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Chapter 19
Biochemistry

19-01
Title
The cell: the smallest structural unit in living organisms
Caption
Physically, cells consist primarily of a nucleus, a cell membrane, and cytoplasm. Chemically, cells consist primarily of carbohydrates, lipids, proteins, and nucleic acids.
Notes
A cell can be an independent organism, or part of a larger organism.
Keywords
cell, organism, nucleus, cell membrane, cytoplasm, carbohydrate, lipid, protein, nucleic acid
19-01-03d
Title
Glucose: a key carbohydrate in living systems
Caption
The structural formula and spacefilling model presented here represent glucose, a carbohydrate. Glucose is involved in short-term energy storage.
Notes
Glucose is an aldehyde that also contains many -OH groups. The -OH groups make glucose soluble in water-based systems, such as blood. The solubility of glucose facilitates its mobility in living systems, allowing glucose to "carry" energy where it is needed.
Keywords
cell, organism, carbohydrate, aldehyde, alcohol , glucose
19-02
Title
Glucose can assume a chain or ring structure
Caption
Glucose is easily convertable from one form to another, by interaction of a terminal -OH with the aldehyde part of the straight-chain molecule. The forms are all isomers.
Notes
Glucose is an aldehyde that also contains many -OH groups. The -OH groups make glucose soluble in water-based systems, such as blood. The solubility of glucose facilitates its mobility in living systems, allowing glucose to "carry" energy where it is needed.
Keywords
cell, organism, carbohydrate, aldehyde, alcohol, ring, chain, isomer, glucose
19-02-01e
Title
The structural formula and spacefilling model presented here represent glucose, a monosaccharide
Caption
Glucose is an example of a monosaccharide, a carbohydrate that cannot be broken into simpler carbohydrates.
Notes
Glucose is an example of a hexose, a six-carbon sugar.
Keywords
glucose, carbohydrate, aldehyde, alcohol, ring, chain, isomer, monosaccharide
19-02-02un
Title
Structures of fructose and galactose
Caption
Fructose and galactose are two examples of monosaccharides that can assume a ring form.
Notes
Glucose and galactose have very similar structures: in the ring form, they differ only in the placement of a single -OH group.
Keywords
glucose, carbohydrate, ring, isomer, monosaccharide, fructose, galactose
19-02-05un
Title
Monosaccharides can join to form disaccharides
Caption
The structural formulas show that pairs of monosaccharides can join together through a glycoside linkage to form a disaccharide. A disaccharide is a carbohydrate that can be broken into two simpler carbohydrates.
Notes
As an example: glucose and fructose can join to form the disaccharide sucrose, common table sugar.
Keywords
glucose, carbohydrate, aldehyde, alcohol, ring, chain, isomer, monosaccharide, glycoside linkage, disaccharide, sucrose, fructose
19-03
Title
Digestion converts disaccharides into monosaccharides
Caption
An important function of digestion is to break the glycoside linkage in disaccharides, converting them to monosaccharides that can be used for energy storage.
Notes
As an example, the disaccharide sucrose (table sugar) is broken into glucose and fructose during digestion.
Keywords
glucose, carbohydrate, aldehyde, alcohol, ring, chain, isomer, monosaccharide, glycoside linkage, disaccharide, sucrose, digestion, fructose
19-03-02un
Title
Starch is an example of a polysaccharide
Caption
Many monosaccharides can form glycoside linkages to build what amounts to a sugar polymer: a polysaccharide. Starch is one example that consists of repeating glucose units.
Notes
Cellulose and glycogen are other examples of polysaccharides.
Keywords
glucose, carbohydrate, monosaccharide, glycoside linkage, polysaccharide, cellulose, glycogen
19-04
Title
Digestion converts polysaccharides into monosaccharides
Caption
An important function of digestion is to break the glycoside linkages in disaccharides, converting them to monosaccharides that can be used for energy storage.
Notes
As an example, the polysaccharide starch is broken into glucose molecules during digestion.
