Vocabulary about work

Vocabulary List 1. Avocation Definition: A hobby or activity someone enjoys doing in addition to their main work. Example: Drawing cartoons was his favorite avocation after school. 2. Supercolossal Definition: Extremely large; even bigger than enormous. Example: They ordered a supercolossal pizza to share. 3. Repress Definition: To hold back or keep feelings or thoughts hidden. Example: She tried to repress her anger during the argument. 4. Subliminally Definition: In a way that affects the mind without someone realizing it. Example: The music subliminally made the store feel calmer. 5. Thrombosis Definition: A medical condition where a blood clot forms inside a blood vessel. Example: The doctor warned that lack of exercise can increase the risk of thrombosis. 6. Sclerosis Definition: A hardening of body tissue, especially arteries or organs. Example: The patient was diagnosed with sclerosis that affected his mobility. 7. Distortion Definition: A change that makes something appear different from what it really is. Example: The funhouse mirror caused a distortion of her reflection. 8. Philanthropy Definition: The act of giving money or help to improve the lives of others. Example: His philanthropy helped build a new library for the town. 9. Prevarications Definition: Lies or evasive statements used to avoid telling the truth. Example: The teacher grew tired of the student’s prevarications about missing homework. 10. Syndrome Definition: A group of symptoms or behaviors that occur together. Example: The doctor studied the syndrome to better understand the illness. 11. Schizophrenic Definition: Relating to a mental disorder where a person may have difficulty distinguishing reality from imagination. Example: The character in the story showed schizophrenic behavior. 12. Subsidize Definition: To support financially, usually with money from the government or an organization. Example: The city decided to subsidize public transportation. 13. Phenomenal Definition: Very remarkable or impressive. Example: The athlete gave a phenomenal performance in the race. 14. Demented Definition: Showing disturbed or irrational behavior. Example: The villain in the movie had a demented laugh. 15. Patron Definition: A person who supports or regularly visits a business, artist, or organization. Example: She was a loyal patron of the local bookstore. 16. Cultural Lag Definition: When ideas and beliefs take longer to change than technology or society. Example: Cultural lag can make it hard for laws to keep up with new technology. 17. Omens Definition: Signs believed to predict something that will happen in the future. Example: Some people think black cats are omens of bad luck. 18. Antagonistic Definition: Showing hostility or opposition. Example: The rival teams were antagonistic toward each other. 19. Voluptuous Definition: Curvy and attractive in a full, rich way. Example: The sculpture showed a voluptuous figure. 20. Oscilloscope Definition: A device used to view and measure electrical signals. Example: The scientist used an oscilloscope to study the sound waves. 21. Putrid Definition: Rotting and giving off a very bad smell. Example: The garbage smelled putrid after sitting in the sun. 22. Fixated Definition: Focused or obsessed with something. Example: He became fixated on winning the competition. 23. Mundane Definition: Ordinary, dull, or routine. Example: She was tired of the mundane chores she had to do every day. 24. Ghouls Definition: Evil or ghost-like creatures that feed on the dead in stories or legends. Example: The haunted house story was filled with ghouls and monsters. 25. Maladjusted Definition: Unable to cope well with the demands of life or society. Example: The counselor helped the maladjusted student deal with stress. 26. Incongruous Definition: Not fitting in; out of place. Example: The fancy chandelier looked incongruous in the small cabin. 27. Tribute Definition: Something done or given to show respect or admiration. Example: The concert was a tribute to the famous musician. 28. Audibly Definition: In a way that can be heard clearly. Example: He audibly sighed when the test ended. 29. Proficiency Definition: Skill or competence in doing something. Example: Her proficiency in math helped her tutor other students.

