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Chapter 4 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. The Cell Theory. All living things are made of cells. A cell The basic unit of all living things. The Historical Context of the Cell Theory.

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Chapter 4

Lecture Outline

See PowerPoint Image Slides

for all figures and tables pre-inserted into

PowerPoint without notes.

the cell theory
The Cell Theory
  • All living things are made of cells.
  • A cell
    • The basic unit of all living things.
the historical context of the cell theory
The Historical Context of the Cell Theory
  • Robert Hooke coined the term “cell.”
    • Look at cork cells under a simple microscope.
  • Anton van Leeuwenhoek
    • Made better microscopes
    • Used them to look at a variety of substances and identified animalcules
the historical context of the cell theory1
The Historical Context of the Cell Theory
  • Mathias Jakob Schleiden
    • Concluded that all plants were made of cells
  • Theodor Schwann
    • Concluded that all animals were made of cells
initial observations of cells
Initial Observations of Cells
  • Cell wall
    • Outer non-living part of plant cells
  • Protoplasm
    • Interior living portion of the cell
    • Nucleus
      • Contains the genetic information of the cell
    • Cytoplasm
      • Fluid part of the protoplasm
    • Organelles
      • “Little organs” within the protoplasm
different kinds of cells
Different Kinds of Cells
  • Prokaryotic
    • Structurally simple cells
    • Lack a nucleus
    • Lack most other organelles, lack membrane bound organelles
    • Bacteria
  • Eukaryotic cells
    • More complex
    • Have a nucleus
    • Have a variety of membrane bound organelles
    • Plants, animals, fungi, protozoa and algae
    • Typically much larger than prokaryotic cells
cell size
Cell Size
  • Prokaryotic cells
    • 1-2 micrometers in diameter
  • Eukaryotic cells
    • 10-200 micrometers in diameter
surface area to volume ratio
Surface Area-to-Volume Ratio
  • Cell size is limited.
    • Cells must get all of their nutrients from their environment through their cell membranes.
    • Volume increases more quickly than surface area.
    • Surface area-to-volume ratio must remain small.
the structure of cell membranes
The Structure of Cell Membranes
  • Cell membranes
    • Thin sheets composed of phospholipids and proteins
  • Fluid-mosaic model
    • Two layers of phospholipids
      • Fluid
        • Has an oily consistency
        • Things can move laterally within the bilayer.
      • Mosaic
        • Proteins embedded within the phospholipid bilayer
the phospholipid bilayer
The Phospholipid Bilayer
  • Phospholipid structure
    • Hydrophobic tails
    • Hydrophilic heads
  • Bilayer
    • Hydrophobic tails of each layer associate with each other.
    • Hydrophilic heads on the surface of the bilayer
  • Cholesterol
    • Hydrophobic
    • Found within the hydrophobic tails
    • Keeps the membrane flexible
membrane proteins
Membrane Proteins
  • Some are on the surface
  • Some are partially embedded.
    • Protrude from one side
  • Some are completely embedded.
    • Protrude from both sides
  • Functions
    • Transport molecules across the membrane
    • Attachment points for other cells
    • Identity tags for cells
voyage to the cell membrane
Voyage to the cell membrane
cells alive
Cells Alive
organelles composed of membranes
Organelles Composed of Membranes
  • Plasma membrane (cell membrane)
  • Different cellular membranous structures serve different functions
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
  • Peroxisomes
  • Vacuoles and vesicles
  • Nuclear membrane
the plasma membrane
The Plasma Membrane
  • Composed of a phospholipid bilayer
  • Separates the contents of the cell from the external environment
  • Important features
    • Metabolic activities
    • Moving molecules across the membrane
    • Structurally different inside and outside
    • Identification: Self vs. nonself
    • Attachment sites
    • Signal transduction
the endoplasmic reticulum
The Endoplasmic Reticulum
  • Consists of folded membranes and tubes throughout the cell