Keywords
glucose, carbohydrate, monosaccharide, glycoside linkage, polysaccharide, digestion
19-04-01un
Title
Example 19.1: Identifying carbohydrates
Caption
Which of the structures, (a), (b), (c), (d) are carbohydrates? Classify the carbohydrates as monosaccharides, disaccharides, or polysaccharides.
Notes
Carbohydrates are either aldehydes or ketones with multiple -OH groups present. Structures (a), (b), and (d) all fit this definition. Structure (c) is a carboxylic acid. A disaccharide will have one glycoside linkage; a polysaccharide will have many. Structures (a) and (b) are monosaccharides; (d) is a disaccharide.
Keywords
carbohydrate, monosaccharide, aldehyde, ketone, glycoside linkage, disaccharide, polysaccharide
19-04-02un
Title
Skillbuilder 19.1: Identifying carbohydrates
Caption
Which of the structures, (a), (b), (c), (d) are carbohydrates? Classify the carbohydrates as monosaccharides, disaccharides, or polysaccharides.
Notes
Carbohydrates are either aldehydes or ketones with multiple -OH groups present. Structures (b), and (d) fit this definition. Structure (a) is an amino acid, and (c) is a carboxylic acid. A disaccharide will have one glycoside linkage; a polysaccharide will have many. Structures (b) is a monosaccharide; (d) is a disaccharide.
Keywords
carbohydrate, monosaccharide, amino acid, carboxylic acid, aldehyde, ketone, glycoside linkage, disaccharide, polysaccharide
19-04-03un
Title
General structure of fatty acids: a type of lipid
Caption
Fatty acids are carboxylic acids with a long hydrocarbon tail. In the general structure, "R" represents the large hydrocarbon tail.
Notes
R generally represents a hydrocarbon chain of 3 to 19 C atoms.
Keywords
general structure, fatty acid, lipid, carboxylic acid, hydrocarbon
19-04-04j
Title
The structural formula and spacefilling model represent myristic acid, a fatty acid
Caption
Fatty acids are carboxylic acids with a long hydrocarbon tail. In the general structure, "R" represents the large hydrocarbon tail. In this example, the hydrocarbon tail has 13 carbons.
Notes
Myristic acid is in butterfat and coconut oil. It is a saturated fatty acid: the hydrocarbon tail has no double bonds.
Keywords
structural formula, spacefilling model, fatty acid, lipid, carboxylic acid, hydrocarbon, myristic acid
19-04-05k
Title
The structural formula and spacefilling model represent oleic acid, a fatty acid
Caption
Fatty acids are carboxylic acids with a long hydrocarbon tail. In the general structure, "R" represents the large hydrocarbon tail. In this example, the hydrocarbon tail has 17 carbons.
Notes
Oleic acid is in olive oil, peanut oil, and human fat. It is an unsaturated fatty acid: the hydrocarbon tail has a double bond. Since there is only one double bond, the fatty acid is monounsaturated.
Keywords
structural formula, spacefilling model, fatty acid, lipid, carboxylic acid, hydrocarbon, oleic acid
19-04-05un
Title
Structure of glycerol, a compound that reacts with fatty acids
Caption
The -OH groups on glycerol can react with the -COOH groups on fatty acids, causing the fatty acid to join to the glycerol, and releasing water.
Notes
The glycerol and fatty acids react to form triglycerides.
Keywords
structural formula, fatty acid, carboxylic acid, glycerol, alcohol, triglyceride
19-04-06l
Title
Glycerol and fatty acids form triglycerides
Caption
The -OH groups on glycerol can react with the -COOH groups on fatty acids, causing the fatty acid to join to the glycerol, and releasing water.
Notes
The glycerol and fatty acids react to form triglycerides.
Keywords
structural formula, fatty acid, carboxylic acid, glycerol, alcohol, triglyceride
19-04-07un
Title
General formulas show how glycerol and fatty acids form triglycerides
Caption
The -OH groups on glycerol can react with the -COOH groups on fatty acids, causing the fatty acid to join to the glycerol, and releasing water.
