The Cell: Fundamental Unit of Life
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Questions and Answers

What is the main function of the plasma membrane?

  • To store genetic information
  • To synthesize proteins
  • To provide structural support to the cell
  • To control the movement of substances in and out of the cell (correct)

    • What is the main component of the cell wall in plant cells?

  • Proteins
  • Cellulose (correct)
  • Peptidoglycan
  • Chitin

    • What is the role of the nucleus in the cell?

  • To synthesize proteins
  • To control the movement of substances in and out of the cell
  • To provide structural support to the cell
  • To regulate all cellular activities (correct)

    • What is the type of transport that requires the cell to use energy?

    <p>Active transport</p> Signup and view all the answers

    What is the movement of molecules from a higher to a lower concentration without using energy?

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

    What is the site of many cellular processes like metabolism and protein synthesis?

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

    What is the term for the movement of water molecules across a selectively permeable membrane from higher to lower water concentration?

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

    What is the structure present outside the plasma membrane in plant cells, bacteria, and fungi?

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

    What is the primary function of the plasma membrane?

    <p>To control the movement of substances into and out of the cell</p> Signup and view all the answers

    Who is credited with the discovery of cells?

    <p>Robert Hooke</p> Signup and view all the answers

    What is the name of the theory that states that all living organisms are composed of cells?

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

    What is the function of the nucleus in a cell?

    <p>To store genetic information</p> Signup and view all the answers

    What is the term for organisms that consist of only one cell?

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

    Who extended the cell theory by stating that new cells arise from the division of pre-existing cells?

    <p>Rudolf Virchow</p> Signup and view all the answers

    What is the term for the jelly-like substance inside the plasma membrane?

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

    What is the characteristic of cells in terms of their shape?

    <p>Cells can vary greatly in their shape</p> Signup and view all the answers

    Study Notes

    Fundamental Unit of Life - The Cell

    • Cells are the structural and functional units of life for all living organisms
    • Living organisms are made up of cells, which carry out all the functions necessary for life
    • Cells are the most basic units that make up the structure and carry out the functions of living things
    • The discovery and understanding of cells has been a key development in biology

    Discovery of Cells

    • Robert Hooke was the first person to observe and describe cells in 1665 using a self-designed microscope
    • Hooke observed and named the "cells" in a sample of cork bark
    • Anthony van Leeuwenhoek later observed the first living cells under a microscope in 1674

    Advances in Cell Theory

    • Matthias Schleiden and Theodor Schwann proposed the cell theory in the 1830s:
      • All plants are composed of cells
      • All animals are composed of cells
    • Rudolf Virchow later extended the cell theory, stating that new cells arise from the division of pre-existing cells (omnis cellula e cellula)

    Diversity of Cells

    • Cells can vary greatly in their:

      • Number - from single-celled organisms to multicellular organisms with trillions of cells
      • Shape - can be spherical, oval, rod-shaped, branched, spindle-shaped, etc.

    • Single-celled organisms (unicellular) have only one cell

    • Multicellular organisms have many cells of different types and functions### Cell Components and Structure

    • Cells have various structural components that perform different functions

    • The plasma membrane is the outermost boundary of the cell, made up of phospholipids and proteins

    • The plasma membrane is selectively permeable, controlling the entry and exit of substances into and out of the cell

    • The cytoplasm is the jelly-like substance inside the plasma membrane, containing various organelles

    • The nucleus is the control center of the cell, containing the cell's DNA

    • Other organelles like mitochondria, chloroplasts, Golgi bodies, etc. perform specialized functions within the cell

    Plasma Membrane

    • The plasma membrane is flexible and fluid in structure, following the fluid mosaic model proposed by Singer and Nicolson
    • It is made up of phospholipids and proteins, which allow selective permeability
    • The plasma membrane controls the movement of substances in and out of the cell

    Cell Wall

    • The cell wall is a non-living, rigid structure present outside the plasma membrane in plant cells, bacteria, and fungi
    • It provides structural support and protection to the cell
    • The cell wall is made of different materials in different organisms - cellulose in plants, peptidoglycan in bacteria, chitin in fungi

    Nucleus

    • The nucleus is the control center of the cell, containing the cell's DNA
    • It regulates all cellular activities and is considered the "brain of the cell"
    • The DNA in the nucleus stores the genetic information that guides the cell's functioning

    Cytoplasm

    • The cytoplasm is the jelly-like substance inside the plasma membrane, containing various organelles

