Bacterial Structure and Function
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Questions and Answers

What is the primary composition of a bacterial capsule?

  • Protein
  • Lipids
  • Polysaccharide (correct)
  • Nucleic acid
  • What role does the cell wall play in bacterial cells?

  • It serves as a site for photosynthesis.
  • It promotes cytolysis under hypotonic conditions.
  • It contains genetic material.
  • It provides rigidity and acts as a protective filter. (correct)
  • What is the main function of mesosomes in bacterial cells?

  • Provide a protective coating.
  • Resist osmotic pressure.
  • Increase membrane surface for respiration. (correct)
  • Store chlorophyll for photosynthesis.
  • Which of the following best describes the role of the cell membrane in bacteria?

    <p>It is a selectively permeable barrier.</p> Signup and view all the answers

    What causes cytolysis in bacterial cells?

    <p>Absorption of excessive water in a hypotonic environment.</p> Signup and view all the answers

    What are thylakoids in prokaryotic cells used for?

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

    What is peptidoglycan primarily made of?

    <p>Cross-linked polysaccharides and amino acids.</p> Signup and view all the answers

    How does the capsule benefit bacterial cells?

    <p>It enhances adherence to surfaces.</p> Signup and view all the answers

    What is the main function of ribosomes?

    <p>Protein synthesis</p> Signup and view all the answers

    What is the composition of ribosomes?

    <p>50% ribosomal RNA and 50% protein</p> Signup and view all the answers

    Which of the following best describes the structure of a 70s ribosome?

    <p>Two subunits of 30s and 50s</p> Signup and view all the answers

    What is the primary role of lysosomes in relation to autophagosomes?

    <p>To fuse with autophagosomes and degrade their contents</p> Signup and view all the answers

    What happens to proteins produced by ribosomes on the rough endoplasmic reticulum (RER)?

    <p>Transported to the Golgi apparatus</p> Signup and view all the answers

    What structural feature of the inner membrane of the mitochondrion increases its surface area?

    <p>Cristae folds</p> Signup and view all the answers

    What occurs during the process of autolysis?

    <p>The whole cell is destroyed by the rupture of lysosome membranes</p> Signup and view all the answers

    Where can ribosomes typically be found in eukaryotic cells?

    <p>On the endoplasmic reticulum and throughout the cytoplasm</p> Signup and view all the answers

    Which of the following components is found in the matrix of mitochondria?

    <p>Circular DNA molecules</p> Signup and view all the answers

    What characterizes cells with high-energy requirements regarding their mitochondria?

    <p>They have a large number of mitochondria</p> Signup and view all the answers

    Which statement is true regarding the types of ribosomes?

    <p>70s ribosomes are exclusive to prokaryotic cells</p> Signup and view all the answers

    What key feature do mature human red blood cells lack?

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

    What happens to undigested products in the lysosome after degradation?

    <p>They are released from the cell through exocytosis</p> Signup and view all the answers

    During what biological process do lysosomes participate in the absorption of a frog's tail?

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

    What is the function of the small and large subunits of ribosomes?

    <p>To facilitate protein synthesis</p> Signup and view all the answers

    What is the significance of the Swedberg unit in relation to ribosomes?

    <p>It measures the size of ribosomal particles during centrifugation</p> Signup and view all the answers

    What is the primary function of mitochondria in a cell?

    <p>Aerobic respiration for energy production</p> Signup and view all the answers

    Which pigment is contained in chloroplasts and is essential for photosynthesis?

    <p>Chlorophyll a and b</p> Signup and view all the answers

    What is the primary role of leucoplasts in plant cells?

    <p>Synthesis of starch, oils, and proteins</p> Signup and view all the answers

    Which statement is true regarding the structure of chloroplasts?

    <p>Chloroplasts are enclosed in a double membrane</p> Signup and view all the answers

    What is the stroma within chloroplasts primarily composed of?

    <p>Semi-fluid matrix with enzymes and DNA</p> Signup and view all the answers

    Where in plants does most photosynthesis activity occur?

    <p>In the leaves</p> Signup and view all the answers

    Which type of plastid is primarily responsible for the storage of starch and oils?

