broadest (at the top) to the most specific (at the bot tom) : D OM A IN K IN G D OM P H YL UM CL A S S OR DER FA M IL Y S E E, IT G ETS M OR E It looks like S P EC IFIC! an upside- down G E N US pyramid. S P ECIE S 30 Use this mnemonic to recall the classification system: D emanding K ids P refer C heese O ver F ried G reen Spinach! D omain, K ingdom, P hylum, C lass, O rder, F amily, G enus, Species There are fewer and fewer organisms as you get to the more specific categories. So, a kingdom has many more organisms than a genus. DOMAIN The domain is the highest rank in the classification system. It is the broadest of all categories. Domain divides life-forms into three categories. All organisms fall under these three groups. Eukarya Bacteria Archaea 31 KINGDOM Kingdom has the second-highest rank in the classification system. It is divided into six groups: Archaebacteria, Eubacteria, Protista, Fungi, Plantae, and Animalia. Organisms within each kingdom have different characteristics from organisms Latin names in the other kingdoms. ARCHAEBACTERIA From the Archaea domain Single-celled organisms Live in extreme environments: hot, toxic, acidic, or salty EUBACTERIA From the Bacteria domain Single-celled organisms Live everywhere that archaebacteria don’t There are more eubacteria living in your mouth than there are humans living on Earth! But most of them are harmless. PROTISTA From the Eukarya domain Single-celled or multicellular organisms Can be similar to Fungi, Plantae, or Animalia kingdoms in behavior and structure 32 FUNGI From the Eukarya domain Single-celled or multicellular organisms Are decomposers Mainly live in soil break down and recycle nutrients back into the environment PLANTAE Also known as the PLANT KINGDOM From the Eukarya domain Y E P! Multicellular organisms Earth’s primary producers of oxygen. Plants are crucial to the life of almost every other organism. ANIMALIA Also known as the ANIMAL KINGDOM From the Eukarya domain Multicellular organisms Breathe oxygen during the process of metabolism 33 PHYLUM Organisms in different phyla (plural of phylum) have different traits from one another. In the Animalia Kingdom, Kingdom there are many phyla. These phyla are divided into two categories: VERTEBRATES- have a backbone VERTEBRATES (for protection and mobility); make up 3 percent of all phyla in the Animalia kingdom. Examples: mammals, fish, amphibians, birds, reptiles INVERTEBRATES- have no INVERTEBRATES backbone; make up 97 percent of all phyla in the Animalia kingdom. Examples: anthropods (lobsters, crabs, insects, spiders), mollusks, worms Because vertebrates have so few organisms in comparison to invertebrates, they have their own phylum: CHORDATA CHORDATA. 34 All CHORDATES (organisms in the Chordata group) have these features at some point in their lives: pharyngeal slits-openings slits that connect the inside of the throat to the outside, the neck; sometimes develop into gills. dorsal nerve cord dorsal nerve cord-runs cord down the back of the animal, connecting the brain with muscles and other organs. notochord-a rod running beneath the notochord nerve cord and supporting it. post-anal tail-a tail section of the body that extends beyond the anus, used for movement. In many vertebrates (like humans) some post-anal tail of these features appear only during the embryonic stage (before the organism is born). CLASS Organisms classified as Chordata are separated further into groups, called CLASSES CLASSES. There are seven classes in all. Three fish classes: agnatha (jawless), chondrichthyes (cartilaginous), and osteichthyes (bony); and: 35 Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Even though these organisms are of various classes, they are related because they are all vertebrates. ORDER There are different groups of animals in each class. These groups are called ORDERS ORDERS. For example, Primates are an order within the Mammalia class. Animals in the Primate order are known for having large brains compared to their body Primates include weight, flat nails on their fingers apes, gorillas, orangutans, lemurs, instead of claws, and demonstrate and baboons. social organization. 36 FAMILY FAMILY is the subgroup of order. For example, there are 16 families within the Primates group. One of the Primate families is the HOMINIDAE HOMINIDAE, also known as the “great apes.” Great apes are known to have a large body size, no tail, and eat both plants and other animals. Gorillas and orangutans are part of the Hominidae family. All members of this family can recognize themselves in mirrors. This type of self-awareness is only possible in complex brains. GENUS There are four genera (plural of genus) in the Hominidae family : Homo - humans Pongo -orangutans gorilla (genus name is Gorilla) Pan -chimpanzees and bonobos 37 The Homo genus is composed of organisms that walk primarily on two legs, can make tools to solve problems, and have well-developed opposable thumbs. thumbs that can touch the other fingers, giving the ability to grip objects Homo comes from the Latin word homonis, which means “human being.” Only humans exist in this genus. SPECIES The smallest and most specific unit of classification is the SPECIES. Species are groups of organisms with similar SPECIES characteristics that are able to reproduce only with one another. For example, humans can reproduce only with other humans. Hi. I’m a Eukaryote- Animalia-Chordata- Mammalia-Primates- There were once three species within Hominidae- Homo - sapiens ; the Homo genus: the habilis , the erectus , aka human. and the sapiens. Now there is only one- the sapiens. The other two species have no living members. Modern humans fall under the sapiens species. This species is separated from the other species by the size of its skull, 38 which developed to protect its large brain. Sapiens are capable of making advanced