Chapter 5 Review

Reviewing Concepts

Multiple Choice - Choose the letter of the best answer.

1. Which of the following is not an organic molecule?

a. cellulose

b. sucrose

c. water

d. testosterone

2. Which of the following terms includes all the other terms on this list?

a. polysaccharide

b. carbohydrate

c. monosaccharide

d. glycogen

3. Which term is most appropriate to describe a molecule that dissolves easily in water?

a. hydrocarbon

b. hydrophobic

c. hydrophilic

d. organic

4. Cholesterol is an example of what kind of molecule?

a. protein

b. lipid

c. amino acid

d. carbohydrate

5. The 20 amino acids vary only in their

a. carboxyl goups.

b. side groups.

c. amino groups.

d. lipid groups.

6. A specific reactant an enzyme acts upon is called the

a. catalyst.

b. sucrase.

c. active site.

d. substrate.

7. An enzyme does which of the following?

a. adds heat to a reaction, speeding it up

b. lowers the activation energy of a reaction

c. cools a reaction, slowing it down

d. raises the activation energy of a reaction

Short Answer

8. Besides satisfying your hunger, why else might you consume a big bowl of pasta the night before a race?

Besides satisfying my hunger, I might consume a big bowl of pasta the night before a race so I could take in some carbohydrates for energy.

9. How are glucose, sucrose, and starch related?

Glucose, sucrose, and starch are related because they are all carbohydrate. Also, they are all in plant because starch is made up of glucose monomers. The sucrose are also in the plant sap and it nourishes all the parts of plant.

10. What are steroids? Describe two functions they have in cells.

Steroids are lipid molecule in which the carbon skeleton forms four fused rings. Ateroids circle around our body as chemical signals. They also make the women and men's hormone.

11. How are polypeptides related to proteins?

Polypeptides are related to proteins because proteins are created by one or more polypeptides.

12. How does denaturation affect the ability of a protein to function?

Denaturation affect the ability of a protein to function because the change in enviornment could cause the protein to unravel and lose its normal shape. When shape changes, the protein loses their ability to function.

Applying Concepts

Analyzing Information

14. Analyzing Diagrams The reaction below shows two amino acids joining together.

a. One product of this reaction is represented by a question mark. Which molecule is it?

The molecule that is represented by a question mark is H2O, water.

b. What is this kind of reaction called? Explain.

This kind of reaction is called the dehydration reaction. Amino acids has no element that is not stable. Which means they don't need to share an electron anymore. Though, able for the amino acids to bond together, they need to give up 2 hydrogen atoms and one oxygen atom. Then, the water is produced.

c. If an amino acid were added to this chain, at what two places could it attach?

If an amino acid were added to this chain, the two places that could be attached to will be the place where there is HO or H. So, for example, the far right hand sides of the Serine or far left hand side of Leucine.

15. Analyzing Graphs Use the graph to answer the questions below.

a. At which temperature does enzyme A perform best? Enzyme B?

At 37°C the enzyme A perform best and at 77°C the enzyme B perform best.

b. Knowing that one of these enzymes is found in humans and the other in thermophilic (heat-loving) bacteria, hypothesize which enzyme came from which organism.

The enzyme A is from humans and enzyme B is from thermophilic bacteria.

c. Propose a hypothesis that explains why the rate of the reaction catalyzed by enzyme A slows down at temperatures above 40°C.

If the rate of the reaction catalzed by enzyme A slows down at temperatures above 40°C, then the reaction is coming to the end.

Chapter 5.5 Summary

• to start a chemical reaction, it is first necessary to weaken chemical bonds in the reactant molecules
• activation energy is "start-up" energy
• one way to provide activation energy is to heat up the mixture of molecules
• heating up a cell would cause many unnecessary reactions
• the main catalysts of chemical reactions in organisms are specialized proteins
• catalyst is a compunds that speed up chemical reaction
• enzyme doesn't supply activation enrgy
• each enzyme catalyzes a specific kind of chemical reaction

• the shape of each enzyme fits the shape of only particular reaction molecule
• specific reactant acted upon by an enzyme is substrate
• the substrate fits into a particular region of the enzyme is active site
• as substrate enters, the shape change slightly
• tighter grip weakens the bonds
• another way that an enzyme can lower activation energy is by accepting two reactant molecules into adjacent sites
• enzymes structure and shape are essential to its function
• enzyme changes shape depending on the enviornment

Concept Check 5.5



1. Explain the role of activation energy in a reaction. How does an enzyme affect activation energy?

Activation energy's role is to activate the reactants and triggers a chemical reaction. Enzymes does effect activation energy by lowering the energy requirement of the barrier so reactons can react at a normal temperature.



2. Describe how a substrate interacts with an enzyme.

A substrate interacts with an enzyme by entering the enzyme's active site, and active site changes shape. This help the subtrate to fit better to enzyme's active site. Then it places certain functional groups of the active site in position to catalyze the reaction.

