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FAUHS Biology Tutoring

Chapter 8: Cell Structure & Function

Danylo Fedkiv

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Pre-Quiz:

  • Name a single part of the cell theory.
    • Everything living has cells; cells are the basic unit of structure and function; new cells are made by old cells.
  • What type of microscope generates 3D images?
    • Electron Scanning Microscope
  • What organelle is responsible for breaking down and recycling cell wastes?
    • Lysosome
  • While _____ generate glucose, _____ use glucose for energy.
    • Chloroplasts; Mitochondrias
  • Diffusion is an example of _____ transport.
    • Passive

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Part 1:

Microscopes

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Famous People Associated with Microscopes

  • Robert Hooke looked at a cork through a microscope and coined the term ‘cell.’
  • Anton Van Leeuwenhoek looked at pond water through a microscope and discovered microorganisms.

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Light Microscope

  • Light Microscopes produce 2D images, allowing for 1000x magnification and color.
  • Uses light.

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Scanning Electron Microscope

  • Uses electrons to view dead samples at a much better zoom.
  • Produces 3D images with no color.

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Transmission Electron Microscope

  • Uses electrons to view alive samples at a much better zoom.
  • These samples must be VERY thin.

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Quick Quiz:

  • Who coined the term ‘cell?’
    • Hooke
  • What microscope can create 3D images?
    • S.E.M.
  • Microscopes can either use light or ______ to view samples.
    • Electrons

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Part 2:

Introduction to Cell Structure

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The Cell Theory

  • Cells are the smallest units of life.
  • The Cell Theory has three parts:
    • Everything living has cells.
    • Cells are the basic unit of life and structure.
    • New cells are produced from old cells.

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Types of Cells: Nucleus

  • Prokaryotes have no nucleus; this means that their genetic material floats around everywhere.
  • Eukaryotes have a nucleus; this means that their genetic material is contained within it.

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Types of Cells: Amount

  • Unicellular cells tend to be a single cell; these are not part of an organism and can be both prokaryotic and eukaryotic.
  • Multicellular cells tend to be found among similar cells; these are part of an organism and can be only eukaryotic.

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Types of Cells: Organization

  • Cells are a single cell.
  • Tissues are a group of cells.
  • Organs are a group of tissues.
  • Organ Systems are a group of organs.
  • Organisms are a group of organ systems.

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Types of Cells: Methods of Communication

  • Desmosomes: Cells use filament ‘hairs’ in protein channels to communicate with each other.
  • Gap Junction: Animal cells use protein channels with filaments to communicate with each other.
  • Plasmodesmata: Plants cells use protein channels with filaments to communicate with each other.
  • Tight Junction: Cells pack tightly together to talk to each other.

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Quick Quiz:

  • Which type of cell has a nucleus?
    • Eukaryotic cells
  • What is a grouping of tissues called?
    • Organ
  • Desmosomes use _____ hairs and _____ channels to communicate with each other.
    • Filament; protein

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Part 3:

Parts of a Cell

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Parts of a Cell Introduction

  • Eukaryotic cells have two parts: the Nucleus and the Cytoplasm (prokaryotic cells only have the cytoplasm).
  • Anything within a cell is known as an Organelle.
  • A cytoplasm has a firm Gel State near the cell’s boundaries and a Sol State near the cell’s center.
  • It’s like a factory.

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Nucleus

  • Nuclei contain the DNA of the cell.
  • They have two layers and Nuclear Pores on the outside, allowing for material to go in and out.
  • Chromosomes are found in the Chromatin.
  • Nucleolus assemble the ribosomes.
  • Factory Analogy: Control Center.

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Cytoplasm: Protein Construction

  • Ribosomes assemble proteins using amino acid, rna, and nucleus instructions.
  • Endoplasmic Reticulum: Produces lipids.
    • Rough: Has ribosomes attached to it; these also in-take proteins for editing.
    • Smooth: Has no ribosomes attached to it; creates lipids only.
  • Golgi Apparatus: Sends proteins to correct location, whether it be inside or outside the cell.
  • Factory Analogy: Packages and releases their product.