Notes
The glycerol and fatty acids react to form triglycerides.
Keywords
general formula, fatty acid, carboxylic acid, glycerol, alcohol, triglyceride
19-04-08un
Title
Structural formulas show how glycerol and stearic acid forms tristearin, a triglyceride
Caption
The -OH groups on glycerol can react with the -COOH groups on stearic acid, causing the stearic acid to join to the glycerol, and releasing water.
Notes
The glycerol and stearic acid react to form tristearin, a triglyceride.
Keywords
structural formula, fatty acid, carboxylic acid, glycerol, alcohol, triglyceride
19-04-11un
Title
Example 19.2: Identifying triglycerides
Caption
Identify the triglycerides and classify each as saturated and unsaturated.
Notes
(a) not a triglyceride; this is a carboxylic acid. (b) triglyceride: the glycerol backbone is present. It is saturated, because there are no double bonds in the hydrocarbon chains. (c) triglyceride: the glycerol backbone is present. It is unsaturated, because there is a double bond in the hydrocarbon chains. (d) not a triglyceride; this is a monosaccharide.
Keywords
structural formula, fatty acid, carboxylic acid, glycerol, alcohol, triglyceride, saturated, unsaturated
19-04-12un
Title
Skillbuilder 19.2: Identifying triglycerides
Caption
Identify the triglycerides and classify each as saturated and unsaturated.
Notes
(a) not a triglyceride; this is an amine. (b) triglyceride: the glycerol backbone is present. It is unsaturated, because there is a double bond in the hydrocarbon chains. (c) not a triglyceride; this is a monosaccharide. (d) triglyceride: the glycerol backbone is present. It is saturated, because there are no double bonds in the hydrocarbon chains.
Keywords
structural formula, fatty acid, carboxylic acid, glycerol, alcohol, triglyceride, saturated, unsaturated
19-04-13o
Title
Triglycerides are broken down by digestion
Caption
Digestion breaks down triglycerides into glycerol, monoglycerides, diglycerol, and fatty acids. These products pass through the intestine walls, where they reassemble into triglycerides as they pass into the blood.
Notes
Digestion of triglycerides is slower than digestion of other food types.
Keywords
structural formula, fatty acid, carboxylic acid, glycerol, alcohol, triglyceride, monoglyceride, diglycerol
19-04-15q
Title
The structural formula and spacefilling model presented here represent tristearin, a triglyceride
Caption
The -OH groups on glycerol can react with the -COOH groups on stearic acid, causing the stearic acid to join to the glycerol, and releasing water.
Notes
The glycerol and stearic acid react to form tristearin, a triglyceride.
Keywords
structural formula, spacefilling model, fatty acid, lipid, carboxylic acid, glycerol, stearic acid, triglyceride, tristearin
19-04-16r
Title
The structural formula and spacefilling model presented here represent trilinolenin, a triglyceride
Caption
The -OH groups on glycerol can react with the -COOH groups on linolenic acid, causing the linolenic acid to join to the glycerol, and releasing water.
Notes
The glycerol and linolenic acid react to form trilinolenin, a triglyceride. The triglyceride contains unsaturated fatty acids.
Keywords
structural formula, spacefilling model, fatty acid, lipid, carboxylic acid, glycerol, linolenic acid, triglyceride, trilinolenin
19-04-17s
Title
Phospholipids are like a triglyceride in which phosphate has replaced a fatty acid
Caption
The phosphate group makes the phospholipid polar.
Notes
Phospholipids are found in cell membranes.
Keywords
structural formula, fatty acid, phosphate, triglyceride, phospholipid, polar
19-04-17un
Title
Structure of phosphatidyl choline: a phospholipid
Caption
The substituted phosphate group makes the phospholipid polar.
Notes
This phospholipid is found in cell membranes of higher animals.
Keywords
structural formula, fatty acid, phosphate, triglyceride, phospholipid, polar, phosphatidyl choline
19-05
Title
Phospholipids have a polar head and nonpolar tails
Caption
How would a phospholipid orient itself if placed in water?
