Proteins and Their Structures
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Questions and Answers

What is the primary characteristic that distinguishes eukaryotic cells from prokaryotic cells?

  • Presence of ribosomes
  • Enclosed nucleus containing DNA (correct)
  • Presence of plasma membrane
  • Lack of a membrane-bound nucleus

    • Which organelle in eukaryotic cells is primarily involved in protein synthesis?

  • Nucleus
  • Ribosomes (correct)
  • Plasma membrane
  • Smooth endoplasmic reticulum

    • What function does the smooth endoplasmic reticulum serve in eukaryotic cells?

  • Protein synthesis
  • Regulation of cell division
  • Lipid synthesis and detoxification (correct)
  • Storage of genetic material

    • In which eukaryotic cell type would you expect to find a high activity of smooth endoplasmic reticulum?

    <p>Adrenal cortex cells</p> Signup and view all the answers

    What is the main role of the golgi apparatus in eukaryotic cells?

    <p>Processing and packaging proteins</p> Signup and view all the answers

    What component of the eukaryotic cell acts as a selective barrier regulating entry and exit of substances?

    <p>Plasma membrane</p> Signup and view all the answers

    Where does ribosomal assembly occur in eukaryotic cells?

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

    Which of the following statements is true regarding the nucleus in eukaryotic cells?

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

    What is the primary function of mitochondria in a cell?

    <p>Site for cellular respiration and ATP production</p> Signup and view all the answers

    Which of the following statements accurately describes lysosomes?

    <p>They contain enzymes for digestion and recycling of cellular components.</p> Signup and view all the answers

    What role do microfilaments play in the cell structure?

    <p>They are involved in intracellular movements.</p> Signup and view all the answers

    What is a key characteristic of the endoplasmic reticulum?

    <p>It is involved in protein transport and glycosylation.</p> Signup and view all the answers

    Which of the following is true regarding cytosol?

    <p>It is an aqueous matrix where metabolic processes occur.</p> Signup and view all the answers

    How do mitochondria maintain their own replication?

    <p>They reproduce by binary fission.</p> Signup and view all the answers

    What distinguishes intermediate filaments from microfilaments and microtubules?

    <p>They provide mechanical support under stress.</p> Signup and view all the answers

    What are the enzymes found in mitochondria responsible for?

    <p>The citric acid cycle and oxidative phosphorylation.</p> Signup and view all the answers

    What percentage of total body water is typically found intracellularly?

    <p>60%</p> Signup and view all the answers

    Which group is likely to have the highest percentage of body water?

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

    What characteristic of water allows it to dissolve most organic and inorganic molecules?

    <p>Its dipolar structure</p> Signup and view all the answers

    How does water act in relation to pH maintenance?

    <p>It can act as both an acid and a base.</p> Signup and view all the answers

    What defines the dielectric constant of a material?

    <p>Its resistance to electric field formation</p> Signup and view all the answers

    Which group tends to have the lowest percentage of body water?

    <p>Older adults</p> Signup and view all the answers

    What role does water play as a chemical reactant?

    <p>It acts as a nucleophile in chemical reactions.</p> Signup and view all the answers

    Why do obese individuals generally have a lower percentage of body water?

    <p>Because fat contains minimal water.</p> Signup and view all the answers

    What is the main purpose of homogenization in cellular studies?

    <p>To disrupt the cell and liberate its constituents</p> Signup and view all the answers

    Which method is NOT a part of the isolation of biomolecules and organelles?

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

    What is the content of the final supernatant after centrifugation?

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

    Which of the following is a method to determine the structure of biomolecules?

    <p>Mass spectrometry</p> Signup and view all the answers

    In centrifugation, what is produced at successively greater speeds?

    <p>Pellet and supernatant</p> Signup and view all the answers

    Which of the following components is NOT associated with a peroxisome?

    <p>Lactate Dehydrogenase</p> Signup and view all the answers

    What is the correct sequence of the fractions produced during centrifugation?