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Cytoplasm: Storage

  • Vacuoles store nutrients in the cell; plants have one big one, whereas anhave many small ones dotted around.
  • Vesicles move things between the vacuoles and their respective destinations.
  • Factory Analogy: Storage Unit

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Cytoplasm: Clean-Up

  • Lysosomes break down and recycle things within the cell; found mainly in plants.
  • Factory Analogy: Janitor

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Cytoplasm: Support

  • Cytoskeletons support and move the cell. They have protein filaments that perform this. Includes:
    • Microfilaments: Made of Actin, moves the cell.
    • Microtubules: Made of Tubulin, moves and supports the cell. Can also help in cell division. In animal cells only, there also exist Centrioles, which help form the Cilia and Flagella.
  • Factory Analogy: Factory Infrastructure

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Cytoplasm: Energy Capture/Release

  • Chloroplasts create energy by conducting Photosynthesis; only in plant cells.
  • Mitochondria use energy/glucose by performing Cellular Respiration; found in both plant and animal cells.
  • Factory Analogy: Generator-Room

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Cytoplasm: Cellular Boundaries

  • Cell Walls are hard coverings that are found only on the outside of plant cells.
  • Cell Membranes are found in both types of cells. They are Semi-Permeable, which means that some may selectively pass through the cell; this is due to the Phospholipid-Bilayer, which allows for polar molecules to not pass through and nonpolar molecules to pass through.
  • Factory Analogy: Factory Walls

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Quick Quiz:

  • What organelle specifically assembles proteins?
    • Ribosome
  • What organelle has a semi-permeable membrane and is made of Phospholipids?
    • Cell Membrane
  • Name a few organelles found only in plants.
    • Cell Wall, Lysosome, Chloroplast, etc.

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Part 4:

Homeostasis and Transport

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Homeostasis

  • Homeostasis is a condition of which the cell is in balance and equilibrium.
  • Homeostasis in a cell is often maintained by the membrane; that is, it moving things in and out of the cell is the reason why the cell is at a constant state.

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Passive Transport

  • Passive Transport is the passive movement of molecules without requiring energy.
  • Diffusion is the movement of molecules from high concentration to low concentration; this happens due to molecules bouncing off and colliding with more molecules in areas with higher concentration (therefore higher molecule count) to areas with lower concentration.
  • Sometimes, cell membranes have Protein Channels that allow for molecules to diffuse across the membrane without using energy; an example of this is Aquaporin, a protein channel for water.
  • When water diffuses across a membrane, that is known as Osmosis. Three different scenarios may occur for osmosis to exist:
    • If a cell is Isotonic, it has the same concentration as the outside; nothing happens.
    • If a cell is Hypotonic, it has less concentration than the outside; when this happens, water rushes into the cell and can cause it to become Turgid (swollen up plant cell) or Lyse (exploded animal cell).
    • If a cell is Hypertonic, it has more concentration than the outside; when this happens, water rushes out of the cell and can cause it to become Flaccid (weak, floppy).

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Active Transport

  • Active Transport uses energy to move molecules across a gradient; generally for food purposes, like glucose intake.
  • 3 Types:
    • Protein Pumps: Uses ATP to surround a protein and push it in.
    • Endocytosis: Membrane takes in materials using either:
      • Phagocytosis: Cells extend outward to eat large particles.
      • Pinocytosis: Cells form a small pocket in the membrane to intake a small particle.
    • Exocytosis: Membranes excrete particles by pushing it out of the cell.

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Quick Quiz:

  • If a cell is hypotonic, what happens?
    • It either swells up or explodes
  • What protein channel helps push water across the cell membrane?
    • Aquaporin
  • What is the difference between endocytosis and exocytosis?
    • Endocytosis takes in; exocytosis puts out

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Post-Quiz:

  • Name a single part of the cell theory.
    • Everything living has cells; cells are the basic unit of structure and function; new cells are made by old cells.
  • What type of microscope generates 3D images?
    • Electron Scanning Microscope
  • What organelle is responsible for breaking down and recycling cell wastes?
    • Lysosome
  • While _____ generate glucose, _____ use glucose for energy.
    • Chloroplasts; Mitochondrias
  • Diffusion is an example of _____ transport.
    • Passive

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Courses To Consider

  • BSC1010(L) - Biological Principles: 3 Credits (Lec) + 1 Credit (Lab)
  • PCB3023 - Cell Biology: 3 Credits
    • Requires BSC1010 and CHM2045 as a prerequisite

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Thank You!

Dfedkiv2022@fau.edu