Notes
The polar head would point into the water; the tails would point away from the water.
Keywords
structural formula, fatty acid, phosphate, triglyceride, phospholipid, polar, water
19-06
Title
Cell membranes are formed from lipid bilayers
Caption
The polar heads point into the cell, and outward, into the cell's environment. The nonpolar tails point toward one another.
Notes
Both phospholipids and glycolipids can form lipid bilayers.
Keywords
structural formula, fatty acid, phosphate, triglyceride, phospholipid, polar, water, glycolipid, bilayer, cell membrane
19-06-01un
Title
Steroids have a four-ring structure
Caption
Steroids are important biological compounds. Like phospholipids and glycolipids, steriods are found in cell membranes.
Notes
Steroids include cholesterol, testosterone, and estrogen.
Keywords
general formula, steroid, phospholipid, glycolipid, cell membrane
19-06-01.01un
Title
Structural formulas of three common steroids
Caption
Steroids include cholesterol (part of cell membranes), testosterone (principal male hormone), and estrogen (principal female hormone).
Notes
Steroids are important biological compounds.
Keywords
structural formula, steroid, cell membrane, cholesterol, testosterone, hormone, estrogen
19-06-05un
Title
General structure of amino acids
Caption
Amino acids combine a carboxylic acid group, an amine group, and a hydrocarbon group (R) in a single molecule.
Notes
Amino acids can polymerize to form proteins.
Keywords
general structure, amino acid, carboxylic acid, amine, hydrocarbon, protein
19-06-06w
Title
Structural formula and spacefilling model of alanine, an amino acid
Caption
Alanine combines a carboxylic acid group, an amine group, and a hydrocarbon group (-CH3) in a single molecule.
Notes
Alanine is a common amino acid in living organisms.
Keywords
structural formula, spacefilling model, alanine, amino acid, carboxylic acid, amine, hydrocarbon, protein
19-06-07x
Title
Structural formula and spacefilling model of serine, an amino acid
Caption
Serine combines a carboxylic acid group, an amine group, and a hydrocarbon group (actually an alcohol, -CH2OH) in a single molecule.
Notes
Serine is a common amino acid in living organisms.
Keywords
structural formula, spacefilling model, serine, amino acid, carboxylic acid, amine, hydrocarbon, protein
19-06-08y
Title
Structural formula and spacefilling model of aspartic acid, an amino acid
Caption
Aspartic acid combines a carboxylic acid group, an amine group, and a hydrocarbon group (actually a carboxylic acid, -CH2COOH) in a single molecule.
Notes
Aspartic acid is a common amino acid in living organisms.
Keywords
structural formula, spacefilling model, aspartic acid, amino acid, carboxylic acid, amine, hydrocarbon, protein
19-06-09z
Title
Structural formula and spacefilling model of lysine, an amino acid
Caption
Lysine combines a carboxylic acid group, an amine group, and a hydrocarbon group (actually an amine. -CH2CH2CH2CH2NH2) in a single molecule.
Notes
Lysine is a common amino acid in living organisms.
Keywords
structural formula, spacefilling model, lysine, amino acid, carboxylic acid, amine, hydrocarbon, protein
19-06-10_T02
Title
Table 19.2: Common amino acids
Caption
The 20 amino acids in this table are all common in living organisms. They all combine a carboxylic acid group, an amine group, and a hydrocarbon group in a single molecule.
Notes
Amino acids react with incredible variety to form proteins. These are considered to be the 20 "essential" amino acids. Students might be asked to research why these are "essential".
Keywords
structural formula, amino acid, carboxylic acid, amine, hydrocarbon, protein, Histidine, Phenylalanine, Tyrosine, Tryptophan, Asparagine, Glutamine, Lysine, Arginine, Serine, Threonine, Aspartic acid, Glutamic acid, Isoleucine, Proline, Methionine, Cysteine , Glycine, Alanine, Valine, Leucine
19-06-11un
Title
Amino acids react with one another by forming a peptide bond
Caption
The peptide bond is a bond that forms between the amine group on one amino acid molecule, and the carboxylic acid group on an adjacent amino acid. Water is released when the bond forms.
