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Questions and Answers
Which of the following is NOT a characteristic of macromolecules?
Which of the following is NOT a characteristic of macromolecules?
What is the basic building block (monomer) of a polymer?
What is the basic building block (monomer) of a polymer?
Which type of reaction removes a water molecule to join two monomers?
Which type of reaction removes a water molecule to join two monomers?
Which macromolecule is responsible for speeding up chemical reactions?
Which macromolecule is responsible for speeding up chemical reactions?
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What is the name of the bond that forms between two monosaccharides?
What is the name of the bond that forms between two monosaccharides?
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Which disaccharide is composed of glucose and fructose?
Which disaccharide is composed of glucose and fructose?
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What determines the structure and function of a polysaccharide?
What determines the structure and function of a polysaccharide?
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Which of the following is NOT a type of polysaccharide?
Which of the following is NOT a type of polysaccharide?
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What bonds join nucleotides together in a polynucleotide chain?
What bonds join nucleotides together in a polynucleotide chain?
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Which nitrogenous base pairs with adenine in DNA?
Which nitrogenous base pairs with adenine in DNA?
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How is the arrangement of the two strands in the DNA double helix described?
How is the arrangement of the two strands in the DNA double helix described?
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What type of sugar is found in RNA?
What type of sugar is found in RNA?
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What component is missing in a nucleoside compared to a nucleotide?
What component is missing in a nucleoside compared to a nucleotide?
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What characterizes primary protein structure?
What characterizes primary protein structure?
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Which interactions are NOT involved in tertiary protein structure?
Which interactions are NOT involved in tertiary protein structure?
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What event can lead to the denaturation of a protein?
What event can lead to the denaturation of a protein?
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Which protein structure is formed by two or more polypeptide chains?
Which protein structure is formed by two or more polypeptide chains?
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What is a common feature of typical secondary protein structures?
What is a common feature of typical secondary protein structures?
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What impact does a slight change in primary structure have on proteins?
What impact does a slight change in primary structure have on proteins?
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Which technique is used to determine the three-dimensional structure of proteins?
Which technique is used to determine the three-dimensional structure of proteins?
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Which disease is associated with misfolded proteins?
Which disease is associated with misfolded proteins?
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What type of fats are solid at room temperature?
What type of fats are solid at room temperature?
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What is the primary characteristic of unsaturated fats?
What is the primary characteristic of unsaturated fats?
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What arrangement do phospholipids form when added to water?
What arrangement do phospholipids form when added to water?
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What distinguishes amino acids from each other?
What distinguishes amino acids from each other?
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What is the role of cholesterol in cell membranes?
What is the role of cholesterol in cell membranes?
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Which statement about peptide bonds is accurate?
Which statement about peptide bonds is accurate?
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What determines a protein's three-dimensional structure?
What determines a protein's three-dimensional structure?
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Which of the following best describes steroids?
Which of the following best describes steroids?
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What distinguishes cellulose from starch in terms of glycosidic linkages?
What distinguishes cellulose from starch in terms of glycosidic linkages?
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Where is glycogen primarily stored in the human body?
Where is glycogen primarily stored in the human body?
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Which of the following accurately describes the role of chitin?
Which of the following accurately describes the role of chitin?
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What is the main structural difference between amylose and amylopectin?
What is the main structural difference between amylose and amylopectin?
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Why are lipids considered hydrophobic?
Why are lipids considered hydrophobic?
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What is the primary function of fats in the human body?
What is the primary function of fats in the human body?
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What prevents fats from mixing with water?
What prevents fats from mixing with water?
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In a triglyceride, how many fatty acids are typically bound to glycerol?
In a triglyceride, how many fatty acids are typically bound to glycerol?
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Study Notes
Macromolecules
- Macromolecules are polymers built from monomers.
- Carbohydrates are used for fuel and structure.
- Lipids are a diverse group of hydrophobic molecules.
- Proteins have a wide variety of structures and functions.
- Nucleic acids store, transmit, and express hereditary information.
Polymers and Monomers
- A polymer is a large molecule made up of similar building blocks.
