What are the chambers of congress?

The Senate and The House of Representatives

3. Which of the following is NOT a power of the Legislative Branch?

B) Approving the federal budget

14. What is the age requirement to become President?

C) Must be at least 35 years old

A) Must be at least 25 years old

D) Must be at least 40 years old

B) Must be at least 30 years old

15. What is the citizenship requirement to become President?

C) Must be a natural-born citizen

A) Must be a naturalized citizen

D) Must be a citizen for at least 20 years

B) Must be a permanent resident

3 Branches of The Government Test

During the Scientific Revolution, scientists used reason to explain the world around them. This led to the Enlightenment. The Enlightenment was a time period of new ideas about government. Enlightenment thinkers challenged the power of absolute monarchs. Absolute monarchs are kings and queens with total power. One Enlightenment thinker was John Locke. Locke believed that people were born with natural rights. These rights are Life, Liberty and Land. Locke believed that governments should protect people's natural rights and that if a government does not then the people have a right to overthrow it. Another Enlightenment thinker was Baron de Montesquieu. Montesquieu believed that the powers of government should be separated into 3 branches. This separation of powers would stop anyone from becoming too powerful. Montesquieu believed that governments ruled with the consent of the governed. That means that governments get their power from the people.

Contact with the Americas In 1001, Viking sailors led by Leif Erikson reached the eastern tip of North America. Archaeologists have found evidence of the Viking settlement of Vinland in present-day Newfoundland, Canada. The Vikings did not stay in Vinland long and no one is sure why they left. However, Viking stories describe fierce battles with Skraelings, the Viking name for the Inuit. Evidence suggests that Asians continued to cross the Bering Sea into North America after the last ice age ended. Some scholars believe that ancient seafarers from Polynesia may have traveled to the Americas using their knowledge of the stars and winds. Modern Polynesians have sailed canoes thousands of miles in this way. Still others think that fishing boats from China and Japan blew off course and landed on the western coast of North or South America. Perhaps such voyages occurred. If so, they were long forgotten. Before 1492, the peoples of Asia and Europe had no knowledge of the Americas and their remarkable civilizations. The Voyages of Columbus Portuguese sailors had pioneered new routes around Africa toward Asia in the late 1400s. Spain, too, wanted a share of the riches. King Ferdinand and Queen Isabella hoped to keep their rival, Portugal, from controlling trade with India, China, and Japan. They agreed to finance a voyage of exploration by Christopher Columbus. Columbus, an Italian sea captain, planned to reach the East Indies by sailing west across the Atlantic. Finding a sea route straight to Asia would give the Spanish direct access to the silks, spices, and precious metals of Asia. The spice trade was a major cause for European exploration and a reason the Spanish rulers supported Columbus’s voyage. They also wanted wealth from any source. “Get gold,” King Ferdinand said to Columbus. “Humanely if possible, but at all hazards—get gold.” Crossing the Atlantic In August 1492, Columbus set out with three ships and about 90 sailors. As captain, he commanded the largest vessel, the Santa María. The other ships were the Niña and the Pinta. After a brief stop at the Canary Islands, the little fleet continued west into unknown seas. Fair winds sped them along, but a month passed without the sight of land. Some sailors began to grumble. They had never been away from land for so long and feared being lost at sea. Still, Columbus sailed on. On October 7, sailors saw flocks of birds flying southwest. Columbus changed course to follow the birds. A few days later, crew members spotted tree branches and flowers floating in the water. At 2 a.m. on October 12, the lookout on the Pinta spotted white cliffs shining in the moonlight. “Tierra! Tierra!” he shouted. “Land! Land!” At dawn, Columbus rowed ashore and planted the banner of Spain. He was convinced that he had reached the East Indies in Asia. He called the people he found there “Indians.” In fact, he had reached islands off the coasts of North America and South America in the Caribbean Sea. These islands later became known as the West Indies. For three months, Columbus explored the West Indies. To his delight, he found signs of gold on the islands. Eager to report his success, he returned to Spain. Columbus Claims Lands for Spain In Spain, Columbus presented Queen Isabella and King Ferdinand with gifts of pink pearls and brilliantly colored parrots. Columbus brought with him many things that Europeans had never seen before: tobacco, pineapples, and hammocks used for sleeping. Columbus also described the “Indians” he had met, the Taino (ty noh). The Taino, he promised, could easily be converted to Christianity and could also be used as slaves. The Spanish monarchs were impressed. They gave Columbus the title Admiral of the Ocean Sea. They also agreed to finance future voyages. The promise of great wealth, and the chance to spread Christianity, gave them a reason to explore further. Columbus made three more voyages across the Atlantic. In 1493, he founded the first Spanish colony in the Americas, Santo Domingo, on an island he called Hispaniola (present-day Haiti and the Dominican Republic). A colony is an area settled and ruled by the government of a distant land. Columbus also explored present-day Cuba and Jamaica. He sailed along the coasts of Central America and northern South America. He claimed all of these lands for Queen Isabella of Spain. Columbus proved to be a better explorer than governor. During his third expedition, settlers on Hispaniola complained of his harsh rule. Queen Isabella appointed an investigator, who sent Columbus back to Spain in chains. In the end, the queen pardoned Columbus, but he never regained the honors he had won earlier. He died in 1506, still convinced that he had reached Asia. The Impact of Columbus’s Voyages Columbus has long been honored