Notes
Amino acids react with incredible variety to form proteins.
Keywords
structural formula, amino acid, carboxylic acid, amine, hydrocarbon, protein, peptide bond
19-06-12un
Title
Glycine and alanine react with one another by forming a peptide bond
Caption
The peptide bond is a bond that forms between the amine group on one amino acid molecule (alanine), and the carboxylic acid group on an adjacent amino acid (glycine). Water is released when the bond forms.
Notes
Amino acids react with incredible variety to form proteins.
Keywords
structural formula, amino acid, carboxylic acid, amine, hydrocarbon, protein, peptide bond, glycine, alanine
19-06-13un
Title
Glycine and alanine react with one another by forming a dipeptide and water
Caption
The peptide bond is a bond that forms between the amine group on one amino acid molecule (alanine), and the carboxylic acid group on an adjacent amino acid (glycine). Water is released when the bond forms.
Notes
Amino acids react with incredible variety to form proteins.
Keywords
structural formula, amino acid, carboxylic acid, amine, hydrocarbon, protein, peptide bond, glycine, alanine
19-06-14un
Title
Valine and leucine react with one another by forming a dipeptide and water
Caption
The peptide bond is a bond that forms between the amine group on one amino acid molecule, and the carboxylic acid group on an adjacent amino acid. Water is released when the bond forms.
Notes
Amino acids react with incredible variety to form proteins.
Keywords
structural formula, amino acid, carboxylic acid, amine, hydrocarbon, protein, peptide bond, valine, leucine
19-06-15un
Title
Valine and leucine react with one another by forming a dipeptide and water
Caption
The peptide bond is a bond that forms between the amine group on one amino acid molecule, and the carboxylic acid group on an adjacent amino acid. Water is released when the bond forms.
Notes
Amino acids react with incredible variety to form proteins.
Keywords
structural formula, amino acid, carboxylic acid, amine, hydrocarbon, protein, peptide bond, valine, leucine
19-07
Title
Protein structure is expressed at four levels
Caption
Proteins are made up of amino acid sequences. The sequences organize into recognizable shapes: pleated sheet, helix, random coil. These structures fold into a polypeptide chain that is ultimately arranged in a distinct position with respect to one or more other polypeptide chains.
Notes
The four levels of structure allow proteins to display extremely specific properties in living organisms.
Keywords
amino acid, protein, peptide bond, primary, secondary, tertiary, quaternary, polypeptide, pleated sheet, helix, random coil
19-08
Title
Hemoglobin displays typical protein structure
Caption
Proteins are made up of amino acid sequences. The sequences organize into recognizable shapes: pleated sheet, helix, random coil. These structures fold into a polypeptide chain that is ultimately arranged in a distinct position with respect to one or more other polypeptide chains.
Notes
The protein surrounds four heme units, the iron-containing groups that reversibly bind with oxygen.
Keywords
amino acid, protein, peptide bond, primary, secondary, tertiary, quaternary, polypeptide, pleated sheet, helix, random coil, heme, hemoglobin
19-09
Title
Secondary structure in proteins: the alpha-helix
Caption
Proteins are made up of amino acid sequences. In many proteins, the sequences organize into the alpha-helix shape.
Notes
The shape is largely due to the interaction between peptide backbones of amino acids that are close to each other in the chain.
Keywords
amino acid, protein, peptide bond, secondary, peptide, helix
19-10
Title
Secondary structure in proteins: the beta-pleated sheet
Caption
Proteins are made up of amino acid sequences. In many proteins, the sequences organize into the beta-pleated sheet shape.
Notes
The shape is largely due to the interaction between peptide backbones of amino acids on neighboring protein chains.
Keywords
amino acid, protein, peptide bond, secondary, polypeptide, pleated sheet
19-11
Title
Block diagram of DNA
Caption
DNA consists of nucleotide units bonded in a specific pattern. Each nucleotide is composed of a sugar, a phosphate group, and a base.
