Cell Organelles and Their Functions
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Questions and Answers

What is the primary use of a centrifuge in cell fractionation?

  • To measure the pH levels of cell organelles
  • To separate cell structures based on their relative density (correct)
  • To increase the temperature of the cell components
  • To enhance the visibility of proteins under a microscope

    • Which organelle is responsible for the synthesis of proteins?

  • Chloroplast
  • Golgi apparatus
  • Mitochondria
  • Ribosomes (correct)

    • Why are membranous organelles important in a cell?

  • They store cellular waste until disposal
  • They enhance the flow of cytoplasm
  • They allow for optimum pH and specific functions detached from the cytoplasm (correct)
  • They facilitate the movement of nutrients in and out of the cell

    • Which of the following is a double membrane-bound organelle?

    <p>Chloroplast (D)</p> Signup and view all the answers

    What role do radioactive labelled chemical substances play in cellular studies?

    <p>They allow tracing of the pathway taken by secreted proteins. (D)</p> Signup and view all the answers

    Which of the following is NOT a non-membranous organelle?

    <p>Golgi apparatus (B)</p> Signup and view all the answers

    Which type of endoplasmic reticulum is covered with ribosomes?

    <p>Rough ER (D)</p> Signup and view all the answers

    What is a function of lysosomes?

    <p>They contain hydrolytic enzymes for digestion. (B)</p> Signup and view all the answers

    What process occurs in the Golgi apparatus to modify proteins?

    <p>Glycosylation (B)</p> Signup and view all the answers

    Which of the following correctly describes the primary function of lysosomes?

    <p>Digest engulfed bacteria and worn-out organelles (B)</p> Signup and view all the answers

    What best describes the structure of mitochondria?

    <p>Double membrane with rod shape (B)</p> Signup and view all the answers

    What is the primary function of the rough endoplasmic reticulum (RER)?

    <p>Modification and transport of proteins (D)</p> Signup and view all the answers

    What is the role of the cristae in mitochondria?

    <p>Increase surface area for ATP synthesis (A)</p> Signup and view all the answers

    Lysosomes bud off from which organelle?

    <p>Golgi apparatus (D)</p> Signup and view all the answers

    What key role do ribosomes play in the cell?

    <p>Site of translation and protein synthesis (B)</p> Signup and view all the answers

    Which type of ribosome is found in prokaryotes?

    <p>70S ribosomes (C)</p> Signup and view all the answers

    What adaptations allow mitochondria to meet energy demands?

    <p>Variable number according to cellular activity (C)</p> Signup and view all the answers

    What is the primary composition of the interior solution of mitochondria known as the matrix?

    <p>Circular DNA and ribosomes (A)</p> Signup and view all the answers

    Which organelle is responsible for the synthesis of lipids, such as cholesterol?

    <p>Smooth endoplasmic reticulum (A)</p> Signup and view all the answers

    What type of enzymes do lysosomes contain?

    <p>Hydrolytic enzymes such as proteases (B)</p> Signup and view all the answers

    How does the Golgi apparatus function in the cell?

    <p>It modifies and packages proteins for secretion (C)</p> Signup and view all the answers

    What structural characteristic distinguishes the smooth endoplasmic reticulum from the rough endoplasmic reticulum?

    <p>Tubular structure with no ribosomes (C)</p> Signup and view all the answers

    What is the primary function of thylakoids in chloroplasts?

    <p>Site of light-dependent reactions (D)</p> Signup and view all the answers

    What is the role of shuttle vesicles in relation to the endoplasmic reticulum?

    <p>They bud off from the ER and transport proteins to the Golgi apparatus (A)</p> Signup and view all the answers

    Which component of chloroplasts connects the stacks of thylakoids?

    <p>Inter granal lamellae (A)</p> Signup and view all the answers

    What is a unique feature of both chloroplasts and mitochondria?

    <p>Double membrane structure (D)</p> Signup and view all the answers

    What do we call the end of the Golgi apparatus where vesicles bud off to transport materials?

    <p>Maturing face (D)</p> Signup and view all the answers

    Which statement accurately describes the stroma of chloroplasts?

    <p>Fluid containing DNA and enzymes (A)</p> Signup and view all the answers

    Which of the following statements about chloroplasts is true?

    <p>Involved in photosynthesis (D)</p> Signup and view all the answers

    What distinguishes plant cells from animal cells concerning organelles?

    <p>Presence of chloroplasts (A)</p> Signup and view all the answers

    Which statement about chloroplast structure is correct?

    <p>Includes an outer membrane and inner folded membrane (D)</p> Signup and view all the answers

    What role do ribosomes in chloroplasts play?

    <p>Assist in protein synthesis (B)</p> Signup and view all the answers

    Which of the following statements about mitochondria is true?

