Book cover for Campbell Biology Concepts & Connections

Campbell Biology Concepts & Connections

Martha R. Taylor, Jean L. Dickey, Eric J. Simon, Kelly Hogan, Jane B. Reece

ISBN #9780134296012

9th Edition

631 Questions

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82,520 Students Helped

Homework Questions

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Summary
Learning Objectives
Key Concepts
Example Problems
Explanations
Common Mistakes

Summary

This chapter emphasizes the central role of carbon in constructing the molecules of life. It explains how simple monomers are linked through dehydration reactions to form complex polymers such as carbohydrates, lipids, proteins, and nucleic acids. The structure of these molecules—shaped by three-dimensional forms, isomerism, and functional groups—directly influences their biological functions. Additionally, the chapter connects molecular biology to genetics by detailing the role of nucleic acids in encoding information and highlights evolutionary adaptations like lactose tolerance, underscoring the dynamic interplay between structure, function, and evolution in biological systems.

Learning Objectives

1

Describe the central role of carbon in forming diverse organic molecules essential for life.

2

Explain how dehydration reactions link simple monomers to form complex polymers including carbohydrates, lipids, proteins, and nucleic acids.

3

Analyze the relationship between the structure (3D shapes, isomeric forms, functional groups) of biomolecules and their biological functions.

4

Understand how genetic information is encoded in nucleic acids and translated into functional proteins.

5

Evaluate evolutionary examples, such as lactose tolerance, to understand biochemical adaptations over time.

Key Concepts

CONCEPT

DEFINITION

Carbon

A chemical element with the unique ability to form four covalent bonds, making it essential for creating the diverse range of organic molecules found in life.

Organic Molecules

Molecules primarily composed of carbon and hydrogen, often with oxygen, nitrogen, sulfur, and phosphorus, that serve as the building blocks of life.

Monomer

A small, simple molecule that can join with other similar molecules through chemical reactions to form a polymer.

Polymer

A large molecule made up of repeating monomer units, connected by chemical bonds.

Dehydration Reaction

A chemical reaction that removes a water molecule to form a bond between monomer units, leading to polymer formation.

Functional Group

Specific groups of atoms within molecules that have characteristic properties and reactivity, influencing the behavior and function of the molecule.

Carbohydrates

Organic compounds made up of sugar units (monosaccharides) that serve as energy sources and structural components in cells.

Lipids

Hydrophobic molecules, including fats and oils, that are important for energy storage, cell membrane structure, and signaling.

Proteins

Complex molecules composed of amino acids; they perform a variety of functions including catalysis, structure, and regulation.

Nucleic Acids

Biopolymers (DNA and RNA) that store and transmit genetic information in cells.

Isomers

Molecules with the same molecular formula but different three-dimensional configurations, leading to different properties.

Example Problems

Example 1

Complete the following table to help you review the structures and functions of the four classes of organic molecules. (TABLE CAN'T COPY)

Example 2

A glucose molecule is to starch as (Explain your answer.) a. a steroid is to a lipid. b. a protein is to an amino acid. c. a nucleic acid is to a polypeptide. d. a nucleotide is to a nucleic acid.

Example 3

What makes a fatty acid an acid? a. It does not dissolve in water. b. It is capable of bonding with other molecules to form a fat. c. It has a carboxyl group that can donate an $\mathrm{H}^{+}$ to a solution. d. It contains only two oxygen atoms.

Example 4

Cows can derive nutrients from cellulose because a. they produce enzymes that recognize the shape of the glucose-glucose bonds and hydrolyze them. b. they re-chew their cud to break down cellulose fibers. c. their digestive tract contains microorganisms that can hydrolyze the bonds of cellulose. d. they convert cellulose to starch and can digest starch.

Example 5

Of the following functional groups, which is/are polar, tending to make organic compounds hydrophilic? a. carbonyl b. amino c. hydroxyl d. all of the above
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Step-by-Step Explanations

QUESTION

How does a dehydration reaction join monomers into a polymer?

STEP-BY-STEP ANSWER:

Step 1: Identify two monomer molecules that each contain an -OH (hydroxyl) group and an -H (hydrogen) atom.
Step 2: The reaction involves the removal of a water molecule (H2O), where the -OH from one monomer and the -H from the other are eliminated.
Step 3: The removal of water enables the remaining parts of the monomers to form a covalent bond, linking them together.
Step 4: This process can repeat multiple times, building long polymer chains from many monomers.
Final Answer: A dehydration reaction removes water to create a covalent bond between monomers, forming a polymer.

Dehydration Reaction

QUESTION

How do the levels of protein structure contribute to its function?

STEP-BY-STEP ANSWER:

Step 1: Recognize that the primary structure is the sequence of amino acids which determines the protein's basic makeup.
Step 2: The secondary structure (e.g., alpha-helices and beta-sheets) is formed by hydrogen bonding, adding local folding patterns.
Step 3: The tertiary structure is the overall three-dimensional shape determined by interactions among side chains.
Step 4: In proteins with multiple subunits, the quaternary structure describes how these subunits assemble.
Final Answer: Each level of protein structure, from primary to quaternary, is critical for the protein’s specific shape and function.

Protein Structure

QUESTION

Describe how nucleic acids encode and transmit genetic information.

STEP-BY-STEP ANSWER:

Step 1: Understand that nucleic acids are polymers of nucleotides, each containing a sugar, a phosphate group, and a base.
Step 2: The sequence of nucleotide bases (adenine, thymine/uracil, cytosine, and guanine) forms a code that specifies genetic information.
Step 3: In DNA, the double helix structure allows complementary base pairing, facilitating replication and transcription.
Step 4: RNA transcribes and translates this genetic information into proteins.
Final Answer: Nucleic acids encode genetic information in the sequence of nucleotide bases, which is transmitted through replication and translated into proteins.

Nucleic Acids

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Common Mistakes

  • Confusing dehydration reactions with hydrolysis, which is the breaking of bonds by adding water.
  • Overlooking the importance of carbon’s bonding versatility in forming diverse molecules.
  • Assuming that the three-dimensional structure of a molecule is static, rather than dynamic and essential for function.
  • Neglecting the link between molecular structure and biological function, assuming that similar molecules behave identically.
  • Underestimating the evolutionary context in which molecular diversity develops, such as in traits like lactose tolerance.