Macromolecules - MCAT Biological and Biochemical Foundations of Living Systems
Card 1 of 976
A peptide bond is formed between .
A peptide bond is formed between .
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Each amino acid has an N and a C terminus. The N terminus contains an amino group and the C terminus contains a carboxylic acid group. In order to make a peptide linkage (and eventually create a polypeptide), a bond must form between the amino and carboxylic groups, with water as a byproduct.
Each amino acid has an N and a C terminus. The N terminus contains an amino group and the C terminus contains a carboxylic acid group. In order to make a peptide linkage (and eventually create a polypeptide), a bond must form between the amino and carboxylic groups, with water as a byproduct.
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Which type of bond is created between carbohydrates and the sidechain amine of select asparagine residues in proteins?
Which type of bond is created between carbohydrates and the sidechain amine of select asparagine residues in proteins?
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A glycosidic bond covalently joins a carbohydrate molecule to another molecule. An O-glycosidic bond is a covalent linkage between a carbohydrate and a protein, joining a serine or threonine hydroxyl side chain and a sugar (oxygen in the bond yields "O"). An N-glycosidic linkage involves bonding of a carbohydrate and a protein, joining an asparagine side chain amide and a sugar (nitrogen in the bond yields "N"). Thus, N-glycosidic is the correct answer.
A glycosidic bond covalently joins a carbohydrate molecule to another molecule. An O-glycosidic bond is a covalent linkage between a carbohydrate and a protein, joining a serine or threonine hydroxyl side chain and a sugar (oxygen in the bond yields "O"). An N-glycosidic linkage involves bonding of a carbohydrate and a protein, joining an asparagine side chain amide and a sugar (nitrogen in the bond yields "N"). Thus, N-glycosidic is the correct answer.
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Which of the following statements is true concerning glucose polymers?
Which of the following statements is true concerning glucose polymers?
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Glucose is the primary carbohydrate absorbed by humans, and exists for its majority of time in the body in ring form. Humans are only capable of digesting alpha linked glucose polymers, and are unable to break down beta linked polymers. As a result, cellulose is incapable of being broken down by humans.
Starch is formed by an 
-1,4 linkage, while glycogen is formed by an 
-1,6 linkage. Both of these can be digested, as they do not contain beta linkages.
Glucose is the primary carbohydrate absorbed by humans, and exists for its majority of time in the body in ring form. Humans are only capable of digesting alpha linked glucose polymers, and are unable to break down beta linked polymers. As a result, cellulose is incapable of being broken down by humans.
Starch is formed by an
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Cellulose is a type of carbohydrate used in plants to store glucose. Cellulose cannot be broken down by humans, but is able to be digested by ruminants (cows for example). What is the best explanation for why ruminants are able to digest cellulose?
Cellulose is a type of carbohydrate used in plants to store glucose. Cellulose cannot be broken down by humans, but is able to be digested by ruminants (cows for example). What is the best explanation for why ruminants are able to digest cellulose?
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Cellulose and other polysaccharides with beta linkages can only be broken down by bacteria. As a result, cows have a symbiotic relationship with bacteria that live in their digestive systems.
Cellulose and other polysaccharides with beta linkages can only be broken down by bacteria. As a result, cows have a symbiotic relationship with bacteria that live in their digestive systems.
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Which carbon in a carbohydrate determines whether a human is capable of digesting it properly?
Which carbon in a carbohydrate determines whether a human is capable of digesting it properly?
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Humans are only capable of digesting the "D" isomer of a carbohydrate. The carbon that determines whether a carbohydrate is "D" or "L" is the first chiral carbon in the sugar. If it points to the right, the sugar can be digested by humans.
Humans are only capable of digesting the "D" isomer of a carbohydrate. The carbon that determines whether a carbohydrate is "D" or "L" is the first chiral carbon in the sugar. If it points to the right, the sugar can be digested by humans.