as the bold sea captain who “discovered America.” Today, we recognize that American Indians had discovered and settled these lands long before 1492. We also recognize that Columbus and the Europeans who followed him treated the ancient inhabitants of the Americas brutally. Still, Columbus’s voyages did change history. They marked the beginning of lasting contact among the peoples of Europe, Africa, and the Americas. For a great many American Indians, contact had tragic results. Columbus and those who followed were convinced that European culture was superior to that of the Indians. The Spanish claimed Taino lands and forced the Taino to work in gold mines, on ranches, or in Spanish households. Many Taino died from harsh conditions or European diseases. The Taino population was wiped out. Still, the voyages of Columbus signaled a turning point for the Americas. A turning point is a moment in history that marks a decisive change. Curious Europeans saw the new lands as a place where they could settle, trade, and grow rich. Spanish Exploration Continues After the voyages of Columbus, the Spanish explored and settled other Caribbean islands that Columbus had found. They sought gold, land for crops, people to enslave, and converts to Christianity for the Spanish crown. By 1511, they had conquered Puerto Rico, Jamaica, and Cuba. They also explored the eastern coasts of North America and South America in search of a western route to Asia. In 1513, Vasco Núñez de Balboa (bal boh uh) crossed the Isthmus of Panama. American Indians had told him that a large body of water lay to the west. With a party of Spanish soldiers and Indians, Balboa reached the Pacific Ocean and claimed the ocean for Spain. The Spanish had no idea how wide the Pacific was until a sea captain named Ferdinand Magellan (muh jel un) sailed across it. The expedition—made up of five ships and about 250 crew members—left Spain in 1519. Fifteen months later, it cut through the stormy southern tip of South America by way of what is now known as the Strait of Magellan and entered the Pacific Ocean. Crossing the vast Pacific, the sailors ran out of food: Primary Source “We remained 3 months and 20 days without taking in provisions or other refreshments and ate only old biscuit reduced to powder, full of grubs and stinking from the dirt which rats had made on it. We drank water that was yellow and stinking.” —Antonio Pigafetta, The Diary of Antonio Pigafetta Magellan himself was killed in a battle with the local people of the Philippine Islands off the coast of Asia. In 1522, only one ship and 18 sailors returned to Spain. They were the first people to circumnavigate, or sail completely around, the world. In doing so, they had found an all-water western route to Asia. Europeans became aware of the true size of the Earth. How Did the Columbian Exchange Affect the Rest of the World? The encounter between the peoples of the Eastern and Western Hemispheres sparked a global exchange of goods and ideas. Because it started with the voyages of Columbus, this transfer is known as the Columbian Exchange. The Columbian Exchange refers to a biological and cultural exchange of animals, plants, human populations, diseases, food, government, technology, the arts, and languages. The exchange went in both directions. Europeans learned much from American Indians. At the same time, Europeans contributed in many ways to the culture of the Americas. This exchange also brought about many modifications, or changes, to the physical environment of the Americas, with both positive and negative results. Changing Environments Europeans introduced domestic animals such as chickens from Europe and Africa. European pigs, cattle, and horses often escaped into the wild and multiplied rapidly. Forests and grasslands were converted to pastures. As horses spread through what would become the United States, Indians learned to ride them and used them to carry heavy loads. Plants from Europe and Africa changed the way American Indians lived. The first bananas came from the Canary Islands. By 1520, one Spaniard reported that banana trees had spread “so greatly that it is marvelous to see the great abundance of them.” Oranges, lemons, and figs were also new to the Americas. In North America, explorers also brought such plants as bluegrass, the daisy, and the dandelion. These plants spread quickly in American soil and modified American grasslands. Tragically, Europeans also brought new diseases, such as smallpox and influenza. American Indians had no resistance to these diseases. Historians estimate that within 75 years, diseases from Europe had killed almost 90 percent of the people in the Caribbean Islands and in Mexico. American Indian Influences on Europe, Africa and Asia American Indians introduced Europeans to valuable food crops such as corn, potatoes, sweet potatoes, beans, tomatoes, manioc, squash, peanuts, pineapples, and blueberries. Today, almost half the world’s food crops come from plants that were first grown in the Americas. Europeans carried the new foods with them as they sailed around the world. Everywhere, people’s diets changed and populations increased. In South Asia, people used American hot peppers and chilies to spice stews. Chinese peasants began growing corn and sweet potatoes. Italians made sauces from tomatoes. People in West Africa grew manioc and corn. European settlers often adopted American Indian skills. In the North, Indians showed Europeans how to use snowshoes and trap beavers and other fur-bearing animals. European explorers learned how to paddle Indian canoes. Some leaders studied American Indian political structures. In the 1700s, Benjamin Franklin admired the Iroquois League and urged American colonists to unite in a similar way. Positive and Negative Consequences Through the Columbian Exchange, Europeans and American Indians modified their environments and gained new resources and skills. At the same time, warfare and disease killed many on both sides. Europeans viewed expansion positively. They gained great wealth, explored trade routes, and spread Christianity. Yet their farming, mining, and diseases took a toll on the physical environment and left many American Indians dead. Despite these negatives, the Columbian Exchange shaped the modern world, including what would become the United States.