tools for both survivability and entertainment. Example of a species classification: a domestic cat. Do m ain: Eu ka ry ota (orga nism s with co mp lex cells) King do m: An im alia Phylum: Chordata Class: Mammalia Order: Carnivora Fam ily: Felidae G en us: Felis S p ecies: catus 39 Binomial Nomenclature Biologists use CAROLUS LINNAEUS’s LINNAEUS Carolus Linnaeus system of classification when (1707–1778) referring to an organism. is known as the father Linnaeus’s system, which entails of taxonomy because his system of classification, naming species using two terms, is created in the 1700s, called BINOMIAL NOMENCLATURE. NOMENCLATURE is still used today. This just means “a name with two terms.” The first word defines the genus genus, which is the smallest group of similar species, and the second word defines the species itself. Binomial nomenclature is sort of like a first and last name-one is more specific than the other. Binomial nomenclature helps scientists from all over the world know which organisms have which characteristics. Examples of binomial nomenclature system: humans = Homo sapiens dogs = Canis familiaris cats = Felis catus Binomial comes from the Latin prefix bi-, which means “two,” and the Latin word nomia, which means “term.” Nomenclature comes from the Latin words nomen, meaning “name,” and clatura , meaning “calling.” Binomial nomenclature translates to “two-term naming.” 40 w 1. What is the purpose of classification? 2. What are the highest and lowest levels of classification? 3. How are eubacteria and archaebacteria different? 4. Which of the kingdoms survives best in hot and acidic environments? 5. What is a special characteristic of fungi? 6. The phylum of organisms with a backbone is called. 7. How are fish, amphibians, reptiles, birds, and mammals related? 8. What species do human beings belong to? 9. A two-term name is called a. 10. What two groups make up the two-term naming system? answers 41  1. To organize the organisms that have been and will be discovered 2. Domain is the highest classification; species is the lowest. 3. Archaebacteria live in extreme environments. Eubacteria live in all other places that are not extreme. 4. Archaebacteria 5. Fungi are decomposers. Their function is to help break down and recycle nutrients into the environment. 6. Chordata 7. They all have a backbone. 8. Homo sapiens 9. binomial 10. The genus and the species 42  Unit 2 The Chemistry of Life 43  Chapter 5 ATOMS AND MOLECULES MATTER describes everything that we can touch, taste, see, MATTER Anything that has mass smell, or feel. Mat ter is anything and takes up space. that has mass (takes up space). The smallest unit of mat ter is the ATOM. Atoms are so small that ATOM The smallest they cannot be seen by the human unit of matter. eye or by a compound microscope. From the Greek word that means "cannot be divided." As an atom absorbs energy (in the Energy comes in the form of heat, light, sound), it vibrates form of light, sound, and heat. and then releases that energy. This is 44 because atoms prefer to have as Because the sun is lit tle energy as possible. For example, out in the morning when the sun’s bright light shines and not in the night, on Earth, it excites the atoms in the mornings are usually warmer than nights. atmosphere, causing them to release energy, mostly in the form of heat. Atoms are more stable the less energy they have. All atoms try to release energy to be as stable as possible. In science, cold temperature is defined as an absence of heat. This is why outer space, an environment with few to no atoms, has temperatures that can be as low as -455 degrees Fahrenheit. ELEMENTS Scientists have determined that there are around 118 different ELEMENT Any substance that kinds of atoms that exist in nature. cannot be broken down Different types of atoms are into any simpler called ELEMENTS ELEMENTS, and each has chemical substance. There are 118 elements. been listed in a PERIODIC TABLE of elements. 45  1 ← period → 1 H Hydrogen 1 1.0078 2 3 4 Li Be 3 Atomic Number 2 Lithium 6.941 Ber y llium 9.0122 Li Lithium Chemical Symbol 11 12 6.941 Element Name Na M g Sodium Ma g nesium Average Atomic Mass 3 22.990 24.305 3 4 5 6 7 8 9 19 20 21 22 23 24 25 26 27 K Potassium Ca Sc Calcium Scandium Ti Titanium V Vanadium Cr Mn Fe Chromium Man g anese Iron Co Cobalt 4 39.098 40.078 44.956 47.867 50.942 51.996 54.938 55.845 58.933 37 38 39 40 41 42 43 44 45 Rb Sr Rubidium Strontium Y Yttrium Zr Nb Mo Tc Zirconium Niobium Mol y bdenum Technetium Ru Ruthenium Rh Rhodium 5 85.468 87.62 88.906 91.224 92.906 95.95 98.9062 101.07 102.91 55 56 72 73 74 75 76 77 Cs Ba Caesium Barium Hf Hafnium Ta W Re Tantalum Tungsten Rhenium Os Osmium Ir Iridium 6 132.91 137.33 178.49 180.95 183.84 186.21 190.23 192.22 87 88 104 105 106 107 108 109 Fr Francium Ra Radium Rf Db S g Bh Hs Mt Rutherfordium Dubnium Seaborg ium Bohrium Hassium Meitnerium 7 ( 223 ) ( 226 ) ( 267 ) ( 268 ) ( 269 ) ( 264 ) ( 269 ) ( 278 ) 57 58 59 60 61 62 ← group → La Ce Pr Nd Pm Sm Lanthanum Cerium Praseody mium Neody mium Promethium Samarium 138.91 140.12 140.91 144.24 ( 145 ) 150.36 89 90 91 92 93 94 Ac Th Actinium Thorium Pa Protactinium U Uranium Np Pu Neptunium Plutonium ( 226 ) 232.04 231.04 238.03 ( 237 ) ( 244 ) 46  → ALKALI METALS → HALOGENS 18 → ALKALINE EARTH METALS → NOBLE GASES 2 → LANTHANIDES → ACTINIDES → NEW AN D PEN DING DISCOVERIES He Helium → TRANSITION METALS 13 14 15 16 17 4.0026 → UNKNOWN PROPERTIES 5 6 7 8 9 10 → POST-TRANSITION METALS → METALLOIDS B Boron C Carbon N Nitrog en O Ox yg en F Fluorine Ne Neon → OTHER NONMETALS 10.806 12.009 14.006 15.999 18.998 20.180 13 14 15 16 17 18 Al Aluminum Si Silicon P Phos phorus S Sulfur Cl Ar Chlorine Arg on 10 11 12 26.982 28.084 30.974 32.059 35.446 39.948 28 29 30 31 32 33 34 35 36 Ni Cu Zn Ga Ge As Nickel Co p p er Zinc Gallium Germanium Arsenic Se Selenium