Download Ch. 7 Cellular Structure and Function

Ch. 7 Cellular Structure and
Function
p. 180 -207
7.1 Cell Discovery and Theory
p. 182-186
Big Idea
Cells are the structural
and functional units of
all living organisms
7.1 Cell Discovery and Theory
p. 182-186
Essential Question
What are the differences
between prokaryotic and
eukaryotic cells?
Main Idea
•  The invention of the microscope led to the
discovery of cells.
Robert Hooke
•  Made a simple microscope
•  Observed small, box-shaped structures in a
piece of cork
•  Most scientists observed tiny organisms
using the first microscopes
Cell
•  The basic structural and functional unit of
all living organisms
Anton van Leeuwenhock
•  Designed a microscope that allowed him to
see living organisms in pond water, milk,
and various other substances
Cell Theory
1.  All living organisms are composed of one
or more cells
2.  Cells are the basic unit of structure and
organization of all living organisms
3.  Cells arise only from previously existing
cells, with cells passing copies of their
genetic material on to their daughter cell
Microscopes
•  Compound light
microscope - Utilizes a
series of glass lenses
and visible light to
magnify an image
•  Magnifies up to 1000
times
• 
Microscopes
•  Electron Microscopes
uses magnets to aim a
beam of electrons at an
object to produce an
image
•  Magnifies up to 500,000
times
Pollen
• 
Plasma Membrane
•  A special boundary that helps control what
enters and leaves the cell
Eukaryotic cells
•  Contain a nucleus and other organelles that
are bound by membranes
Prokaryotic cells
•  Cells without a nucleus or other membranebound oragnaelles
Comparison of Eukaryotic and
Prokaryotic cells
•  Eukaryotic Cells
–  True nucleus
–  Membrane-bound
organelles
–  Usually larger in size
–  Example: cells that
make up a human
•  Prokaryotic Cells
–  No true nucleus
–  No membrane-bound
organelles
–  Smaller in size
–  Example: bacteria
End of 7.1
7.2 The Plasma Membrane
p. 187-190
Main Idea
•  The plasma membrane helps to maintain a
cell’s homeostasis
Essential Question
What is the plasma
membrane and what
is its function?
Homeostasis
•  Is maintaining balance in an organism’s
internal environment
Plasma Membrane
•  Responsible for maintaining homeostasis in
a cell
•  A thin flexible boundary between a cell and
its environment
•  Allows nutrients into the cell and allows
waste and other products to leave the cell
Selective permeability
•  When a membrane allows some substances
to pass through while keeping others out
p. 187, fig 7.5 (right)
•  What substances are allowed into the cell by
the plasma membrane?
•  What substances are allowed out of the cell
by the plasma membrane?
•  What is selective permeability?
p. 187, fig 7.5 (right)
•  What substances are allowed into the cell by the
plasma membrane?
–  Water, oxygen and glucose
•  What substances are allowed out of the cell by the
plasma membrane?
–  Water, wastes and carbon dioxide
•  What is selective permeability?
–  When a membrane allows some substances to pass
through, and keeps others out
Phospholipid bilayer
•  2 layers of phospholipids arranged tail-totail
•  This arrangement allows the membrane to
exist in watery environments
Phospholipid
•  Polar head – faces the watery environment
–  Is attracted to the water
•  Nonpolar tail – faces each other
Find the polar head, and nonpolar
tail
Phospholipid bilayer
•  Functions to separate the environment
inside the cell from the environment outside
of the cell
Transport Proteins
•  Move substances or waste materials through
the plasma membrane
Proteins
•  Transmit signals inside the cell
•  Act as a support structure
•  Provide pathways for substances to enter
and leave
Cholesterols
•  Prevent fatty acid tails from sticking
together
Carbohydrates
•  Identify chemical signals
Fluid mosaic model
  The phospholipid bilayer allows other
molecules to “float” in the membrane.
End of 7.2
7.3 Structure and Organelles
p. 191 - 200
Main Idea
•  Eukaryotic cells contain organelles that
allow the specialization and the separation
of functions within the cell
Essential Question
What are the component
parts of a cell and what
are their functions?
Cytoplasm
•  The environment inside the plasma
membrane that is a semifluid material
Cytoskeleton
•  A supporting network of long, thin protein
fibers that form a framework for the cell and
provide an anchor for the organelles inside
the cell
•  Made up of microfilaments and
microtubules
Nucleus
•  “manages” the cell
•  Contains DNA that stores genetic
information
•  Nucleolus – where ribosomes are made
Nuclear Membrane
•  Double membrane that surrounds the
nucleus
•  Nuclear pore –opening that allows largersized substances to move in and out of the
nucleus
Ribosome
•  Help manufacture proteins
•  Made up of RNA and protein
Endoplasmic Reticulum
•  Aka ER
•  A membrane system of folded sacs and
interconnected channels that serves as the
site for protein and lipid synthesis
•  Rough ER – area of ER where ribosomes
are attached
•  Smooth ER – area of the ER where there
are no ribosomes attached
Golgi Apparatus
•  A flattened stack of membranes that
modifies, sorts, and packages proteins for
distribution into and outside of the cell
Vacuole
•  A sac used to store food, enzymes, and
other materials needed by a cell
•  Mostly found in plant cells
Lysosomes
•  Vesicles that contain substances that digest
excess or worn-out organelles and food
particles
Centrioles
•  Groups of microtubules
•  Function during cell division
•  We will learn more about these in ch. 9
Mitochondria
•  “energy generators” that convert fuel
particles (sugars) into usable energy
•  Aka “powerhouse” of the cell
Chloroplast
•  Organelles that capture light energy and
convert it to chemical energy through a
process called photosynthesis
•  Only found in plant cells
Cell Wall
•  Thick, rigid mesh of fibers that surrounds
the outside of the plasma membrane,
protecting the cell and giving it support
•  Only in plant cells
Cilia and Flagella
•  Structures that project outside the plasma
membrane
•  Cilia – short, numerous projections that
look like hairs
•  Flagella – long, less numerous projections
that move in a whiplike motion
End of 7.3
7.4 Cellular Transport
p. 201 - 207
Main Idea
•  Cellular transport moves substances within
the cell and moves substances into and out
of the cell
Essential Question
How are substances moved
into and out of a cell?
Diffusion
•  The net movement of particles from an area
where there are many particles of the
substance to an area where there are fewer
particles of the substance
•  Example: a drop of ink in water
Dynamic equilibrium
•  The condition in which there is continuous
movement but no overall change
•  Example: ink that has been dropped in
water last hour
Facilitated Diffusion
•  Substances move into the cell through a
water-filled transport protein called a
channel
•  The protein is “facilitating” the diffusion of
the water
Osmosis
•  Diffusion of water across a selectively
permeable membrane
•  Look at fig 7.22 pg. 203
Isotonic solution
•  A solution that has the same concentration
of water and solutes (ions, sugars, proteins)
–  Iso means same
Hypotonic solution
•  A solution that has a lower concentration of
solute
–  There is more water outside the cell than in it
–  Cell swells
Hypertonic solution
•  The concentration of the solute outside of
the cell is higher than inside
–  Cell shrivels
Active Transport
•  The movement of substances across the
plasma membrane against a concentration
gradient
•  Requires energy
•  Example: sodium-potassium ATPase pump
Endocytosis
•  The cell engulfs an object
•  Example: cellular eating in unicellular
organisms
Exocytosis
•  The secretion of materials at the plasma
membrane
•  Example: to expel waste from a cell
End of 7.4
End of ch. 7