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Drain cleaners a common household staple, used to open clogged drains in bathtubs and sinks. Human hair is a common culprit that clogs pipes, and hair is made predominately of protein. Drain cleaners are effective at breaking down proteins that have accumulated in plumbing. Drain cleaners can be either acidic or basic, and are also effective at breaking down fats that have accumulated with proteins.
A typical reaction—reaction 1—which would be expected for a drain cleaner on contact with human hair, would be as follows in an aqueous solution:
Another reaction that may occur, reaction 2, would take place as follows in an aqueous solution:
In contrast to the proteins in Reactions 1 and 2, the body uses carbohydrates .
Drain cleaners a common household staple, used to open clogged drains in bathtubs and sinks. Human hair is a common culprit that clogs pipes, and hair is made predominately of protein. Drain cleaners are effective at breaking down proteins that have accumulated in plumbing. Drain cleaners can be either acidic or basic, and are also effective at breaking down fats that have accumulated with proteins.
A typical reaction—reaction 1—which would be expected for a drain cleaner on contact with human hair, would be as follows in an aqueous solution:
Another reaction that may occur, reaction 2, would take place as follows in an aqueous solution:
In contrast to the proteins in Reactions 1 and 2, the body uses carbohydrates .
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Carboydrates are the main energy currency of cells. They are typically burned first, before fats and proteins, to generate energy. Proteins, in contrast, are usually the functional biomolecules, serving structural and enzymatic roles.
Carboydrates are the main energy currency of cells. They are typically burned first, before fats and proteins, to generate energy. Proteins, in contrast, are usually the functional biomolecules, serving structural and enzymatic roles.
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Which of the following accurately describes glucose?
Which of the following accurately describes glucose?
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Glucose is composed of six carbons. When not in ring form, there is an aldehyde at the end of the molecule. As a result, glucose is an example of an aldohexose.
Glucose is composed of six carbons. When not in ring form, there is an aldehyde at the end of the molecule. As a result, glucose is an example of an aldohexose.
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Which of the following carbohydrates is created in animals, but not in plants?
Which of the following carbohydrates is created in animals, but not in plants?
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Glucose is stored in animals cells in the form of glycogen. Plants store glucose as either starch or cellulose. Amylose is a specialized component of starch, and plays a key role in plant energy storage.
Plants do not form glycogen, similar to the way that humans cannot form (or break down) cellulose.
Glucose is stored in animals cells in the form of glycogen. Plants store glucose as either starch or cellulose. Amylose is a specialized component of starch, and plays a key role in plant energy storage.
Plants do not form glycogen, similar to the way that humans cannot form (or break down) cellulose.
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Which of the following statements is true concerning glucose?
Which of the following statements is true concerning glucose?
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Maltose and cellulose are both composed of glucose monomers that are combined in a 1,4 glycosidic linkage, however they differ by the type of 1,4 linkage used. Cellulose uses a beta 1,4 linkage, while maltose uses an alpha 1,4 linkage.
Maltose and cellulose are both composed of glucose monomers that are combined in a 1,4 glycosidic linkage, however they differ by the type of 1,4 linkage used. Cellulose uses a beta 1,4 linkage, while maltose uses an alpha 1,4 linkage.
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Drain cleaners are a common household staple, used to open clogged drains in bathtubs and sinks. Human hair is a common culprit that clogs pipes, and hair is made predominately of protein. Drain cleaners are effective at breaking down proteins that have accumulated in plumbing. Drain cleaners can be either acidic or basic, and are also effective at breaking down fats that have accumulated with proteins.
A typical reaction—reaction 1—which would be expected for a drain cleaner on contact with human hair, would be as follows in an aqueous solution:
Another reaction that may occur, reaction 2, would take place as follows in an aqueous solution:
The drain cleaner in Reaction 1 was used to break down fats as well as the protein depicted. How would the fats be most different in molecular structure?