- Monomers are the smaller building blocks of polymers.
- An oligomer is a chain containing few monomers.
- Examples of biological polymers are carbohydrates, proteins, and nucleic acids.
Dehydration Reaction
- A dehydration reaction joins two monomers together by removing a water molecule.
- Enzymes speed up chemical reactions, including those that form and break down polymers.
Hydrolysis
- Polymers are broken down into monomers by hydrolysis reactions, which are the reverse of dehydration reactions.
Carbohydrates Introduction
- Carbohydrates include sugars and polymers of sugars.
- Monosaccharides are simple sugars like glucose and fructose.
- Disaccharides are double sugars like sucrose and lactose.
- Polysaccharides are complex carbohydrates which are polymers of many sugar building blocks like starch, glycogen, and cellulose.
Monosaccharides
- Monosaccharides are classified by the number of carbons in the carbon skeleton and the location of the carbonyl group.
- Glucose is the most common monosaccharide.
Cyclization of Sugars
- In aqueous solutions, many sugars form rings.
- The ring structure is more stable in aqueous solutions.
Disaccharides
- A disaccharide forms when a dehydration reaction joins two monosaccharides.
- The bond formed is a glycosidic linkage.
- Examples include maltose (glucose + glucose), sucrose (glucose + fructose), and lactose (glucose + galactose).
Polysaccharides
- Polysaccharides are polymers of sugars that have storage and structural roles.
- The structure and function of a polysaccharide are determined by the monomers and their glycosidic linkages.
- Examples include starch (storage in plants), glycogen (storage in animals), and cellulose (structural component of plant cell walls).
Starch
- Starch is a storage polysaccharide in plants consisting of glucose monomers.
- Plants store starch within chloroplasts and other plastids.
- Starch has two forms: amylose (unbranched) and amylopectin (branched).
Glycogen
- Glycogen is a storage polysaccharide in animals, mainly found in liver and muscle cells.
- Hydrolysis of glycogen releases glucose if energy demand increases.
Cellulose
- Cellulose is a structural polysaccharide in plant cell walls.
- Cellulose polymers are straight and unbranched, unlike starch.
- Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ.
Chitin
- Chitin is a structural polysaccharide found in arthropod exoskeletons and fungal cell walls.
Lipids Introduction
- Lipids are a class of large biological molecules that do not form polymers.
- Lipids have little or no affinity for water (hydrophobic).
- Biologically important lipids include fats, phospholipids, and steroids.
Fats
- Fats are constructed from glycerol and fatty acids.
- Glycerol is a three-carbon alcohol.
- Fatty acids have a carboxyl group linked to a hydrocarbon chain.
- Fats are joined to glycerol by ester linkages in a triacylglycerol (or triglyceride).
- Fats separate from water because water molecules hydrogen bond to each other but exclude non-polar fats.
Saturated Fats
- Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds.
- Fats made from saturated fatty acids are solid at room temperature.
Unsaturated Fats
- Unsaturated fatty acids have one or more double bonds.
- Fats made from unsaturated fatty acids are liquid at room temperature.
Phospholipids
- Phospholipids have two fatty acid tails and a phosphate group attached to glycerol.
- The fatty acid tails are hydrophobic.
- The phosphate group and its attachments are hydrophilic.
- Phospholipids form bilayers in cell membranes.
Phospholipids in Biological Membranes
- Phospholipids are the major component of cell membranes.
- When phospholipids are added to water, they spontaneously self-assemble into a bilayer with the hydrophobic tails facing inward and the hydrophilic heads facing outward.
Steroids
- Steroids are lipids with a carbon skeleton consisting of four fused rings.
- Cholesterol is a steroid that is a component of animal cell membranes.
Proteins Introduction
- Proteins account for more than 50% of the dry mass of most cells.
- Proteins have diverse roles in catalyzing chemical reactions (enzymes), providing support, storage, transport, coordination of organismal responses, defense, movement, etc.
Protein Functions Overview
- Enzymatic proteins catalyze chemical reactions.
- Defensive proteins protect against disease.
- Storage proteins store amino acids.
- Transport proteins transport substances within organisms.
