Cell Biology: Golgi Apparatus and Lysosomes
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Questions and Answers

What are microtubules primarily made of?

  • Collagen
  • Keratins
  • Actin
  • Tubulin (correct)

    • Microtubules cannot be easily formed and broken down at microtubule organizing centres (MTOCs).

    False

    What process do α- and β-tubulin molecules undergo to form dimers?

    Polymerisation

    Thirteen protofilaments join to form a hollow cylinder called a ______.

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

    Match the following functions with their descriptions:

    <p>Transport = Movement of organelles along microtubules Spindle formation = Separation of chromosomes during cell division Cilia and flagella movement = Beating movements controlled by microtubules Microtubule organising centres = Locations in cells that control microtubule assembly</p> Signup and view all the answers

    What is the primary function of the Golgi apparatus?

    <p>To collect and process proteins</p> Signup and view all the answers

    Lysosomes are involved in the synthesis of new cell walls during plant cell division.

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

    What term is used to describe the pathway followed by molecules released from the cell?

    <p>secretory pathway</p> Signup and view all the answers

    The Golgi apparatus processes proteins into _____.

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

    What do Golgi vesicles primarily form after processing in the Golgi apparatus?

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

    Match the following components with their descriptions:

    <p>Golgi apparatus = Processes proteins and lipids Lysosomes = Contains digestive enzymes for cellular waste disposal Cisternae = Flattened sacs in the Golgi apparatus Mucin = Substance released by goblet cells</p> Signup and view all the answers

    What is the primary role of centrioles in relation to cilia and flagella?

    <p>They serve as basal bodies from which cilia and flagella grow.</p> Signup and view all the answers

    Centrioles are involved in the assembly of microtubules for the spindle during nuclear division.

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

    Which of the following is NOT a function of lysosomes?

    <p>Packaging proteins for secretion</p> Signup and view all the answers

    Lysosomes are primarily formed from the _____ apparatus.

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

    What protein is responsible for the sliding motion of microtubules during the beating of cilia?

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

    Cilia and flagella are used for __________ in single-celled organisms.

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

    Match the following structures with their functions:

    <p>Cilia = Remove debris from the respiratory tract Flagella = Locomotion in single-celled organisms Basal body = Base structure for cilia and flagella Dynein = Protein responsible for sliding motion</p> Signup and view all the answers

    What is the primary function of lysosomes?

    <p>Digestion of unwanted substances</p> Signup and view all the answers

    Hydrolysis in lysosomes occurs best at a pH of 7.0.

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

    What process involves the engulfing and destruction of unwanted cell components by lysosomes?

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

    The acrosome is a specialized lysosome found in the heads of __________.

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

    Match the following lysosomal functions with their descriptions:

    <p>Endocytosis = Material taken into the cell and digested Exocytosis = Release of enzymes for extracellular digestion Autolysis = Self-digestion of the entire cell Digestion of old organelles = Breakdown of cellular components such as organelles</p> Signup and view all the answers

    Which of the following enzymes is NOT typically found in lysosomes?

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

    Microtubules are part of the cytoskeleton and help determine cell shape.

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

    What is the diameter of microtubules?

    <p>25 nm</p> Signup and view all the answers

    What is the main function of microtubules in eukaryotic cells?

    <p>Cell support and shape determination</p> Signup and view all the answers

    Ribosomes are larger in prokaryotic cells than in eukaryotic cells.

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

    What molecule is converted to ATP through phosphorylation during cell respiration?

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

    The Golgi apparatus is responsible for chemically modifying molecules and packaging them into __________.

    <p>Golgi vesicles</p> Signup and view all the answers

    Match the cellular components to their functions:

    <p>ADP = Converted to ATP during phosphorylation Microtubules = Support and shape determination Golgi apparatus = Modification and packaging of molecules Ribosomes = Protein synthesis</p> Signup and view all the answers

    Which structure is absent from most plant cells?

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

    Microvilli are extensions that decrease the surface area of the cell surface membrane.

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

    What are the structural units that form each centriole?

    <p>Nine triplets of microtubules</p> Signup and view all the answers

    What is the Golgi apparatus?

    <p>A stack of flattened sacs called cisternae that processes and transports molecules, particularly proteins.</p> Signup and view all the answers

    What are the main functions of the Golgi apparatus? (Select all that apply)

    <p>Modification of proteins</p> Signup and view all the answers

    The Golgi apparatus is found in prokaryotic cells.

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

    What is the role of lysosomes?