Notes
The nucleotides join together through the phosphate groups. The sugar is deoxyribose.
Keywords
DNA, nucleotide, sugar, phosphate, base, deoxyribose
19-11-01un
Title
The sugars in DNA and RNA
Caption
In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose.
Notes
The sugar is deoxyribose for every nucleotide in DNA. Likewise, the sugar is ribose for every RNA nucleotide.
Keywords
structural formula, DNA, RNA, nucleotide, sugar, phosphate, base, deoxyribose, ribose
19-11-02un
Title
DNA uses four bases
Caption
In DNA, the four bases, adenine, cytosine, guanine, and thymine, code genetic information.
Notes
In DNA, neither the sugar (deoxyribose) nor the phosphate group differ among the nucleotides. Only the base pairs differ.
Keywords
DNA, nucleotide, sugar, phosphate, base, deoxyribose, adenine, cytosine, guanine, thymine, genetic
19-11-03un
Title
Like DNA, RNA uses four bases, one of which is uracil
Caption
In DNA, the four bases, adenine, cytosine, guanine, and thymine, code genetic information. RNA also uses four bases, but thymine is replaced by uracil.
Notes
In RNA, neither the sugar (ribose) nor the phosphate group differ among the nucleotides. Only the base pairs differ.
Keywords
DNA, RNA, nucleotide, sugar, phosphate, base, ribose, adenine, cytosine, guanine, thymine, uracil
19-12
Title
A codon is a sequence of three nucleotides
Caption
Codons are three-nucleotide sequences that code for an amino acid.
Notes
Sequences of codons in a DNA molecule make up the genes.
Keywords
DNA, nucleotide, sugar, phosphate, base, adenine, cytosine, guanine, thymine, codon, amino acid, gene
19-13
Title
Chromosome structures within cell nucleus to nucleotide
Caption
A codon is a sequence of three nucleotides. A gene is a sequence of codons that code for a protein. A chromosome is a collection of genes.
Notes
Genetic information instructs matter in its organization into proteins and, ultimately, to a living organism.
Keywords
DNA, nucleotide, sugar, phosphate, base, codon, amino acid, gene, chromosome, protein
19-14
Title
DNA has a double-helix structure
Caption
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G).
Notes
The base pairs interact through hydrogen bonds.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-14-01un
Title
A base sequence in a DNA strand I
Caption
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). The strand would join with its complement, T-A-C-T-T-A-G-G-C-T-G.
Notes
The base pairs interact through hydrogen bonds.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-14-02un
Title
A base sequence in a DNA strand II
Caption
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). The strand would join with its complement, A-T-G-A-A-T-C-C-G-A-C.
Notes
The base pairs interact through hydrogen bonds.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-14-03un
Title
Example 19.4: Complementary DNA strand I
Caption
What is the complementary strand of the DNA strand shown?
Notes
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). The strand would join with its complement, T-A-C-T-C-A-G.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-15
Title
Structural formulas of the complementary DNA bases
Caption
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G).
Notes
The base pairs are held together by hydrogen bonding.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-15-02un
Title
Example 19.4 Complementary DNA strand II
Caption
The answer to Example 19.4. The original strand was A-T-G-A-G-T-C.
Notes
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). The strand would join with its complement.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-15-03un
Title
Skillbuilder 19.4: Complementary DNA strand
Caption
What is the complementary strand of the DNA strand shown?
Notes
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). The strand would join with its complement, G-G-T-A-A-C-C.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-15-04un
Title
Skillbuilder 19.4: Complementary DNA strand - answer
Caption
The complementary strand of the DNA strand shown in Skillbuilder 19.4 is G-G-T-A-A-C-C.
Notes
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). The strand would join with its complement.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-16
Title
DNA Replication
Caption
DNA replicates when the double helix strands separate. The separated strands then collect nucleotides from the surrounding environment, reassembling two copies of the double helix.
