Download Cells

Cells
Chapter 7
The Cell Theory
• All living things are composed of cells
• Cells are the basic unit of structure and
function in living things
• New cells are produced from existing cells
• Bacteria
Prokaryotic Cells
– Very small cells
– Have cell wall
– No nucleus
– No membrane bound organelles
Eukaryotic Cells
• Much larger than prokaryotic cells
• Animals, plants, fungi, protists
– DNA is stored in nucleus
– Membrane bound organelles
– May or may not have cell wall
What is an organelle?
• It is a part of the
cell that performs
a particular
function
Organelle Wanted Poster
• Your team has been hired by the microscopic FBI to
create WANTED! posters for cell organelles.
• You will be given an organelle by your agency
contact (Mrs. Maxwell), and you must create a
wanted poster with the following information:
• The organelle name.
• A drawing of what the organelle looks like (both by
itself and in a cell).
• A description of why the cell organelle is WANTED.
– You will need to include what the organelle actually does in
a cell. You may also note what crimes the organelle has
committed.
• Any friends the organelle has (i.e. other organelles
that might be in its gang).
• What type of cell this organelle might be found in.
• The reward for information leading to the arrest of
this organelle.
• Cell Wall
– Made up of Cellulose
– Adds rigidity to the cell
– Protects the cell
– Found only in plants, fungi,
bacteria, some protists
• Cell Membrane
– Allows materials into and out of the cell
– Flexible barrier
– Made of Phospholipids with proteins scattered
throughout
• Cytoplasm
– Everything inside the cell
• The jelly-like cytosol, cytoskeleton and all
organelles
• Nucleus
– Control center of the cell
– Where DNA is stored
– Largest organelle in animal cells
• Nucleolus
– Contains RNA needed to make ribosomes
• Chromatin
– Unorganized strands of DNA bound with
Proteins
• Chromosomes
– Highly organized and condensed DNA
– Only seen during cell division
• Mitochondrion
– Site of cellular respiration
– Sugars are broken down into ATP (energy)
– “Powerhouse” of the cell
– Found in plant and animal cells
• Chloroplast
– Found only in plant cells
– Site of Photosynthesis
– Contain Chlorophyll
Endosymbiosis
• Simply stated, the theory of
endosymbiosis is the concept that
mitochondria and chloroplasts are the
result of years of evolution initiated by the
endocytosis of bacteria and blue-green
algae which, instead of becoming
digested, became symbiotic.
• Chlorophyll
– Green pigment found in chloroplasts that
captures sunlight needed for photosynthesis
• Vacuole
– In plants, it is a large storage area for water,
salts, carbohydrates and other nutrients
– In animals, it is much smaller
– Also plays a part in intracellular digestion
• Lysosome
– Small digestive sacs found in animal cells
– Contains enzymes needed to break down
food particles and discarded organelles
• Endoplasmic Reticulum
– Smooth ER makes lipids for membranes
– Rough ER contains ribosomes for making
proteins associated with the membrane
• Golgi Apparatus
– The “post office” of the cell
– Packages and sends proteins to different
parts of the cell
• Ribosome
– Site of protein synthesis
– Not membrane bound so prokaryotes also
have them
• Centrioles
– Small barrel like structures in animal cells that
may aid in cell division
• Vesicles
– Carry proteins that have been sorted and
modified by the golgi apparatus
Review
Cell Membrane
• The job of the membrane is to regulate
what comes into and leaves the cell
• It is a flexible barrier made up of
phospholipids
• Phospholipids are amphipathic
– They are both hydrophilic and hydrophobic
• The hydrophobic tails bury themselves
into the middle of the bilayer and the
hydrophilic heads face the water on the
inside and outside of the cell
Transport through the membrane
• There are two types of transport through
the membrane
• Passive – which requires no energy (ATP)
• Active – which requires energy (ATP)
Diffusion
• Passive transport
• Molecules move down a concentration
gradient from high to low concentration
MovieMovies from lecture June 2
Diffusion Demo
• A starch and glucose solution is placed
into a sac made from dialysis tubing. The
sac is placed into pure water.
• The sac is permeable to glucose, but not
to starch
• What do you expect to see in the water
within 24 hours? Why?
• How could we test for this?
Demo Set-up
OSMOSIS
http://www.indiana.edu/~phys215/le
cture/lecnotes/facdiff.html
• The movement of water across the
membrane from high concentration to low
concentration.
• Also passive transport
• Hypertonic – The solute concentration is
higher, meaning the water concentration is
lower.
• Hypotonic – Solute concentration is lower,
meaning the water concentration is higher
• Isotonic – Solute concentration is the
same on both sides of the membrane
Facilitated Diffusion
• Movement through proteins in the
membrane
• Does not require energy (ATP)
http://www.indiana.edu/~phys215/lecture/lecnotes/facdiff.html
Active Transport
• Movement of molecules against the
concentration gradient
• Requires ATP (energy)
• Low  High concentration
http://w3.ouhsc.edu/human_physiology/Garrett.html
How do we get the ATP to do
these things?
• Photosynthesis provides the sugars (fuel)
for the power plant
• Cellular Respiration breaks down the
sugars to make ATP (energy)
• Think of photosynthesis as the process
that makes coal and Respiration as the
power plant that burns the coal to make
electrical energy for our homes
Endocytosis and Exocytosis
• Endocytosis – Cell envelops and engulfs
large materials
• Phagocytosis – solid materials
• Pinocytosis – liquid materials
• Exocytosis – Large particles leave the cell