Make a vocabulary quiz with below.Crisis: a very difficult situation or emergency; “Investors are worried that continuing problems in the stock market might lead to another financial crisis.” Short-staffed: not having enough employees or workers; “We laid off dozens of employees to save money, but now we’re short-staffed and can’t fill orders quickly.” To drive someone nuts: to make someone upset or annoyed; “The autocorrect feature on my mobile phone really drives me nuts.” To arise: to happen or start to develop, especially for problems or situations; “Problems arose for the developers when local residents voted against construction of the new shopping mall.” To moan: to complain about something, especially in a way that bothers other people; “Every Monday morning my colleagues moan about having to come to the office so early.” Optimism: the feeling or belief that good things will happen; “Analysts are expressing optimism that the real estate market will bounce back quickly.” Pessimism: the tendancy or belief that the worst will happen. “Now is not the time for pessimism, we need to believe we can do this or we will fail.” Hurdle: a problem that must be overcome or dealt with in order to reach a goal or do something; “Lack of capital is a major hurdle for many young entrepreneurs with good business ideas.” © 2013 All rights reserved: www.businessenglishpod.com 2 To give up: to stop trying to do or achieve something; “After being rejected by over a dozen universities, Roger gave up on his plans to study for an MBA.” To keep your eye on the prize: to stay motivated and focused on your final goal or reward; “Okay folks, I know things have been really busy, but let’s keep our eye on the prize and we’ll get this done before Christmas.” Down the road: in the future; “Sales our good in our retail outlets, but 10 years down the road we’re going to have to be more competitive in the online market.” To overcome: to deal with a problem successfully; “You are going to have to overcome your lack of confidence if you want to be a good salesman.” Decisiveness: having the ability to make decisions and act firmly. “Decisiveness is a quality we look for in new managers.” Bumpy: we can use “bumpy” to describe a road or process that has many problems; “We had a pretty bumpy start-up phase, but we finally managed to turn a profit in our fifth year of operations.” To display: to show a feeling, emotion, or characteristic; “David displayed tremendous preparation and diplomacy during the negotiations.” On the fence: someone who is “on the fence” is having difficulty making a decision or taking a position; “While the executives support expansion wholeheartedly, the shareholders are still on the fence about it.” All-in: in poker, if you are “all-in” you put all your money on one bet, but we can use this expression more generally to say you are completely committed to something, especially a plan; “This sounds like a good idea, but before I go all-in I need to know more about the project partners.” To have what it takes: to have the ability or intelligence to do something; “I thought I’d enjoy law, but after a few years as a junior lawyer I realized I don’t really have what it takes.

Sure! Here's a solid list of **AP English Literature vocabulary**—terms that often come up in class, essays, and the AP exam. I'll break it down into categories to make it easier to study. --- ### 📚 **Literary Devices & Techniques** 1. **Alliteration** – Repetition of initial consonant sounds 2. **Allusion** – A reference to another text, event, or figure 3. **Anaphora** – Repetition of a word or phrase at the beginning of successive clauses 4. **Antithesis** – Contrast of ideas in a balanced or parallel construction 5. **Apostrophe** – Addressing someone absent, dead, or nonhuman as if present and able to respond 6. **Assonance** – Repetition of vowel sounds within nearby words 7. **Asyndeton** – Omission of conjunctions between parts of a sentence 8. **Consonance** – Repetition of consonant sounds, often at the end of words 9. **Diction** – Word choice (formal, informal, colloquial, etc.) 10. **Enjambment** – Continuation of a sentence without pause beyond the end of a line in poetry --- ### 🧠 **Figurative Language** 1. **Hyperbole** – Extreme exaggeration 2. **Imagery** – Descriptive language that appeals to the senses 3. **Irony** - *Verbal*: Saying the opposite of what’s meant - *Situational*: When the outcome is the opposite of what's expected - *Dramatic*: Audience knows something characters don’t 4. **Metaphor** – A direct comparison without using "like" or "as" 5. **Metonymy** – Substituting the name of one thing with something closely related (e.g. "The crown" for royalty) 6. **Synecdoche** – A