Br Bromine Kr Kr ypton 58.693 63.546 65.38 69.723 72.63 74.922 78.96 79.904 83.798 46 47 48 49 50 51 52 53 54 Pd A g Cd In Palladium Silver Cadmium Indium Sn Sb Tin Antimony Te Tellurium I Iodine Xe Xenon 106.42 107.87 112.41 114.82 118.71 121.76 127.60 126.90 131.29 78 79 80 81 82 83 84 85 86 Pt Au Hg Platinum Gold Mercur y Tl Thallium Pb Bi Lead Bismuth Po At Rn Polonium Astatine Radon 195.08 196.97 200.59 204.38 207.2 208.98 ( 209 ) ( 210 ) ( 222 ) 110 111 112 113 114 115 116 117 118 Ds Rg Cn Nh Darmstadtium Roentg enium Co p ernicium Nihonium Fl Mc Lv Flerovium Moscovium Livermorium Tn Tennessine Og Oganesson ( 281 ) ( 281 ) ( 285 ) ( 286 ) ( 289 ) ( 289 ) ( 293 ) ( 294 ) ( 294 ) 63 64 65 66 67 68 69 70 71 Eu Gd Tb D y Ho Er Tm Yb Euro p ium Gadolinium Terbium D y s p rosium Holmium Erbium Thulium Ytterbium Lu Lutetium 151.96 157.25 158.93 162.50 164.93 167.26 168.93 173.04 174.97 95 96 97 98 99 100 101 102 103 Am Cm Bk Americium Curium Berkelium Cf Californium Es Einsteinium Fm Md No Lr Fermium Mendelevium Nobelium Lawrencium ( 243 ) ( 247 ) ( 247 ) ( 251 ) ( 252 ) ( 257 ) ( 258 ) ( 259 ) ( 262 ) 47  Dmitry Ivanovich Mendeleyev, a Russian scientist, invented the periodic table in 1869. The periodic table is like a huge grid in which all the elements are organized. Each element sits in a specific place in the grid, according to its ATOMIC NUMBER. The number of protons in an element define its position in the table according to MODERN PERIODIC LAW. LAW SYMBOLS, NUMBERS, AND NAMES OF THE PERIODIC TABLE Each element on the periodic table is assigned a CHEMICAL SYMBOL , which is one or two let ters. The first let ter is always uppercase and the second let ter (if there is one) is lowercase. For example: Sodium is Na Magnesium is Mg Sulfur is S Element- composed of one type of atom Element Periodic table-a table table of all the elements Chemical symbol-one symbol or two let ters that represent each element 48 Each square on the periodic table has the same information: the atomic number, the chemical symbol, the element name, and the average atomic mass. Atom ic num ber Chem ical symb ol Elem ent nam e Aver age atom ic mass The atomic number is the number of protons an atom contains. Each element has a different number of protons that makes it unique. The atomic mass is the average mass of a typical atom of that element. The periodic table is organized by rows and columns. A horizontal row is called a PERIOD. A vertical column is called a GROUP or FAMILY. The elements are arranged from left to right by increasing ATOMIC NUMBER. As you go across from left to right, each element has one more electron and one more proton than the element to the left of it. 49 For example, Hydrogen (H) has one proton, Helium (He) has two protons, and so on. Elements in the same column have similar physical and chemical properties. Despite elements being different from one another, they are all made up of the same three particles: PROTONS PROTONS, NEUTRONS, and ELECTRONS NEUTRONS ELECTRONS. All three of these elements SUBATOMIC PARTICLE are referred to as A substance that is smaller than an atom. SUBATOMIC PARTICLES. Neutron ATOM Proton Electron Sub is a prefix meaning “under” or “below”; subatomic means “below an atom.” Subatomic particles refer to particles that are below an atom in size. All three particles have different qualities. Both protons and electrons contain ELECTRICAL CHARGES , or quantities 50 of electricity that can be either positive or negative. Protons hold a positive electrical charge. Electrons hold a negative charge. Particles with the same electrical REPEL To push away from. charge tend to REPEL one another, while those with opposite charges ATTRACT one another. ATTRACT To bring closer to. Neutrons do not have a charge. Neutrons play a key role in the structure of the atom. The center of an atom is its NUCLEUS , which is made of both protons and neutrons. The protons within the nucleus give it a positive charge, which at tracts the negatively charged electrons, causing the electrons to orbit (move around) the nucleus. Atoms that have the same number of protons, but different numbers of neutrons, are called isotopes. Because atoms are so small, scientists need to use models to represent them. However, because the atom cannot be seen 51 by humans, the model of the atom has changed many times as scientists have learned more about it. Nucleus Orbit path Electron THE RUTHERFOR D MO DEL OF THE ATOM named after Ernest Rutherford The Rutherford model showed the atom as a tiny solar system with electrons orbiting around a nucleus. ELECTRON SHELL Electrons move outside the nucleus in various SHELLS, or energy levels. Think of shells as rings. The ring closer to the nucleus is numbered 1, followed by a ring around it numbered 2, which then has a ring around it numbered 3, and so on, as they extend outward. The greater the energy of the electron, the higher level shell it occupies (or the farther the outermost ring is from the nucleus). The relationship between the nucleus and the electron shells is similar to the relationship between the planets and the sun within the solar system. Planets orbit at certain distances 52 away from the sun. Some planets, such as Mercury, Venus, and Earth, have smaller orbits, while Mars, Jupiter, and Saturn have larger orbits. All the planets’ orbits are affected by the gravity of the sun. The planets that are farthest from the sun feel less of its gravity. An atom acts as its own solar system: The shells are the orbits taken by electrons, and the nucleus is the center that the electrons navigate around. The electrons in the shells closest to the nucleus (those that have the smallest orbits) are referred to as CORE ELECTRONS. Core electrons have the strongest at tractive force to the positively CORE charged nucleus, and so they are ELECTRONS The electrons in the the most stable. Stable subatomic shells closest to particles have the lowest energy the nucleus. within their atom. The electrons in the shells farthest VALENCE from the nucleus (those that have ELECTRONS the largest orbits) are called Electrons in the shells VALENCE ELECTRONS. Valence that are farthest away from the nucleus. electrons are more unstable than core electrons and have the highest energy levels. Because of this they are more likely to break away from the influence of the nucleus. 