Notes
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). The strand would join with its complement.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix, replication
19-17
Title
Sequence for protein synthesis
Caption
As m-RNA moves through a ribosome, each codon instructs the protein to add the amino acid specified by the codon.
Notes
When protein is synthesized, the gene's base sequence is transferred to m-RNA.
Keywords
RNA, m-RNA, ribosome, protein, codon, amino acid
19-17-07un
Title
Chapter 19, Problem 51: Carbohydrates
Caption
Which of the structures, (a), (b), (c), (d) are carbohydrates? Classify the carbohydrates as monosaccharides, disaccharides, or trisaccharides.
Notes
Carbohydrates are either aldehydes or ketones with multiple -OH groups present. Structures (a), and (d) fit this definition. Structure (b) is a carboxylic acid, and (c) is an amino acid. A monosaccharide will have one glycoside linkage; a disaccharide will have two; a trisaccharide will have three. Structures (a) is a monosaccharide; (d) is a disaccharide.
Keywords
carbohydrate, monosaccharide, amino acid, carboxylic acid, aldehyde, ketone, glycoside linkage, disaccharide, trisaccharide
19-17-08un
Title
Chapter 19, Problem 52: Carbohydrates
Caption
Which of the structures, (a), (b), (c), (d) are carbohydrates? Classify the carbohydrates as monosaccharides, disaccharides, or trisaccharides.
Notes
Carbohydrates are either aldehydes or ketones with multiple -OH groups present. Structures (b), and (c) fit this definition. Structure (a) is a triglyceride, and (d) is an amino acid. A monosaccharide will have one glycoside linkage; a disaccharide will have two; a trisaccharide will have three. Structure (b) is a monosaccharide; (c) is a trisaccharide.
Keywords
carbohydrate, monosaccharide, amino acid, carboxylic acid, aldehyde, ketone, glycoside linkage, disaccharide, trisaccharide
19-17-09un
Title
Chapter 19, Problem 53: Carbohydrates
Caption
Classify the structures as a triose, tetrose, pentose, etc.
Notes
The Greek prefix specifies how many carbon atoms are in the carbohydrate. (a) hexose (b) tetrose (c) pentose (d) tetrose
Keywords
carbohydrate, hexose, tetrose, pentose, triose
19-17-10un
Title
Chapter 19, Problem 54: Carbohydrates
Caption
Classify the structures as a triose, tetrose, pentose, etc.
Notes
The Greek prefix specifies how many carbon atoms are in the carbohydrate. (a) pentose (b) triose (c) pentose (d) pentose
Keywords
carbohydrate, hexose, tetrose, pentose, triose
19-17-11un
Title
Chapter 19, Problem 59: Lipids
Caption
Identify the lipids. If the compound is a lipid, determine the type. If it is a fatty acid or triglyceride, classify it as saturated and unsaturated.
Notes
(a) a saturated fatty acid: this is a carboxylic acid with no double bonds in the hydrocarbon part. (b) lipid: this is a steroid, because of the 4-ring structure. (c) triglyceride: the glycerol backbone is present. It is unsaturated, because there is a double bond in the hydrocarbon chains. (d) a carbohydrate.
Keywords
structural formula, fatty acid, carboxylic acid, steroid, lipid, triglyceride, saturated, unsaturated
19-17-12un
Title
Chapter 19, Problem 60: Lipids
Caption
Identify the lipids. If the compound is a lipid, determine the type. If it is a fatty acid or triglyceride, classify it as saturated and unsaturated.
Notes
(a) an unsaturated fatty acid: this is a carboxylic acid with double bonds in the hydrocarbon part. (b) an amino acid, not a lipid. (c) lipid: this is a steroid, because of the 4-ring structure. (d) triglyceride: the glycerol backbone is present. It is saturated, because there are no double bonds in the hydrocarbon chains.
Keywords
structural formula, fatty acid, carboxylic acid, steroid, lipid, triglyceride, saturated, unsaturated
19-17-13un
Title
Chapter 19, Problem 65: Amino acids and proteins
Caption
Which of the following are amino acids?