  • Provides a large surface area for important chemical reactions
    • Because it is folded, it fits into a small space.
  • Two types of ER
    • Rough
      • Has ribosomes on its surface
        • Sites of protein synthesis
    • Smooth
      • Lacks ribosomes
      • Metabolizes fats
      • Detoxifies damaging chemicals
the golgi apparatus
The Golgi Apparatus
  • Stacks of flattened membrane sacs
  • Functions
    • Modifies molecules that were made in other places
    • Manufactures some polysaccharides and lipids
    • Packages and ships molecules
traffic through the golgi
Traffic Through the Golgi
  • Vesicles bring molecules from the ER that contain proteins.
  • Vesicles fuse with the Golgi apparatus.
  • The Golgi finishes the molecules and ships them out in other vesicles.
    • Some are transported to other membrane structures.
    • Some are transported to the plasma membrane.
    • Some vesicles become lysosomes.
  • Vesicles containing enzymes that digest macromolecules
    • Carbohydrates
    • Proteins
    • Lipids
    • Nucleic acids
  • Interior contains low pH
    • These enzymes only work at pH=5.
    • The cytoplasm is pH=7.
      • If the lysosome breaks open, these enzymes will inactivate and will not damage the cell.
functions of lysosomes
Functions of Lysosomes
  • Digestion
    • Of food taken into the cell
  • Destruction
    • Disease-causing organisms
    • Old organelles
  • Not formed from golgi membrane, but from ER membrane
  • Contain the enzyme catalase
    • Breaks down hydrogen peroxide
    • Breaks down long-chain fatty acids
    • Synthesizes cholesterol and bile salts
    • Synthesizes some lipids
vacuoles and vesicles
Vacuoles and Vesicles
  • Membrane-enclosed sacs
  • Vacuoles
    • Larger sacs
    • Contractile vacuoles found in many protozoa
      • Forcefully expel excess water from the cytoplasm
  • Vesicles
    • Smaller vesicles
the nuclear membrane
The Nuclear Membrane
  • Separates the genetic material from the rest of the cell
  • Filled with nucleoplasm
  • Composed of two bilayers
  • Contains holes called nuclear pore complexes
    • Allow large molecules like RNA to pass through the membrane into the cytoplasm
the endomembrane system interconversion of membranes
The Endomembrane System ̶ Interconversion of Membranes
  • Membranes are converted from one membranous organelle to another.
energy converting organelles
Energy Converting Organelles
  • Mitochondrion
    • A small bag with a large bag stuffed inside
    • Larger internal bag is folded into cristae
      • Cristae contain proteins for cellular respiration.
        • Releases the energy from food
        • Requires oxygen
        • Uses the energy to make ATP
energy converting organelles1
Energy Converting Organelles
  • Chloroplasts
    • Sac-like organelle
    • Contain chlorophyll
    • Perform photosynthesis
      • Uses the energy in light to make sugar
    • Contain folded membranes called thylakoids
      • Thylakoids stacked into grana
      • Thylakoids contain chlorophyll and other photosynthetic proteins.
    • Thylakoids surrounded by stroma
nonmembranous organelles
Nonmembranous Organelles
  • Ribosomes
  • Cytoskeleton
  • Centrioles
  • Cilia flagella
  • Inclusions
  • Made of RNA and proteins
  • Composed of two subunits
    • Large
    • Small
  • Are the sites of protein production
  • Found in two places
    • Free floating in the cytoplasm
    • Attached to endoplasmic reticulum
  • Provides shape, support and movement
  • Made up of
    • Microtubules
    • Microfilaments (actin filaments)
    • Intermediate filaments
  • Two sets of microtubules arranged at right angles to each other
  • Located in a region called the centrosome
    • Microtubule-organizing center near nucleus
  • Organize microtubules into spindles used in cell division
cilia and flagella
Cilia and Flagella
  • Hair-like projections extending from the cell
  • Composed of microtubules covered by plasma membrane
  • Flagella
    • Long and few in number
    • Move with an undulating whip-like motion
  • Cilia
    • Small and numerous
    • Move back and forth like oars on a boat
  • 9 + 2 arrangement of microtubules
  • Cell can control their activity
