BIOC 601: Molecular Aspects of Cell Biology

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Questions and Answers

What is the role of neurotransmitters in synaptic signaling?

Neurotransmitters are chemical messengers that transmit signals across synapses by binding to receptors on the postsynaptic neuron.

How do receptors function in synaptic transmission?

Receptors are proteins on the postsynaptic membrane that bind neurotransmitters, initiating a response in the neuron.

What is the function of transport proteins in neurotransmitter signaling?

Transport proteins help in the reuptake of neurotransmitters from the synaptic cleft back into the presynaptic neuron.

What distinguishes active transport from passive transport in the context of neurotransmitter reuptake?

<p>Active transport requires energy to move neurotransmitters against their concentration gradient, while passive transport does not.</p> Signup and view all the answers

Explain the significance of receptor-ligand interactions in cellular communication.

<p>Receptor-ligand interactions are critical for signal transduction, as they determine how cells respond to external stimuli.</p> Signup and view all the answers

Describe how gap junctions facilitate cell communication.

<p>Gap junctions are specialized intercellular connections that allow direct communication between neighboring cells by facilitating the passage of ions and small molecules.</p> Signup and view all the answers

What are the characteristics of slow signaling mechanisms in cells?

<p>Slow signaling mechanisms involve long-term changes in gene expression and cellular function, typically mediated by intracellular receptors.</p> Signup and view all the answers

Define the cytoskeleton and its importance in cell structure and function.

<p>The cytoskeleton is a dynamic network of fibers that provides structural support, facilitates cellular movement, and organizes cellular components.</p> Signup and view all the answers

What are the three main components of the cytoskeleton?

<p>Microfilaments, intermediate filaments, and microtubules.</p> Signup and view all the answers

How does the cytoskeleton contribute to cell movement?

<p>The cytoskeleton enables cell movement by facilitating cilia and flagella movement and allowing shape changes during cell division and migration.</p> Signup and view all the answers

What is the role of spectrin in the cytoskeleton?

<p>Spectrin provides structural support and maintains cell shape by forming a meshwork beneath the plasma membrane.</p> Signup and view all the answers

How do active and passive transport differ in biological membranes?

<p>Active transport requires energy to move molecules against their concentration gradient, while passive transport does not require energy and moves molecules down their concentration gradient.</p> Signup and view all the answers

Describe the role of microtubules in intracellular transport.

<p>Microtubules serve as tracks for the movement of organelles and other cellular components within the cell.</p> Signup and view all the answers

In what ways does the cytoskeleton assist during cell division?

<p>The cytoskeleton helps organize and separate chromosomes during mitosis.</p> Signup and view all the answers

What is a key feature of G-protein coupled receptors?

<p>G-protein coupled receptors have a seven-transmembrane domain structure and activate intracellular G-proteins upon ligand binding.</p> Signup and view all the answers

Describe the significance of gap junctions in cell communication.

<p>Gap junctions allow for direct cytoplasmic transfer of ions and small molecules between adjacent cells, facilitating coordinated cellular responses.</p> Signup and view all the answers

What function does the cytoskeleton have in maintaining cell shape?

<p>The cytoskeleton provides mechanical support, helping the cell maintain its shape and structural integrity.</p> Signup and view all the answers

What consequences may arise from abnormal cell-cell communication?

<p>Abnormal cell-cell communication can lead to diseases such as cancer, where the signaling pathways that regulate cell growth and apoptosis become disrupted.</p> Signup and view all the answers

Explain the relationship between microfilaments and muscle contraction.

<p>Microfilaments, primarily composed of actin, are involved in muscle contraction.</p> Signup and view all the answers

What is the significance of the cytoskeleton in signal transduction?

<p>The cytoskeleton plays a role in signal transduction by facilitating intercellular communication and coordination.</p> Signup and view all the answers

Provide an example of a disease caused by abnormal signaling pathways.

<p>Graves' disease is caused by abnormal signaling in the thyroid gland, leading to hyperthyroidism due to overstimulation by antibodies.</p> Signup and view all the answers

How does the cytoskeleton participate in the formation of vacuoles?

<p>The cytoskeleton aids in the development of vacuoles by providing support and structure during vacuole formation.</p> Signup and view all the answers

What are the electrical properties of membranes primarily determined by?

<p>The electrical properties of membranes are primarily determined by the distribution of ions across the membrane and the permeability of the membrane to those ions.</p> Signup and view all the answers

How does the inositol phospholipid signaling pathway contribute to cellular responses?