A BAD CASE OF THE STRIPES By David Shannon Parts(18): Camilla Narrator 1 Narrator 2 Narrator 3 Narrator 4 Mr. Harms Mother Father Dr. Bumble Old Woman Environmental Therapist Dr. Grop Dr. Gourd Dr. Sponge Mr. Mellon Dr. Cricket Dr. Young <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> Narrator 1: A BAD CASE OF THE STRIPES By David Shannon Narrator 2: Camilla Cream loved lima beans. But she never ate them. Narrator 3: All of her friends hated lima beans, and she wanted to fit in. Camilla always worried about what other people thought of her. Narrator 4: Today she was fretting even more than usual. It was the very first day of school, and she couldn't decide what to wear. There were so many people to impress! Narrator 1: She tried on forty-two outfits, but none seemed quite right. She put on a pretty red dress and looked in the mirror. Then she screamed. Narrator 2: Her mother ran into the room, and she screamed, too. Mother: "Oh my heavens! You're completely covered with stripes!" Narrator 3: she cried. This was certainly true. Camilla was striped from head to toe. She looked like a rainbow. Narrator 4: Mrs. Cream felt Camilla's forehead. Mother: "Do you feel all right?" Narrator 1: she asked. Camilla: "I feel fine, but just look at me!" Narrator 2: Camilla answered. Mother: "You get back in bed this instant. You're not going to school today." Narrator 3: her mother ordered. Camilla was relieved. She didn't want to miss the first day of school, but she was afraid of what the other kids would say. And she had no idea what to wear with those crazy stripes. Narrator 4: That afternoon, Dr. Bumble came to examine Camilla. Dr. Bumble: "Most extraordinary! I've never seen anything like it! Are you having any coughing, sneezing, runny nose, aches, pains, chills, hot flashes, dizziness, drowsiness, shortness of breath, or uncontrollable twitching?" Narrator 1: he asked. Camilla: "No, I feel fine." Narrator 2: Camilla told him. Dr. Bumble: "Well then, I don't see any reason why she shouldn't go to school tomorrow. Here's some ointment that should help clear up those stripes in a few days. If it doesn't, you know where to reach me." Narrator 3: Dr. Bumble said, turning to Mrs. Cream. And off he went. Narrator 4: The next day was a disaster. Everyone at school laughed at Camilla. They called her "Camilla Crayon" and "Night of the Living Lollipop." Narrator 1: She tried her best to act as if everything were normal, but when the class said the Pledge of Allegiance, her stripes turned red, white, and blue, and she broke out in stars! Narrator 2: The other kids thought this was great. One yelled out, Narrator 3: "Let's see some purple polka dots!" Narrator 4: Sure enough, Camilla turned all purple polka-dotty. Someone else shouted, Narrator 1: "Checkerboard!" Narrator 4: and a pattern of squares covered her skin. Soon everyone was calling out different shapes and colors, and poor Camilla was changing faster than you can change channels on a T.V. Narrator 2: That night, Mr. Harms, the school principal, called. Mr. Harms: "I'm sorry, Mrs. Cream, I'm going to have to ask you to keep Camilla home from school. She's just too much of a distraction, and I've been getting phone calls from the other parents. They're afraid those stripes may be contagious." Narrator 3: he said. Camilla was so embarrassed. She couldn't believe that two days ago everyone liked her. Now, nobody wanted to be in the same room with her. Narrator 1: Her father tried to make her feel better. Father: "Is there anything I can get you, sweetheart?" Narrator 2: he asked. Camilla: "No, thank you," Narrator 3: sighed Camilla. What she really wanted was a nice plate of lima beans, but she had been laughed at enough for one day. Dr. Bumble: "Hmm, well, yes, I see. I think I'd better bring in the Specialists. We'll be right over.” Narrator 4: said Dr. Bumble to Mr. Cream on the phone. About an hour later, Dr. Bumble arrived with four people in long white coats. He introduced them to the Creams. Dr. Bumble: "This is Dr. Grop, Dr. Sponge, Dr. Cricket, and Dr. Young." Narrator 1: Then the Specialists went to work on Camilla. They squeezed and jabbed, tapped and tested. It was very uncomfortable. Dr. Grop: "Well, it's not the mumps." Dr. Sponge: "Or the measles." Dr. Cricket:"Definitely not chicken pox." Dr. Young: "Or sunburn." Narrator 2: replied the Specialists. Specialists:"Try these. Take one of each before bed." Narrator 4: said the specialists. They each handed her a bottle filled with different colored pills. Then they filed out the front door followed by Dr. Bumble. Narrator 1: That night, Camilla took her medicine. It was awful. Narrator 2: When she woke up the next morning, she