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Cell Structure and Function. Cell Discovery and Theory. The Cell. A cell is the basic unit of structure and function Humans have trillions and trillions of cells You can’t see cells with the naked eye. Cell Dudes. Robert Hooke- 1665

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Cell structure and function

Cell Structure and Function

Cell Discovery



The cell
The Cell

  • A cell is the basic unit of structure and function

    • Humans have trillions and trillions of cells

    • You can’t see cells with the naked eye

Cell dudes
Cell Dudes

  • Robert Hooke- 1665

    • Looked at cork, saw little box-shaped structures and called it cellulae

  • Anton van Leeuwenhoek- late 1600s

    • Looked at pond water and milk and saw


Cell dudes1
Cell Dudes

  • Matthias Schleiden- 1838-botanist

    • Studied plants and concluded that all plants are made of cells

  • Theodor Schwann- zoologist

    • Concluded that all animal tissues were made of cells

  • Rudolph Virchow- Suggested that cells come from cells


  • A compound light microscope has a 10X ocular lens and a 460X objective lens.

    • Where is the ocular lens? ____________________

    • Where is the objective lens? _________________

    • What is the total magnification ___________X


  • 2 Kingdoms

    • Eubackteria

    • Archeabacteria

  • No nucleus

  • DNA in a central nucleoid


  • Contains ribosomes

  • First organisms on earth

Eukaryotic cells
Eukaryotic Cells

  • 4 Kingdoms

    • Protist (single celled)

    • Plants (cell wall/chloroplasts)

    • Animals (lack cell wall/lack chloroplasts)

    • Fungi (cell wall/lack chloroplasts)

  • Contain membrane bound organelles

    • Organelles are specialized structures that carry out functions

The cell membrane
The Cell Membrane

  • The cell membrane is selectively permeable

    • Some things can pass but others can’t

  • Cell membranes are made from a phospholipidbilayer

Phospholipid bilayer structure


of cell







of cell




Lipid bilayer

PhospholipidBilayer Structure

  • Each phospholipid has a polar head and two nonpolar tails

    • Polar head is attracted to water

    • Nonpolar tails are repelled by water

Phospholipid bilayer function
PhospholipidBilayer Function

  • The function is to let some things in and not others

    • Polar molecules do not easily pass

      • H2O is an exception because it is small

      • Allows membrane to separate environment inside from outside the cell

    • The plasma membrane is always in motion

      • Fluid mosaic model

Animal cells plant cells
Animal Cells/Plant Cells

  • Eukaryotic cell which makes up tissues in animals

  • Lack cell walls and chloroplasts, and have smaller vacuoles.

  • Appears to be circular because of the lack of a rigid cell wall.

  • Eukaryotic cell that makes up plants

  • Cell Wall

  • Chloroplast

  • Large Vacuoles


  • Semi-fluid material inside the plasma membrane

  • Consists of cytosol and the cellular organelles (all organelles except the cell nucleus)

  • Cytosol - fluid in which the cellular organelles are suspended


  • Network of long, thin protein fibers provide an anchor for organelles

  • Microtubules-long hollow cylinders that assist in moving substances within the cell

  • Microfilaments-thin threads that give the cell shape and enable the cell to move

Cytoskeleton in

Red and Green


  • Contains genetic material (DNA)

  • Nuclear envelope

  • Nuclear pores allow substances in and out

  • Nucleolus in center

    • Very dense center


Produce proteins

Made of RNA and protein

Made in the nucleolus

Some float freely in the cytoplasm

Others attach to endoplasmic reticulum


Endoplasmic reticulum
Endoplasmic Reticulum

  • Interconnected network of tubules

  • Rough ER

    • Where ribosomes attach and make proteins

    • Appear to create bumps and rough areas on the membrane

  • Smooth ER

    • No ribosomes

    • Produces complex carbohydrates and lipids

Golgi apparatus
Golgi Apparatus

  • Modifies, sorts, and packs proteins in sacs called vesicles

  • Vesicles fuse with plasma membrane

  • They release proteins which move through membrane to get outside of the cell


  • Act as temporary storage unit for materials in the cytoplasm

  • Store, transport, or digest food and waste

  • Plant cells have one large one

  • Animal cells have little ones


  • Vesicles that contain digestive enzymes to digest excess or worn-out organelles and food particles

  • They also digest bacteria and viruses that enter the cell

  • They are built in the Golgi apparatus.


  • Microtubules

  • Found near nucleus

  • Animal Cells only

  • Aid in cell replication


  • Powerhouse

  • Converts organic materials into energy

    • ATP

  • Outer and inner membranes with lots of folds

    • Provides large surface area to break sugar molecule bonds (produce energy)

Chloroplasts plant only
Chloroplasts- Plant only

  • Capture light energy and convert it to chemical energy through photosynthesis

Cell wall
Cell Wall

  • Mesh of fibers that surrounds the plasma membrane

  • Protects and supports the cell

  • Made of carbohydrate, cellulose

Cilia and flagella
Cilia and Flagella

  • Cilia- short projections that look like hairs

    • Move back and forth like oars on a rowboat

    • Move substances along surface of the cell

  • Flagella- longer projections that move in a whip-like motion

  • Both are composed of microtubules

  • Move cells through watery environment

Cell transport
Cell Transport

  • Diffusion -net movement of particles from high concentration to low concentration

    • Doesn’t require energy because the particle are in motion

  • Dynamic equilibrium- the overall concentration does not change, but molecules are still moving randomly

What affects the rate of diffusion
What affects the rate of diffusion?

  • What makes molecules move faster

    • High temperature

    • High Pressure

    • High concentration

Facilitated diffusion
Facilitated Diffusion

  • Some ions and molecules can’t diffuse across the cell membrane

  • Facilitated diffusion – uses transport proteins to help move some molecules across the plasma membrane


  • Osmosis – diffusion of water

  • Most cells undergo osmosis because they are surrounded by water

Hyper hypo iso tonic
Hyper—Hypo– Iso tonic

  • These are comparing words

    • Hypertonic -more solute than

    • Hypotonic- less solute than

    • Isotonic- same solute as

  • What would happen if you

    • Put a red blood cell in a hypertonic solution

    • Put a red blood cell in a hypotonic solution

    • Put a red blood cell in an isotonic solution

Active transport
Active Transport

  • Goes from low to high concentration

  • Requires Energy

    • ATP

  • Moves large substances


  • Endocytosis- moving large substances into the cell


  • Exocytosis- moving large substances out of the cell