    <p>To break down unwanted substances and cellular components using digestive enzymes.</p> Signup and view all the answers

    What is the primary function of hydrolytic enzymes found in lysosomes? (Select all that apply)

    <p>Digestion of macromolecules</p> Signup and view all the answers

    Lysosomes maintain a neutral pH in their interior.

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

    What is endocytosis?

    <p>The process by which cells take in substances by engulfing them.</p> Signup and view all the answers

    What are microtubules made of?

    <p>A protein called tubulin, consisting of alpha-tubulin and beta-tubulin.</p> Signup and view all the answers

    What are the functions of microtubules?

    <p>Supporting cell structure, aiding intracellular transport, and forming the spindle during nuclear division.</p> Signup and view all the answers

    Match the following structures with their functions:

    <p>Golgi apparatus = Processing and transporting molecules Lysosome = Digestion of unwanted substances Microtubules = Forming part of the cytoskeleton Centrioles = Producing basal bodies for cilia and flagella</p> Signup and view all the answers

    What are cilia and flagella used for?

    <p>Locomotion and movement of fluids across epithelial surfaces.</p> Signup and view all the answers

    Study Notes

    Golgi Apparatus

    • A stack of flattened sacs called cisternae
    • More than one Golgi apparatus can be found in a cell
    • Consistently forms at one end from vesicles budding from the ER and breaks down at the other end into Golgi vesicles
    • Collects and processes molecules, particularly proteins from the RER
    • Contains hundreds of enzymes
    • Molecules are transported in Golgi vesicles to other parts of the cell or released outside the cell
    • The process of releasing molecules outside the cell is called secretion
    • Pathway of molecule movement is called the secretory pathway
    • Adds sugars to proteins to make glycoproteins
    • Adds sugars to lipids to make glycolipids
    • Glycoproteins and glycolipids are important components of cell membranes and important molecules in cell signalling
    • Golgi enzymes are involved in the synthesis of new cell walls during plant cell division

    ### Lysosomes

    • Simple sacs surrounded by a single membrane
    • Found in animal cells
    • In plant cells, the large central vacuole may act as a lysosome
    • Contain digestive enzymes called hydrolases
    • Enzymes are kept separate from the rest of the cell to prevent damage
    • Responsible for breaking down unwanted substances and structures such as old organelles or entire cells
    • The contents of lysosomes are acidic with a pH of 4-5 compared with 6.5-7.0 in the surrounding cytoplasm
    • Contain proteases, lipases and nucleases which break down proteins, lipids and nucleic acids respectively
    • Synthesised on the RER and delivered to lysosomes via the Golgi apparatus
    • Can engulf and destroy unwanted cell components
    • May fuse with endocytic vacuoles, releasing enzymes to digest the contents
    • Lysosomal enzymes can be released from the cell for extracellular digestion
    • The head of sperm contains a special lysosome called the acrosome for digesting a path through layers of cells surrounding the egg prior to fertilisation
    • The contents of lysosomes may be released into the cytoplasm, resulting in the entire cell being digested
    • This process of cell digestion is called autolysis
    • It occurs during normal development and after the death of an individual

    Microtubules

    • Long, rigid, hollow tubes found in the cytoplasm
    • Approximately 25nm in diameter
    • Together with actin filaments and intermediate filaments, make up the cytoskeleton
    • Made of a protein called tubulin
    • Tubulin has two forms, α-tubulin and β-tubulin
    • α- and β- tubulin molecules combine to form dimers
    • Dimers are then joined end to end to form long protofilaments
    • Thirteen protofilaments line up alongside each other in a ring to form a cylinder with a hollow centre
    • This cylinder is the microtubule
    • Apart from support, microtubules are involved in intracellular transport, nuclear division, centriole structure and the beating movements of cilia and flagella
    • The assembly of microtubules from tubulin molecules is controlled by special locations in cells called microtubule organizing centers (MTOCs)

    Centrioles

    • Appear as a small structure close to the nucleus under a light microscope
    • Two centrioles are present in a region called the centrosome
    • Lie at right angles to each other
    • Absent in most plant cells
    • A hollow cylinder about 500 nm long, formed from a ring of short microtubules
    • Contains nine triplets of microtubules
    • Centrioles are needed for the production of cilia
    • Found at the bases of cilia and flagella, where they are known as basal bodies
    • The microtubules that extend from the basal bodies into the cilia and flagella are essential for the beating movements of these organelles