did feel different, but when she got dressed, her clothes didn't fit right. She looked in the mirror, and there, staring back at her, was a giant, multi-colored pill with a face on it. Narrator 3: Dr. Bumble rushed over as soon as Mrs. Cream called. But this time, instead of the Specialists, he brought the Experts. Narrator 4: Dr. Gourd and Mr. Mellon were the finest scientific minds in the land. Once again, Camilla was poked and prodded, looked at and listened to. Narrator 1: The Experts wrote down lots of numbers. Then they huddled together and whispered. Dr. Gourd finally spoke. Dr. Gourd: "It might be a virus," Narrator 2: he announced with authority. Suddenly, fuzzy little virus balls appeared all over Camilla. Mr. Mellon: "Or possibly some form of bacteria," Narrator 3: said Mr. Mellon. Out popped squiggly little bacteria tails. Dr. Gourd: "Or it could be a fungus," Narrator 4: added Dr. Gourd. Instantly, Camilla was covered with different colored fungus blotches. The experts looked at Camilla, then each other. Experts: "We need to go over these numbers again back at the lab. We’ll call you when we know something," Narrator 1: said the Experts. But the Experts didn't have a clue, much less a cure. Narrator 2: By now, the T.V. news had found out about Camilla. Reporters from every channel were outside her house, telling the story of "The Bizarre Case of the Incredible Changing Kid." Narrator 3: Soon a huge crowd was camped out on the front lawn. Narrator 4: The Creams were swamped with all kinds of remedies from psychologists, allergists, herbalists, nutritionists, psychics, an old medicine man, a guru, and even a veterinarian. Narrator 1: Each so-called cure only added to poor Camilla's strange appearance until it was hard to even recognize her. She sprouted roots and berries and crystals and feathers and a long furry tail. But nothing worked. Narrator 2: One day, a woman who called herself an Environmental Therapist claimed she could cure Camilla. She said, Environmental Therapist: "Close your eyes, breathe deeply, and become one with your room." Camilla: "I wish you hadn't said that," Narrator 3: Camilla groaned. Slowly, she started to melt into the walls of her room. Her bed became her mouth, her nose was a dresser, and two paintings were her eyes. The therapist screamed and ran from the house. Mother: "What are we going to do? It just keeps getting worse and worse!" Narrator 4: cried Mrs. Cream. She began to sob. Narrator 1: At that moment, Mr. Cream heard a quiet little knock at the front door. He opened it, and there stood an old woman who was just as plump and sweet as a strawberry. Old Woman: "Excuse me, but I think I can help." Narrator 2: she said brightly. Narrator 3: She went into Camilla's room and looked around. Old Woman: "My goodness, what we have here is a bad case of the stripes. One of the worst I've ever seen!" Narrator 4: she said with a shake of her head. She pulled a container of small green beans from her bag. She said, Old Woman: "Here. These might do the trick." Mother: "Are those magic beans?" Narrator 1: asked Mrs. Cream. The old woman replied, Old Woman: "Oh my, no, there's no such thing. These are just plain old lima beans. I'll bet you'd like some, wouldn't you?" Narrator 2: she asked Camilla. Camilla wanted a big, heaping plateful of lima beans more than just about anything, but she was still afraid to admit it. She said, Camilla: "Yuck! No one likes lima beans, especially me!" Old Woman: "Oh, dear, I guess I was wrong about you." Narrator 3: said the old woman sadly. She put the beans back in her bag and started toward the door. Narrator 4: Camilla watched the old woman walk away. Those beans would taste so good. And being laughed at for eating them was nothing, compared to what she'd been going through. She finally couldn't stand it. Camilla: "Wait! The truth is...I really love lima beans." Narrator 1: she cried. The old woman smiled, popping a handful of beans into Camilla's mouth, and said, Old Woman: "I thought so." Camilla: "Mmmmmmm," Narrator 2: said Camilla. Suddenly the branches, feathers, and squiggly tails began to disappear.Then the whole room swirled around. When it stopped, there stood Camilla, and everything was back to normal. Camilla: "I'm cured!" Narrator 3: she shouted. The old woman said, Old Woman: "Yes, I knew the real you was in there somewhere." Narrator 4: She patted Camilla on the head and went outside and vanished into the crowd. Narrator 1: Afterward, Camilla wasn't quite the same. Narrator 2: Some of the kids at school said she was weird, but she didn't care a bit. Narrator 3: She ate all the lima beans she wanted, and she never had even a touch of stripes again.

