Biology 161 Study Guide – Step-by-Step Guidance for Key Concepts and Example Questions

Study Guide - Smart Notes

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Q1. How do we distinguish the four classes of biomolecules on the basis of their functional groups?

Background

Topic: Biomolecule Classification and Functional Groups

This question tests your understanding of how proteins, carbohydrates, lipids, and nucleic acids can be identified and differentiated based on the functional groups present in their structures.

Key Terms and Concepts:

Functional group: A specific group of atoms within a molecule that is responsible for certain chemical reactions and properties.
Biomolecule classes: Proteins, carbohydrates, lipids, nucleic acids.
Examples of functional groups: amino (-NH2), carboxyl (-COOH), hydroxyl (-OH), phosphate (-PO4), methyl (-CH3), sulfhydryl (-SH).

Step-by-Step Guidance

List the four main classes of biomolecules: proteins, carbohydrates, lipids, and nucleic acids.
Recall the key functional groups associated with each class. For example, proteins contain amino and carboxyl groups, nucleic acids contain phosphate and nitrogenous bases, etc.
Think about how the presence or absence of these groups helps you identify the class. For instance, a molecule with many hydroxyl groups is likely a carbohydrate.
Consider the unique functional groups that are only found in one class (e.g., phosphate in nucleic acids, sulfhydryl in some proteins).

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Q2. Which monomers form which polymers? Why are polymerization reactions called condensation or dehydration and why are depolymerization reactions called hydrolysis?

Background

Topic: Monomers, Polymers, and Chemical Reactions in Biology

This question tests your ability to match monomers to their corresponding polymers and understand the chemical processes that build up and break down biological macromolecules.

Key Terms and Concepts:

Monomer: A small molecule that can join with others to form a polymer.
Polymer: A large molecule made up of repeating monomer units.
Dehydration (condensation) reaction: A reaction where two molecules are joined by removing a water molecule.
Hydrolysis reaction: A reaction where a polymer is broken down by adding a water molecule.

Step-by-Step Guidance

List the main biological polymers (proteins, nucleic acids, polysaccharides, lipids) and their corresponding monomers (amino acids, nucleotides, monosaccharides, fatty acids/glycerol).
Recall the type of bond formed during polymerization for each class (e.g., peptide bonds for proteins, glycosidic bonds for carbohydrates).
Describe what happens during a dehydration (condensation) reaction: two monomers join, and a water molecule is released.
Explain what happens during hydrolysis: a polymer is split into monomers by the addition of water.

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Q3. What is the relationship between pH, [H+], and whether a compound functions as an acid or base?

Background

Topic: Acid-Base Chemistry and pH

This question tests your understanding of how pH relates to hydrogen ion concentration and the definitions of acids and bases.

Key Terms and Formulas:

pH: A measure of the hydrogen ion concentration in a solution.
Acid: A substance that increases [H+] in solution.
Base: A substance that decreases [H+] in solution.

Key formula:

$\text{pH} = -\log_{10}[H^+]$

Step-by-Step Guidance

Recall the definition of pH and how it is calculated from hydrogen ion concentration.
Understand that a lower pH means higher [H+] (more acidic), and a higher pH means lower [H+] (more basic).
Relate the definitions of acids and bases to their effect on [H+].
Think about how changes in [H+] affect the pH value and the acidic or basic nature of a solution.

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Q4. Why do we say that “primary structure dictates secondary and tertiary structure”? What is the difference between the secondary, tertiary, and quaternary structure of a protein?

Background

Topic: Protein Structure and Function

This question tests your understanding of the levels of protein structure and how the sequence of amino acids determines the final shape and function of a protein.

Key Terms:

Primary structure: The sequence of amino acids in a polypeptide chain.
Secondary structure: Local folding patterns (e.g., alpha-helix, beta-sheet) stabilized by hydrogen bonds.
Tertiary structure: The overall 3D shape of a single polypeptide chain.
Quaternary structure: The arrangement of multiple polypeptide subunits in a protein.

Step-by-Step Guidance

Define each level of protein structure (primary, secondary, tertiary, quaternary).
Explain how the sequence of amino acids (primary structure) determines the way the chain folds into secondary and tertiary structures.
Describe the types of bonds and interactions that stabilize each level (e.g., hydrogen bonds, disulfide bridges, hydrophobic interactions).
Compare and contrast the secondary, tertiary, and quaternary structures in terms of complexity and function.