    Cilia and Flagella

    • The beating motion of cilia and flagella is caused by the dynein (protein) arms making contact with, and moving along, neighbouring microtubules
    • This movement produces bending
    • If the cell is attached to something so that it cannot move, fluid will move past the cell. If the cell is not attached, the cell will swim through the fluid.
    • Single-celled organisms use cilia and flagella for locomotion
    • Beating cilia are found on some epithelial cells, such as those lining the airways
    • They maintain a flow of mucus which removes debris such as dust and bacteria from the respiratory tract

    Golgi Apparatus

    • Stack of flattened sacs called cisternae
    • Collects and processes molecules from the ER, especially proteins
    • Contains enzymes for processing molecules
    • Golgi vesicles transport processed molecules to other parts of the cell or out of the cell
    • Secretory pathway refers to the pathway followed by molecules as they are released from the cell
    • Adds sugars to proteins to make glycoproteins and adds sugars to lipids to make glycolipids
    • Glycoproteins and glycolipids are important components of membranes and cell signalling
    • Golgi enzymes are involved in the synthesis of new cell walls during plant cell division
    • Goblet cells release mucin from the Golgi apparatus

    Lysosomes

    • Simple sacs surrounded by a single membrane
    • Found in animal and plant cells (plant cells have the large central vacuole which may act as a lysosome)
    • Contain digestive enzymes called hydrolases
    • Maintain an acidic environment (pH 4–5)
    • Break down unwanted substances and structures such as old organelles or whole cells
    • Enzymes are synthesized in the RER and delivered to lysosomes via the Golgi apparatus
    • Lysosomes can engulf and destroy unwanted cell components
    • Can fuse with endocytic vacuoles formed by endocytosis to digest their contents
    • Lysosomal enzymes can be released from the cell for extracellular digestion
    • Heads of sperm contain a special lysosome called the acrosome used to digest a path through the layers surrounding the egg during fertilization
    • Release their contents into the cytoplasm leading to self-digestion (autolysis) which can happen during normal development or after cell death

    Microtubules

    • Long, rigid, hollow tubes found in the cytoplasm
    • Made of the protein tubulin
    • Two forms of tubulin: α-tubulin and β-tubulin
    • α- and β-tubulin molecules combine to form dimers
    • Dimers join end to end forming protofilaments
    • Thirteen protofilaments line up to form a cylinder with a hollow centre – the microtubule
    • Provide cell support and determine cell shape
    • Secretory vesicles, organelles, and cell components can move along microtubules forming a transport system
    • Microtubules form the spindle that separates chromatids or chromosomes during nuclear division
    • Part of the structure of centrioles
    • Essential part of the beating mechanism of cilia and flagella

    Microtubule Organizing Centres (MTOCs)

    • Special locations in cells that control the assembly of microtubules
    • Microtubules can be formed and broken down at the MTOCs easily
    • Centrioles act as an MTOC

    Centrioles

    • Small structures near the nucleus
    • Hollow cylinders about 500 nm long
    • Two per cell, lying close together at right angles to each other in a region called the centrosome
    • Absent from most plant cells
    • Formed from a ring of short microtubules
    • Each centriole contains nine triplets of microtubules
    • Previously believed to be the MTOC for the assembly of spindle microtubules during nuclear division, now known that this is done by the centrosome
    • Needed for the production of cilia, found at the bases of cilia and flagella
    • Replicate to produce basal bodies which are identical in structure to the centriole
    • Cilia and flagella grow from basal bodies

    Cilia and Flagella

    • Finger-like extensions of the cell surface membrane
    • Much smaller and more numerous than flagella
    • Beating motion generates force for movement
    • Cilia and flagella are essential for the beating movements of these organelles
    • Cilia and flagella are composed of microtubules which extend from the basal body in the cilia/flagellum
    • The dynein (protein) arms move along neighboring microtubules producing the force needed for cilia to beat
    • Movement of cilia and flagella is caused by the dynein (protein) arms making contact with, and moving along, neighbouring microtubules
    • This sliding motion is converted into bending by other parts of the cilium

    Functions of Cilia and Flagella:

    • Locomotion: allows single-celled organisms to move through fluids
    • Beating cilia in vertebrates: help move mucus to remove debris from the respiratory tract.

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    Biology Chapter 1: Golgi Apparatus & Lysosomes PDF

    Description

    Explore the functions and structures of the Golgi apparatus and lysosomes in cells. This quiz covers key concepts such as the secretory pathway, glycoproteins, and the roles of lysosomes in digestion and waste processing. Test your knowledge on how these organelles contribute to cellular processes.

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