Title: The Adventures of Max and the Magical Computer (Shortened Version) Once upon a time, in a small town called Techville, there lived a curious fourth-grader named Max. One day, while exploring his grandma’s attic, he found an old, dusty computer. As he cleaned it, the screen lit up, and a cheerful voice said, “Hello, Max! I’m Compy, your magical computer. Let’s learn about operating systems, files, and folders!” Max was thrilled. “A talking computer? Let’s go!” Chapter 1: The World of Windows Compy explained, “I run on Windows, the brain of the computer. It uses a Graphical User Interface (GUI), so you can interact with me using icons, menus, and buttons. Let’s start by changing my desktop background—the image on the screen.” Max chose a spaceship picture. “Cool! Can I add a screen saver too?” “Of course!” said Compy. “It’s an image that appears when I’m inactive. Try this swirling galaxy!” Max set the screen saver and giggled as it appeared. “This is fun!” Chapter 2: Organizing with Folders and Files Compy’s screen filled with random icons. “Oh no! My files are a mess. Can you help?” “Sure! What are files and folders?” asked Max. “A file is information, like a picture or document. Files have names, like ‘Homework.docx.’ The part after the dot, like .docx, is the file extension. It tells you the file type,” Compy explained. Max pointed to “Game.exe.” “So, this is a program file?” “Yes!” said Compy. “To organize, we use folders—like drawers for files. You can even put folders inside folders!” Max created a “School” folder, added his homework files, and made a “Projects” folder inside it. “Now everything’s neat!” Chapter 3: The File Explorer Adventure Compy’s screen flickered. “Some files are missing. Let’s use Windows Explorer to find them. It’s like a map for files and folders.” Max opened Windows Explorer and saw a tree-like list of folders. “This is like a tree with branches!” “Exactly!” said Compy. “Search for the missing files and move them to the right folders.” Max found the files in “Downloads” and moved them. “I feel like a computer detective!” Chapter 4: The Final Challenge Compy’s screen turned into a game board. “Time for a quiz! What’s the purpose of an operating system? How do you change the desktop background? What’s the difference between a file and a folder?” Max answered all the questions correctly, and fireworks lit up the screen. “Congratulations, Max! You’re a computer whiz!” The End Max smiled. “Thanks, Compy! I can’t wait to teach my friends!” Compy replied, “Remember, Max, learning is an adventure. Keep exploring!” As Max turned off the computer, he knew his journey into technology had just begun.

