Biochemistry: Basic Molecules and Enzymes
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Questions and Answers

What is the simplest amino acid formed when the R group is substituted by H?

  • Methionine
  • Alanine
  • Glycine (correct)
  • Cysteine

    • Methionine is encoded by the AUG codon and is polar.

    False

    What term describes amino acids that possess both basic and acidic properties?

    amphoteric

    The pH at which an amino acid exists in its neutral zwitterion form is called the ______.

    <p>isoelectric point</p> Signup and view all the answers

    What happens to an amino acid when placed in a more acidic solution?

    <p>It becomes positively charged.</p> Signup and view all the answers

    Match the following amino acids with their characteristics:

    <p>Methionine = Non-polar and initiator amino acid Cysteine = Contains sulfur Glycine = Simplest amino acid Alanine = Substituted by –CH3</p> Signup and view all the answers

    Amino acids are generally insoluble in water and soluble in organic solvents.

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

    What is the property of amino acids at their isoelectric point regarding their migration in an electric field?

    <p>They do not migrate.</p> Signup and view all the answers

    How many monomers compose proteins?

    <p>20</p> Signup and view all the answers

    A change in a protein's structure will change the protein's function.

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

    What groups do all amino acids have in common?

    <p>An amino group, a carboxyl group, and an R group (side chain).</p> Signup and view all the answers

    A __________ is formed when two amino acids bond together.

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

    Match the following protein structures with their description:

    <p>Primary Structure = Sequence of amino acids Secondary Structure = Alpha helices and beta sheets Tertiary Structure = Three-dimensional folding Quaternary Structure = Multiple polypeptide chains</p> Signup and view all the answers

    What happens to a protein if it is denatured?

    <p>It loses its functional shape.</p> Signup and view all the answers

    The Biuret test detects carbohydrates in food.

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

    What interactions occur in the secondary structure of proteins?

    <p>Hydrogen bonds.</p> Signup and view all the answers

    What property of ice causes it to float on water?

    <p>It is less dense than water</p> Signup and view all the answers

    Water has low cohesion, which means its molecules do not stick together well.

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

    What role does water play in photosynthesis?

    <p>Water is used as a source of hydrogen.</p> Signup and view all the answers

    Ice floating on water provides an insulating layer that delays the freezing of the rest of the __________.

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

    Match the following functions of water with their descriptions:

    <p>Transport = Movement of nutrients and waste Cooling = Reduction of heat by evaporation Support = Providing structure to cells and organisms Solvent = Dissolving substances for biochemical reactions</p> Signup and view all the answers

    Which process involves water aiding in the support of plant structure through osmosis?

    <p>Guard cell mechanism</p> Signup and view all the answers

    High surface tension of water is not significant for small organisms.

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

    Name one way in which water benefits aquatic organisms.

    <p>Support for swimming gametes or protection from environmental threats.</p> Signup and view all the answers

    Which of the following describes the role of triglycerides in mammals?

    <p>They store extra energy and provide insulation.</p> Signup and view all the answers

    Phospholipids are lipids that contain a phosphate group.

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

    What metabolic product is formed when fats are oxidized?

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

    Mammals that live in cold climates store extra fat in the form of __________ tissue.

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

    Match the following types of lipids with their characteristics:

    <p>Triglycerides = Store energy and provide insulation Phospholipids = Make up cell membranes Oils = Liquid at room temperature Blubber = Insulation in aquatic mammals</p> Signup and view all the answers

    Which type of fatty substance do plants primarily store?

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

    Adipose tissue helps mammals regulate their body temperature.

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

    Name one commercial source of oil found in seeds.

    <p>coconut or soybean</p> Signup and view all the answers

    How many polypeptide chains are present in the quaternary structure of haemoglobin?

    <p>4</p> Signup and view all the answers

    Which of the following interactions holds the quaternary structure of proteins in place?

    <p>Hydrophobic interactions</p> Signup and view all the answers

    Haemoglobin is a fibrous protein.

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

    The heme group in haemoglobin contains a central __________ ion.

    <p>iron (II)</p> Signup and view all the answers

    How many amino acids are present in the α-chains of haemoglobin?

    <p>141</p> Signup and view all the answers

    Match the following components of haemoglobin with their roles:

    <p>Fe2+ = Binds oxygen Heme group = Carries oxygen Alpha chains = Structural component Beta chains = Structural component</p> Signup and view all the answers

    What is the primary function of the heme group in haemoglobin?

    <p>To bind oxygen molecules</p> Signup and view all the answers

    Haemoglobin consists of __________ types of polypeptide chains.

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

    What role do enzymes play in metabolic reactions?

    <p>They act as biological catalysts.</p> Signup and view all the answers

    Enzymes are completely consumed in the reactions they catalyze.

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

    What is the region of an enzyme that directly interacts with the substrate called?

    <p>active site</p> Signup and view all the answers

    Enzymes lower the activation energy required for a chemical reaction, which __________ the rate of reaction.

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

    Match the types of reactions with their definitions:

    <p>Catabolic = Involved in breakdown Anabolic = Involved in synthesis Exergonic = Energy releasing processes Endergonic = Reactions that require energy to initiate</p> Signup and view all the answers

    Which hypothesis suggests that the substrate's shape is complementary to that of the enzyme?

