Full file at ://fratstock.eu/sample/Solutions-Manual-Life-on-Earth-5th-Editio… · Fructose—found in corn syrup B. Disaccharides Store Energy (Figure 2-14) 1. Disaccharides—two

Full file at https://fratstock.eu

13

CHAPTER 2 ATOMS, MOLECULES,

AND LIFE

AT A GLANCE

Case Study: Improving on Nature?

2.1 What Are Atoms?

â Web Animation: Interactive Atoms

A. Atoms Are Composed of Even Smaller Particles

1. Atom—basic structural unit of matter (Figure 2-1)

a. Atomic nucleus—positively charged protons and neutrons

b. Negatively charged electrons—orbit atomic nucleus

2. Elements—atoms with same number of protons (atomic number)

a. Isotopes—same element; different number of neutrons

b. Radioactive isotopes—release energy

B. Electrons Orbit the Nucleus, Forming Electron Shells (Figure 2-2)

1. Innermost shell—lowest energy

2. First shell holds 2 electrons

3. Subsequent shells hold up to 8 electrons

2.2 How Do Atoms Form Molecules?

A. Atoms Interact When There Are Vacancies in Their Outermost Electron Shells

1. Chemical bonds—hold atoms together; gain, loss, sharing of electrons

2. Chemical reactions—making and breaking of chemical bonds

3. A molecule may be depicted in different ways (Figure 2-4)

B. Charged Atoms Interact to Form Ionic Bonds (Figure 2-5)

1. Outermost electron shell is almost empty or almost full

2. Ions—atoms become stable by gaining or losing electrons

3. Ionic bonds—electrical attraction between positive and negative ions

C. Uncharged Atoms Share Electrons to Form Covalent Bonds (Table 2.1)

1. Most biological molecules use covalent bonding

2. Covalent bonds are either nonpolar or polar

a. Nonpolar covalent bonds—equal sharing of electrons

b. Polar covalent bonds—unequal sharing of electrons (H2O)

D. Hydrogen Bonds Form Between Molecules with Polar Covalent Bonds (Figure 2-7)

1. Hydrogen bonds—bonds between parts of polar molecules

2. Responsible for unique properties of water

â Lecture Activity 2.1: Exercise in Chemical Bonding

â Lecture Activity 2.2: Atomic Love Connection

2.3 Why Is Water So Important to Life?

A. Water Interacts with Many Other Molecules

1. Water is involved in most chemical reactions in a cell

2. Water plays a role in photosynthesis and digestion

B. Many Molecules Dissolve Easily in Water (Figure 2-8)

â Web Animation: Water and Life

â Health Watch: Health Food?

1. A good solvent because it is a polar molecule

2. Hydrophilic molecules—dissolve easily in water (ex. sugars)

3. Hydrophobic molecules—do not dissolve in water (ex. fats and oils)

Full file at https://fratstock.eu14 Instructor Guide

C. Water Molecules Tend to Stick Together (Figure 2-9)

1. Cohesion—water molecules stick together

2. Surface tension—surface of water is resistant to being broken

3. Adhesion—water sticks to polar surfaces

D. Water Can Form Ions (Figure 2-10)

1. Water is ionized to form hydrogen ions (H+) and hydroxide ions (OH–)

2. Acidic solutions—more hydrogen ions (H+) than hydroxide ions (OH–)

3. Basic solutions—more hydroxide ions (OH–) than hydrogen ions (H+)

4. pH measures acidity

a. Acids have a pH below 7 (more H+ than OH–)

b. Bases have a pH above 7 (more OH– than H+)

c. Water has a pH of 7 (equal amount of H+ and OH–)