part representing the whole (e.g. "All hands on deck") 7. **Personification** – Giving human traits to nonhuman things 8. **Simile** – A comparison using "like" or "as" 9. **Symbol** – An object, character, or color that represents something beyond itself --- ### ✍️ **Poetic & Rhetorical Terms** 1. **Caesura** – A pause in a line of poetry, often marked by punctuation 2. **Couplet** – Two lines of poetry that usually rhyme 3. **Iambic Pentameter** – A line with five iambs (unstressed-stressed syllables) 4. **Blank Verse** – Unrhymed iambic pentameter 5. **Free Verse** – Poetry with no fixed meter or rhyme 6. **Elegy** – A mournful poem, often for the dead 7. **Ode** – A lyric poem expressing emotion, often in honor of something 8. **Sonnet** – A 14-line poem with a specific rhyme scheme (Shakespearean or Petrarchan) --- ### 📖 **Narrative & Structure Terms** 1. **Tone** – The author's attitude toward the subject 2. **Mood** – The feeling or atmosphere the reader experiences 3. **Theme** – The central idea or message in a work 4. **Motif** – A recurring element that has symbolic significance 5. **Foil** – A character who contrasts with another character to highlight traits 6. **Foreshadowing** – Clues or hints about what will happen later 7. **Juxtaposition** – Placing two elements side by side to present a contrast 8. **Point of View** – Perspective from which the story is told (1st, 2nd, 3rd person) 9. **Stream of Consciousness** – Narrative style that mimics thoughts and feelings 10. **Frame Narrative** – A story within a story --- Want me to make flashcards, a quiz, or a PDF study guide with these? Or need help using them in a literary analysis essay?

Alright, Isti — here’s a longer and more detailed English version of the Isaac Newton text, still written at a level that’s accessible for Grade 4 students, but rich enough in information to meet PISA literacy expectations and EF A2-level vocabulary. I’ve kept sentences short, clear, and with explanations for new concepts so it’s easier for young learners to follow, while still including both famous facts and lesser-known stories. ⸻ Isaac Newton: The Man Who Changed the Way We See the World A Boy from a Small Village Isaac Newton was born on January 4, 1643, in Woolsthorpe, a small village in England. His life was not easy. His father died before he was born. When he was just a few months old, his mother remarried and left him to live with his grandmother. Isaac missed his parents, but he kept himself busy by making things and exploring the world around him. As a child, Isaac liked to build models and machines. He made a small windmill that could turn with the wind. He built a water clock that told the time by dripping water into a container. He even made a sundial — a clock that tells the time by using the shadow of the sun. 💡 Did you know? The sundial marks that Isaac carved as a boy can still be seen today on the wall of his old house. ⸻ School and Curiosity When Newton first went to school, he was not the top student. At first, he did not pay much attention in class. But one day, another boy teased him for not being smart. Newton decided to study hard to prove him wrong. Soon, he became the best in his class. Isaac loved asking questions. He wanted to know how and why things happened. He enjoyed watching the stars at night and thinking about how the world worked. ⸻ The Falling Apple and Gravity One of the most famous stories about Newton is the falling apple. One afternoon, Isaac sat in his mother’s garden and saw an apple drop from a tree. This made him think: “Why does the apple fall straight down? Why doesn’t it fly up into the sky?” From this question, Newton began to think about gravity — an invisible force that pulls objects toward each other. Gravity is what keeps our feet on the ground. It’s also what keeps the Moon moving around the Earth and the planets moving around the Sun. 💡 Fun fact: The apple did not hit Newton’s head. That’s just a story people made up later to make the tale more exciting. ⸻ Newton’s Three Laws of Motion Newton studied movement and wrote three important rules: 1. Objects stay still or keep moving unless something makes them change. • Example: A ball will not roll unless you push it. 2. The bigger the push, the bigger the movement. • Example: If you kick a ball harder, it will go faster and farther. 