    • It is the site of many cellular processes like metabolism, protein synthesis, etc.### Transport and Osmosis

    • Transport of substances across the cell membrane can be passive or active

    • Passive transport involves movement of substances from higher to lower concentration without using energy

    • Active transport requires the cell to use energy (ATP) to move substances against the concentration gradient

    Passive Transport

    • Diffusion - movement of molecules (solids, liquids, gases) from higher to lower concentration, no energy required
    • Osmosis - movement of water molecules across a selectively permeable membrane from higher to lower water concentration

    Osmosis

    • Occurs when water molecules move from a region of higher water concentration (lower solute concentration) to a region of lower water concentration (higher solute concentration)
    • Requires the cell membrane to be selectively permeable to allow water but not solute molecules to pass through
    • Can be:
      • Endosmosis - water moves into the cell, causing it to swell
      • Exosmosis - water moves out of the cell, causing it to shrink

    Hypotonic, Hypertonic, Isotonic Solutions

    • Hypotonic solution has lower solute concentration than inside the cell, water moves in, cell swells
    • Hypertonic solution has higher solute concentration than inside the cell, water moves out, cell shrinks
    • Isotonic solution has equal solute concentration as inside the cell, no net movement of water

    Fundamental Unit of Life - The Cell

    • Cells are the structural and functional units of life for all living organisms
    • They carry out all the functions necessary for life and are the most basic units that make up the structure and functions of living things

    Discovery of Cells

    • Robert Hooke was the first person to observe and describe cells in 1665 using a self-designed microscope
    • He observed and named the "cells" in a sample of cork bark
    • Anthony van Leeuwenhoek later observed the first living cells under a microscope in 1674

    Advances in Cell Theory

    • Matthias Schleiden and Theodor Schwann proposed the cell theory in the 1830s, stating that:
      • All plants are composed of cells
      • All animals are composed of cells
    • Rudolf Virchow later extended the cell theory, stating that new cells arise from the division of pre-existing cells (omnis cellula e cellula)

    Diversity of Cells

    • Cells can vary greatly in their:
      • Number, from single-celled organisms to multicellular organisms with trillions of cells
      • Shape, such as spherical, oval, rod-shaped, branched, or spindle-shaped
    • Single-celled organisms (unicellular) have only one cell
    • Multicellular organisms have many cells of different types and functions

    Cell Components and Structure

    • The plasma membrane is the outermost boundary of the cell, made up of phospholipids and proteins, and is selectively permeable
    • The cytoplasm is the jelly-like substance inside the plasma membrane, containing various organelles
    • The nucleus is the control center of the cell, containing the cell's DNA and regulating all cellular activities
    • Other organelles like mitochondria, chloroplasts, and Golgi bodies perform specialized functions within the cell

    Plasma Membrane

    • The plasma membrane is flexible and fluid in structure, following the fluid mosaic model
    • It is made up of phospholipids and proteins, allowing selective permeability
    • The plasma membrane controls the movement of substances in and out of the cell

    Cell Wall

    • The cell wall is a non-living, rigid structure present outside the plasma membrane in plant cells, bacteria, and fungi
    • It provides structural support and protection to the cell
    • The cell wall is made of different materials in different organisms, such as cellulose in plants, peptidoglycan in bacteria, and chitin in fungi

    Nucleus

    • The nucleus is the control center of the cell, containing the cell's DNA
    • It regulates all cellular activities and is considered the "brain of the cell"
    • The DNA in the nucleus stores the genetic information that guides the cell's functioning

    Cytoplasm

    • The cytoplasm is the jelly-like substance inside the plasma membrane, containing various organelles
    • It is the site of many cellular processes like metabolism, protein synthesis, etc.

    Transport and Osmosis

    • Transport of substances across the cell membrane can be passive or active
    • Passive transport involves movement of substances from higher to lower concentration without using energy
    • Active transport requires the cell to use energy (ATP) to move substances against the concentration gradient

    Passive Transport

    • Diffusion is the movement of molecules from higher to lower concentration, without using energy
    • Osmosis is the movement of water molecules across a selectively permeable membrane from higher to lower water concentration

    Osmosis

    • Occurs when water molecules move from a region of higher water concentration (lower solute concentration) to a region of lower water concentration (higher solute concentration)
    • Requires the cell membrane to be selectively permeable to allow water but not solute molecules to pass through

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    Discover the basics of cells, the structural and functional units of life, and learn about their discovery and significance in biology.

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