5. A buffer maintains a solution at a constant pH

2.4 Why Is Carbon So Important to Life?

A. Organic Molecules vs. Inorganic Molecules

1. Organic molecules contain carbon and hydrogen

2. Inorganic molecules do not contain carbon

3. Functional groups—attached to carbon backbones; determine characteristics of different molecules

2.5 How Are Biological Molecules Joined Together or Broken Apart?

â Web Animation: Structure of Biological Molecules

A. Construction of Large Molecules Yields Water

1. Dehydration synthesis

a. Individual subunits—linked together to make larger molecules

b. Water is formed during reaction

B. Breakdown of Large Molecules Uses Water (Table 2.3)

1. Hydrolysis

a. Splitting larger molecules into individual subunits

b. Water is needed to complete reaction

2.6 What Are Carbohydrates?

A. A Variety of Simple Sugars Occurs in Organisms (Figure 2-13)

1. Monosaccharides—one sugar molecule

a. Glucose—subunit of most polysaccharides

b. Fructose—found in corn syrup

B. Disaccharides Store Energy (Figure 2-14)

1. Disaccharides—two simple sugar molecules linked together

a. Sucrose—table sugar (glucose + fructose)

b. Lactose—milk sugar (glucose + galactose)

2. Cells—can break apart disaccharides to get energy

Improving on Nature? Continued

C. Polysaccharides Store Energy and Provide Support

1. Polysaccharides—polymers of many monosaccharides

a. Starch—energy storage in plants

b. Glycogen—energy storage in animals

c. Cellulose—structural support in plants (Figure 2-15)

d. Chitin—exoskeletons of insects, crabs, spiders

â Lecture Activity 2.3: Carbohydrate Reverse Questions

2.7 What Are Lipids?

A. Oils, Fats, and Waxes Contain Only Carbon, Hydrogen, and Oxygen (Figure 2-16)

1. Fats and oils

a. Formed by dehydration synthesis

b. Contain three fatty acids and a glycerol molecule

c. Used for long-term storage in plants and animals

d. Store same energy with less weight than carbohydrates

2. Saturated vs. unsaturated fats

a. Saturated fats—no double bonds; solid at room temperature

b. Unsaturated fats—contain double bonds; liquid at room temperature

Full file at https://fratstock.euChapter 2 Atoms, Molecules, and Life 15

Improving on Nature? Continued

â Lecture Activity 2.4: Fake Fats: To Eat or Not to Eat?

â Health Watch: Cholesterol—Friend and Foe

B. Phospholipids Have Water-Soluble Heads and Water-Insoluble Tails (Figure 2-20)

1. Phospholipids contain 2 fatty acids, 1 glycerol, and 1 phosphate group

2. Fatty acid “tails” are hydrophobic (water insoluble)

3. Phosphate group “head” is polar and hydrophilic (water soluble)

4. Central component of cell membranes

C. Steroids Consist of Four Carbon Rings Fused Together (Figure 2-21)

1. Cholesterol is a steroid molecule

a. Important component of animal cell membranes

b. Used to synthesize other steroids

2.8 What Are Proteins?

A. Proteins Are Formed from Chains of Amino Acids (Figure 2-22)

1. Amino acids contain central carbon + four functional groups

a. Nitrogen-containing amino group (—NH2)

b. Carboxyl group (—COOH)

c. Hydrogen (—H)