3. Every action has an equal and opposite reaction. • Example: When you jump off a boat, the boat moves backward as you move forward. These three laws are still used today to understand how cars, rockets, and even roller coasters work. ⸻ Discoveries in Light and Color Newton also studied light. He found that white light is not just one color — it is made of many colors. He used a glass prism to split sunlight into a rainbow. This helped scientists understand how colors work. ⸻ Inventions and New Ideas Newton made a special telescope that used mirrors instead of lenses. This type of telescope made images of planets and stars much clearer. It is still called the Newtonian telescope today. He also worked in mathematics and helped create a new type of math called calculus, which is used to study changes and movement. ⸻ Strange Experiments Newton was so curious that he sometimes tested ideas on himself. Once, he put a thin needle, called a bodkin, beside his eye to see how it would change his vision. It was very dangerous, but luckily he did not go blind. 💡 Did you know? Newton also studied alchemy — an old kind of science where people tried to turn metal into gold. He never succeeded, but it showed how wide his interests were. ⸻ Later Life and Work At the age of 27, Newton became a professor at Cambridge University. He later worked for the Royal Mint, making sure coins were made safely and stopping people from making fake money. He was very strict, and some criminals were sent to prison because of his work. Newton never married. He spent most of his life reading, writing, and doing experiments. ⸻ The End of His Life Isaac Newton died in 1727 at the age of 84. He was buried in Westminster Abbey, a famous place in London where great people of Britain are honored. His work changed the world forever. Even today, scientists, engineers, and students still use Newton’s laws and ideas. 💬 Newton once said: “If I have seen further, it is by standing on the shoulders of giants.” This means we can make new discoveries by learning from the work of others who came before us. give 10 questions to each passage with PISA literacy standard for kid 10 years, 1. Nikola Tesla: The Man Who Dreamed of Lightning Born: July 10, 1856 Died: January 7, 1943 When Nikola Tesla was a boy in Croatia, he saw a flash of lightning and asked his mother, “Can we catch the light?” That question never left him. As he grew older, Tesla became a brilliant inventor, especially fascinated by electricity. He believed in a future where energy could be sent wirelessly through the air—like music through the radio! Tesla invented the alternating current (AC) system, which became the foundation of modern electricity. At the time, Thomas Edison promoted direct current (DC), and the two men had a fierce competition. Many laughed at Tesla's bold ideas, but he never gave up. He dreamed of wireless communication, flying machines, and even free energy for everyone. Though he died alone and poor, today the world honors his vision. Think About It: Why do you think people didn’t believe Tesla at first? What can we learn from Tesla’s courage to dream big? 2. Charles Darwin: The Man Who Studied the World’s Weirdest Creatures Born: February 12, 1809 Died: April 19, 1882 When young Charles Darwin got on a ship called HMS Beagle, he didn’t know he would change science forever. He sailed around the world for five years, collecting plants, animals, and fossils. On the Galápagos Islands, he noticed something curious: finches had different beaks depending on their island. Why? Darwin’s observations led him to write the theory of evolution by natural selection. It explained how animals adapt and survive. But his ideas shocked many people because they seemed to challenge religious beliefs. Despite the controversy, Darwin continued his work. His book On the Origin of Species changed how we see life on Earth. Think About It: Should scientists share their ideas even if they go against what others believe? How did traveling help Darwin make new discoveries? 3. Marie Curie: The Woman Who Glowed in the Dark Born: November 7, 1867 Died: July 4, 1934 Marie Curie was born in Poland at a time when girls were not allowed to study science. But that didn’t stop her. She moved to France, worked day and night, and discovered radioactivity, a powerful energy hidden inside atoms. She and her husband, Pierre Curie, found two new elements: polonium and radium. She became the first woman to win a Nobel Prize, and the only person to win in two different sciences: physics and chemistry. Even when Pierre died in an accident, Marie continued their work. Her discoveries helped doctors treat cancer—but working with radioactive materials also harmed her health. She died from radiation exposure, but her legacy lives on. Think About It: What challenges did Marie Curie face as a woman in science? Why is it important to balance discovery with safety? 