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

    What distinguishes the outer membrane of the chloroplast from the inner membrane?

    <p>The outer membrane is less permeable</p> Signup and view all the answers

    What is the primary function of chloroplasts in higher plants?

    <p>Site of photosynthesis</p> Signup and view all the answers

    What are thylakoids stacked together known as?

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

    What is the composition of thylakoid membranes?

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

    What is the arrangement of microtubules in centrioles?

    <p>9+0 arrangement</p> Signup and view all the answers

    During which cellular process do centrioles play a critical role?

    <p>Cell division</p> Signup and view all the answers

    What is contained in the stroma of chloroplasts?

    <p>Enzymes for light independent reactions</p> Signup and view all the answers

    Which component is generally absent in plant cells?

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

    Which pigment is primarily found embedded in the membranes of thylakoids?

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

    Study Notes

    Bacterial Structure and Function

    • Pili aid bacteria in adhering to solid surfaces.
    • Capsules serve as protective, jellylike outer layers composed of polysaccharides and have high water retention capacity (hygroscopic).
    • The cell envelope consists of a cell wall and plasma membrane, providing rigidity, protection, and selective permeability.
    • Bacterial cell walls are primarily made of peptidoglycan, which consists of polysaccharide chains linked by amino acids, preventing cell lysis from osmotic pressure.
    • Bacterial cell sizes range from 1 to 10 micrometers in diameter.

    Cellular Membrane and Mesosomes

    • The cell membrane is selectively permeable and forms mesosomes, which increase surface area for aerobic respiration.
    • Mesosomes are clusters of membrane folds that enhance cellular respiration efficiency.

    Photosynthesis in Prokaryotes

    • Photosynthetic prokaryotes, including blue-green algae and purple bacteria, possess thylakoids containing chlorophyll, providing large surface areas for photosynthesis.

    Lysosomal Function and Autolysis

    • Lysosomes degrade cellular components via enzymes, absorbing useful products and releasing undigested waste through exocytosis.
    • Autolysis occurs when lysosomal enzymes destroy non-functional cells, as seen in the metamorphosis of frogs.

    Ribosome Structure and Function

    • Ribosomes, essential for protein synthesis, can be found in various locations within cells.
    • Prokaryotic ribosomes (70S) differ from eukaryotic ribosomes (80S) in size and composition.
    • Each ribosome consists of a small and a large subunit, forming only during protein synthesis.
    • Ribosomes are composed of 50% ribosomal RNA and 50% protein, facilitating the translation of genetic information into polypeptides.

    Mitochondria

    • Mitochondria, known as the cell's powerhouses, are enclosed by a double membrane; the inner membrane is folded into cristae to increase surface area.
    • The presence of stalked particles (oxysomes) on cristae is crucial for ATP production from glucose oxidation.
    • Mitochondrial matrix contains enzymes, ribosomes, RNA, and circular DNA. The quantity of mitochondria varies according to cellular energy demands.

    Functions of Mitochondria

    • Mitochondria are key sites for aerobic respiration, converting glucose to ATP while releasing carbon dioxide and water.

    Plastids

    • Plastids include leucoplasts (synthesize starch, oils, proteins), chromoplasts (produce carotenoids), and chloroplasts (involved in energy storage and photosynthesis).
    • Chloroplasts contain chlorophyll pigments essential for capturing light energy during photosynthesis, densely packed in the surface of leaves.

    Chloroplast Structure and Function

    • Chloroplasts feature a double membrane, with an inner fluid matrix (stroma) containing enzymes and DNA.
    • Thylakoids are stacked to form granum, enabling efficient light absorption for photosynthesis.

    Centrioles

    • Centrioles are hollow, cylindrical structures composed of microtubule triplets and play a role in organizing spindle fibers during cell division in animal cells.
    • They serve as basal bodies for the formation of cilia and flagella.

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    Cell Structure and Function PDF

    Description

    Explore the essential features of bacterial cells such as pili, capsules, and cell envelopes. Understand how these structures contribute to bacterial adherence and protection. This quiz will test your knowledge on the unique characteristics that define bacteria.

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