    <p>Lock and key hypothesis</p> Signup and view all the answers

    Enzymes can only catalyze endergonic reactions.

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

    What happens to the enzyme-substrate complex after the reaction occurs?

    <p>It breaks up into products and the enzyme.</p> Signup and view all the answers

    Study Notes

    Biochemistry (Basic Molecules and Enzymes)

    • Biochemistry is the study of chemical processes in living organisms.
    • Basic molecules and enzymes are fundamental to life processes.

    The Biomolecules of Life

    • The biomolecules of life are crucial for life processes, and include carbohydrates, lipids, proteins, and nucleic acids.

    Basic Chemistry

    • Matter is anything that takes up space and has mass.
    • Elements are substances that cannot be broken down into simpler substances.
    • Atoms are the smallest units of an element.
    • Atoms contain a nucleus (protons and neutrons) with electrons orbiting around it.
    • Electrons occupy discrete energy levels (shells).
    • The first shell holds 2 electrons.
    • The second shell and subsequent shells hold 8 electrons each (exceptions in some elements).
    • Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
    • The atomic number is the number of protons in an atom.
    • The mass number is the sum of protons and neutrons.

    Chemical Bonds

    • Chemical bonds form when there are forces of attraction between atoms.
    • Ionic bonds form when electrons are transferred between a metal and a nonmetal.
    • Covalent bonds form when atoms share electrons.
    • Polar covalent bonds occur when electrons are unequally shared between atoms leading to partial charges.
    • Nonpolar covalent bonds occur when electrons are equally shared between atoms resulting in no partial charges.
    • Hydrogen bonds are weak attractions between a partially positive hydrogen atom and a partially negative atom such as oxygen or nitrogen.
    • Van der Waals forces are weak attractions between molecules caused by temporary fluctuations in electron distribution.

    Water

    • Water is a crucial component of life due to its unique properties.
    • Water molecules are polar, with a slightly negative oxygen atom and slightly positive hydrogen atoms.
    • Hydrogen bonds between water molecules lead to its high surface tension and cohesion.
    • Water has a high specific heat capacity due to hydrogen bonds, meaning a large amount of heat is required to change its temperature.

    Water as a Solvent

    • Water is a good solvent for polar molecules and ionic compounds due to its polarity.
    • Water molecules surround the polar or ionic solute, forming a hydration shell.

    Carbon Chemistry

    • Carbon is the essential element for building organic molecules.
    • Carbon atoms can form four covalent bonds with other atoms.
    • Functional groups are clusters of atoms attached to carbon chains that give molecules characteristics properties.

    Isomers

    • Isomers are molecules with the same molecular formula but different structures.
    • Structural isomers differ in the arrangement of atoms.
    • Geometric isomers differ in the spatial arrangement of atoms.

    Monomers and Polymers

    • Monomers are small, repeating units.
    • Polymers are large molecules made from monomers joined by condensation reactions.

    Carbohydrates

    • Carbohydrates have the general formula Cx(H2O)y.
    • Monosaccharides are single sugar units, e.g., glucose.
    • Disaccharides are formed by joining two monosaccharides.
    • Polysaccharides are polymers of monosaccharides, e.g., starch, glycogen, and cellulose.

    Lipids

    • Lipids are diverse hydrophobic molecules.
    • Triglycerides are formed from glycerol and fatty acids.
    • Phospholipids have a hydrophilic head and two hydrophobic tails.
    • Steroids are composed of four fused carbon rings.

    Proteins

    • Proteins are polymers of amino acids.
    • Amino acids have a central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable side chain (R group).
    • Primary structure is the linear sequence of amino acids.
    • Secondary structure involves hydrogen bonding, forming α-helices or β-sheets.
    • Tertiary structure is the overall three-dimensional shape of a folded polypeptide chain.
    • Quaternary structure is the association of multiple polypeptide chains.

    Enzymes

    • Enzymes are proteins that catalyze biochemical reactions.
    • Enzymes have an active site that binds to the substrate.
    • Enzymes lower the activation energy of a reaction.
    • Two main models explain-lock and key and induced fit.

    Enzyme Inhibition

    • Enzyme inhibitors reduce the rate of enzyme-catalyzed reactions.
    • Competitive inhibitors bind to the active site.
    • Noncompetitive inhibitors bind to a different site.
    • Allosteric enzymes are regulated by molecules binding to allosteric sites.

    Nucleic Acids

    • Nucleic acids are polymers of nucleotides.
    • Nucleotides are composed of a sugar, a nitrogenous base, and a phosphate group.
    • DNA is a double helix formed by two strands of nucleotides.
    • RNA is a single-stranded molecule with uracil instead of thymine.

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    Biochemistry Basic Molecules and enzymes 2024-25 PDF

    Description

    This quiz explores the fundamental concepts of biochemistry, focusing on basic molecules and enzymes that are essential for life. Learn about the key biomolecules, including carbohydrates, lipids, proteins, and nucleic acids, along with foundational chemistry principles. Test your knowledge on how these compounds interact in biological processes.

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