Drain cleaners are a common household staple, used to open clogged drains in bathtubs and sinks. Human hair is a common culprit that clogs pipes, and hair is made predominately of protein. Drain cleaners are effective at breaking down proteins that have accumulated in plumbing. Drain cleaners can be either acidic or basic, and are also effective at breaking down fats that have accumulated with proteins.
A typical reaction—reaction 1—which would be expected for a drain cleaner on contact with human hair, would be as follows in an aqueous solution:
Another reaction that may occur, reaction 2, would take place as follows in an aqueous solution:
The drain cleaner in Reaction 1 was used to break down fats as well as the protein depicted. How would the fats be most different in molecular structure?
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Fats are less reactive, more reduced, and less acidic than proteins. They have much lower overall polarity, but do contain polar bonds, such as between C and O.
Fats are less reactive, more reduced, and less acidic than proteins. They have much lower overall polarity, but do contain polar bonds, such as between C and O.
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Drain cleaners a common household staple, used to open clogged drains in bathtubs and sinks. Human hair is a common culprit that clogs pipes, and hair is made predominately of protein. Drain cleaners are effective at breaking down proteins that have accumulated in plumbing. Drain cleaners can be either acidic or basic, and are also effective at breaking down fats that have accumulated with proteins.
A typical reaction—reaction 1—which would be expected for a drain cleaner on contact with human hair, would be as follows in an aqueous solution:
Another reaction that may occur, reaction 2, would take place as follows in an aqueous solution:
The fats that are broken down by drain cleaners in the preceeding passage come predominately from oil secretions in skin and on hair. What is a main function of fats in the body?
Drain cleaners a common household staple, used to open clogged drains in bathtubs and sinks. Human hair is a common culprit that clogs pipes, and hair is made predominately of protein. Drain cleaners are effective at breaking down proteins that have accumulated in plumbing. Drain cleaners can be either acidic or basic, and are also effective at breaking down fats that have accumulated with proteins.
A typical reaction—reaction 1—which would be expected for a drain cleaner on contact with human hair, would be as follows in an aqueous solution:
Another reaction that may occur, reaction 2, would take place as follows in an aqueous solution:
The fats that are broken down by drain cleaners in the preceeding passage come predominately from oil secretions in skin and on hair. What is a main function of fats in the body?
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Of the choices provided, only energy storage in the form of tricacylglycerols makes sense. Free fatty acids do not act as the main storage form for fats, but are used to create triacylglycerols.
Of the choices provided, only energy storage in the form of tricacylglycerols makes sense. Free fatty acids do not act as the main storage form for fats, but are used to create triacylglycerols.
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Given the same weight of each, from which macromolecule can the most heat be generated in a combustion reaction?
Given the same weight of each, from which macromolecule can the most heat be generated in a combustion reaction?
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The correct answer is saturated fat. Rather than attempting to draw each one of these macromolecules, one should view this conceptually. In a combustion reaction, heat is generated for every carbon-hydrogen bond that is oxidized. In other words, the higher the density of C-H bonds in a compound, the more potential energy it can store. Fats, which primarily consist of only carbon and hydrogen, will contain the most energy and subsequently generate the most heat when oxidized. This is the same reason why animals and plants store energy as fat molecules.
*Note: A polyunsaturated fat has more than one double bond between its carbons, which reduces the total number of C-H bonds.
The correct answer is saturated fat. Rather than attempting to draw each one of these macromolecules, one should view this conceptually. In a combustion reaction, heat is generated for every carbon-hydrogen bond that is oxidized. In other words, the higher the density of C-H bonds in a compound, the more potential energy it can store. Fats, which primarily consist of only carbon and hydrogen, will contain the most energy and subsequently generate the most heat when oxidized. This is the same reason why animals and plants store energy as fat molecules.
*Note: A polyunsaturated fat has more than one double bond between its carbons, which reduces the total number of C-H bonds.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
What is likely true of the lipid A found on the glucosamine molecule in Figure 1?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
What is likely true of the lipid A found on the glucosamine molecule in Figure 1?