d. Variable group—gives each amino acid its distinctive properties

2. Sequence of amino acids dictates function of protein

B. Amino Acids Join by Dehydration Synthesis to Form Chains (Figure 2-24)

1. Peptide bond—amino group of one amino acid is joined to carboxyl group of another amino acid

2. Polypeptide chain or protein—long chain of amino acids

C. Three-Dimensional Shapes Give Proteins Their Functions (Figure 2-25)

1. Primary structure

a. Sequence of amino acids that make up the protein

b. Different proteins have different sequences of amino acids

2. Secondary structure

a. Due to interactions between hydrogen bonds of amino acids

b. Helix arrangement—coiled structure

c. Pleated sheet arrangement—chains that fold back upon themselves

3. Tertiary structure

a. Three-dimensional configuration of amino acid chain

b. Interactions among different R groups of the chain

4. Quaternary structure—individual polypeptides linked together

5. Proteins whose shape is disrupted are said to be denatured

â Lecture Activity 2.5: Protein Structure and Function

2.9 What Are Nucleic Acids?

A. DNA and RNA, the Molecules of Heredity, Are Nucleic Acids (Figure 2-26)

1. Nucleic acids—long chains of subunits known as nucleotides

a. Five-carbon sugar

b. Phosphate group

c. Nucleotide base

2. DNA—deoxyribonucleic acid—contains deoxyribose nucleotides

3. RNA—ribonucleic acid—contains ribose nucleotides

B. Other Nucleotides Perform Other Functions

1. Cyclic nucleotides—intracellular messengers (ex. cyclic AMP)

2. Adenosine triphosphate—carries energy from place to place (ex. ATP)

â Lecture Activity 2.6: Molecular Twenty Questions

â Web Animation: Functions of Macromolecules

Improving on Nature? Revisited


KEY TERMS

acid cohesion ion polar molecule

amino acid covalent bond ionic bond protein

atom dehydration synthesis isotope proton

atomic nucleus denature lipid radioactive

atomic number electron molecule solvent

base electron shell neutron surface tension

buffer element nonpolar molecule wax

carbohydrate functional group nucleic acid

chemical bond hydrogen bond organic molecule

chemical reaction hydrolysis pH scale

ANSWERS TO TEXT QUESTIONS

Figure-based Questions

Figure 2-2 Why do biologically active atoms tend to be ones whose outer shells are not full?

Atoms with partially empty outer shells have a strong tendency to react with other atoms in ways that gain or share

electrons to fill their outer shells, or that give up electrons to empty their outer shells.

Figure 2-6 In water’s polar bonds, why is oxygen’s pull on electrons stronger than hydrogen’s?

Oxygen’s nucleus has eight protons, while hydrogen’s has only a single proton. So the positive charge of the oxygen nucleus

attracts electrons far more strongly than that of the hydrogen nucleus.

Figure 2-8 Why is it important to human physiology that sugars dissolve easily in water?

Cellular energy is derived from the chemical bonds in sugar molecules. Blood, the fluid surrounding each cell, and

cytoplasm consist largely of water, so the solubility of sugar in water allows sugar molecules to be transported to and into

all of the body’s cells.

Figure 2-11 How would the concentration of hydrogen ions in a cup of tea change if you added lemon juice to it?

The pH of lemon juice is lower than the pH of tea, so the hydrogen ion concentration would increase.

Figure 2-15 Many types of plastic are composed of molecules derived from cellulose, but engineers are working hard to

develop plastics based on starch molecules. Why might starch-based plastics be an improvement over existing types of plastic?

Starch is easily digested by decomposer microbes, so starch-based plastics would be far more biodegradable than plastics

made from more microbe-resistant molecules such as cellulose.

Figure 2-24 Why do most proteins, when heated, lose their ability to function?

The hydrogen bonds that account for secondary and higher level protein structure can be broken by heat. Because a

protein’s function generally depends on its shape, breaking shape-controlling bonds disrupts function.

Consider This

Some experts argue that we should encourage people to use artificial sweeteners and fake fats, because obesity will decline if

people eat appealing food while limiting fat and sugar consumption. Critics of fake foods, however, contend that people

should avoid the risks associated with artificial food additives and, instead, consume nutritious foods that are naturally low in

sugar and fats. What do you think?


Hints: Research the risks of obesity and of food additives that reduce calories. Research the effectiveness of the additives in

helping people lose weight. Also consider whether it is possible to promote behavior that avoids both kinds of risks.

