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: Biomolecules 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: Amino group (–NH2), carboxyl group (–COOH), hydroxyl group (–OH), phosphate group (–PO4), methyl group (–CH3).

Step-by-Step Guidance

List the four major classes of biomolecules: proteins, carbohydrates, lipids, and nucleic acids.
Identify the key functional groups associated with each class. For example, proteins contain amino and carboxyl groups, carbohydrates have multiple hydroxyl groups, nucleic acids contain phosphate and nitrogenous bases, and lipids often have long hydrocarbon chains and sometimes phosphate groups (in phospholipids).
Think about how these functional groups influence the chemical properties and reactivity of each biomolecule class.
Consider how the presence or absence of certain functional groups can be used to distinguish between these classes.

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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

This question tests your ability to associate monomers with their corresponding polymers and to understand the chemical processes involved in building and breaking 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.
Condensation/Dehydration reaction: A reaction where two molecules are joined together with the removal of a water molecule.
Hydrolysis: A reaction where a polymer is broken down into monomers by the addition of water.

Step-by-Step Guidance

List the main biological polymers (proteins, nucleic acids, polysaccharides, and some lipids) and their corresponding monomers (amino acids, nucleotides, monosaccharides, fatty acids/glycerol).
Describe how monomers are joined together to form polymers, focusing on the removal of water (dehydration/condensation reaction).
Explain how polymers are broken down into monomers by adding water (hydrolysis reaction).
Think about why the terms 'dehydration' and 'hydrolysis' are used to describe these reactions.

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

Background

Topic: Acids, Bases, and pH

This question tests your understanding of how pH relates to hydrogen ion concentration and the acidic or basic nature of compounds.

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:

Step-by-Step Guidance

Recall the definition of pH and how it is calculated from the hydrogen ion concentration.
Understand that a lower pH means a higher [H+] (more acidic), and a higher pH means a lower [H+] (more basic).
Relate the behavior of acids and bases to changes in [H+] and pH.
Think about examples of acids and bases and how they affect pH when added to water.

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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

This question tests your understanding of the levels of protein structure and how the sequence of amino acids determines the overall 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 and the types of bonds/interactions involved.
Explain how the primary structure (amino acid sequence) determines the way the chain folds into secondary and tertiary structures.
Describe the differences between secondary, tertiary, and quaternary structures, focusing on their organization and interactions.
Consider examples of how changes in primary structure (mutations) can affect higher levels of structure 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 compare and contrast the structural differences between DNA and RNA at the nucleotide 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 and note the difference (deoxyribose vs. ribose).
List the nitrogenous bases found in DNA and RNA, highlighting which base is unique to each.
Consider the structural implications of these differences for the overall molecule (e.g., stability, double vs. single strand).
Think about how these differences affect the function of DNA and RNA.

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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).
Isomer: Molecules with the same formula but different structures.

Step-by-Step Guidance

List the three main structural features that can vary among monosaccharides (e.g., number of carbons, position of carbonyl group, arrangement of hydroxyl groups).
Explain how each feature contributes to the diversity of monosaccharides.
Think about examples of monosaccharides that differ in these features.
Consider how these differences affect the function and reactivity of the sugars.

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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: Types of Bonds in Biomolecules

This question tests your understanding of the chemical linkages that join monomers in biological polymers and why some bonds have more variability than others.

Key Terms:

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

Step-by-Step Guidance

Describe the chemical nature of glycosidic, phosphodiester, and peptide bonds.
Explain why glycosidic bonds can form in different orientations (alpha, beta, 1-4, 1-6, etc.), while phosphodiester and peptide bonds have a single main linkage type.
Discuss how the type of glycosidic bond affects the structure and function of polysaccharides.
Think about examples where the bond type leads to different properties (e.g., starch vs. cellulose).

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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 structural features of polysaccharides used for energy storage (like starch and glycogen) versus those used for structure (like cellulose and chitin).

