Proteins and Their Structures Quiz
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Questions and Answers

How many monomers make up proteins?

  • 10
  • 25
  • 20 (correct)
  • 15

    • A change in a protein’s structure will change the protein’s function.

    True

    What groups do all amino acids have in common?

    Amino and carboxyl groups

    A protein is denatured when its structure is __________.

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

    Match the levels of protein structure with their descriptions:

    <p>Primary Structure = A linear sequence of amino acids Secondary Structure = Alpha helices and beta sheets Tertiary Structure = Three-dimensional folding of a single polypeptide Quaternary Structure = Multiple polypeptides forming a functional protein</p> Signup and view all the answers

    How many amino acids are needed to form a dipeptide?

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

    Which factor is responsible for the formation of a dipeptide?

    <p>Peptide bond</p> Signup and view all the answers

    Condensation is the process involved in forming a peptide bond.

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

    What type of bond is a peptide bond?

    <p>Covalent bond</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 the presence of amino acids.

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

    Proteins contain the elements carbon, hydrogen, oxygen, nitrogen, and sometimes ______.

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

    Which statement about protein structure is correct?

    <p>The primary structure is the number and sequence of amino acids in a polypeptide chain.</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Peptide bond = Covalent bond between two amino acids Dipeptide = Two amino acids linked together Polypeptide = Chain formed from multiple amino acids Primary structure = Sequence of amino acids in a protein</p> Signup and view all the answers

    What are the common elements found in proteins?

    <p>Carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur.</p> Signup and view all the answers

    The sequence of amino acids in proteins is encoded by genes.

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

    Which type of bond occurs only between cysteine amino acids?

    <p>Disulfide bridge</p> Signup and view all the answers

    Hydrogen bonds in protein tertiary structures primarily occur between the backbone of polypeptides.

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

    What structure is formed when a polypeptide chain bends and folds extensively?

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

    Which hypothesis suggests that enzyme structure changes when a substrate combines with it?

    <p>Induced Fit hypothesis</p> Signup and view all the answers

    Weak __________ interactions occur between non-polar R groups in proteins.

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

    Extracellular enzymes are found inside the cell membrane.

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

    Match the bond type with its description:

    <p>Hydrogen bond = Occurs between R groups Disulfide bridge = Occurs between cysteine amino acids Ionic bond = Occurs between charged R groups Hydrophobic interactions = Between non-polar R groups</p> Signup and view all the answers

    Name one example of an intracellular enzyme.

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

    What type of functional groups are necessary for hydrogen bonding to occur in amino acids?

    <p>Carboxyl groups and hydroxyl groups</p> Signup and view all the answers

    The main hub of cellular metabolism is the ______.

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

    How many polypeptide chains are present in a typical tertiary protein structure?

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

    Ionic bonds in proteins form between _______ R groups.

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

    Which of the following is NOT a type of extracellular enzyme?

    <p>Glycogen phosphorylase</p> Signup and view all the answers

    Match each process with its corresponding enzyme activity:

    <p>Glycolysis = Intracellular Salivary Amylase = Extracellular Urea cycle = Intracellular Pancreatic amylase = Extracellular</p> Signup and view all the answers

    Digestive enzymes, such as pepsin, are considered extracellular enzymes.

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

    What are the two environments where enzymes can catalyse reactions?

    <p>Intracellular and extracellular</p> Signup and view all the answers

    Which of the following is NOT a function of proteins?

    <p>Storing genetic information</p> Signup and view all the answers

    Animals can synthesize all amino acids they need from simpler substances.

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

    Which of the following correctly describes phospholipids?

    <p>They contain both hydrophilic and hydrophobic regions.</p> Signup and view all the answers

    What are the building blocks of proteins?

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

    Steroids are structurally similar to phospholipids.

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

    The general formula of an amino acid is ________.

    <p>H2N-R-COOH</p> Signup and view all the answers

    What is the role of cholesterol in eukaryotic cell membranes?