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Q5. What nucleotide structural features distinguish DNA and RNA molecules?

Background

Topic: Nucleic Acid Structure

This question tests your ability to identify the differences between DNA and RNA at the molecular level.

Key Terms:

Nucleotide: The monomer of nucleic acids, consisting of a sugar, phosphate group, and nitrogenous base.
DNA: Deoxyribonucleic acid; contains deoxyribose sugar and bases A, T, C, G.
RNA: Ribonucleic acid; contains ribose sugar and bases A, U, C, G.

Step-by-Step Guidance

Identify the sugar component in DNA and RNA nucleotides (deoxyribose vs. ribose).
List the nitrogenous bases found in each (DNA: A, T, C, G; RNA: A, U, C, G).
Note any structural differences in the overall molecule (e.g., double-stranded vs. single-stranded).

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Q6. What three structural features distinguish one monosaccharide from another?

Background

Topic: Carbohydrate Structure

This question tests your understanding of the structural diversity among monosaccharides (simple sugars).

Key Terms:

Monosaccharide: The simplest form of carbohydrate (e.g., glucose, fructose).
Structural features: Number of carbons, arrangement of hydroxyl groups, and ring vs. linear form.

Step-by-Step Guidance

List the possible features that can vary among monosaccharides (e.g., length of carbon chain, position of carbonyl group).
Consider the orientation of hydroxyl groups around asymmetric carbons (stereochemistry).
Think about the formation of ring structures and how alpha and beta forms differ.

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Q7. Why are there different types of glycosidic bonds but just one type of phosphodiester bond and one type of peptide bond? Why does the type of glycosidic bond matter?

Background

Topic: Bond Types in Biological Macromolecules

This question tests your understanding of the chemical bonds that link monomers in polymers and why some bonds have more variation than others.

Key Terms:

Glycosidic bond: The covalent bond that joins monosaccharides in carbohydrates.
Phosphodiester bond: The bond linking nucleotides in nucleic acids.
Peptide bond: The bond linking amino acids in proteins.

Step-by-Step Guidance

Recall how glycosidic bonds can form between different carbons (e.g., 1→4, 1→6) and in different orientations (alpha or beta).
Understand that phosphodiester and peptide bonds always form between the same functional groups in the same orientation.
Explain why the type of glycosidic bond affects the structure and function of the resulting polysaccharide.

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Q8. What is the difference structurally between storage and structural polysaccharides?

Background

Topic: Polysaccharide Structure and Function

This question tests your ability to compare the structure of polysaccharides used for energy storage (like starch and glycogen) versus those used for structure (like cellulose and chitin).

Key Terms:

Storage polysaccharide: Polysaccharides that store energy (e.g., starch, glycogen).
Structural polysaccharide: Polysaccharides that provide support (e.g., cellulose, chitin).
Branching: The presence of side chains in the polymer structure.

Step-by-Step Guidance

Identify examples of storage and structural polysaccharides.
Compare the types of glycosidic bonds and degree of branching in each.
Relate these structural differences to their biological functions.

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Q9. Can you associate each class of polymer with their monomers and the name of the bond that holds the monomers together? Can you name an example of each polymer and identify its function too?

Background

Topic: Biological Macromolecules and Their Functions

This question tests your ability to connect the structure of biological polymers to their building blocks, the bonds that link them, and their biological roles.

Key Terms:

Polymer: Large molecule made of repeating monomers.
Monomer: The building block of a polymer.
Bond types: Peptide, glycosidic, phosphodiester, ester.

Step-by-Step Guidance

List the four main classes of biological polymers and their monomers.
Identify the type of bond that links the monomers in each class.
Give an example of each polymer and describe its function in the cell.

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Example Multiple Choice Q1. Which one of the following elements is not found in a nucleic acid?

Background

Topic: Nucleic Acid Composition

This question tests your knowledge of the elements that make up nucleic acids (DNA and RNA).

Key Terms:

Nucleic acid: A polymer made of nucleotide monomers, containing elements such as C, H, O, N, and P.

Step-by-Step Guidance

Recall the chemical formula and structure of nucleic acids.
List the elements present in nucleic acids (carbon, hydrogen, oxygen, nitrogen, phosphorus).
Compare the answer choices to your list and identify which element is not present.