Fill-in-the-Blank

1. An atom that has lost or gained one or more electrons is called a(n) ________. If an atom loses an electron it takes on

a(n) ________ charge. If it gains an electron it takes on a(n) ________ charge. Atoms with opposite charges attract one

another, forming ________ bonds.

ion; positive; negative; ionic

2. In addition to protons, all atoms except hydrogen have ________ in their nuclei. Atoms of the same element that differ

in the number of neutrons in their nuclei are called ________ of one another. Some of these atoms spontaneously break

apart, releasing ________ and forming different atoms in the process. Such atoms are described as ________.

neutrons; isotopes; energy; radioactive

3. An atom with an outermost electron shell that is either completely full or completely empty is described as ________. Atoms with partially full outer electron shells are ________ and may gain, lose, or share electrons, forming ________.

inert; reactive, chemical bonds

4. Water is described as ________ because each water molecule has partial negative and positive charges. This property of

water allows water molecules to form ________ bonds with one another. The bonds between water molecules give

water a high ________ and result in surface tension.

polar; hydrogen; cohesion

5. Large biological molecules are often formed from a series of similar smaller molecules that are linked together.

The chemical reaction that creates bonds between the smaller subunits by removing water is called ________.

The reverse reaction that breaks down these molecules by adding water is called ________. Starch and cellulose are

both formed from subunit molecules of ________, and proteins are formed from ________.

dehydration synthesis; hydrolysis; glucose, amino acids

6. The four general classes of biological molecules are: ________, ________, ________, ________.

After each molecule, identify the general class to which it belongs:

cellulose: ________; steroid: ________; enzyme: ________; fat: ________;

disaccharide: ________; DNA: ________; glycogen: ________.

carbohydrates, lipids, proteins, nucleic acids; carbohydrate; lipid; protein; lipid; carbohydrate; nucleic acid; carbohydrate

Review Questions

1. Distinguish atoms from molecules; elements from compounds; and protons, neutrons, and electrons from each other.

An atom is the smallest particle of an element that still retains the properties of that element. A molecule consists of

two or more atoms chemically bonded together. Protons are positively charged subatomic particles found in the atomic

nucleus. Neutrons are uncharged subatomic particles found in the atomic nucleus. Electrons are negatively charged

subatomic particles found in electron shells around the atomic nucleus.

2. Compare and contrast covalent bonds, ionic bonds, and hydrogen bonds.

Covalent bonds are formed by sharing electrons between two atoms. Ionic bonds result when oppositely charged ions

attract one another. The charges on the atoms result from the transfer of one or more electrons from one atom to

another to fill or empty the outer electron shell.


3. Describe how water dissolves a salt.

The polar water molecules are attracted to the charged ions. The water molecules surround and insulate the ions from

one another, allowing the ions to separate.

4. Define acid, base, and buffer. How do buffers reduce changes in pH when hydrogen ions or hydroxide ions are added

to a solution? Why is this phenomenon important in organisms?

An acid is a substance that releases hydrogen ions when dissolved in water. A base is a substance that combines with

hydrogen ions in water. A buffer is a compound that tends to maintain a solution at a constant pH by accepting or

releasing hydrogen ions in response to small changes in hydrogen ion concentration. Small changes in pH from normal

levels found in the body can interfere with the structure and proper functioning of biological molecules.

5. Which elements are common components of biological molecules?

The three most abundant atoms are carbon (C), hydrogen (H), and oxygen (O); nitrogen (N) is also relatively common

(found in all amino acids and nucleic acids), and phosphorus (P) is present in nucleic acids and ATP.

6. List the four principal types of biological molecules, and give an example of each.

Carbohydrates—glucose, sucrose, starch, glycogen, cellulose, chitin

Lipids—oils, fats, waxes, cholesterol

Proteins—keratin, silk, hemoglobin

Nucleic acids—DNA, RNA

7. What roles do nucleotides play in organisms?

Nucleotides are subunit monomers in DNA and RNA; ATP serves as a short-term energy storage molecule; cyclic

AMP is an intracellular messenger.

8. Distinguish among the following: monosaccharide, disaccharide, and polysaccharide. Give two examples of each and

their functions.