Chapter 5.4 Summary

• protein is a polymer constructed from a set of just 20 kinds of monomers called amino acids
• proteins with less-visible functions include proteins that circulate in the blood and defend the body from harmful microorganisms
  
  
  

• amino acid monomer consists of a central carbon atom bonded to four partners: hydrogen atoms, carboxl grup, amino group, and functional group
• the side group (R-group) is responsible for the particular chemical properties of each amino acids
• cells create proteins by linking amino acids together into a chain called polypeptide
  
• proteins are composed of one or more polypeptide chains
• our body can make various proteins by arranging the amino acids in different order
• 20 letters of amino acids
• most polypeptide chains are at least 100 amino acids in length
• a functional protein consists of one or more polypeptides precisely twisted, folded, and coiled in a unique way
• protein's shape is influenced in the surrounding enviornment
• the change in temperature, pH, or some other enviornment change can change protein's shape
• protein's function depends on shape

Concept Check 5.4

1. Give at least two examples of proteins you can "see" in the world around you. What are their functions?

The two examples of proteins I can "see" in the world around are texture of an animal's coat and the muscles of an animal. Their function is to give texture and muscles to an animal.

2. Relate amino acids, polypeptides, and proteins.

A protein is a polmer constructed from a set of 20kinds of monomers called amino acids. However, the proteins are created by linking the amino acids into a chain called polypeptide.

3. Explain how heat can destroy a protein.

Heat can destroy a protein because heat unfolds the protein. This process is called denaturation. So, there is not much force to maintain the folding between pairs of side groups. Since a protein's function depends on the shape, a protein that becomes denatured and loses shape, it would lose it's ability too.

4. Which parts of an amino acid's structure are the same in all amino acids? Which part is unique?

The parts of an amino acid's structure are the amino group, caboxl group, and a hydrogen atom. The part that are unique is the side group. The side group, also called "R-group", is responsible for the particular chemical properties of each amino acids.

Chapter 5.3 Summary

• hydrophobic means "water-fearing"
• the function of hydro phobic is really important in starch
• lipids act as boundary and contains watery contents of human cells
• some fat are solid at room temperature
• most animal fats are saturated fats
• the fats in fruits, vegetables, fish are unsaturated fats
• saturated fats are unhealty (large amount)
• steroids are classified a lipid
• cholesterol, a steroid, is found in membranes
• cholesterol has a bad reputation because high level of particular cholesterol-containing substances in the blood increases the risk of getting heart and blood vessel disease

Concept Check 5.3

1. What property do lipids share?

All lipids share the property of hydrophobic. Hydrophpbic means a water-avoiding molecules.

2. What are the parts of a fat molecule?

The parts of a fat molecule are the three-carbon backbone called glycerol attached to three fatty acids, which contain long hydrocarbon chains.

3. Descrive two ways that steroids differ from fats.

The steroids are different from fats in two way. Those two ways are structure and function. The steroids circulate body as chemical signals when fats stores the energy. Also, the steroids are formed from four rings.

4. What does the term unsaturated fat on a food label mean?

The term unsaturated fat on a food label means that the food contains less than the maximum number of hydrogen atoms in one or more of its fatty acid chains because some of its carbon atoms are double-bonded to each other.

Chapter 5.2 Summary

• sugar contains the elements carbon, hydrogen, and oxygen

• monosaccharide: glucose, fructose, and galactose
• sugar, usually glucose, are the main fuel supply

• disaccharide: sucrose
• body can also store glucose in larger molecules for later use
• starch chains serve as sugar stockpile
• humans and most other animals are also able to use plant starch as food by breaking it down within their digestive systems
• rich in starch: potatoes, rice, corn
• animal cells has no starch
• animal cells has glycogen
• when body needs energy, it breaks down glycogen granules, releasing glucose
• almost all carbohydrates are hydrophilic
• some starch doesn't dissolve in water
  

Concept Review 5.2

1. Explain the difference between a monosaccharide and a disaccharide. Give an exmaple of each.

Monosaccharide is simple sugars contain just one sugar unit. Example of monosaccharide are glucose, fructose, and galactose. The disaccharide is sugar with two monosaccharide. For example, sucrose are disaccharide.

2. Compare and contrast starch, glycogen, and cellulose.

Starch, glycogen, and cllulose are all polysaccharide and glucose monomers. First, the starch are only contained in the plant cell, and glycogen is only contained in the animal cells. Cellulose is containted in both plant and animal cells. Starch serves as sugar stockpiles, in the use of enrgy. The glycogen is also store for the use of energy. Finally, cellulose serves as building materials. These protect cells and stiffen the plant, preventing it from flopping over.

3. How do animals store excess glucose molecules?

The animals store excess glucose molecules by the form of polysaccharide called glycogen. For humans, the glycogen is stored usually in granules in liver and muscle cells. When human needs energy, the glycogen is broken down and released.

Chapter 5.1 Summary

• carbon can form up to four bonds
• most carbon-based molecules are classified as organic molecules
• non-carbon based molecule classified as inorganic molecules
• carbon can bond with other elements
• hydrocarbons are important fuels
• Methane: abundant hydrogen, natural gas
• Some biomolecule can be composed of hundreds or even millions of atoms
• large molecules classified in four main categories: carbohydrates, lipids, proteins, and nucleic acids
• Dehydration reaction involves removing water
• Organisms not only build polynomers, but they also have to brek them down
• water is removed to build a polynomer, and water is added to break it down
  

Concept Check 5.1

1. Draw a molecule that has a three-carbon skeleton and a hydroxyl group on the middle carbon. (Hint: The molecule's formula is C3H8O.)

2. Explain the connection between monomers and polymers.

The connection between monomers and polymer is that polynomer is a straight chain of monomers. Other polymer have branching chains. So the monomer comes together to form polymer.

3. What molecule is released during construction of a polymer? What is this reaction called?

During the construction of a polymer water molecule is released. This reaction is called dehydration reaction.

4. Draw at least three ways in which five carbon atoms could be joined to make different carbon skeletons.