<p>The inositol phospholipid signaling pathway generates second messengers, such as inositol trisphosphate (IP3) and diacylglycerol (DAG), leading to the release of calcium ions and activation of protein kinases.</p> Signup and view all the answers

What role do intermediate filaments play in cellular structure?

<p>Intermediate filaments provide structural support for microfilaments and microtubules, helping to maintain cell integrity.</p> Signup and view all the answers

Describe how spectrin contributes to the cytoskeleton of eukaryotic cells.

<p>Spectrin contributes by forming a hexagonal arrangement alongside actin filaments, creating a scaffold that maintains plasma membrane integrity.</p> Signup and view all the answers

What happens in Drosophila neurons when a or ß spectrin is knocked out?

<p>Knocking out a or ß spectrin results in neurons that appear morphologically normal but exhibit reduced neurotransmission at the neuromuscular junction.</p> Signup and view all the answers

Explain the significance of spectrin in maintaining the shape of red blood cells.

<p>Spectrin forms a meshwork that gives red blood cells their characteristic biconcave shape, crucial for their function.</p> Signup and view all the answers

How do the arrangements of spectrin subunits contribute to cellular function?

<p>Spectrin subunits arrange into pentagonal or hexagonal structures, facilitating the formation of junctional complexes that enhance cell stability.</p> Signup and view all the answers

What are the three main parts of a cell?

<p>The three main parts of a cell are the cell membrane, nucleus, and cytoplasm.</p> Signup and view all the answers

What distinguishes eukaryotic cells from prokaryotic cells?

<p>Eukaryotic cells contain a defined nucleus, while prokaryotic cells lack a nucleus and have a nucleoid region.</p> Signup and view all the answers

Why do plant cells have a cell wall and chloroplasts, and how do these organelles benefit them?

<p>Plant cells have a cell wall for structure and support, and chloroplasts for photosynthesis, allowing them to produce their own food.</p> Signup and view all the answers

What is the size range of most cells visible under a light microscope?

<p>Most cells are between 1 and 100 micrometres in size.</p> Signup and view all the answers

What is the smallest known type of cell and its diameter?

<p>The smallest known type of cell is mycoplasmas, with diameters as small as 0.2 μm.</p> Signup and view all the answers

What is the primary role of Actin in the cytoskeleton?

<p>Actin forms microfilaments that are essential for various cellular processes including muscle contraction and cell motility.</p> Signup and view all the answers

How does a mutation in actin-associated genes impact cell function?

<p>Mutations can lead to diseases by disrupting the normal production and function of actin, impairing cellular processes.</p> Signup and view all the answers

Describe the structure of microtubules.

<p>Microtubules are polymers of alpha and beta tubulin that form hollow tubes, with a diameter of 23 to 27 nm.</p> Signup and view all the answers

What functions do microtubules serve in eukaryotic cells?

<p>Microtubules provide structural support, facilitate intracellular transport, and are essential for mitosis.</p> Signup and view all the answers

Explain the composition of intermediate filaments.

<p>Intermediate filaments are made up of various proteins characterized by a central alpha-helical rod domain.</p> Signup and view all the answers

What is the significance of tensile strength provided by intermediate filaments?

<p>Tensile strength is crucial for maintaining cellular integrity and stability under stress.</p> Signup and view all the answers

Discuss the role of actin in wound healing.

<p>Actin assists in cellular migration and contraction, which are vital for tissue repair during wound healing.</p> Signup and view all the answers

How do microtubules contribute to the movement of organelles?

<p>Microtubules serve as tracks for motor proteins that transport organelles within the cell.</p> Signup and view all the answers

What are the key differences between microfilaments, microtubules, and intermediate filaments?

<p>Microfilaments are made of actin, microtubules are made of tubulin, and intermediate filaments are made of various proteins, each serving distinct structural and functional roles.</p> Signup and view all the answers

What cellular processes are microtubules involved in during cell division?

<p>Microtubules form the mitotic spindle, which is crucial for the separation of chromosomes during mitosis and meiosis.</p> Signup and view all the answers

Flashcards

Cell-cell communication

The process by which cells interact with each other to coordinate their activities.

Macromolecule assembly

How individual molecules join together to form larger structures in the cell, influencing cell function.

Cytoskeleton

A network of protein filaments that give cells their shape and support, enabling movement and cellular processes.