53 There can be more than Valence electrons one valence electron within a shell. The maximum 2 1 number of valence Core electrons in any orbit is electrons dependent on how small the orbit is. The closer the shell is to the nucleus, the fewer electrons there are. Nucleus This is due to the negative charge of each electron. If there were too many electrons in a small orbit, they would repel one another. This would cause the energy of the whole atom to increase, leading to a more unstable atom. The larger the orbit becomes, the more electrons can fit in it without influencing one another. The shell closest to the nucleus holds a maximum of 2 electrons, the next shell holds a maximum of 8, and the third holds a maximum of 18. Because of an atom’s preference for stability, electrons will always occupy the shells closest to the nucleus- the core shells-before occupying the shells farthest away. 54  Proton (red) Neutron Core electron (white) shell The Bohr model of Valence electron an atom includes the shell electron shells but is based on orbiting electrons like the BOHR MO DEL Rutherford model. The Bohr model shows 8 protons and neutrons in the nucleus of the atom, and 2 energy levels with 8 electrons. ATOMIC BONDING An atom usually seeks to be at its lowest energy state so that it can remain stable. There are two exceptions: Energy is added to it. An atom’s valence electron shell is not completely filled. Valence electrons contain a higher energy than other electrons in an atom. When an electron shell is filled, all electrons in that shell behave similarly to core electrons, increasing the atom’s stability and lowering its energy. An incomplete valence shell causes at tractive forces from the positively charged nucleus to spill out of the atom. Electrons that are nearby will move toward the nucleus and plug those leaks, completing the valence shell in the process. 55 Positive charge of nucleus attracts outside electrons The atom with an incomplete valence shell is like a leaky cup of water. Electrons plug the leaks and complete the valence shell. CARBON There are many atoms that have incomplete valence shells. These atoms participate in ATOMIC BONDING , the process where atoms interact with other atoms to lower their energy. There are different types of atomic bonding. One of the most prevalent is COVALENT BONDING. During this process atoms share pairs of electrons. The shared pairs of electrons fill the outermost energy levels of the bonded atom. A carbon atom needs 4 electrons to fill its outer energy shell. It bonds with 4 hydrogen atoms to share 1 electron from Electrons shared each atom. between carbon + hydrogen COVALENT BON D BETW EEN CARBON + 4 HY DROGEN 56 Atoms will bond with as many other MOLECULES atoms as necessary to complete A group of atoms their shells. These groupings are bonded together. called MOLECULES. If a molecule is made of two or more different elements, it is called a COMPOUND. COMPOUND Combinations of two or more Some elements are DIATOMIC , different atoms. meaning that they exist as molecules composed of two of the same atom. Diatomic molecules include oxygen, hydrogen, nitrogen, bromine, iodine, fluorine, and chlorine. DIATOMIC HY DROGEN MATTER Scientists define anything that takes up space as mat ter. Mat ter is created by the various ways that atoms bond. Mat ter can appear in different states-solid, liquid, or gas. The arrangement of the molecules or atoms (generally called "particles") and how they behave determine the characteristics of substances. The amount of movement of the molecules and the distance between them determine its state. 57 STATE OF DEFINITION EXAMPLE MATTER Solid Tightly packed atoms Rocks Rigid Ice Wood atom Liquid Atoms are close to one Water another, but not tightly Blood packed together. Gasoline Atoms slide past one another, so it does not atom have a defined shape. Gas Atoms are relatively Air distant from one Water Vapor another. Carbon Dioxide atom 58 w 1. How many elements have been cataloged in the periodic table of elements? 2. What three particles are atoms made of? 3. What does it mean to say that a particle is “subatomic”? 4. What do protons and electrons contain that a neutron does not? 5. electrons are electrons with shells close to the nucleus. 6. What is the reason for the small number of electrons in the shell closest to the nucleus? 7. Why does an atom bond? 8. What occurs in a covalent bond? 9. What is the difference between an atom and a molecule? 10. What is the difference between a solid and a gas? answers 59  1. 118 elements 2. Protons, electrons, and neutrons 3. A subatomic particle is a particle that is smaller than an atom. 4. An electrical charge 5. Core 6. The shell closest to the nucleus has a small orbit. A small number of electrons ensures that they don’t interfere with one another. 7. It bonds to lower its energy and increase its stability. 8. Atoms “share” their electrons with one another. 9. An atom is the smallest unit of an element which may or may not exist independently. A molecule is a group of atoms bonded together. 10. In solids, atoms are tightly packed together. In gases, atoms are farther apart. 