A monosaccharide is a single sugar molecule; glucose and ribose are examples. Monosaccharides provide energy

and serve as a building block for polysaccharides. A disaccharide is two monosaccharides bonded together; sucrose

and lactose are examples. Disaccharides are used for short-term energy storage. A polysaccharide is a long chain of

bonded monosaccharides; cellulose and glycogen are examples. Polysaccharides are used for long-term energy

storage, and many are structural components of cells.

9. Describe the manufacture of a protein from amino acids.

Proteins are produced by dehydration synthesis of amino acids to form polypeptides bonded together by peptide bonds.

Applying the Concepts

1. IS THIS SCIENCE? Headlines on a magazine cover proclaim: “Turn fat into muscle!” Evaluate this claim from a

scientific standpoint.

Hints: Fat tissue consists mostly of fat molecules, and muscle tissue consists mostly of protein molecules. Do they

contain all of the same kinds of atoms?

2. Drugstores sell many different brands of “antacid” remedies, which are intended to bring relief from “acid stomach.”

Each brand claims to eliminate symptoms faster than its competitors. How do these compounds work? Use your

knowledge of acids, bases, and buffers to design an experiment to determine which brand of antacid works best.

Hints: Antacids may work by being basic and neutralizing stomach acid or by buffering the stomach contents at a pH

that is normal for the stomach. Experiments might involve mixing fixed amounts of different antacids into solutions with


acidity in the range found in stomachs and seeing how much the pH changes. Trials with different starting pH would

help make the experiments more revealing.

3. Many of water’s unique properties are the result of its polar covalent bonds, which allow water molecules to form

hydrogen bonds with each other. What if water molecules instead had nonpolar covalent bonds? Using information

from this chapter, make a list of hypotheses about the ways in which this change might affect the properties of water.

Describe how each change would affect living things. Design an experiment to test one of your hypotheses.

Hints: If water molecules were nonpolar, there would be no hydrogen bonds between water molecules. As a result, we

might hypothesize that water would be less effective as a solvent, and that it would have less internal cohesion.

Think about how such changes would affect such biological processes as transport of substances in blood and movement of

water and nutrients in plants.

FOR MORE INFORMATION

Atkins, P. W. Molecules. New York: Scientific American Library, 1987. A layperson’s introduction to atoms and molecules,

with superb illustrations.

Burdick, A. “Cement on the Half Shell.” Discover, February 2003. Mussels produce a protein polymer that is waterproof

and incredibly strong.

Goodsell, D. S. The Machinery of Life. New York: Springer, 1993. Goodsell depicts the molecules of a cell in all their

three-dimensional, interactive glory. A great way to gain a feel for the beauty and intricacy of the organic molecules of life.

Hill, J. W., and Kolb, D. K. Chemistry for Changing Times. 10th ed. Upper Saddle River, NJ: Prentice Hall, 2004.

A chemistry textbook for nonscience majors that is both clearly readable and thoroughly enjoyable.

King, J., Haase-Pettingell, C., and Gossard, D. “Protein Folding and Misfolding.” American Scientist, September–October

2002. Protein folding holds the key to proteins’ diverse functions.

Kunzig, R. “Arachnomania.” Discover, September 2001. Researchers work to unravel the mystery of spider silk protein

and develop a process to synthesize it.

Morrison, P., and Morrison, P. Powers of Ten. New York: W. H. Freeman, 1982. A fascinating journey from the universe to

the nucleus of an atom.

LECTURE ACTIVITIES

Lecture Activity 2.1: Exercise in Chemical Bonding

Estimated Time to Complete: 10–20 minutes

Introduction

This activity is a basic introduction to the concept of chemical bonding. This is a short, in-class exercise that can follow an

introductory discussion of atomic structure and bonding. Students will take the number of their birth month as their atomic

number. Given this information, they will be able to determine the configuration of electrons. They will then be able to

determine how this atom will interact with other atoms, if at all. Students will form groups with other students to form ions or

molecules and will present their bond formation to the class.