Membrane transport

The movement of molecules across cell membranes, crucial for cellular functions.

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Signal transduction

Process by which a cell conveys a signal throughout the cell, leading to a specific cellular response.

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Membrane potential

The difference in electrical charge across a cell's membrane, crucial for many cellular processes.

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G-protein coupled receptors (GPCRs)

Cell surface receptors that bind to signaling molecules, initiating downstream cellular responses.

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Abnormal signalling pathways

Disrupted or altered cell signaling processes that can lead to diseases.

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Neurotransmitters

Chemical messengers that transmit signals across a synapse from one neuron to another or to a target cell.

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Receptors

Specialized protein molecules on the surface or inside a cell that bind to specific neurotransmitters or other signaling molecules (ligands) to initiate a cellular response.

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Transport Proteins

Proteins found in cell membranes that facilitate the movement of molecules across the membrane, such as neurotransmitters.

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Synapse

The space between two neurons or a neuron and a target cell where nerve impulses are transmitted from one to another.

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Passive Transport

Movement of molecules across a cell membrane without energy input from the cell.

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Active Transport

Movement of molecules across a cell membrane requiring energy input from the cell.

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Cell Communication

Process by which cells interact and send/receive signals to coordinate activities and responses.

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Intermediate filaments role

Support microfilaments and microtubules, forming keratins in epithelial cells and neurofilaments in neurons.

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Spectrin's structure

Cytoskeletal protein lining plasma membrane; forms hexagonal arrangements from spectrin tetramers connected to actin filaments.

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Spectrin's function

Maintains plasma membrane integrity and cytoskeletal structure by forming a scaffold.

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Spectrin in red blood cells

Forms meshwork, maintaining red blood cell shape.

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Spectrin in neurons

Plays a role in neurotransmission at the neuromuscular junction.

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Cytoskeleton definition

A network of protein filaments in all cells (bacteria, archaea, eukaryotes), providing structural support, cell shape, and intracellular transport.

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Cytoskeleton components

Microtubules, microfilaments, and intermediate filaments.

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Microtubules function

Support cell structure, form tracks for organelle movement, and are crucial in cell division.

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Microfilaments function

Involved in muscle contraction and cell movement; also help with organelle movement.

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Intermediate filaments function

Provide strength and stability to the cell.

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Cytoskeleton supports

Maintains cell shape, position of organelles, and resists external forces.

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Cytoskeleton in movement

Responsible for cell movement, including cilia and flagella.

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Cytoskeleton and Cell Division

Essential to the organization and separation of chromosomes during cell division (mitosis).

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What are the main parts of a cell?

Most cells have three main parts: the cell membrane, the nucleus, and the cytoplasm.

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What are eukaryotic cells?

Eukaryotic cells have a nucleus, a membrane-bound organelle that contains the cell's genetic material.

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What are prokaryotic cells?

Prokaryotic cells lack a nucleus, but have a nucleoid region where their DNA is located.

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What are the differences between plant and animal cells?

Plant cells have a cell wall, chloroplasts, and a large central vacuole, whereas animal cells do not.

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What is the size of most cells?

Most cells are microscopic, ranging in size from 1 to 100 micrometers.

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Uncoordinated phenotype

A phenotype where an organism's movement is disrupted, often leading to paralysis and a shortened body length. This is observed in C. elegans.

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Actin's role in the cytoskeleton

Actin is a protein that forms microfilaments in the cytoskeleton, giving the cell its shape and supporting movement.

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What are Actin's functions?

Actin participates in crucial cellular processes like muscle contraction, cell motility, cell division, vesicle movement, and cell shape maintenance.

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Microtubules in the cytoskeleton

Microtubules, made of tubulin, provide structure and shape to eukaryotic cells, acting as internal tracks for transport.

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What are Intermediate filaments made of?

Intermediate filaments (IFs) are made of proteins with central alpha-helical rod domains, providing structural stability to cells.

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Functions of Intermediate filaments

Intermediate filaments provide tensile strength, acting as the central scaffold of the cell, giving it stability and structure.

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Living cell definition

A living cell is a basic unit of life, enclosed by a membrane and carrying out essential functions such as growth, metabolism, and reproduction.