Notes
Amino acids fit the general formula: an amine and a carboxylic acid group in the same molecule. (a) not an amino acid: a carboxylic acid (b) an amino acid (c) not an amino acid (d) an amino acid
Keywords
structural formula, amino acid, carboxylic acid
19-17-14un
Title
Chapter 19, Problem 66: Amino acids and proteins
Caption
Which of the following are amino acids?
Notes
Amino acids fit the general formula: an amine and a carboxylic acid group in the same molecule. (a) an amino acid (b) not an amino acid: a polyalcohol (c) not an amino acid: a carbohydrate (d) an amino acid
Keywords
structural formula, amino acid, carboxylic acid, alcohol, carbohydrate
19-17-15un
Title
Chapter 19, Problem 75: Nucleic acids
Caption
Which of the following is a nucleotide? For each nucleotide, identify the base as A, T, C, or G.
Notes
(a) a nucleotide: G (b) not a nucleotide: a carbohydrate (c) not a nucleotide: an amino acid (d) not a nucleotide: a base (G)
Keywords
structural formula, amino acid, nucleotide, carbohydrate, base, guanine
19-17-16un
Title
Chapter 19, Problem 76: Nucleic acids
Caption
Which of the following is a nucleotide? For each nucleotide, identify the base as A, T, C, or G.
Notes
(a) not a nucleotide: an amino acid (b) a nucleotide: (A) (c) a nucleotide: (C) (d) not a nucleotide: a base (T)
Keywords
structural formula, amino acid, nucleotide, carbohydrate, base, thymine, adenine, cytosine
19-17-17un
Title
Chapter 19, Problem 77: Nucleic acids
Caption
What is the complementary strand of the DNA strand shown?
Notes
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). The strand would join with its complement, T-T-A-C-G-C-G.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-17-18un
Title
Chapter 19, Problem 78: Nucleic acids
Caption
What is the complementary strand of the DNA strand shown?
Notes
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). The strand would join with its complement, A-T-A-G-C-C-A.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-17-19un
Title
Chapter 19, Problem 79: Nucleic acids
Caption
The DNA strand shown will replicate to two identical copies.
Notes
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). Each single strand would join with its complement.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-17-20un
Title
Chapter 19, Problem 80: Nucleic acids
Caption
The DNA strand shown will replicate to two identical copies.
Notes
The strands of the double helix are complementary to each other. This is so because the bases interact in pairs: adenine with thymine (A and T), and cytosine with guanine (C and G). Each single strand would join with its complement.
Keywords
DNA, nucleotide, adenine, thymine, cytosine, guanine, base, double helix
19-17-21un
Title
Chapter 19, Problem 87: Highlight problems I
Caption
One way to fight viral infections is to prevent the virus' DNA from replicating. Fake nucleotides, such as the one shown, will stop replication when introduced into DNA. Suggest a mechanism by which the fake nucleotide would halt DNA replication.
Notes
The nucleotides join together through the sugar phosphate backbone. All nucleotides in DNA use the same sugar, deoxyribose. Some other sugar would not interact to continue the chain of nucleotides. Once the chain breaks, replication stops, and the virus could not reproduce.
Keywords
DNA, nucleotide, sugar, phosphate, base, virus, replication
19-17-22un
Title
Chapter 19, Problem 87: Highlight problems II
Caption
One way to fight viral infections is to prevent the virus' DNA from replicating. Fake nucleotides, such as the one shown, will stop replication when introduced into DNA. Suggest a mechanism by which the fake nucleotide would halt DNA replication. In AZT, a fake nucleotide replaces the one shown.
Notes
The nucleotides join together through the sugar phosphate backbone. All nucleotides in DNA use the same sugar, deoxyribose. Some other sugar would not interact to continue the chain of nucleotides. Once the chain breaks, replication stops, and the virus could not reproduce.
Keywords
DNA, nucleotide, sugar, phosphate, base, virus, replication

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