Biology Chapter 5 Flashcards
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Questions and Answers

Which polymers are composed of amino acids?

Proteins

Which of the following is not attached to the central carbon atom in an amino acid?

  • An oxygen (correct)
  • A hydrogen
  • An amino group
  • A carboxyl group

    • Which part of an amino acid is always acidic?

    Carboxyl functional group

    Which monomers make up RNA?

    <p>Nucleotides</p> Signup and view all the answers

    Which of the following statements about the formation of polypeptides from amino acids is true?

    <p>A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid.</p> Signup and view all the answers

    Enzymes in the digestive tract catalyze hydrolysis reactions.

    <p>True</p> Signup and view all the answers

    A dehydration reaction (or condensation reaction) is the process in which _____.

    <p>water molecules are produced as a polymer is formed from monomers</p> Signup and view all the answers

    The four main categories of large biological molecules present in living systems are _____

    <p>proteins, nucleic acids, carbohydrates, and lipids</p> Signup and view all the answers

    How many molecules of water are released during the polymerization of a 20 monomer-long cellulose molecule?

    <p>19</p> Signup and view all the answers

    Plant cell walls consist mainly of _____

    <p>cellulose</p> Signup and view all the answers

    A molecule with the chemical formula C6H12O6 is probably a _____

    <p>monosaccharide</p> Signup and view all the answers

    The molecule shown is ________.

    <p>a hexose</p> Signup and view all the answers

    Which of these is NOT a lipid?

    <p>RNA</p> Signup and view all the answers

    This figure is an example of a(n) _____

    <p>saturated fat</p> Signup and view all the answers

    Which of these is a phospholipid?

    <p>Phospholipids are composed of a phosphate group, a glycerol, and fatty acids.</p> Signup and view all the answers

    Which of these is rich in unsaturated fats?

    <p>olive oil</p> Signup and view all the answers

    A function of cholesterol that does not harm health is its role _____

    <p>as a component of animal cell membranes</p> Signup and view all the answers

    How many fatty acids are in a phospholipid?

    <p>2</p> Signup and view all the answers

    What functional feature(s) does the phosphate group contribute to the structure of a phospholipid?

    <p>negative charge to interact with water; place to attach another small charged molecule</p> Signup and view all the answers

    What holds phospholipids together in a bilayer formation?

    <p>hydrophilic and hydrophobic interactions with water</p> Signup and view all the answers

    Which molecule is less soluble in water--a fat or a phospholipid? Why?

    <p>A fat molecule is less soluble in water because it has three non-polar fatty acids and no polar or charged head like a phospholipid has.</p> Signup and view all the answers

    The characteristic that all lipids have in common is that _____.

    <p>none of them dissolves in water</p> Signup and view all the answers

    What makes lipids/fats hydrophobic?

    <p>presence of relatively nonpolar CH bonds</p> Signup and view all the answers

    The molecule illustrated in the figure ________.

    <p>will be liquid at room temperature</p> Signup and view all the answers

    Proteins are polymers of _____

    <p>amino acids</p> Signup and view all the answers

    What type of bond joins the monomers in a protein's primary structure?

    <p>peptide</p> Signup and view all the answers

    Which of these illustrates the secondary structure of a protein?

    Signup and view all the answers

    The secondary structure of a protein results from _____

    <p>hydrogen bonds</p> Signup and view all the answers

    Tertiary structure is NOT directly dependent on _____

    <p>peptide bonds</p> Signup and view all the answers

    Some regions of a polypeptide may coil or fold back on themselves. This is called _____, and the coils or folds are held in place by _____.

    <p>secondary structure...hydrogen bonds</p> Signup and view all the answers

    A hydrophobic amino acid R group (side group) would be found where in a protein?

    <p>on the inside of the folded chain, away from water</p> Signup and view all the answers

    A glycosidic linkage is analogous to which of the following in proteins?

    <p>a peptide bond</p> Signup and view all the answers

    You disrupt all hydrogen bonds in a protein. What level of structure will be preserved?

    <p>primary structure</p> Signup and view all the answers

    The chemical reaction illustrated ________.

    <p>results in a peptide bond</p> Signup and view all the answers

    Your body contains tens of thousands of different proteins, each with a specific structure and function. The unique three-dimensional shape of each of these diverse proteins is based on several superimposed levels of structure. Which of the following statements is an accurate description of proteins?