  • Collections of miscellaneous materials
    • Can be called granules
  • Temporary sites for the storage of nutrients and waste
nuclear components
Nuclear Components
  • Contains chromatin
    • DNA + proteins
    • Becomes condensed during cell division into chromosomes
  • Surrounded by double layer of membrane
  • Nuclear membrane contains pores to control transport of materials in and out of nucleus
  • Contains one or more nucleoli
    • Site of ribosome synthesis
  • Contains nucleoplasm
    • Water, nucleic acids, etc.
cell parts empire state of mind
Cell Parts / Empire State of Mind
getting through membranes
Getting Through Membranes
  • Diffusion
  • Facilitated diffusion
  • Osmosis
  • Active transport
  • Endocytosis
  • Exocytosis
  • Molecules are in constant, random motion.
  • Molecules move from where they are most concentrated to where they are less concentrated.
    • This is called diffusion.
    • Involves a concentration gradient (diffusion gradient)
      • No concentration gradient=dynamic equilibrium
the rate of diffusion
The Rate of Diffusion
  • Depends on
    • The size of the molecule
      • Smaller molecules diffuse faster.
    • The size of the concentration gradient
      • The greater the concentration difference, the faster the diffusion.
diffusion in cells
Diffusion in Cells
  • Diffusion can only happen if there is no barrier to the movement of molecules.
  • Can only happen across a membrane if the membrane is permeable to the molecule
    • Membranes are semi-permeable; they only allow certain molecules through.
    • Membrane permeability depends on the molecules size, charge, and solubility.
the direction of diffusion
The Direction of Diffusion
  • Determined solely by the concentration gradient
  • Diffusion that does not require energy input is passive.
  • Example:
    • Oxygen diffusion
  • The diffusion of water through a selectively-permeable membrane
  • Occurs when there is a difference in water concentration on opposite sides of the membrane.
  • Water will move to the side where there is less water
    • Or more solute
facilitated diffusion
*Facilitated Diffusion
  • Some molecules have to be carried across the membrane.
    • Accomplished by carrier proteins
  • Still involves diffusion
    • Follows a concentration gradient
    • Is passive transport
passive transport animation
Passive Transport animation
what are 3 types of passive transport1
What are 3 types of passive transport?
  • Diffusion
  • Osmosis
  • Facilitated diffusion
  • What makes it “Passive”?
  • Why is no energy required?
active transport
Active Transport
  • Opposite of diffusion
  • Moves molecules across a membrane UP their concentration gradient
  • Uses transport proteins in the membrane
    • Specific proteins pump specific molecules
  • Requires the input of energy
  • Ex Na-K pump, amino acids, Ca
  • Moves large molecules or sets of molecules into the cell
    • Phagocytosis
      • Cell eating
      • Food engulfed by the membrane
      • Material enters the cell in a vacuole.
    • Pinocytosis
      • Cell drinking
      • Just brings fluid into the cell
    • Receptor-mediated endocytosis
      • Molecules entering the cell bind to receptor proteins first.
  • Moves large molecules or sets of molecules out of the cell
  • Vesicles containing the molecules to be secreted fuse with the plasma membrane.
    • Contents are dumped outside the cell.
complete last page of in class
Complete last page of in class
  • You may work together and use notes
prokaryotic cells
Prokaryotic Cells
  • Two different types of prokaryotes
    • Domain eubacteria
      • Contains bacteria
    • Domain archaea
      • Contains prokaryotes that live in extreme environments
prokaryotic cell structure
Prokaryotic Cell Structure
  • Contain DNA and enzymes
    • Able to reproduce
    • Engage in metabolism
  • Surrounded by a plasma membrane
    • Plasma membrane surrounded by a cell wall
      • Maintains the shape of the cell
    • Cell wall surrounded by a capsule
      • Helps them adhere to hosts
      • Protects them from destruction
  • Contain ribosomes
  • May contain flagella
    • Facilitates movement
cells alive1
Cells Alive