    <p>Nuclear fraction, mitochondrial fraction, microsomal fraction</p> Signup and view all the answers

    What role do marker enzymes play in the analysis of organelle purity?

    <p>To measure the purity of organelle fractions</p> Signup and view all the answers

    What effect does water have on the attraction between charged particles?

    <p>It decreases the attraction because of its high dielectric constant.</p> Signup and view all the answers

    Which of the following molecules can act as a nucleophile?

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

    What is the main consequence of dehydration?

    <p>A decrease in the total volume of bodily fluids.</p> Signup and view all the answers

    What type of bond is formed by the sharing of electron pairs between atoms?

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

    In what two ways can water act in chemical reactions?

    <p>As both an acid and a base</p> Signup and view all the answers

    What is the primary characteristic of a substance with a high dielectric constant?

    <p>It can easily break ionic bonds.</p> Signup and view all the answers

    Which of the following statements about dehydration is correct?

    <p>It occurs when fluid loss is greater than intake.</p> Signup and view all the answers

    How does water's ability to act as both an acid and a base influence its role in reactions?

    <p>It allows for greater versatility in chemical reactions.</p> Signup and view all the answers

    What is the dissociation constant of water (Kw) at 25 degrees Centigrade?

    <p>$1.0 \times 10^{-14} \text{ (mol / L)}^2$</p> Signup and view all the answers

    What is the relationship between pH and pOH in a neutral solution?

    <p>pH + pOH = 14</p> Signup and view all the answers

    Which of the following correctly expresses the formula for the dissociation constant (K)?

    <p>$K = \frac{[H^+][OH^-]}{[H2O]}$</p> Signup and view all the answers

    How does the concentration of H3O+ and OH- in pure water at 25 degrees Centigrade compare?

    <p>Both are equal to $1 \times 10^{-7} \text{ mol / L}$</p> Signup and view all the answers

    What does the term -log[H3O+] represent?

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

    Study Notes

    • Proteins are high molecular weight polypeptides.
    • Protein classification can be based on components (simple or complex), overall shape (globular or fibrous), or function (catalytic, contraction, hormonal, etc).
    • Globular proteins have an axial ratio of less than 10, while fibrous proteins have an axial ratio greater than 10.
    • Protein structure is hierarchical, with primary, secondary, tertiary, and quaternary structures.
    • Primary structure is the linear sequence of amino acids.
    • Secondary structure includes a-helices and b-pleated sheets, stabilized by hydrogen bonds.
    • Tertiary structure is the three-dimensional arrangement of the polypeptide chain.
    • Quaternary structure involves the aggregation of multiple polypeptide chains.
    • Protein folding is driven by hydrophobic interactions, hydrogen bonds, disulfide bonds, and salt bridges.
    • Denaturation disrupts the native conformation of proteins, causing loss of biological activity.
    • Protein folding can be aided by accessory proteins such as chaperonins.
    • Proline and Glycine are frequently found in turns and bends of proteins.
    • There are 20 common amino acids.
    • Amino acids are classified by their R-groups as nonpolar, polar uncharged, polar charged, and aromatic.
    • Specific groups such as hydroxyl (-OH), sulfhydryl (-SH), and carboxyl (-COOH) play roles in protein synthesis, structure, and function.
    • pH affects the charge of amino acids.
    • Isoelectric point (pI) is the pH at which a protein has no net charge.
    • Peptide bonds connect amino acids in proteins
    • Disulfide bond forms between pairs of cysteine residues.
    • Protein structure is essential for its function.
    • Different types of bonds maintain the structure (e.g., hydrogen, hydrophobic, ionic, Van der Waals).

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    Description

    This quiz explores the fascinating world of proteins, focusing on their classification, structure, and folding mechanisms. You'll learn about the different types of proteins, from globular to fibrous, and understand the hierarchical nature of protein structures. Test your knowledge on protein functionalities and the effects of denaturation.

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