Chapter Section Reference


Materials Needed

Pen

Paper


Procedures

1. Instruct the students to identify their birth month on a piece of paper. They will consider the number of their birth

month to be their atomic number.

2. Next, instruct them to draw their appearance as an atom. Specifically, they must determine their electron configuration

and how many electrons are in their outermost shell.

3. Using this information, they should determine what type of bond they might like to form to become stable and fill the

outermost shell.

4. Students must then form a bond with another classmate so that both “atoms” become stable.

5. These student groups of bonded atoms can then present their bond to the class and explain why they are both now

stable. Alternatively, to save class time, they could write this information on a sheet of paper to be handed in.

Assessment Suggestions

Evaluate the student bonds that are formed and assign a grade for class participation.

Lecture Activity 2.2: Atomic Love Connection

Estimated Time to Complete: 20 minutes

Introduction

This activity reinforces students’ understanding of atomic structure, as well as ionic and covalent bonds. These topics should

be covered in class prior to beginning this activity. In this activity, the students will either choose or be assigned a particular

element and will write a “personal ad” for that atom. This ad should describe the properties of the atom and also describe

what type of bond the atom would “like” to form. Following completion of the handout, students should share their “ads”

with each other to find a good bonding match between atoms.



Materials Needed

Handout included in this activity

Periodic table for the entire class or for each student

Pen or pencil

Procedures

1. Hand out worksheet with background information.

2. Students should work individually to write their own personal ad for their atom. The instructor may choose to assign an

element or students may choose from the elements listed on the worksheet. In larger classes, more than one student can

be assigned the same element.

3. The students should first determine the atomic number of their element and how many electrons are in the outer shell.

This information can then be used to determine if the atom is most likely to form a covalent or ionic bond.

4. Students can then interact with each other in groups to find matches to their ads. For example, a carbon ad would match

up well with a hydrogen ad to form covalent bonds.


You may collect the student’s sheets for grading or assign an in-class participation grade if the student reads their ad to the class.

Lecture Activity 2.3: Carbohydrate Reverse Questions


Introduction

This activity allows the students to begin to think about carbohydrates in preparation for an exam or quiz. You can explain to

your students that this may not be a bad way to study, not just for the carbohydrates, but for any topic.



2.6 What Are Carbohydrates?

Materials Needed

Pen

Paper

Procedure

1. Break the students up into groups of three or four.

2. Instruct each group to take approximately 5 minutes to create three to four carbohydrate questions that have one or two

word answers. Have the groups write down the questions and answers.

3. Have each group select their best (or favorite) question and give the answer to the class as a whole. Give the class time

to come up with the question that matches the answer presented.


You can have the groups turn in their questions and consider using a few on the exam.

Lecture Activity 2.4: Fake Fats: To Eat or Not to Eat?


Introduction

This activity allows students to engage in a debate related to the real-life issues surrounding the use of the fat substitute

Olestra. Students are assigned to two opposing groups: one in favor of the use of fake fats and the other against the use of

fake fats. They are given Web links to different sources of information. This debate announcement can be posted on the

course Web page on the day the details of the debate are introduced to the class. Alternatively, the debate announcement and

details can be distributed as a handout to the students. At the end of the debate, students will take part in a “taste test” to

sample chips made with “real fat” versus “fake fat.”


2.7 What Are Lipids?

Materials Needed

Debate announcement/handout

Regular and Olestra-containing potato chips for taste test

Procedures

1. The students are given this assignment in the class before the debate is to occur. Before the debate, the students must

gather information to support their argument for the debate. Part of this preparation involves understanding the

structural differences between fake fats and real fats.

2. On the day of the debate, they are given approximately 5 minutes to meet with others on their “side” to come up with

their game plan for the debate.

3. When the debate begins, the two groups take turns presenting their arguments either for or against the use of fat

substitutes. The debate lasts about 15 minutes. The instructor keeps track of each side’s arguments on the board and, at

the end, the students are given time to copy down what is on the board.