60  Chapter 6 THE IMPORTANCE OF WATER PROPERTIES OF WATER Water is one of the molecules that is crucial to all living things. It is also one of the most abundant molecules on Earth. Water is made through the covalent bonding of two hydrogen atoms and one oxygen atom. Oxygen Hydrogen WATER MOLECULE 61 Water is unique because of the kinds of atomic bonds that it can form. Water utilizes HYDROGEN BONDING, BONDING a type of chemical bond between hydrogen and one or more atoms such as fluorine, oxygen, or nitrogen. Fluorine, oxygen, and nitrogen are different from other atoms because of their high ELECTRONEGATIVITY. Atoms that are very electronegative, like oxygen, at tract the ELECTRONEGATIVITY electrons in the bond The ability to attract electrons. closer to its nucleus. Remember the three electronegative atoms by the acronym FON (sounds like fun): Fluorine, O xygen, N itrogen. Electronegativity causes the creation of a positive and a negative DIPOLE within a molecule. When an electronegative atom pulls electrons toward it, that atom becomes more negatively charged and the other DIPOLE Occurs due to unequal atoms in the bond become sharing of electrons between more positively charged. atoms in a molecule. 62 In water, oxygen is more electronegative than hydrogen. This means that the oxygen atom acts as a negative dipole, while both hydrogen atoms act as positive dipoles. Dipole comes from the prefix di-, which means “two,” and the word pole, which refers to a point or position. A dipole refers to two positions within a molecule: a negative and a positive position. Electrons, represented by the dots, are drawn to the more electronegative oxygen, which makes the oxygen atom more negative and the hydrogen atoms more positive. Molecules like water, which have these dipoles, are called POLAR MOLECULES. MOLECULES Just as opposite electrical charges at tract, so do opposite electrical dipoles. The negative dipole created by the oxygen atom in one water molecule is attracted to the positive dipoles created by the hydrogen atoms in another water molecule, resulting in the hydrogen bond between two molecules. 63 Hydrogen bonds are weak bonds; they tend to break and re-form between many different water molecules. Although these bonds are weak, they are formed just as fast as they are SURFACE broken. This breaking and re- TENSION forming of bonds are what makes The rigidity of a liquid the surface of water flexible and caused by the bonds created in its surface. strong. Hydrogen bonds increase water’s SURFACE TENSION. Negative Positive dipole dipole Having a high surface tension makes water incredibly stable. As the stability of a liquid increases, it is less likely to change its state. As a result, it is more difficult to boil water into a gas or to freeze it into a solid than other liquids. 64  Water’s boiling point is 100 degrees Celsius, and its freezing point is 0 degrees Celsius. On Earth, air temperatures never get hot enough for water to boil, and only get cold enough for it to freeze on some days in winter. WATER IN BIOLOGY Biologists have traced the history of living things back nearly four billion years. Many scientists believe that the first living organisms originated in the depths of the seas, near volcano-like vents that provided valuable heat. Since then, all organisms have relied on water to survive. For example, plants need water to begin their food-making process (photosynthesis) and fish need water to breathe. Humans are made of more than 60 percent water. Our lungs, skin, kidneys, muscles, and brains are all more liquid than solid. The primary reason that humans breathe is to create both energy and water through the process of cellular respiration. Because water is so important, humans need to consume a lot of it just to maintain homeostasis. 65 The most abundant element in Human brains, humans is oxygen, which not hearts, and lungs are more than 60 percent only helps us breathe but also water. So are most helps us create our own water. muscles in the body. Water also has biological importance because of its ability to dissolve many other molecules. For example, blood is composed of a liquid part, called PLASMA , and a solid part, which contains various types of cells. The blood’s plasma is a mixture of solids, proteins, and salt, dissolved in water. 66 w 1. What is water composed of? 2. What atoms are necessary for hydrogen bonding? 3. What is electronegativity? 4. How are dipoles related to electronegativity? 5. What is a hydrogen bond in terms of dipoles? 6. What is the function of hydrogen bonds in water? 7. Having a high makes water stable. 8. As the stability of a liquid increases, it’s less likely to change. 9. What is blood plasma composed of? answers 67 1. Two hydrogen atoms and one oxygen atom 2. Hydrogen and one or more atoms of either oxygen, fluorine, or nitrogen 3. Electronegativity is an atom’s ability to at tract electrons. 4. Electronegative atoms create dipoles when bonding. 5. Hydrogen bonds are the bonds between negative and positive dipoles. 6. Hydrogen bonds increase the surface tension of water. 7. surface tension 8. state 9. Blood plasma is composed of solids, salt, and proteins dissolved in water. 68  Chapter 7 ORGANIC COMPOUNDS Water is one of the most important molecules for life because of its stability and ability to bond with other water molecules. Its components, hydrogen and oxygen, are two of the most abundant elements on Earth and within living organisms. However, life requires more than just hydrogen and oxygen to exist. Life also depends on the element CARBON CARBON. Carbon and hydrogen are called ORGANIC ELEMENTS because they make up more than 90 percent of every living organism. Any molecules created by the bonding of Organic means “related carbon and hydrogen with to ‘organisms.’” Anything organic is related to living other elements are called things. Organic chemistry is ORGANIC COMPOUNDS. a discipline in chemistry that studies organic compounds. 