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Example Multiple Choice Q2. Beta-hemoglobin is:

Background

Topic: Protein Structure and Function

This question tests your ability to classify beta-hemoglobin based on its structure and function.

Key Terms:

Polypeptide: A chain of amino acids linked by peptide bonds.
Hemoglobin: A protein in red blood cells that carries oxygen.

Step-by-Step Guidance

Recall the structure of hemoglobin and its subunits.
Determine whether beta-hemoglobin is a single amino acid, a chain of amino acids, a carbohydrate, or a nucleic acid.
Eliminate answer choices that do not fit the definition of beta-hemoglobin.

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Example Multiple Choice Q3. In sickle cell anemia, a single amino acid substitution leads to beta-hemoglobin that is less able to carry oxygen. The reason this occurs is best explained as:

Background

Topic: Protein Structure and Disease

This question tests your understanding of how changes in protein structure can affect function, specifically in the context of sickle cell anemia.

Key Terms:

Amino acid substitution: A change in the primary structure of a protein.
Hydrophobic region: A part of a molecule that repels water and tends to associate with other hydrophobic regions.

Step-by-Step Guidance

Recall what happens to hemoglobin in sickle cell anemia at the molecular level.
Consider how a single amino acid change can alter the protein's shape and properties.
Evaluate each answer choice based on your understanding of protein structure and function.

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Example Fill-in-the-Blank Q1. When nucleic acids are polymerized, the second _ (monomer) is attached to the first one by the formation of a _ linkage, which is formed by the phosphate group of the second monomer attaching to the 3’ carbon of the first one. As a result, a sugar-phosphate is created with the _ off to the side. In DNA, two _ - _ DNA strands are used to form a double helix, in which ‘G pairs with C’ and ‘A with T’ in what is called _______ pairing.

Background

Topic: Nucleic Acid Structure and Polymerization

This question tests your knowledge of how nucleic acids are built from monomers and the terminology used to describe their structure.

Key Terms:

Nucleotide: The monomer of nucleic acids.
Phosphodiester linkage: The bond that connects nucleotides in a nucleic acid chain.
Sugar-phosphate backbone: The repeating structure in nucleic acids.
Nitrogenous base: The part of the nucleotide that is not part of the backbone.
Antiparallel: The orientation of the two DNA strands.
Complementary pairing: The specific pairing of bases (A with T, G with C).

Step-by-Step Guidance

Identify the monomer of nucleic acids.
Recall the name of the bond that links nucleotides together.
Describe what forms the backbone of the nucleic acid.
Remember what is attached to the backbone and the orientation of the two DNA strands.
Recall the term for the specific base pairing in DNA.

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Example Short Answer Q1. Rank the following in order by size: atom, electron, biomolecule, functional group, monomer

Background

Topic: Biological Organization and Scale

This question tests your understanding of the relative sizes of different chemical and biological entities.

Key Terms:

Electron: A subatomic particle.
Atom: The basic unit of a chemical element.
Functional group: A group of atoms within a molecule.
Monomer: A small molecule that can join with others to form a polymer.
Biomolecule: A large molecule found in living organisms.

Step-by-Step Guidance

List the entities from smallest to largest based on your knowledge of atomic and molecular structure.
Consider the definitions and typical sizes of each (e.g., electron is smaller than an atom, a monomer is larger than a functional group).
Arrange them in order, starting with the smallest.

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Example Short Answer Q2. Using boxes to represent monomers, draw how two monomers become linked, including any -H and -OH groups that are directly involved in the reaction. Also, is this a dehydration or a hydrolysis reaction?

Background

Topic: Polymerization and Chemical Reactions

This question tests your ability to represent the process of forming a polymer from monomers and to identify the type of reaction involved.

Key Terms:

Monomer: The building block of a polymer.
Dehydration (condensation) reaction: A reaction that joins two molecules by removing water.
Hydrolysis reaction: A reaction that breaks a bond by adding water.

Step-by-Step Guidance

Draw two boxes to represent two monomers, each with an -H or -OH group at the ends.
Show how the -H from one monomer and the -OH from the other are removed to form water ($H_2O$).
Indicate the new bond formed between the monomers after water is removed.
Decide whether this is a dehydration (condensation) or hydrolysis reaction based on whether water is produced or consumed.