- Hormonal proteins coordinate organismal responses.
- Receptor proteins respond to chemical signals.
- Contractile and motor proteins are responsible for movement.
- Structural proteins provide support.
Amino Acids and Peptides
- Proteins are polymers constructed from the same set of 20 amino acids.
- Amino acids are linked together by peptide bonds forming a polypeptide.
- The amino acid sequence dictates a protein's 3D structure and subsequently, its function, making it unique.
- Amino acids have a central carbon (alpha carbon), an amino group, a carboxyl group, and a variable side chain (R group).
20 Amino Acids
- Amino acids differ due to the variable side chains (often called R-groups).
- These groups contribute to the distinct properties of each amino acid.
Peptide Bond
- Amino acids are joined by peptide bonds.
- A polypeptide has a unique sequence of amino acids, with an amino end (N-terminus) and a carboxyl end (C-terminus).
Primary Protein Structure
- Primary structure is the sequence of amino acids in a polypeptide chain, like the order of letters in a word.
- Inherited genetic information dictates the primary structure.
Secondary Protein Structure
- Secondary structure involves hydrogen bonds between repeating constituents in the polypeptide backbone.
- Typical secondary structures include -helices and β-pleated sheets.
Tertiary Protein Structure
- Tertiary structure is the overall shape of a polypeptide.
- Interactions between R groups (hydrogen bonds, ionic bonds, hydrophobic interactions, van der Waals interactions) determine tertiary structure.
- Disulfide bridges (strong covalent bonds) may reinforce the protein's structure.
Quaternary Protein Structure
- Quaternary structure results from interactions between multiple polypeptide chains.
- Examples include collagen (three polypeptides) and hemoglobin (four polypeptides).
Change in Primary Structure
- A small change in primary structure can drastically affect a protein's structure and thus its function.
- Sickle-cell disease is an example of a genetic disorder resulting from a single amino acid substitution in the hemoglobin protein.
Change in Higher Levels
- Physical and chemical conditions (e.g., pH, salt concentration, temperature) can affect protein structure.
- Denaturation is the loss of a protein's native structure, resulting in a biologically inactive protein.
- Misfolded proteins are linked to diseases like Alzheimer's, Parkinson's, and mad cow disease.
X-ray Crystallography
- X-ray crystallography is used to determine a protein's 3-D structure.
Nucleic Acids Introduction
- Nucleic acids are the two types of biological macromolecules: DNA and RNA.
- DNA stores hereditary information.
- RNA plays various roles in gene expression, including carrying instructions from DNA to ribosomes.
Synthesis of Nucleic Acids
- DNA provides directions for its own replication.
- DNA directs the synthesis of mRNA, which in turn controls protein synthesis.
- This multi-step process is referred to as gene expression.
- Transcription
- Translation
Nucleotides
- Nucleic acids are polymers called polynucleotides, composed of monomers called nucleotides.
- Each nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups.
- The portion without the phosphate group is called a nucleoside.
Nucleoside Components
- Two types of nitrogenous bases: pyrimidines (cytosine, thymine, uracil) and purines (adenine, guanine).
- In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose.
Polynucleotide
- Nucleotides are linked together to form polynucleotides via phosphodiester linkages.
- Phosphodiester linkages form strong, stable bonds between nucleotides.
- This forms a sugar-phosphate backbone with nitrogenous bases as appendages.
DNA Double Helix
- DNA molecules have two polynucleotide strands, spiralling around an axis forming a double helix.
- The strands run antiparallel (opposite 5' to 3' directions).
- Complementary base pairing occurs between adenine (A) and thymine (T), and between guanine (G) and cytosine (C).
RNA is Single-Stranded
- RNA molecules are usually single-stranded.
- Complementary base pairing can occur between two RNA molecules or within the same molecule.
- In RNA, thymine is replaced by uracil (U), so A pairs with U.
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Description
Test your knowledge on macromolecules, their characteristics, and their building blocks in this quiz. Answer questions about polymers, nucleotides, and the structure of DNA and RNA. This quiz covers essential concepts foundational to understanding biology.