    <p>Cholesterol provides stability and fluidity to the cell membrane.</p> Signup and view all the answers

    Which type of amino acids are not synthesized by animals and must be obtained from the diet?

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

    The formation of triglycerides involves the esterification of glycerol with _____ fatty acids.

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

    Match the following lipid types with their characteristics:

    <p>Phospholipids = Amphipathic molecules with a hydrophilic head and hydrophobic tails Triglycerides = Composed of three fatty acids and glycerol Cholesterol = A sterol that stabilizes cell membranes Steroids = Composed of four carbon rings with functional groups</p> Signup and view all the answers

    Match the type of amino acid with its description:

    <p>Neutral amino acids = Contain one amino and one carboxyl group Basic amino acids = Have more than one amino group Acidic amino acids = Have more than one carboxyl group Imino acids = Include proline and hydroxyproline</p> Signup and view all the answers

    What is the primary reason phospholipids form bilayers in water?

    <p>Their amphipathic nature causes the hydrophilic heads to face outward.</p> Signup and view all the answers

    All amino acids possess both an acidic carboxylic group and a basic amino group.

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

    What is the role of actin and myosin in muscle cells?

    <p>Enabling muscle contraction</p> Signup and view all the answers

    Fatty acids and phosphoric acid create phospholipids.

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

    What are the primary components of triglycerides?

    <p>Glycerol and three fatty acids.</p> Signup and view all the answers

    Proteins provide strength to animal tissues, such as bones and ________ walls.

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

    Study Notes

    Biochemistry (Basic Molecules and Enzymes)

    • This section of the syllabus covers basic biochemistry, including basic molecules and enzymes.

    The Biomolecules of Life

    • Carbohydrates: These include sugars, starches, and fibers.
    • Lipids: These are fats, oils, and waxes, primarily composed of carbon and hydrogen. Important types include phospholipids, triglycerides, and cholesterol.
    • Proteins: These are complex molecules made up of amino acids linked together.
    • Nucleic Acids: These include DNA and RNA, which carry genetic information.

    Basic Chemistry

    • Matter: Anything that occupies space and has mass.
    • Elements: Substances that cannot be broken down into simpler substances. Key elements in living organisms include carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.
    • Atoms: The smallest units of an element. Atoms contain a nucleus composed of protons and neutrons, with electrons orbiting the nucleus.
    • Atomic Number (Z): The number of protons in an atom's nucleus.
    • Mass Number (A): The total number of protons and neutrons in an atom's nucleus.
    • Isotopes: Atoms of the same element that have different numbers of neutrons.
    • Electron Shells: Regions around the nucleus where electrons orbit. Shells fill in order, starting closest to the nucleus.
    • Electron shells: First shell holds up to two, second shell up to eight, third shell up to eight (often more in chemistry). Number of protons and electrons are usually equal, and the charge is neutral.

    Chemical Bonds

    • Ionic Bonding: Electrons are transferred between metal and nonmetal atoms, forming ions with opposite charges that attract each other.
    • Covalent Bonding: Atoms share electrons to fill their outer electron shells.
    • Polar Covalent Bonds: Unequal sharing of electrons, leading to partially charged atoms. Example: water.
    • Nonpolar Covalent Bonds: Equal sharing of electrons.
    • Hydrogen Bonding: Attraction between a slightly positive hydrogen atom and a slightly negative atom (e.g., oxygen or nitrogen) in another molecule. This bond is important in water.
    • Van der Waals Forces: Weak attractive forces between molecules, often in nonpolar molecules.

    Water

    • Structure: Two hydrogen atoms covalently bonded to one oxygen atom. The oxygen has a partial negative charge, and hydrogens a partial positive charge due to unequal sharing of electrons.
    • Polarity: Results from the uneven distribution of charges causes it to have an attraction to other polar molecules (hydrophilic).
    • Hydrogen Bonding: The partial charges in water molecules lead to hydrogen bonds with other water molecules.
    • High Specific Heat Capacity: Water absorbs and releases heat energy more slowly than other substances, which is crucial for regulating temperatures in living organisms.
    • High Heat of Vaporization: A large amount of energy to change liquid to gas. Essential for cooling living organisms through sweating/panting.
    • Density and Freezing Properties: Ice is less dense than liquid water, essential for aquatic life in cold environments (prevents freezing of bodies of water).
    • Cohesion and Adhesion: Water molecules stick together (cohesion) and to other substances (adhesion). Important for transport of water in plants and for surface tension.
    • Solvent Properties: Water dissolves many substances (polar and ionic) easily. This is critical for many biochemical reactions in living systems.