4. After the debate, the students take part in a taste test of potato chips made with “real fat” and “fake fat.” During the taste

test, the instructor reiterates the important points of the topic and revisits the structural comparison between the fake fat

molecule and the real fat molecule. The students should offer their opinions about the taste differences and how they

relate to the structural differences between the two molecules.


A. One option for assessment is to assign the following:

1. To hand in: (no more than one page)

a. State which side of the debate you were on.

b. List two reliable resources that you used to prepare for this debate.

c. List at least two arguments on your side of the debate.


B. Another option involves either assigning the following questions for homework or including them as essay questions on

an exam:

1. Your aunt calls you because she has heard a report about Olestra on the news. The news report has raised her

concern about using products containing Olestra. She knows you are taking a biology class and hopes you can

provide some facts. Write a short note to your aunt filling her in on the pros and cons of using Olestra, based on

the information you learned in class. Let her know what your conclusions are AND what scientific facts you have

based these conclusions on.

2. Explain how the structure of a fake fat is different from that of real fat. Why does this make a difference in the

digestive system? Additionally, explain how this structure is related to the debate over the use of fake fats in foods.

Lecture Activity 2.5: Protein Structure and Function


Introduction

This activity allows students to learn more about the science of protein structure analysis. A great deal of biological research

is now focused on determining the structure of different proteins. Scientists then use that information to generate hypotheses

about the function of that protein. In this exercise, you will display three different three-dimensional protein structures and

ask the students to describe the structure and then make predictions about possible functions of that protein based on its

structural characteristics. The students may work individually or as part of a team to complete the exercise. Included in this

activity are three Web sites with pictures of particular protein structures. Additionally, a set of three PowerPoint slides

containing the specific pictures and their Web site sources is included.


2.8 What Are Proteins?

Materials Needed

Computer with projector capabilities (or the pictures can be copied onto overhead transparencies)

Pen and paper

Procedures

1. Advise the students that you will be presenting them with two pictures of proteins for which scientists have determined

the structure.

2. For each of the proteins, the students should first write down their observations of the protein’s structure. Ask the

students: How would you describe what you see in your own words?

3. Now, working in small groups, the students should try to determine the function of each protein. They should state their

hypothesis AND the reasoning behind their hypothesis. Explain that they will not be graded based on a right or wrong

answer. Instead, they should put themselves in the place of scientists who are currently working on these same

problems. Encourage them to be creative!

Here are the links for the two pictures to be used (alternatively, you may use the PowerPoint slides that are included):

A. www.biologie.uni-konstanz.de/folding/Structure%20gallery%201.html

B. www.msi.umn.edu/general/Bulletin/Vol.14-No.1/Protein.html

Instructor’s guide for protein structures:

1. This is a picture of outer membrane proteins that are “tunnels” used to transport items in and out of bacterial cells. This

is a side view, but if you were to look from the top, you would see that these proteins form circular channels for

moving molecules.

2. This is a helicase protein that interacts with DNA (shown in the picture). Scientists determined that the opening of this

ring-shaped protein could accommodate the DNA molecule. This protein plays a role in unraveling a DNA molecule

during DNA replication.


You may collect the sheets containing the students’ observations and hypotheses. Alternatively, you may assign the students

to go online to find a recent study that identified the structure of a protein. They can then write a short paragraph about the

significance of the study.


Lecture Activity 2.6: Molecular Twenty Questions

Estimated Time to Complete: 15–20 minutes

Introduction

In this activity, the students will get an opportunity to test their knowledge of biological molecules. The students will form

groups of three or four. Each student will draw the name of a biological molecule from a hat. The other students in the group

will then take turns asking yes or no questions until one of them is able to correctly guess the identity of the molecule in

question.


2.9 What Are Nucleic Acids?

Materials Needed

Names of different molecules on pieces of paper for each student to draw (The sheet included with this activity contains

the names of a few molecules that can be used in this exercise. You can cut out the names from this sheet to use in class.