    <p>The primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the DNA of a gene.</p> Signup and view all the answers

    Identify the level(s) of protein structure present in this molecule.

    <p>Tertiary</p> Signup and view all the answers

    What could happen if a mutation in a gene caused a hydrophobic amino acid in a polypeptide to be replaced by a hydrophilic amino acid?

    <p>The new amino acid would not form the same interactions with hydrophobic R groups, and the protein's shape would likely be affected.</p> Signup and view all the answers

    If a strand of DNA has the nitrogen base sequence 5'-ATTTGC-3', what will be the sequence of the matching strand?

    <p>3'-TAAACG-5</p> Signup and view all the answers

    If a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain?

    <p>75</p> Signup and view all the answers

    The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases.

    <p>hydrogen bonds</p> Signup and view all the answers

    A nucleotide is composed of a(n) _____

    <p>phosphate group, a nitrogen-containing base, and a five-carbon sugar</p> Signup and view all the answers

    When nucleotides polymerize to form a nucleic acid _____

    <p>a covalent bond forms between the sugar of one nucleotide and the phosphate of a second</p> Signup and view all the answers

    Which of the following is a major difference between RNA and DNA?

    <p>Type of sugar</p> Signup and view all the answers

    Identify three possible components of a DNA nucleotide.

    <p>deoxyribose, phosphate group, thymine</p> Signup and view all the answers

    These figures show the four levels of protein structure: primary, secondary, tertiary, and quaternary structure. Which level of protein structure is characteristic of some, but not all, proteins?

    <p>Quaternary level of protein structure</p> Signup and view all the answers

    Study Notes

    Proteins and Amino Acids

    • Proteins are polymers made of amino acids.
    • In amino acids, an oxygen atom is not attached to the central carbon atom.
    • The carboxyl functional group is always acidic in an amino acid.
    • Polypeptides form when the carboxyl group of one amino acid bonds with the amino group of another.

    Nucleic Acids

    • RNA is composed of nucleotides.
    • DNA has a complementary strand based on base pairing rules, e.g., 5'-ATTTGC-3' matches 3'-TAAACG-5'.
    • DNA is made of nucleotides consisting of a phosphate group, nitrogenous base, and five-carbon sugar.

    Biological Molecules

    • Large biological molecules include proteins, nucleic acids, carbohydrates, and lipids.
    • Cell walls of plants are primarily made of cellulose.

    Lipids

    • Lipids are defined by their inability to dissolve in water.
    • Fats contain three non-polar fatty acids, making them less soluble than phospholipids, which have a polar head.
    • Phospholipids comprise a phosphate group, glycerol, and fatty acids, contributing to membrane structure.

    Chemical Reactions in Biomolecules

    • Hydrolysis reactions in the digestive tract are catalyzed by enzymes.
    • A dehydration (condensation) reaction produces water when forming polymers from monomers.
    • Glycosidic linkages in carbohydrates are analogous to peptide bonds in proteins.

    Protein Structure

    • Proteins exhibit four levels of structure: primary, secondary, tertiary, and quaternary.
    • The primary structure is the linear sequence of amino acids coded in DNA.
    • Secondary structure results from hydrogen bonding; coils and folds are held by these bonds.
    • The tertiary structure is influenced by various interactions, including hydrophobic interactions of amino acid R groups.
    • Quaternary structure involves multiple polypeptide chains interacting, seen in some but not all proteins.

    Characteristics of Amino Acids

    • A hydrophobic R group in an amino acid is typically found on the inside of a folded protein, away from water.
    • Mutations affecting R groups can alter protein structure and function due to changes in interactions.

    Nucleotide Composition

    • A DNA nucleotide can consist of deoxyribose, a phosphate group, and a nitrogenous base like thymine.
    • RNA nucleotides differ from DNA due to their sugar type.

    Structural Stability

    • Proteins retain primary structure even when hydrogen bonds are disrupted.
    • Hydrogen bonds between nitrogenous bases connect the two strands of DNA, stabilizing the double helix.

    Fatty Acids and Cholesterol

    • Saturated fats have no double bonds in their fatty acid tails, while unsaturated fats contain double bonds.
    • Cholesterol is crucial as a component of animal cell membranes, contributing to membrane stability.

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    Description

    Test your knowledge on essential concepts from Chapter 5 of MasteringBiology. This quiz covers topics such as amino acids, proteins, and RNA structure. Perfect for students looking to reinforce their understanding of biological macromolecules.

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