4. Galileo Galilei: The Star Watcher Who Defied the Church Born: February 15, 1564 Died: January 8, 1642 Galileo loved looking at the stars. He built one of the first powerful telescopes and made stunning discoveries: mountains on the Moon, moons around Jupiter, and that the Earth orbits the Sun—not the other way around. This idea, called heliocentrism, went against the teachings of the Church. He was put on trial and forced to say he was wrong. But he wasn’t. He spent his last years under house arrest, quietly writing. Today, Galileo is called the father of modern science for daring to question what others blindly believed. Think About It: Why do you think Galileo was punished for telling the truth? Should science always follow evidence, even if it goes against powerful beliefs? 5. Isaac Newton: The Man Who Asked “Why?” When an Apple Fell Born: January 4, 1643 Died: March 31, 1727 One day, an apple fell from a tree, and Isaac Newton began to wonder: Why did it fall down, not sideways or up? This simple question led to his theory of gravity. Newton also invented calculus, described the laws of motion, and changed physics forever. But Newton wasn’t just a genius—he was curious, quiet, and often worked alone. He believed everything in nature followed rules, and it was our job to discover them. Thanks to him, we understand how planets move, how rockets launch, and why you fall when you trip. Think About It: How did Newton’s curiosity lead to great discoveries? Do you think working alone helped or hurt Newton? 6. Ada Lovelace: The First Computer Programmer Before Computers Existed Born: December 10, 1815 Died: November 27, 1852 Ada Lovelace was the daughter of the famous poet Lord Byron, but she didn’t love poetry—she loved numbers! At a time when girls were expected to sew, Ada studied mathematics. She met Charles Babbage, who designed an early computer called the Analytical Engine. Ada imagined the machine could do more than just math—it could create music, art, and even write! She wrote what is now considered the first computer program, long before real computers were built. Think About It: How did Ada imagine something that didn’t exist yet? Why do we call her a pioneer in technology? 7. Albert Einstein: The Man Who Brought Time and Space Together Born: March 14, 1879 Died: April 18, 1955 Albert Einstein wasn’t always a good student. In fact, his teachers thought he was slow. But Einstein thought deeply. He asked big questions like, “What if you could ride a beam of light?” His theories of relativity changed how we see space, time, and gravity. He also warned the world about the dangers of nuclear weapons, even though his ideas helped create them. Einstein believed science should help people, not harm them. With his messy hair, kind smile, and brilliant mind, he remains a symbol of genius. Think About It: Can someone be bad in school but still be brilliant? Should scientists be responsible for how their inventions are used? 8. Pythagoras: The Musician Who Loved Math Born: Around 570 BC Died: Around 495 BC Long ago in ancient Greece, Pythagoras believed the universe followed numbers. He discovered the Pythagorean Theorem, a rule about triangles that helps us build houses, design computers, and navigate space. He also believed that music had math inside it—that certain notes made perfect harmony because of mathematical ratios. Pythagoras started a secret school and taught his students to search for truth through numbers, shapes, and sound. Think About It: Why do you think Pythagoras saw math in everything? How does music relate to math? 9. Rosalind Franklin: The Woman Behind the DNA Discovery Born: July 25, 1920 Died: April 16, 1958 Rosalind Franklin loved looking closely at things. She used a special machine called X-ray crystallography to photograph molecules. One of her greatest photos, called Photo 51, showed the shape of DNA, the molecule that carries life’s instructions. But her work was taken without credit. Two men, Watson and Crick, used her photo to build their famous model of DNA and won the Nobel Prize. Rosalind died young and never knew how important her work became. Think About It: Why is it important to give credit in science? What can we learn from Rosalind’s quiet strength? 10. Carl Linnaeus: The Man Who Gave Names to Everything Born: May 23, 1707 Died: January 10, 1778 Have you ever wondered why a tiger is called Panthera tigris? That’s thanks to Carl Linnaeus, a Swedish scientist who created a way to name and organize every living thing. His system is still used today in biology. Linnaeus loved nature and spent his life collecting plants, animals, and even rocks. He believed that by organizing life, we could better understand it. Thanks to him, we now have a global “dictionary of nature.” Think About It: Why is it important to name and organize living things? How does order help us understand the world?