For a larger class, you may repeat the same molecules.)

Hat or box to place names in

Procedures

1. Instruct the students to form groups of three or four students. Explain how the game will work and have the students

determine who will go first in each group.

2. Allow one member from each team to draw the name of a biological molecule from the hat.

3. The other members of each group must then take turns asking a yes or no question about the molecule.

4. If a student in a group guesses correctly, they must wait until their turn to answer.

5. Each member of the group must take a turn drawing the name of a molecule for the others to guess.

6. This is a useful means of reviewing for an exam that is not time consuming.


You may have the students keep track of how many they guess correctly and give out a grade or extra credit for those who

get above a certain score.


Name: __________________________ Date: __________________

Instructor: ______________________ Course Section: _________

Lecture Activity 2.1 Handout—Exercise in Chemical Bonding

1. Write the number of your birth month: ________ The corresponding element is: __________

2. Draw your atom. The number of electrons in the outermost shell is: ________

3. Which element or elements would you bond with?

4. Find at least one classmate who has the atom you need. That classmate is: _______________.

5. Briefly explain why bonding with the above classmate’s element has made both atoms stable.


Name: __________________________ Date: __________________


Lecture Activity 2.2 Handout—Atomic Love Connection

Choose one of the following elements:

carbon magnesium hydrogen

nitrogen chlorine calcium

oxygen sodium phosphorus

sulfur potassium bromine

1. Determine the atomic symbol: ___________

2. Use the periodic table to determine the atomic number: ___________

3. Describe how you will determine if the atoms of your element are inert or reactive.

4. Use the characteristics of your atom to write a “personal ad” for it. Be creative! See the example below as a guide for

the information you should include.

Example: Fluorine (F); atomic number = 9

Personal ad: Single fluorine atom seeking another kind atom willing to donate one electron to add stability to my life.

I currently have seven electrons in my outer shell and am willing to form an ionic bind with any atom who answers this ad.

5. When you are done, see if you can find another personal ad that is a good match for yours (your atomic love

connection). Write your match below. What kind of bond will you form?


Name: __________________________ Date: __________________


Lecture Activity 2.3 Handout—Carbohydrate Reverse Questions

1. Write your three or four questions and their one to two word answers.

2. Select your best question from the list above. Read the ANSWER to the class. Did anyone come up with your question?

Did anyone come up with a question that matches your answer? If so, what was the other question?

3. Were you able to develop a question for any of the other answers from other groups? If so, what was it?


Name: __________________________ Date: __________________


Lecture Activity 2.4 Handout—Fake Fats: To Eat or Not to Eat?

For this debate:

You must research the scientific and medical arguments on your side.

You should also research what the arguments will be on the other side, so that you are prepared to argue against

their points.

Start your debate prep by visiting the sites below:

Center for Science in the Public Interest (www.cspinet.org/olestra/index.html) are against fake fats; Proctor and Gamble

(www.olean.com/), the makers of Olean, are in favor of fake fats


Name: __________________________ Date: __________________


Lecture Activity 2.5 Handout—Protein Structure and Function

1. For each of the proteins your group is assigned, make your observations. What do you see and what do you not see?

2. What is your hypothesis regarding the function of each? What support do you have to defend this hypothesis?

3. If your instructor has a class discussion after the groups have met, are there any ideas that your group did not originally

think about? Does that alter your hypothesis? Why or why not?


Name: __________________________ Date: __________________


Lecture Activity 2.6 Handout—Molecular Twenty Questions

DNA Glucose Cholesterol

RNA Phospholipid Starch

Lactose Sucrose Protein

Amino acid Nucleotide Lipid

Documents

Full file at ://fratstock.eu/sample/Solutions-Manual-Life-on-Earth-5th-Editio… · Fructose—found in corn syrup B. Disaccharides Store Energy (Figure 2-14) 1. Disaccharides—two