4.2 Vocabulary and O:UE Verb Assessment

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.

Aquí tienes un cuestionario para enseñar inglés. Está diseñado para evaluar el nivel de los estudiantes en varias áreas clave del idioma, como vocabulario, gramática, comprensión lectora y habilidades de escritura. Puedes ajustarlo según el nivel de tus estudiantes: ### **Cuestionario de Inglés** --- **Parte 1: Vocabulario** 1. **Escribe el equivalente en inglés de las siguientes palabras:** - Casa - Perro - Feliz - Escuela - Comida 2. **Elige la palabra correcta:** - She is very ____. (smart / smarts) - I like to play ____ football. (the / to) - This is my ____ book. (my / I) 3. **Completa las oraciones con la palabra correcta:** - My father _____ (is / are) a doctor. - I ____ (can / cans) speak three languages. --- **Parte 2: Gramática** 1. **Elige la opción correcta para completar la oración:** - They ____ to the park every Saturday. (go / goes) - She ____ my best friend. (is / are) 2. **Escribe las preguntas correctas para las siguientes respuestas:** - ____ (Yes, I have three brothers.) - ____ (No, I don’t like pizza.) 3. **Pon en la forma correcta del verbo en presente continuo:** - He ____ (study) for his test right now. - They ____ (play) football at the moment. --- **Parte 3: Comprensión Lectora** Lee el siguiente texto y responde a las preguntas. **Texto:** "Maria is a student. She lives in London with her parents. Every day, she goes to school at 8:00 in the morning. She likes reading books and playing the piano in her free time." 1. ¿Dónde vive Maria? 2. ¿A qué hora va Maria a la escuela? 3. ¿Qué le gusta hacer en su tiempo libre? --- **Parte 4: Escritura** 1. **Escribe una breve presentación sobre ti mismo (5-7 oraciones).** - Incluye tu nombre, edad, lo que te gusta hacer, y tu rutina diaria. 2. **Describe tu día favorito de la semana y qué actividades haces en ese día.** --- Este cuestionario cubre una variedad de aspectos importantes para enseñar inglés y puede ser modificado o ampliado según las necesidades y el nivel de los estudiantes.

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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

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