69 CARBON Carbon is an incredibly stable substance that can bond with itself. Because carbon contains four valence electrons and space for four more electrons in its valence shell, it is capable of covalently bonding with four different atoms. Carbon is capable of bonding with other carbon atoms, and often forms a long chain composed only of itself, called a CARBON CHAIN, on which multiple elements bond. CHAIN Hydrogen is the element that most commonly binds to carbon in organisms, forming the simplest kind of organic compound, referred to as a HYDROCARBON. Multiple hydrocarbons bonded together form a HYDROCARBON CHAIN. CHAIN Carbon + Carbon = Carbon Chain Hydrogen + Carbon = Hydrocarbon Chain Hydrocarbon + Hydrocarbon = Hydrocarbon Chain Hy dr oc ar bo n ch ain Long hydrocarbon chains are common in the human body. 70 ESSENTIAL ORGANIC COMPOUNDS Depending on the elements added to a hydrocarbon chain, an organic compound can change in complexity and function. There are four such organic compounds. When oxygen is added onto the hydrocarbon chain, it forms a complex group of molecules called CARBOHYDRATES. Carbohydrates provide an organism with energy. In humans and plants, the most valuable carbohydrate is a sugar called GLUCOSE , All sugars are carbohydrates. which is broken down to produce energy. LIPIDS have a larger amount of carbon and hydrogen than oxygen. Lipids assist in the storage of energy. The human body often converts carbohydrates into lipids and vice versa depending on whether energy is needed or not. PROTEINS contain oxygen, nitrogen, and, in some cases, sulfur on the hydrocarbon chain. Proteins are required for the function of the body, including its structure and regulation. In NUCLEIC ACIDS, oxygen, nitrogen, and phosphorus are bonded to the hydrocarbon. Nucleic acids are responsible for storing the information that allows the body to make proteins. These organic compounds are necessary for reproduction. Each organism’s DNA is made of nucleic acids. 71  FOUR ESSENTIAL ORGANIC COMPOUNDS ORGANIC ATOMS FUNCTION COMPOUND INVOLVED Carbohydrates Carbon, Hydrogen, Provides energy Oxygen for an organism Lipids Carbon, Hydrogen , Stores energy for Oxygen (in small an organism concentrations) Proteins Carbon, Hydrogen, Helps with the Oxygen, Nitrogen function of the (and Sulfur, in body, including some cases) structure and regulation Nucleic Acids Carbon, Hydrogen, Stores information Oxygen, Nitrogen, that the body uses Phosphorus to make proteins 72 w 1. What three elements are most necessary for life? 2. What percentage of living organisms are hydrocarbons? 3. Carbon and hydrogen are referred to as elements. 4. What makes carbon similar to water? 5. How many other atoms can carbon bond with? 6. What is the most common element that binds with carbon in organisms? 7. What is the basis for all complex organic compounds? 8. What atoms are carbohydrates and lipids made of? 9. What atoms are proteins made of? 10. What is the function of nucleic acids? answers 73  1. Carbon, hydrogen, and oxygen 2. More than 90 percent 3. organic 4. Like water, carbon is a very stable substance, because it is capable of bonding with other carbon atoms. 5. Four 6. Hydrogen 7. Hydrocarbons 8. Carbon, hydrogen, and oxygen 9. Carbon, hydrogen, oxygen, nitrogen-and sulfur in some cases 10. Nucleic acids store the information that allows the body to make proteins. 74  Chapter 8 CHEMICAL REACTIONS AND ENZYMES Atoms and molecules try to lower their energy level to the lowest possible state. In order to do so, they will often form CHEMICAL BONDS. BONDS Each chemical bond also changes the identity of the original substances that were combined. For example, when two hydrogen atoms and one oxygen atom bond, it creates water, which is a different substance from either hydrogen or oxygen alone. Whenever chemical bonds are formed or broken, a CHEMICAL REACTION takes place. In all chemical reactions, there are REACTANTS REACTANTS, which are the substances that interact with one Water is the product of its reactants: hydrogen another, and PRODUCTS PRODUCTS, the result and oxygen. of the reaction. ENZYMES Molecules that affect the rate of chemical reactions. 75 CHEMICAL REACTIONS There are four different types of chemical reactions. TYPES OF CHEMICAL REACTIONS Combination Reaction Two or more reactants (atoms) form a product (molecule). A+B AB Decomposition Reaction A molecule (reactant) becomes two or more simpler molecules or atoms (products). AB A+B Combustion Reaction Hydrocarbon + oxygen become carbon dioxide and water. Displacement Reaction A reactant replaces an atom in another reactant. Single-displacement : AB + C A + CB Double-displacement : AB + CD AD + CB 76 COMBINATION REACTIONS The most common reaction is a combination reaction. This is where two or more reactants combine to form a molecule. If there are many reactants, then it is likely that more than one product will be created. atoms A+B AB (reactants) molecule (product) An example of combination reaction is the reaction that creates water: two hydrogen atoms and one oxygen atom reacting to form water. DECOMPOSITION REACTIONS Decomposition reactions are the opposite of combination reactions. These reactions occur when a complex molecule is broken down into simpler molecules or atoms. In this case, the molecule is the reactant, and the atoms are the products. AB A+B atoms (product) molecule (reactant) 77 COMBUSTION REACTIONS Combustion reactions are chemical reactions in which the reactants include a molecule and oxygen. If the reactant is a hydrocarbon, the products will always include carbon dioxide and water. water reactants (hydrocarbon) carbon dioxide A combustion reaction is the reason humans breathe out carbon dioxide! DISPLACEMENT REACTIONS Displacement reactions are those in which one or more reactant element replaces another element within a compound. This is a single-displacement reaction, in which one element replaces