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Lipids are hydrocarbons, and are the most energy-rich biological macromolecules due to their heavily reduced state. This reduced state is a function of the roughly equal electronegativity between carbon and hydrogen atoms.
Lipids are hydrocarbons, and are the most energy-rich biological macromolecules due to their heavily reduced state. This reduced state is a function of the roughly equal electronegativity between carbon and hydrogen atoms.
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Water is the solvent in which all chemical reactions take place for living organisms. In addition, water has a number of critical characteristics that allows it to be invaluable to life as we know it.
Which of the following statements is FALSE concerning the properties of water?
Water is the solvent in which all chemical reactions take place for living organisms. In addition, water has a number of critical characteristics that allows it to be invaluable to life as we know it.
Which of the following statements is FALSE concerning the properties of water?
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Water is able to solvate hydrophilic compounds. Hydrophobic molecules, such as fatty acids, are typically aggregated together by water and can be separated.
Water is able to solvate hydrophilic compounds. Hydrophobic molecules, such as fatty acids, are typically aggregated together by water and can be separated.
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Water often acts as a reactant or solvent in biological reactions. Which of the following cellular components would not be sufficiently solvated in the body?
Water often acts as a reactant or solvent in biological reactions. Which of the following cellular components would not be sufficiently solvated in the body?
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A molecule is solvated when it is surrounded by water molecules, and separated from the other molecules in the body. This separation is possible because of charge or polarity present in the molecule, which causes it to be attractive to water.
Lipids have very low solubility in water due to their nonpolarity. As a result, we conclude that lipids would not be properly solvated in the body, and would instead be clustered together by water molecules.
A molecule is solvated when it is surrounded by water molecules, and separated from the other molecules in the body. This separation is possible because of charge or polarity present in the molecule, which causes it to be attractive to water.
Lipids have very low solubility in water due to their nonpolarity. As a result, we conclude that lipids would not be properly solvated in the body, and would instead be clustered together by water molecules.
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Which if the following lipids is responsible for the storing of energy in the body?
Which if the following lipids is responsible for the storing of energy in the body?
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Triacylglycerols (triglycerides) are composed of three fatty acids and a glycerol backbone. Their primary function is to store energy. As a secondary function they can also provide thermal insulation for an organism.
Phospholipids (glycerophospholipids) are primarily used in the cell membrane, but can also be involved in signaling. Sterol lipids (steroids) are primarily used as hormones, or involved in cell signaling. Eicosanoids are a family of fatty acid involved in signaling.
Glycogen is used to store energy, but it is a carbohydrate glucose polymer. The question specifies that the answer must be a lipid.
Triacylglycerols (triglycerides) are composed of three fatty acids and a glycerol backbone. Their primary function is to store energy. As a secondary function they can also provide thermal insulation for an organism.
Phospholipids (glycerophospholipids) are primarily used in the cell membrane, but can also be involved in signaling. Sterol lipids (steroids) are primarily used as hormones, or involved in cell signaling. Eicosanoids are a family of fatty acid involved in signaling.
Glycogen is used to store energy, but it is a carbohydrate glucose polymer. The question specifies that the answer must be a lipid.
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Which of the following will you most likely find in a steroid molecule?
Which of the following will you most likely find in a steroid molecule?
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Steroids are a type of lipid that are characterized by their four-ring molecular structure. The four rings consist of three six-membered rings and one five-membered ring. Recall that six-membered rings are called cyclohexanes and five-membered rings are called cyclopentanes; therefore, you will most likely find a cyclohexane in a steroid.
Phosphate groups, pentose sugars, and nitrogenous bases are found in nucleotides, which are monomers that make up nucleic acids. Steroids are a type of lipid; therefore, you will most likely not find these substances in a steroid.
