CHAPTER 7
CELL STRUCTURE AND FUNCTION
Biology
7.1: THE CELL THEORY: LETS MEET THE PLAYERS
Anton Van Leeuwenhoek
• Discovered: red blood cells, bacteria,
and Protista
Theodor Schwann and Matthias Schleiden
• From Germany
• Credited with the Cell theory
7.1: THE CELL THEORY: LETS MEET THE PLAYERS
Zacharias Janssen
• Credited with trying to create
lenses with stronger
magnification for people with
poor eyesight (evolved into a
lens for a scope)
Robert Hooke
•
He was the first person to
have seen cork cells (using a
microscope)
7.1: THE CELL THEORY
1. All known living things are made up of cells.
2. The cell is the basic structural & functional unit of all
living things.
3. All cells come from pre-existing cells by division.
4. Cells contain hereditary information which is passed
from
cell to cell during cell division
5. All cells are basically the same in chemical composition.
6. All energy flow (metabolism & biochemistry) of life
occurs within cells.
7.1: TWO TYPES OF CELLS
Prokaryotes
•
“Pro” means without
•
Do not have membrane bound nucleus
•
DNA is free floating
Eukaryotes
•
“Eu” means true
•
Have membrane bound nucleus
•
DNA contained in the nucleus
7.2: THE PLASMA MEMBRANE
 Thin, flexible boundary between the cell and its
environment
 Allows nutrients into the cell
 Allows waste to leave the cell
Selective Permeability
 The plasma membrane controls the movement of
substances into
and out of the cell.
Plasma Membrane
 Controls the amount of a
substance entering the cell
 Controls the amount of a
substance leaving the cell
 The plasma membrane is composed of the
phospholipid bilayer.
 A phospholipid molecule is composed of a glycerol
backbone, two fatty acid chains, and a phosphate
group.
Fluid Mosaic Model
 The phospholipid
bilayer allows other
molecules to “float”
in the membrane.
Other Components
 Proteins
 Cholesterol
 Carbohydrates
Proteins
 Transmit signals inside the cell
 Act as a support structure
 Provide pathways for substances to enter and leave
Cholesterol
 Prevents fatty acid tails from sticking
together
Carbohydrates
 Identify chemical signals
7.3: STRUCTURES AND ORGANELLES
Plant and Animal Cell Structures
Animal Cell
Plant Cell
ANIMAL CELL
CELL ORGANELLES
Cilia
 Short, numerous
projections that look
like hairs
Flagella
400x
 Longer and less
numerous than cilia
 Create movement
with a whiplike
motion
26,367x
Cell Membrane
•
found in both plants and animal cells
•
Allows only certain materials to move
into and out of the cell.
•
Made up of a double layer of fat with
some proteins scattered throughout.
•
Is flexible.
•
Helps to maintain a chemical balance
between materials inside and outside
the cell.
Cytoplasm
• found in both plants and animal cells
• Gel-like material inside the cell
membrane and outside the nucleus.
• Where all the organelles “float”
around.
Nucleus
•
Found in both plants and animal
cells
•
The largest organelle in the
cytoplasm.
•
Directs all the activities of the cell.
•
Surrounded by a nuclear envelope.
•
Contains the genetic blueprints for
the operations of the cell in the form
of DNA.
Endoplasmic Reticulum
• A membrane system of folds
and channels that are the site
of protein and lipid synthesis.
• If there are ribosomes (the
bumps) attached it is the
Rough ER.
Mitochondria
• This is the energy generator for the
cell.
• It converts fuel (sugar) into usable
energy for the body.
• The “powerhouse” of the cell
Nucleolus
• This is inside of the
nucleus
• This makes the ribosomes
Ribosomes
• These are either free floating in the
cytoplasm or attached to the ER.
• They make proteins.
• Ribosomes are composed of RNA and
protein.
Gogi Bodies
• Stacks of membrane covered
sacs that package & move
materials out of the cell.
Vacuoles
• Store materials and waste
products temporarily in the
cytoplasm.
• Store enzymes, food and
other materials needed by
the cell
Lysosomes
• They contain substances that
digest excess or worn-out
organelles and food particles.
• They also digest bacteria and
viruses that have entered the cell.
Chloroplasts
• Are found ONLY in plant cells.
• Contain chlorophyll which is a green
pigment.
• Trap light energy from the sun which
is then changed into chemical
energy in the form of SUGAR.
Cell Wall
• Is found only in plant cells.
• Is a rigid structure outside the
cell membrane.
• Supports and protects the plant
cell.
7.3: CELLULAR TRANSPORT
Passive Transport
 Movement of particles across the cell
membrane without using energy
Three Modes of Passive Transport
 Diffusion
 Facilitated Diffusion
 Osmosis
Diffusion
 Movement of particles from an area of high
concentration to an area of lower
concentration
Initial Conditions
Low
Diffusion
High
High
Low
• Diffusion animation
• http://www.indiana.edu/~phys215/lecture/lecnotes/lecgrap
hics/diffusion.gif
• http://www.stolaf.edu/people/giannini/flashanimat/transpor
t/diffusion.swf
• http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animat
ion__how_diffusion_works.html
 Diffusion is controlled by
 Temperature
 Pressure
 Concentration
Dynamic Equilibrium
 Reached when diffusion of material into the
cell equals diffusion of material out of the cell
 Molecules continue to move, but the overall
concentration remains the same.
Diffusion in a Cell
Facilitated Diffusion
 Movement of materials across the plasma
membrane using proteins
 http://programs.northlandcollege.edu/biology/Biology1111/animations/tra
nsport1.html
Channel Proteins
Carrier Proteins
Osmosis
 Diffusion of water across a selectively
permeable membrane
Three Types of Solutions
 Isotonic
 Hypotonic
 Hypertonic
Isotonic Solution
 Water and dissolved substances diffuse
into and out of the cell at the same rate.
Plant Cell
Blood Cell
11,397x
Hypotonic Solution
 Solute concentration is higher inside the
cell.
 Water diffuses into the cell.
Plant Cell
Blood Cell
13,000x
Hypertonic Solution
 Solute concentration is higher outside the
cell.
 Water diffuses out of the cell.
Plant Cell
Blood Cell
13,000x
Active Transport
 Movement of particles across the cell
membrane using energy
Active Transport Using Carrier Proteins
Types of Active Transport Pumps
 Na+/K+ ATPase pump
 Moves three Na+ ions out of the cell and
two K+ ions into the cell
 http://www.brookscole.com/chemistry_d/templates/student_resourc
es/shared_resources/animations/ion_pump/ionpump.html
Endocytosis
 Process by which the
cell surrounds and
takes particles into the
cell
Exocytosis
 Secretion of material
out of the plasma
membrane