another. AB + C A + CB 78 This is a double-displacement reaction, in which two elements replace each other. AB + CD AD + CB ENZYME Chemical reactions don’t just happen randomly. Often, the reactants must have a certain level of energy for the reaction to take place. Otherwise, any atom that was near another atom would be able to bond with it, which could have bad consequences. The amount of energy needed to start a chemical reaction is referred to as ACTIVATION ENERGY. A chemical reaction is like a hill that reactants need to climb. At the bot tom of the hill there are two or more reactants. In order for the reactants to become a product, the reactants must climb the hill, reach the peak, and roll down the other side. That peak is the activation energy required. Reactant Product + Energy Reaction Occurs Activation energy hill 79 This energy requirement ensures that an organism can control when reactions take place. If they couldn’t, then reactants would be used up at random times and they wouldn’t be around when an organism needed them. If there was no activation energy, an organism would have to spend most, if not all, of its time taking in nutrients to replace reactants used in chemical reactions. proteins that act as biological regulators Organisms use ENZYMES to trigger chemical reactions. Enzymes provide reactants with an alternate pathway-one with lower activation energy- to become products. In other words, enzymes make the activation energy hill much lower. Because enzymes control when chemical reactions happen, they are often referred to as the CATALYSTS or REGULATORS of the body. Enzymes are necessary components for the functioning of organisms. However, they only function perfectly in the right environment. For example, temperature is one of the conditions that determine if an enzyme functions well. Cold- blooded animals, such as snakes, seek warmth in order for their bodies to function properly. When an organism’s enzymes cannot properly function, that organism will likely die. 80 w 1. Why do atoms bond? 2. What takes place when a bond forms or is broken? 3. What creates the products of a chemical reaction? 4. What kind of reaction takes place when two or more reactants combine to form a product? 5. What will always result from the combustion reaction of a hydrocarbon and oxygen? 6. The amount of energy needed for reactants to participate in a chemical reaction is called. 7. What is the benefit of a chemical reaction needing a certain amount of energy? 8. What do enzymes do? 9. Name two factors that can control whether an enzyme works. 10. What can occur if the conditions that enzymes need are not met? answers 81  1. Atoms bond to lower their energy level. 2. A chemical reaction 3. An interaction between reactants 4. Combination reaction 5. Both carbon dioxide and water 6. activation energy 7. It prevents chemical reactions from occurring when they’re not necessary. 8. Enzymes provide reactants with an alternate pathway that requires lower activation energy. 9. Temperature and environment 10. The death of the organism 82 Unit 3 Cell Theory 83  Chapter 9 CELL STRUCTURE AND FUNCTION For life to happen, there must be a place where organisms perform the functions crucial to life. This place is the cell cell. The cell is the foundation of all life. Cells perform most of the chemistry within an organism, and they also make up the structures within the body. There are three principles that are true of all cells: 1. They make up all organisms (one or more cells). 2. The cell is the basic building block of the structure and function of life. 84 3. Every cell comes from another existing cell (cells divide to form new cells). Cells work together in groups called TISSUES TISSUES. These tissues work together to form ORGANS ORGANS, like the heart and brain. Every organ works together within an organism, performing different functions to keep the organism alive. Many cells ➜ tissues Many tissues ➜ organs All organs ➜ organism Cells are able to perform different functions because of ORGANELLES. Organelles are parts of a cell, each having a different job. For example, organelles can: ORGANELLES The parts of a cell. produce energy make new proteins destroy and digest objects Organelle means “small organ.” They are the small organs that help the cell function, just like the heart, brain, and lungs help the human body function. 85 ANIMAL CELL ORGANELLES Animal cells are similar in the organelles that they contain: A Typical Animal Cell A typical animal cell is made up of these organelles: 1. Cell Membrane The outer boundary of the cell in humans and animals is called the CELL MEMBRANE. MEMBRANE The cell membrane is SEMIPERMEABLE. It is also flexible, giving the cell SEMIPERMEABLE Allowing some things the ability to stretch and to selectively pass through. bend in many ways. 86  Cells are similar to houses. In order to get into a house with a locked door, you need the key that fits the lock. Materials can get into cells only if they have the correct key to open the cell’s door. 2. Cytoplasm Within the cell membrane, a jellylike substance exists in which all the organelles float. This substance is the CYTOSOL. The cytosol is mostly made of water; however, CYTOSOL the cytoplasm also contains a CYTOSKELETON , which is a network of protein fibers and tubes that maintain the structure of the cell and help move organelles within it. The cytoplasm acts as cushions to the organelles and like a road system to transport proteins, metabolites, and other substances. 3. Ribosome A RIBOSOME is a small organelle that produces proteins. The proteins are based on information given to the ribosomes by the organism’s nucleic acids. Ribosomes are told which types of protein to make according to the cell that they reside in. 87  “-some” comes from the Greek soma, which The suffix means “body.” “ribo-” refers to the carbohydrate ribose, which is an organic compound that forms the backbone of the ribosome. 