Steroids are a type of lipid that are characterized by their four-ring molecular structure. The four rings consist of three six-membered rings and one five-membered ring. Recall that six-membered rings are called cyclohexanes and five-membered rings are called cyclopentanes; therefore, you will most likely find a cyclohexane in a steroid.
Phosphate groups, pentose sugars, and nitrogenous bases are found in nucleotides, which are monomers that make up nucleic acids. Steroids are a type of lipid; therefore, you will most likely not find these substances in a steroid.
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Which of the following best describes steroid molecules?
Which of the following best describes steroid molecules?
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Steroids are a type of lipid. This means that steroids are nonpolar molecules, composed of primarily of hydrogen and carbon. Recall that the interior of the plasma membrane consists of the nonpolar tails of phospholipids. Since nonpolar molecules tend to dissolve in other nonpolar molecules, steroids will be able to traverse the interior (nonpolar phospholipid tail) of plasma membranes and cross into the cell.
Steroids are a type of lipid. This means that steroids are nonpolar molecules, composed of primarily of hydrogen and carbon. Recall that the interior of the plasma membrane consists of the nonpolar tails of phospholipids. Since nonpolar molecules tend to dissolve in other nonpolar molecules, steroids will be able to traverse the interior (nonpolar phospholipid tail) of plasma membranes and cross into the cell.
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Which of the following is false regarding steroids?
Which of the following is false regarding steroids?
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A steroid is a type of lipid molecule that is found extensively in living organisms. Recall that triglycerides are also a type of lipid; therefore, steroids and triglycerides are classified as the same type of macromolecule. One of the characteristics of steroids is that they have four cycloalkane rings. Three of the four rings are six-membered rings (cyclohexane) and one ring is a five-membered ring (cyclopentane). Steroids are found in several biomolecules, such as hormones. Some examples of steroid hormones include the sex hormones (estrogen, progesterone, and testosterone), aldosterone, and cortisol. Since they are nonpolar, steroid hormones can traverse the lipid bilayer and enter the cell; therefore, the steroid hormone receptors are found inside the cell (on the nuclear membrane).
A type of steroid, called cholesterol, can be found in plasma membranes but it is not the major component of the membrane. Recall that plasma membranes are primarily composed of a phospholipid bilayer; therefore, phospholipids (another type of lipid) are the major component of plasma membranes.
A steroid is a type of lipid molecule that is found extensively in living organisms. Recall that triglycerides are also a type of lipid; therefore, steroids and triglycerides are classified as the same type of macromolecule. One of the characteristics of steroids is that they have four cycloalkane rings. Three of the four rings are six-membered rings (cyclohexane) and one ring is a five-membered ring (cyclopentane). Steroids are found in several biomolecules, such as hormones. Some examples of steroid hormones include the sex hormones (estrogen, progesterone, and testosterone), aldosterone, and cortisol. Since they are nonpolar, steroid hormones can traverse the lipid bilayer and enter the cell; therefore, the steroid hormone receptors are found inside the cell (on the nuclear membrane).
A type of steroid, called cholesterol, can be found in plasma membranes but it is not the major component of the membrane. Recall that plasma membranes are primarily composed of a phospholipid bilayer; therefore, phospholipids (another type of lipid) are the major component of plasma membranes.
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Which of the following is not a lipid?
Which of the following is not a lipid?
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Lipids are hydrophobic molecules that have low solubility in water and high solubility in nonpolar organic solvents. The following choices all describe lipid molecules, with the exception of glycine. Glycine is an amino acid and contains a carboxyl group (like fatty acid lipids), but also a amine group. These function groups make glycine hydrophilic and polar, unlike lipids.
Lipids are hydrophobic molecules that have low solubility in water and high solubility in nonpolar organic solvents. The following choices all describe lipid molecules, with the exception of glycine. Glycine is an amino acid and contains a carboxyl group (like fatty acid lipids), but also a amine group. These function groups make glycine hydrophilic and polar, unlike lipids.
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