1. SA node sends an impulse causing the atria to contract 2. Blood moves from the right atrium into the right ventricle past the tricuspid valve 3. Blood moves from the left atrium into the left ventricle past the mitral or bicuspid valve 4. Impulse pauses at AV node to allow for maximum blood to be squeezed into the ventricles 5. Impulse travels to the AV bundle (or bundle of His) and down the bundle branches 6. Impulse travels out Purkinje fibers causing the apex to contract 7. The apex contraction increases the blood pressure in the ventricles causing the Mitral and Tricuspid (AV) valves to close. 8. Atria repolarize and begin to fill 9. Purkinje fibers cause the ventricle walls and papillary muscles to depolarize (contract) 10. Papillary muscles hold the AV valves shut (keep them from prolapsing) through the chordae tendineae connection 11. The aortic and pulmonary semilunar valves open when the pressure is higher in the ventricles than in the major arteries 12. Blood moves from right ventricle to pulmonary trunk/arteries past the pulmonary semilunar valve 13. Blood moves from left ventricle to aorta past the aortic semilunar valve 14. Blood pathway is arteries to arterioles, to capillaries (or capillary bed), to venules, veins and vena cava back to the right atrium 15. The ventricles start to repolarize (relax) which decreases the pressure in the ventricles 16. When the pressure is lower in the ventricles than in the major arteries, blood moves back toward heart shutting semilunar valves 17. When the aortic valve closes, the openings to the coronary arteries are exposed 18. Back pressure in the aorta pushes blood out the left and right coronary arteries supplying the heart with oxygenated blood 19. The AV valves open and blood moves from the atria into the ventricles when the ventricular pressure falls below atrial pressure. 20. The process starts again when the SA node fires causing the atria to contract.

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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