4. Endoplasmic Reticulum The ENDOPLASMIC RETICULUM (ER) is composed of flat sacs and tubes that package proteins, transport materials throughout the cytoplasm, and get rid of waste that builds up within the cell from other organelles. Ribosomes can at tach themselves to the walls of the cell’s ER. This allows the cell to make protein and then immediately package it and send it off to where it needs to go inside or outside of the cell. 5. Golgi Apparatus The GOLGI APPARATUS works closely with the endoplasmic reticulum. These organelles are flat sacs that temporarily store, package, and transport materials through and out of the cell. 88 6. Lysosome A LYSOSOME is like a sac that contains enzymes that break down any kind of food, cell waste, or destroyed foreign organisms, such as bacteria or viruses. If waste products of the cell need to be disposed of, the Golgi apparatus will bring them to the lysosomes. If a cell is injured or damaged, lysosomes release their enzymes into the cytoplasm, digesting the cell from within. 7. Vacuole The cell doesn’t always have to use everything the moment it creates it or takes it in. VACUOLES help by storing water and nutrients until the cell needs them. Vacuoles can also provide a space for waste. often referred to as the cell’s powerhouses 8. Mitochondria The MITOCHONDRIA are some of the most critical organelles for the survival of an organism. In the mitochondria oxygen and sugars from food react in a series of chemical reactions to create energy. Just as ribosomes create different proteins according to which type of cell they’re in, mitochondria show up in various amounts according to the type of cell. 89  Muscle cells, which require the most energy, have the most mitochondria of all cells. Some cells, such as red blood cells, have no mitochondria. This is because the only function of red blood cells is to carry oxygen from the lungs to the cells. 9. Nucleus The NUCLEUS is called the “brain” of the cell because it holds the information needed to conduct most of the cell’s functions. It is usually the largest and is the most important organelle in the animal cell. In healthy cells, the nucleus contains CHROMATIN CHROMATIN, which are tightly wound strands of DNA (an acronym for deoxyribonucleic acid), the code for genetic traits like hair, skin, and eye color. This genetic information is passed down from cell to cell when they reproduce. The chromatin in a nucleus: This is how DNA exists in an ordinary nucleus. The length of all the DNA within one cell is about six feet long. 90 The nucleus has its own NUCLEAR MEMBRANE. MEMBRANE This membrane is different from that of the other organelles; it’s similar to the cell membrane. Other organelles have a single- layered membrane separating them from the cytoplasm, but the nuclear membrane has two layers offering it extra protection. The nuclear membrane also contains pores (small openings) so that materials can pass into and out of the nucleus. The nucleus has a NUCLEOLUS NUCLEOLUS, which creates RIBOSOMAL RNA (an acronym for ribonucleic acid). RNA exists to read and carry out the instructions given in DNA. Unlike DNA, which is trapped within the nucleus, RNA is able to leave through the openings in the nuclear membrane to deliver the instructions. Chromatin Nuclear envelope Nucleolus Nuclear pores 91 PLANT CELL ORGANELLES Plant cells contain the same organelles that animal cells have. But they have two additional organelles. A Typical Plant Cell 1. Cell Wall A plant cell’s cell wall lies outside the cell membrane. It behaves like the cell’s shield, protecting the cell. It also acts like a plant’s skeleton, giving it structure and keeping it upright. Cells still need to bring materials within these walls. Therefore, the cell walls, like cell membranes, are semipermeable. Plant cell walls are made of a carbohydrate called CELLULOSE. 92  Plants do not have a skeleton like humans do, yet they push through the soil and can rise up to incredible heights, like the redwood tree, which can grow up to 380 feet tall. Cellulose is the major component of cotton fiber and wood, and it is used in paper production. Cells in fungi, bacteria, algae, and some archaea also have cell walls. However, their cell walls are composed of different materials. Bacterial cell walls, for example, are composed of a sugar-and-amino-acid polymer called peptidoglycan. 2. Chloroplasts Plants use light and carbon dioxide to generate glucose through photosynthesis. The process happens in the CHLOROPLASTS CHLOROPLASTS, which contain CHLOROPHYLL CHLOROPHYLL, the substance that powers synthesis. Chlorophyll is the pigment that gives green plants their color. Chloroplasts are natural solar panels. Like solar panels on houses, chloroplasts use the light of the sun to create energy. 93 PLANT CELLS VS. ANIMAL CELLS The main difference between animal cells and plant cells lies in their structure. Without a rigid cell wall, animal cells stretch and bend and are able to take on multiple shapes. There are more than 200 kinds of animal cells. There are far fewer plant cells. This is partially due to how much more complex animals are than plants, but it is also because the rigidity of the plant cell wall prevents the cell from taking various shapes. The vacuoles of plant cells are also much larger than those of animal cells. This is because the plant has to store more water and generate its own food. Finally, plant cells have chloroplasts and animal cells do not. 94 w 1. All organisms are made of. 2. What is the function of an organelle? 3. What does it mean to say that a cell membrane is semipermeable? 4. What organelle do many ribosomes attach themselves to? 5. Which organelles transport waste outside the cell? 6. How do lysosomes break down various mater