AP Biology Chapter 3 Review

Questions and Answers

What is a monomer?

A type of carbohydrate

Repeating units of a polymer (correct)

A long molecule made of similar building blocks

A reaction involving water

What defines a polymer?

A protein structure

A long molecule made of similar building blocks linked by covalent bonds (correct)

A single sugar molecule

A type of amino acid

What is dehydration (condensation reaction)?

A type of sugar

A protein formation process

The addition of water to separate monomers

Monomers connect by two molecules bonding and losing water (correct)

What is hydrolysis?

When two monomers separate when a water molecule is added Signup and view all the answers

What are monosaccharides?

Simple sugars that have carbonyl and hydroxyl groups and are 3-7 carbons long. Signup and view all the answers

What are disaccharides?

Two monosaccharides joined by glycosidic linkage. Signup and view all the answers

What characterizes polysaccharides?

Macromolecules made of hundreds to thousands of monosaccharides joined by glycosidic linkages. Signup and view all the answers

Describe starch.

A polysaccharide found in plants consisting of alpha-glucose monomers. Signup and view all the answers

What is glycogen?

A polymer of glucose stored in liver and muscle cells. Signup and view all the answers

What is cellulose?

A component of cell walls and the most abundant organic compound on Earth, made of beta-glucose. Signup and view all the answers

What is chitin?

A hard outer shell material found in arthropods, consisting of interwoven strands. Signup and view all the answers

What is the difference between alpha glucose and beta glucose?

In alpha glucose, the hydroxyl group is facing down, while in beta glucose, it is above the ring on the first carbon. Signup and view all the answers

Describe the structure of a fat (triglyceride).

A glycerol head bonded to three fatty acid tails by ester bonds. Signup and view all the answers

What is the difference between saturated and unsaturated fatty acids?

Saturated fatty acids are saturated with H+, while unsaturated typically have double bonds and are kinked. Signup and view all the answers

Describe the structure of a phospholipid.

A phospholipid consists of two fatty acid tails and one negatively charged phosphate head. Signup and view all the answers

What is a steroid?

A lipid with a carbon skeleton of four fused rings. Signup and view all the answers

What is the structure of an amino acid?

An amino acid has a carboxyl group (COOH) and an amino group (NH2). Signup and view all the answers

What is a polypeptide?

A polymer made of amino acids linked by peptide bonds. Signup and view all the answers

What kind of bonds hold amino acids together?

Peptide bonds. Signup and view all the answers

What is primary structure in proteins?

The sequence of amino acids linked by peptide bonds via dehydration synthesis. Signup and view all the answers

What is secondary structure in proteins?

The formation of alpha helices and beta sheets through hydrogen bonds. Signup and view all the answers

What is tertiary structure in proteins?

The overall 3-dimensional shape formed by interactions between R groups. Signup and view all the answers

What is quaternary structure in proteins?

A structure formed when two or more polypeptide chains aggregate. Signup and view all the answers

What are different R groups in amino acids?

Different amino acids have different R groups. Signup and view all the answers

Describe the structure and function of DNA.

DNA consists of nucleotides bonded by phosphodiester bonds and has complementary pairs held by hydrogen bonds. Signup and view all the answers

What is a nucleic acid?

A chain of nucleotides. Signup and view all the answers

What are nucleotides?

Each nucleotide is composed of a phosphate, a pentose sugar, and a nitrogenous base. Signup and view all the answers

What is the structure and function of RNA?

RNA is similar to DNA but is not double-stranded and contains uracil. It transports information. Signup and view all the answers

What is the difference between pyrimidine and purine?

Purines have a six-membered ring fused to a five-membered ring, while pyrimidines have only a six-membered ring. Signup and view all the answers

Study Notes

Key Concepts in Biochemistry

Monomers are the repeating units that serve as building blocks for larger structures, known as polymers.
Polymers are long molecules formed by linking similar building blocks via covalent bonds.

Reactions Involving Monomers

Dehydration (Condensation) Reaction: This process involves the bonding of two monomers, resulting in the release of a water molecule.
Hydrolysis: In this reaction, a water molecule is added to separate two monomers, breaking down polymers into their monomer components.

Sugars and Their Structures

Monosaccharides are simple sugars with a carbonyl group (C=O) and hydroxyl groups (-OH); they can range from 3 to 7 carbons. Examples include glucose, fructose, and ribose.
Disaccharides consist of two monosaccharides linked by glycosidic linkages through dehydration. Common examples are sucrose, lactose, and maltose.
Polysaccharides are macromolecules formed from hundreds to thousands of monosaccharides joined by glycosidic linkages, serving various functions like storage or structural material. Key examples include starch, cellulose, and glycogen.

Specific Polysaccharides

Starch: A plant polysaccharide composed of α-glucose monomers, stored in plastids; it allows plants to stockpile surplus sugars, later accessible via hydrolysis.
Glycogen: A polymer of glucose stored in the liver and muscle cells of vertebrates; it can be quickly mobilized through hydrolysis when energy needs increase.
Cellulose: A structural component of cell walls, this β-glucose polymer is the most abundant organic compound on Earth; most animals cannot digest it due to its β linkages.
Chitin: A structural polysaccharide in arthropod exoskeletons, comprising interwoven strands providing strength and flexibility.

Structural Variations of Glucose

Alpha vs. Beta Glucose: The hydroxyl group's position varies; in alpha glucose, it faces down, while in beta glucose, it is positioned above the ring on the first carbon. They are isomers, sharing the same molecular formula.

Lipids and Their Structures

Triglycerides (Fats): Comprise a glycerol head bonded to three fatty acid tails through ester bonds, formed via dehydration synthesis.
Saturated Fatty Acids: Fully saturated with hydrogen atoms, lacking double bonds, while unsaturated fatty acids contain one or more double bonds, resulting in a kinked structure.
Phospholipids: Consist of two fatty acid tails and a negatively charged phosphate head. They are crucial for forming cell membranes.
Steroids: A class of lipids characterized by a carbon skeleton with four fused rings; examples include cholesterol, sex hormones, and vitamin D.

Proteins and Their Structures

Amino Acids: Basic building blocks, characterized by a carboxyl group (COOH) and an amino group (NH2).
Polypeptides: Chains of amino acids linked by peptide bonds, formed through dehydration reactions.
Peptide Bonds: Specialized covalent bonds that connect amino acids in a polypeptide.
Protein Structures:
- Primary Structure: Sequence of amino acids linked by peptide bonds.
- Secondary Structure: Formed by hydrogen bonds between backbone atoms, resulting in alpha helices or beta sheets.
- Tertiary Structure: The overall 3D shape driven by interactions among R groups, including hydrophobic interactions, hydrogen bonds, ionic bonds, and disulfide bridges.
- Quaternary Structure: The assembly of two or more polypeptide chains into a functional protein.

Nucleic Acids

DNA Structure: Composed of nucleotides bonded by phosphodiester bonds, with specific complementary base pairing (G with C, T with A).
Nucleotides: Each contains a phosphate group, a pentose sugar, and a nitrogenous base.
RNA Structure: Similar to DNA but single-stranded and contains uracil instead of thymine, playing a key role in information transport.

Nitrogenous Bases

Pyrimidines: Single six-membered rings of carbon and nitrogen; include cytosine, uracil, and thymine.
Purines: Larger structures comprising fused six-membered and five-membered rings; include adenine and guanine.

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Test your knowledge with this flashcard quiz on Chapter 3 of AP Biology. Cover key concepts such as monomers, polymers, dehydration reactions, and hydrolysis. Great for students preparing for the AP exam or reviewing essential biological macromolecules.