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Study Notes

BIOC 601: Molecular Aspects of Cell Biology

  • Course taught by Professor Neils Ben Quashie and others
  • Focuses on the assembly and functions of macromolecules and signal transduction pathways/cell-to-cell communication
  • Covers self-assembly of macromolecules and cytoskeleton dynamics
  • Includes the role of spectrin, actin, microtubules, and intermediate filaments in cytoskeleton formation
  • Examines principles of membrane transport, transport proteins (active and passive), and biological membrane transport systems
  • Discusses ion channels, membrane potential, and mechanisms of cell communication (receptor-ligand interaction, super-families of membrane receptors, ligands, intracellular receptors, slow and rapid signaling)
  • Includes gap junction communications, signaling through G-protein-coupled receptors, and inositol phospholipid signaling pathways
  • Aims to equip students with an understanding of how macromolecule assembly in cell membranes defines cell structure and function
  • Also provides insights into cell-cell communication and the consequences of communication abnormalities
  • Course objectives encompass in-depth understanding of cell-cell communication mechanisms, diverse cell signaling forms, and abnormal signaling pathways implicated in diseases
  • Aims to illustrate the relevance of neurotransmission pathways in cell signaling, such as mechanisms of cell-cell communication and diverse forms of signaling
  • Explains abnormal signaling pathways leading to Graves' disease, cholera, whooping cough, Myasthenia gravis, and cell transformation
  • Describes neurotransmitters, receptors, and transport proteins in signal transmission at synapses
  • Provides a reading list featuring textbooks by Alberts et al., Cooper and Adams, Karp et al., Lodish et al., Plopper and Ivankovic, and Roelen and Rodrigues

Cytoskeleton

  • A network of protein filaments in the cytoplasm of all cells, from the nucleus to the cell membrane
  • Composed of the same proteins in all organisms
  • Composed of three main components: microfilaments, intermediate filaments, and microtubules
  • Present in eukaryotes and prokaryotes
  • Microfilaments:
    • Diameter of 6 nanometers
    • Double helix structure
    • Composed of actin
    • Involved in muscle contraction, cell motility, cell division, and intracellular transport
    • Play regulatory roles in embryogenesis, wound healing, and cancer
  • Intermediate Filaments:
    • Diameter of 10 nanometers
    • Composed of various proteins (e.g., keratins in epithelial cells, neurofilaments in neurons)
    • Provide tensile strength and support to the cell's structure
  • Microtubules:
    • Diameter of 24-25 nanometers
    • Hollow structure made up of 13 protofilaments
    • Composed of alpha and beta tubulin
    • Involved in intracellular transport, cell motility (cilia and flagella), cell division, and maintaining cell shape

Spectrin

  • A cytoskeletal protein lining the intracellular side of the plasma membrane in eukaryotic cells
  • Forms hexagonal arrangements using spectrin tetramers and short actin filaments
  • Plays a crucial role in maintaining plasma membrane integrity and red blood cell shape

Actin

  • A family of globular multi-functional proteins that form microfilaments
  • Present in eukaryotic cells at high concentrations (over 100 µM)
  • Diameter of 4-7 nanometers
  • Participates in various cellular processes, including muscle contraction, cell motility, cell division, vesicle & organelle transport, cell signaling, and establishment of cell junctions

Microtubules

  • Polymers of tubulin and components of the eukaryotic cytoskeleton
  • Provide structure and shape to eukaryotic cells
  • Vary in length (up to 50 micrometers) and have diameters ranging from 23-27 nm
  • Formed by polymerization of alpha and beta tubulin dimers into protofilament, which form a hollow tube
  • Involved in cellular processes like intracellular transport, cilia/flagella formation, and cell division

Intermediate Filaments

  • Cytoskeletal structural components in vertebrate and some invertebrate cells
  • Composed of a central alpha-helical rod domain with segments (1A, 1B, 2A, 2B) separated by linker regions
  • Approximately 70 different human genes code for various intermediate filament proteins
  • Provide tensile strength and support to the cell's structure

Cell Types

  • Cells are categorized as prokaryotic or eukaryotic
  • Prokaryotic cells lack a nucleus, while eukaryotic cells contain a membrane-enclosed nucleus
  • Eukaryotic cells can be single-celled or multicellular, while prokaryotic cells are usually single-celled

Cell Structure

  • Animal cells have a variety of organelles, including a nucleus, endoplasmic reticulum, mitochondria, Golgi apparatus, and lysosomes.
  • Plant cells generally have a cell wall, chloroplasts, large central vacuoles, and various other organelles.
  • Characteristics of living things (e.g., growth, reproduction, movement, respiration, sensitivity, excretion, and nutrition).

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