Chapter 4
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Chapter 4 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint PPT Presentation

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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

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

Major cell types

Major Cell Types

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

Vacuoles and vesicles1

Vacuoles and 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

Cilia and flagella1

Cilia and Flagella



  • 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




Osmotic influences on cells

Osmotic Influences on Cells

What happens if rbc is placed in a beaker of solution that is

What happens if rbc is placed in a beaker of solution that is

  • Isotonic?

  • Hypertonic?

  • Hypotonic?


Osmosis in animal and plant cells

Osmosis in Animal and Plant Cells

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 transport

What are 3 types of passive transport?

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.

Endocytosis and exocytosis

Endocytosis and Exocytosis

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

Different types of eukaryotic cells

Different Types of Eukaryotic Cells

Summary of cell organelles and their functions

Summary of Cell Organelles andTheir Functions

Cells alive1

Cells Alive


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