1. What is the main purpose of including theme and main idea questions in a text? a) To test your reading comprehension skills b) To understand the overall message or lesson of the text c) To practice identifying specific details in the text d) To improve your vocabulary and word knowledge 2. What is the purpose of finding the theme in a text? a) To summarize the main idea of the text in a few words b) To identify the specific details and examples in the text c) To understand the order of events in the text d) To analyze the author's writing style and techniques 3. Which of the following represents the theme of a text? a) A long sentence that describes the setting of the story b) A single word or short phrase that captures the main idea of the text c) A list of characters and their traits d) A detailed description of the plot and conflict in the story 4. How does identifying the main idea of a paragraph help you understand the text? a) It allows you to make connections between different parts of the text b) It helps you identify the author's purpose for writing the text c) It enables you to predict what will happen next in the story d) It helps you remember the specific details and examples in the paragraph 5. Which of the following best describes the main idea of a paragraph? a) The specific details and examples that support the theme of the text b) The order of events and actions in the paragraph c) The overall message or lesson conveyed by the paragraph d) The vocabulary words and their definitions in the paragraph 6. In a short paragraph about dogs, what could be a possible theme? a) Running and playing in the park b) Different breeds of dogs and their characteristics c) The loyalty and companionship dogs provide d) How to train a dog to do tricks 7. What might be the main idea of a paragraph about the importance of recycling? a) Recycling reduces pollution and conserves natural resources b) The process of recycling and how it works c) The different types of materials that can be recycled d) The history of recycling and its impact on society 8. Which of the following could be the theme of a paragraph about the benefits of reading? a) The importance of reading for academic success b) How to choose the right book to read c) The different genres of literature and their characteristics d) The role of libraries in promoting reading 9. If a paragraph discusses the life cycle of a butterfly, what would be the most likely main idea? a) The different colors and patterns of butterfly wings b) The stages of a butterfly's life from egg to adult c) The habitats and environments where butterflies live d) The types of plants that attract butterflies for feeding 10. What is the purpose of including vocabulary words and their meanings in context in a text? a) To test your knowledge of different words and their definitions b) To understand the specific details and examples in the text c) To improve your reading comprehension skills d) To practice using new words in your own writing

Owls, such as the young snowy owls on the previous page, have for centuries been symbols of both wisdom and mystery. To many cultures their piercing eyes have conveyed a look of intelligence. Their silent flight through darkened landscapes in search of prey has projected an air of power or wonder. For this chapter and this book, owls are an engaging example of a living organism from the world of biology—the study of life. BIOLOGY AND YOU Living in a small town, in the country, or at the edge of the suburbs, one may be lucky enough to hear an owl's hooting. This experience can lead to questions about where the bird lives, what it hunts, and how it finds its prey on dark, moonless nights. Biology, or the study of life, offers an organized and scientific framework for posing and answering such questions about the natural world. Biologists study questions about how living things work, how they interact with the environment, and how they change over time. Biologists study many different kinds of living things ranging from tiny organisms, such as bacteria, to very large organisms, such as elephants. Each day, biologists investigate subjects that affect you and the way you live. For example, biologists determine which foods are healthy. As shown in Figure 1-1, everyone is affected by this impor- tant topic. Biologists also study how much a person should exer- cise and how one can avoid getting sick. Biologists also study what your air, land, and food supply will be like in the near future. SECTION 1 OBJECTIVES ● Relate the relevance of biology to a person’s daily life. ● Describe the importance of biology in human society. ● List the characteristics of living things. ● Summarize the hierarchy of organization within complex multicellular organisms. ● Distinguish between homeostasis and metabolism and between growth, development, and reproduction. VOCABULARY biology organization cell unicellular multicellular organ tissue organelle biological molecule homeostasis metabolism cell division development reproduction gene Copyright © by Holt, Rinehart and Winston. All rights reserved. Biology, the study of life, directly applies to your health, life, and future in ways as simple as daily food choices. FIGURE 1-1 6 CHAPTER 1 Biology and Society By studying biology you can make informed decisions on issues that impact you and our society. Every day newspapers, television, and the Internet contain issues that relate to biology. For example, you may read that your local water or air supply is polluted. How will that pollution affect your health and the health of other living things? You may hear about new technologies or tools that biolo- gists have invented. How will we control how those technologies and tools are used? Biologists actively work to solve these and other real-world issues and problems, including improving our food supply, curing diseases and preserving our environment.