Key Terms:

Polysaccharide: A polymer of many monosaccharides.
Storage polysaccharide: Used for energy storage (e.g., starch, glycogen).
Structural polysaccharide: Used for support (e.g., cellulose, chitin).

Step-by-Step Guidance

Identify the main examples of storage and structural polysaccharides.
Describe the types of glycosidic bonds and branching patterns found in each type.
Explain how these structural differences relate to their biological roles.
Consider how the digestibility of these polysaccharides differs in animals and humans.

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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: Biomolecule Structure and Function

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

Key Terms:

Polymer: Large molecule made of repeating monomers.
Monomer: Building block of a polymer.
Bond types: Peptide (proteins), glycosidic (carbohydrates), phosphodiester (nucleic acids), ester (lipids).

Step-by-Step Guidance

List the four main classes of biological polymers and their corresponding monomers.
Identify the type of bond that links the monomers in each class.
Provide an example of each polymer and briefly state its function in living organisms.
Think about how the structure of each polymer relates to its function.

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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: Polymer made of nucleotides (DNA, RNA).
Common elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P).

Step-by-Step Guidance

Recall the basic structure of a nucleotide (sugar, phosphate, nitrogenous base).
List the elements present in each component of a nucleotide.
Compare the answer choices to the list of elements found in nucleic acids.
Identify which element is not present in any part of a nucleic acid.

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Example Multiple Choice Q2. Beta-hemoglobin is:

Background

Topic: Protein Structure and Function

This question tests your ability to classify biomolecules based on their structure and function.

Key Terms:

Hemoglobin: A protein in red blood cells that carries oxygen.
Polypeptide: A chain of amino acids (protein subunit).

Step-by-Step Guidance

Recall the structure of hemoglobin and its subunits.
Understand the difference between a polypeptide, amino acid, carbohydrate, and nucleic acid.
Determine which category beta-hemoglobin fits into based on its structure and function.
Eliminate answer choices that do not match 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 primary structure can affect protein function and lead to disease.

Key Terms:

Sickle cell anemia: A genetic disorder caused by a mutation in the beta-globin gene.
Hydrophobic region: Part of a molecule that repels water and tends to cluster 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.
Review the answer choices and match them to your understanding of the molecular consequences of the mutation.
Eliminate options that do not fit the known mechanism of sickle cell anemia.

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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 understanding of how nucleic acids are formed and the terminology associated with their structure.

Key Terms:

Monomer: Nucleotide
Linkage: Phosphodiester bond
Sugar-phosphate backbone
Nitrogenous base
Antiparallel strands
Complementary pairing

Step-by-Step Guidance

Recall the process of nucleic acid polymerization and the role of the phosphate group in forming the linkage.
Identify the structural components that make up the backbone and the side groups.
Remember the orientation of DNA strands and the base pairing rules.
Fill in each blank with the appropriate term based on your understanding of nucleic acid structure.

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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: Subatomic particle
Atom: Basic unit of matter
Functional group: Group of atoms within a molecule
Monomer: Single building block of a polymer
Biomolecule: Large molecule found in living organisms

Step-by-Step Guidance

Define each term and consider its relative size compared to the others.
Arrange the terms from smallest to largest based on your definitions.
Double-check your order by comparing the scale of each entity.

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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 Reactions

This question tests your ability to represent the chemical process of joining monomers and to identify the type of reaction involved.

Key Terms:

Monomer: Building block of a polymer
Dehydration (condensation) reaction: Joins monomers by removing water
Hydrolysis reaction: Breaks polymers by adding water

Step-by-Step Guidance

Draw two boxes to represent monomers, each with an -H or -OH group at the ends where they will join.
Show the removal of an -H from one monomer and an -OH from the other, forming a water molecule.
Illustrate the new bond formed between the monomers after water is removed.
Identify whether this process is dehydration (condensation) or hydrolysis based on the direction of the reaction.