    <p>Mitochondria contain circular DNA and replicate through binary fission. (C)</p> Signup and view all the answers

    What role do centrioles play during nuclear division?

    <p>They act as microtubule organizing centers. (B)</p> Signup and view all the answers

    Which of the following functions is associated with the nucleus?

    <p>Control of cell activities via gene expression. (B)</p> Signup and view all the answers

    What structural feature distinguishes centrioles from other organelles?

    <p>They are made of 9 groups of triplet microtubules. (B)</p> Signup and view all the answers

    How do the membranes of the nuclear envelope contribute to nuclear function?

    <p>They control material exchange with the cytoplasm. (C)</p> Signup and view all the answers

    What is the primary function of mitochondria in cells?

    <p>Production of ATP through aerobic respiration. (C)</p> Signup and view all the answers

    Which of the following is an example of a function that mitochondria contribute to?

    <p>Exocytosis of hormones. (D)</p> Signup and view all the answers

    Which of the following features is true regarding centrioles?

    <p>They align at poles during prophase of mitosis. (C)</p> Signup and view all the answers

    Study Notes

    Cell Organelles and Their Functions

    • Cell fractionation uses centrifugation to separate cell structures based on their density. Higher centrifuge speeds result in greater separation ability.
    • Radioactive labeled chemicals are used to track specific cell components. Radioactively labeled amino acids can identify protein synthesis pathways.

    Cell Organelle Structure and Function

    • Cell organelles are grouped into membrane-bound and non-membrane-bound organelles.
    • Membrane-bound organelles are separated from cytoplasm by a membrane, allowing for specific pH and function. Examples include mitochondria, chloroplasts, lysosomes, ER, Golgi apparatus, vacuoles, and secretory vesicles.
    • Single membrane bound organelles include large vacuoles, endoplasmic reticulum, Golgi apparatus, lysosomes, and secretory vesicles.
    • Double membrane bound organelles include nucleus, mitochondria, chloroplast, amyloplast.

    Endoplasmic Reticulum

    • The endoplasmic reticulum is a membrane-bound organelle connected to the nuclear envelope.
    • RER has ribosomes bound to its surface, performing protein synthesis and protein folding.
    • Proteins are transported in vesicles from RER to Golgi apparatus.
    • SER does not have ribosomes, synthesizes lipids, carbohydrates (e.g., cholesterol, testosterone).

    Ribosomes

    • Ribosomes are non-membrane-bound organelles.
    • They are made of rRNA and proteins.
    • Two types of ribosomes: 70S (prokaryotes, mitochondria, chloroplasts) and 80S (eukaryotes - cytoplasm).
    • Ribosomes synthesize proteins in the cytoplasm or on the RER.

    Golgi Apparatus

    • Golgi apparatus modifies proteins from RER, packages them for secretion or transport to other cell parts.
    • Involved in processing and packaging lipids, and producing components of lysosomes.

    Lysosomes

    • Lysosomes are single-membrane bound, spherical sacs.
    • These contain digestive enzymes (proteases, lipases) to break down excess or worn-out cell components, food particles, and engulfed viruses/bacteria.

    Mitochondria

    • Mitochondria are double membrane-bound, rod-shaped organelles.
    • The inner membrane is folded into cristae, increasing surface area for ATP production during cellular respiration.
    • Mitochondria are responsible for aerobic respiration and lipid synthesis.

    Nucleus

    • The nucleus is a double membrane-bound, spherical organelle.
    • The nuclear envelope regulates the passage of mRNA and proteins in and out.
    • Contains chromatin (DNA, proteins), and nucleolus (where ribosomes are synthesized).
    • Controls cell activities and carries inheritance information.

    Chloroplast

    • Chloroplasts are double membrane bound organelles.
    • Found in plant cells, responsible for photosynthesis.
    • Consists of thylakoids that are stacked into grana, and stroma that surround the grana
    • Has own DNA and ribosomes (70S).

    Centrioles

    • Centrioles are non-membrane-bound organelles.
    • Found in animal cells, involved in cell division by organizing microtubules during prophase.
    • Centrioles are part of a larger centrosome structure.

    Notice:

    • The number of mitochondria in a cell depends on the cell's energy demand(eg., liver cells have many mitochondria for energy needs).
    • The endosymbiotic theory suggests that mitochondria and chloroplasts were once free-living prokaryotes.
    • Plant cells have no centrioles or lysosomes.

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    Description

    This quiz covers the essential roles and structures of cell organelles, including membrane-bound and non-membrane-bound organelles. It explores methods like cell fractionation and the use of radioactive chemicals in studying cellular functions. Test your knowledge on the functions of organelles such as mitochondria, ER, and lysosomes.

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