CARBOHYDRATES Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen in a ratio of about one carbon atom to two hydrogen atoms to one oxygen atom. The number of carbon atoms in a carbohydrate varies. Some carbohydrates serve as a source of energy. Other carbohydrates are used as structural materials. Carbohydrates can exist as monosaccharides, disaccharides, or polysaccharides. Monosaccharides A monomer of a carbohydrate is called a monosaccharide (MAHN-oh-SAK-uh-RIED). A monosaccharide—or simple sugar— contains carbon, hydrogen, and oxygen in a ratio of 1:2:1. The gen- eral formula for a monosaccharide is written as (CH2O)n, where n is any whole number from 3 to 8. For example, a six-carbon mono- saccharide, (CH2O)6, would have the formula C6H12O6. The most common monosaccharides are glucose, fructose, and galactose, as shown in Figure 3-6. Glucose is a main source of energy for cells. Fructose is found in fruits and is the sweetest of the monosaccharides. Galactose is found in milk. Notice in Figure 3-6 that glucose, fructose, and galactose have the same molecular formula, C6H12O6, but differing structures. The different structures determine the slightly different properties of the three compounds. Compounds like these sugars, with a single chemical formula but different structural forms, are called isomers (IE-soh-muhrz). SECTION 2 OBJECTIVES ● Distinguish between monosaccharides, disaccharides, and polysaccharides. ● Explain the relationship between amino acids and protein structure. ● Describe the induced fit model of enzyme action. ● Compare the structure and function of each of the different types of lipids. ● Compare the nucleic acids DNA and RNA. VOCABULARY carbohydrate monosaccharide disaccharide polysaccharide protein amino acid peptide bond polypeptide enzyme substrate active site lipid fatty acid phospholipid wax steroid nucleic acid deoxyribonucleic acid (DNA) ribonucleic acid (RNA) nucleotide C HO H C H OH C OH H C CH2OH H C H OH O Glucose C OH C O H OH C OH H CH2OH C H CH2OH Fructose C H HO C OH H C OH H C CH2OH H C H OH O Galactose Glucose, fructose, and galactose have the same chemical formula, but their structural differences result in different properties among the three compounds. FIGURE 3-6 Copyright © by Holt, Rinehart and Winston. All rights reserved. 56 CHAPTER 3 Disaccharides and Polysaccharides In living things, two monosaccharides can combine in a condensa- tion reaction to form a double sugar, or disaccharide (die-SAK-e-RIED). For example in Figure 3-4, the monosaccharides fructose and glu- cose can combine to form the disaccharide sucrose. A polysaccharide is a complex molecule composed of three or more monosaccharides. Animals store glucose in the form of the polysaccharide glycogen. Glycogen consists of hundreds of glucose molecules strung together in a highly branched chain. Much of the glucose that comes from food is ultimately stored in your liver and muscles as glycogen and is ready to be used for quick energy. Plants store glucose molecules in the form of the polysaccha- ride starch. Starch molecules have two basic forms—highly branched chains that are similar to glycogen and long, coiled, unbranched chains. Plants also make a large polysaccharide called cellulose. Cellulose, which gives strength and rigidity to plant cells, makes up about 50 percent of wood. In a single cellu- lose molecule, thousands of glucose monomers are linked in long, straight chains. These chains tend to form hydrogen bonds with each other. The resulting structure is strong and can be broken down by hydrolysis only under certain conditions. PROTEINS Proteins are organic compounds composed mainly of carbon, hydrogen, oxygen, and nitrogen. Like most of the other biological macromolecules, proteins are formed from the linkage of monomers called amino acids. Hair and horns, as shown in Figure 3-7a, are made mostly of proteins, as are skin, muscles and many biological catalysts (enzymes). Amino Acids There are 20 different amino acids, and all share a basic structure. As Figure 3-7b shows, each amino acid contains a central carbon atom covalently bonded to four other atoms or functional groups. A single