    Carbohydrates

    • General Formula: Cx(H2O)y
    • Monosaccharides: Single sugar units (e.g., glucose, fructose, galactose). Key distinction between a-glucose and B-glucose in ring structure differs only in position of hydroxyl (OH) on carbon-1.
    • Disaccharides: Two monosaccharides joined together (e.g., maltose, sucrose, lactose). Glycosidic bonds formed.
    • Polysaccharides: Many monosaccharides joined together (e.g., starch, glycogen, cellulose). These have different structures and functions.

    Lipids

    • Triglycerides: Three fatty acids bonded to a glycerol molecule (energy storage).
    • Fatty Acids: Long hydrocarbon chains with a carboxyl group (-COOH) at one end. Saturated (no double bonds) and unsaturated (one or more double bonds).
    • Glycerol: A three-carbon alcohol.
    • Phospholipids: Two fatty acids and a phosphate group attached to a glycerol molecule.
    • Steroids: Four interconnected hydrocarbon rings. An example: cholesterol.

    Proteins

    • Amino Acids: Building blocks of proteins. 20 different amino acids. Consist of an amino group (-NH2), a carboxyl group (-COOH), and a unique side chain (R group determining characteristics).
    • Primary Structure: The linear sequence of amino acids.
    • Secondary Structure: Local folding patterns (e.g., alpha helix, beta pleated sheet) formed by hydrogen bonding between peptide backbone.
    • Tertiary Structure: The overall 3-dimensional shape of a protein formed by interactions between amino acid side chains (hydrophobic interactions, hydrogen bonds, ionic bonds, disulfide bridges).
    • Quaternary Structure: The arrangement of multiple polypeptide chains in a protein. An example: hemoglobin.

    Enzymes

    • Catalysts: Substances that speed up chemical reactions without being consumed.
    • Active Site: The specific region on an enzyme where the substrate binds.
    • Lock and Key Model: The substrate fits precisely into the active site like a key into a lock. Substrates are matched like lock and key.
    • Induced Fit Model: The active site changes shape slightly on binding the substrate.
    • Factors Affecting Enzyme Activity: Temperature, pH, substrate concentration, enzyme concentration, and inhibitors.
    • Enzyme Inhibition: Competitive inhibitors, non-competitive inhibitors, and allosteric regulation.

    Nucleic Acids

    • Nucleotides: The building blocks of nucleic acids. Consist of a sugar, a nitrogenous base, and a phosphate group.
    • Deoxyribonucleic acid (DNA): A double helix. Two strands of nucleotides, linked together by hydrogen bonds between complementary bases (adenine with thymine, cytosine with guanine).
    • Ribonucleic acid (RNA): Usually, a single-stranded molecule. Contains different bases (adenine, uracil, cytosine, guanine), nucleotides are linked together by phosphate groups joining them. Different types (e.g., mRNA, tRNA, rRNA).

    Vitamins and their Role as Coenzymes

    • Coenzymes: Non-protein molecules that help enzymes work by carrying electrons, protons, or other chemical groups.
    • Examples: NAD+, NADP+, FAD, coenzyme A. These play critical roles in metabolic reactions. Specific vitamins are critical in the production of these molecules.

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    Biochemistry Basic Molecules and enzymes 2024-25 PDF

    Description

    Test your knowledge on proteins, their structures, and functions with this quiz. From monomers and amino acids to peptide bonds and denaturation, assess your understanding of key concepts in protein biology. Ideal for students studying biochemistry or related fields.

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