Chapter 7
Cell Structure and Function
Section 7-1
The History of the Cell Theory and
Microscopes
Historical View of the Cell Theory
• As science improves, so do improvements
in scientific instruments, and improved
scientific instruments lead to new
discoveries.
1590 – Zacharias Janssen
• Built first simple microscope (one
set of lenses)
1670’s Anton Van Leeuwenhoek
• Made improvements
• 270x magnification
• Saw bacteria, protozoa,
sperm cells, red blood
cells and yeast cells
1665 – Robert Hooke
• Produced a compound microscope
• Saw hollow boxes and named them
“cells”
1665 – Robert Hooke
1831 – Robert Brown
• Saw central structure in plant cells,
called this structure a nucleus
1838 – Theodore Schwann
• Concluded that all animals are
made of cells
1838 – Matthias Schleiden
• Concluded that all plants are
made of cells
1839 – Johannes Purkinje
• Stated that “the cell is the unit of
function of life”
1858 – Rudolf Virchow
• Concluded that “ cells come only from
previously existing cells”
The Cell Theory
1. All living things are composed of
cells
2. Cells are the basic units of
structure and function
3. New cells are produced from
existing cells
Section 3-2
Prokaryotes and
Eukaryotes
Eukaryotes
• Have a nucleus and membrane
covered organelles
Prokaryotes
• Don’t have a nucleus and
membrane covered organelles
Eukaryotic Cell
Structures
Plasma Membrane
• Separates the cell from its
environment
• Controls the transport of materials
in and out
• Allows some materials but not
others to pass through this is
called…
–Selectively permeable
Endoplasmic Reticulum
• Extensive network of tube-like
structures that forms a
passageway that functions in the
transport of materials throughout
the cells
Ribosomes
• Site of protein
synthesis
• Attached to the
walls of the ER
or move freely in
the cytoplasm
Golgi Bodies
• Stack of tiny, flattened sac-like
tubes used in secretion
• Package protein molecules in a
membrane and send the package
to the cells surface
Mitochondria
• Where cellular respiration takes
place to release energy
• “Mighty Mitochondria”
• Powerhouse of the cell
Microtubules
• Tubes that serve as support for
the cell
Microfilaments
• Thin threads attached to the cell
membranes, play a role in
movement
Lysosomes
• Vesicles that contain enzymes
used in digestion
• Fuses with food vacuoles to
digest food into smaller pieces
• Digest old cell structures to
dispose of them or even entire
cells
Nucleus
• Regulates all the cells activities
Chromosomes
• Long coiled fibers that carry the
material of heredity
• Made of protein and DNA
Nucleolus
• Composed of
RNA
• Involved in the
passage of
RNA into the
cytoplasm
Centrioles
• Small cylinders in the cytoplasm
that play a role in cell division
Cilia
Flagella
Chloroplasts
• Organelle found only in plants,
used to make food
Vacuoles
• Spherical, bubble-like storage
sacs
• Plant cells have very large
vacuoles compared to animal
cells
Cell Wall
• Rigid structure
that surrounds the
cell membrane
• Made of cellulose
• Permits most
things to pass
through
Cell Wall
Section 3-3
Cellular Processes
The Big Idea
• Cells need to regulate the
movement of dissolved molecules
on either side of the membrane
Cell membrane
• Regulates what enters and leaves the
cell and also provides protection and
support
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
Cell membrane
• Made of a double layered sheet called a
lipid bilayer
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
Cell Wall
• Provide support and protection for
cell
• Found in more than just plants
• Contrary to popular belief, not
selectively permeable
Cell Walls
Diffusion Through Cell
Boundaries
• One of the more important
functions of the cell membrane is
to regulate the movement of
dissolved molecules from one
side of a membrane to the other
Concentration
• The mass of solute in a given
volume of solution
• Mass/volume
• What is the concentration of 12 grams
of salt in 3 liters of water?
• What is the concentration of 12 grams
of salt in 6 liters of water?
In a solution, particles move constantly
Diffusion
• Process by which molecules of a
substance move from areas of high
concentration to areas of low
concentration
Diffusion
Diffusion
Equilibrium
• When the concentration of the
solute is the same throughout a
system
• Because diffusion depends on
random particle movements,
substances diffuse across
membranes without energy being
used
• Even during equilibrium, particles
still move, but there is no net
change in concentration
Osmosis
• The diffusion of water
Osmosis
Isotonic
• The concentration of solutes is
the same inside and outside the
cell
Hypertonic
• Solution has a higher solute
concentration than the cell
Hypotonic
• Solution has a lower solute
concentration than the cell
Facilitated Diffusion
• Movement of specific molecules across
cell membranes through protein channels
•Only go from high
concentrations to
low
concentrations
•Does not require
energy
Glucose
molecules
High
Concentration
Cell
Membrane
Low
Concentration
Protein
channel
Types of Active
Transport
• Sometimes cells must move
materials in the opposite direction
–Low concentrations to high
concentrations
Active Transport
• Energy requiring process that
moves materials across a cell
membrane against a
concentration gradient
Molecule to
be carried
Active Transport
Energy
Molecule
being carried
Molecular transport
• Small molecules and ions are
actively transported
Carrier proteins
• Proteins that act like pumps
Endocytosis
• The process of taking material into the
cell by means of infolding of the
membrane
Food particle
engulfing
Forms a
vacuole
Phagocytosis
• Cell eating
• White blood
cells do this
Pinocytosis
• Cell drinking
Exocytosis
• Forces contents out of the cell
• Endocytosis in reverse
Section 3-4
The Diversity of Cellular life
Unicellular Organism
• Single celled
• Do everything a living organism does
Multicellular Organism
• Many celled
• Depend on
communication
and cooperation
among
specialized cells
Specialization
• When cells develop in different
ways to perform different tasks
Red Blood Cells
• Transport
oxygen
Pancreatic Cells
• Make
proteins
• Packed with
ribosomes
Skeletal Muscle
• Generate force
• Packed with
mitochondria
• Overdeveloped
cytoskeleton
Nerve Cell
• Send messages
Guard Cells
• Open and close the stomata
Levels of Organization
Cells
Tissues
Organs
Organ Systems
Tissues
• Group of similar cells that perform
specific function
• Ex.) smooth muscle
Organ
• Group of tissues that work
together to perform a specific
function
• Ex.) stomach
Organ System
• Group of organs that work together to
perform a specific function
• Ex.) digestive system
• This organization creates a division of
labor that makes multicellular life
possible
Biological Organization