hydrogen atom, highlighted in blue in the illustration, bonds at one site. A carboxyl group, —COOH, highlighted in green, bonds at a second site. An amino group, —NH2, highlighted in yel- low, bonds at a third site. A side chain called the R group, high- lighted in red, bonds at the fourth site. The main difference among the different amino acids is in their R groups. The R group can be complex or it can be simple, such as the CH3 group shown in the amino acid alanine in Figure 3-7b. The differences among the amino acid R groups gives different proteins very different shapes. The different shapes allow pro- teins to carry out many different activities in living things. Amino acids are commonly shown in a simplified way such as balls, as shown in Figure 3-7c. (a) Many structures, such as hair and horns are made of proteins. (b) Proteins are made up of amino acids. Amino acids differ only in the type of R group (shown in red) they carry. Polar R groups can dissolve in water, but nonpolar R groups cannot. (c) Amino acids have complex structures, so, in this and other textbooks, they are often simplified into balls. FIGURE 3-7 (b) Alanine (an amino acid) (c) Simplified version of amino acid CH3 H N OH C C H O H (a) Copyright © by Holt, Rinehart and Winston. All rights reserved. BIOCHEMISTRY 57 H H N C C OH H O H CH3 H2O Glycine Alanine H N OH C C H O H H H N C C H O H CH3 N OH C C H O H (a) (b) (a) The peptide bond (shaded blue) that binds amino acids together to form a polypeptide results from a condensation reaction that produces water. (b) Poly- peptides are commonly shown as a string of balls in this textbook and elsewhere. Each ball represents an amino acid. FIGURE 3-8 Substrate Products Enzyme 1 2 3 In the induced fit model of enzyme action, the enzyme can attach only to a substrate (reactant) with a specific shape. The enzyme then changes and reduces the activation energy of the reaction so reactants can become products. The enzyme is unchanged and is available to be used again. 3 2 1 FIGURE 3-9 Dipeptides and Polypeptides Figure 3-8a shows how two amino acids bond to form a dipeptide (die-PEP-TIED). In this condensation reaction, the two amino acids form a covalent bond, called a peptide bond (shaded in blue in Figure 3-8a) and release a water molecule. Amino acids often form very long chains called polypeptides (PAHL-i-PEP-TIEDZ). Proteins are composed of one or more polypep- tides. Some proteins are very large molecules, containing hun- dreds of amino acids. Often, these long proteins are bent and folded upon themselves as a result of interactions—such as hydrogen bonding—between individual amino acids. Protein shape can also be influenced by conditions such as temperature and the type of solvent in which a protein is dissolved. For exam- ple, cooking an egg changes the shape of proteins in the egg white. The firm, opaque result is very different from the initial clear, runny material. Enzymes Enzymes—RNA or protein molecules that act as biological catalysts—are essential for the functioning of any cell. Many enzymes are proteins. Figure 3-9 shows an induced fit model of enzyme action. Enzyme reactions depend on a physical fit between the enzyme molecule and its specific substrate, the reactant being catalyzed. Notice that the enzyme has folds, or an active site, with a shape that allows the substrate to fit into the active site. An enzyme acts only on a specific substrate because only that substrate fits into its active site. The linkage of the enzyme and substrate causes a slight change in the enzyme’s shape. The change in the enzyme’s shape weakens some chemical bonds in the substrate, which is one way that enzymes reduce activation energy, the energy needed to start the reaction. After the reaction, the enzyme releases the products. Like any catalyst, the enzyme itself is unchanged, so it can be used many times. An enzyme may not work if its environment is changed. For example, change in temperature or pH can cause a change in the shape of the enzyme or the substrate. If such a change happens, the reaction that the enzyme would have catalyzed cannot occur.

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