Transcript Cellular Structure and Function

Cellular Structure
and Function
Chapter 7
An introduction to Eukaryotic cells
Objectives
 Cell theory 7-1
 Distinguish prokaryotic and
eukaryotic cell types
 Identify cellular structures 7-2
 Define the function of each
structure within the cell
 Preview Cellular functions
What is the cell theory?
7-1
 With the
invention of the
microscope
scientists could
see tiny little
chambers, now
called cells.
What are the three parts
to the cell theory?
 All living things are composed of
cells
 Cells are the basic units of
structure and function in living
things
 New cells are produced from living
cells
 Like cars:
 All cars have engines
 Engines are the structure and function
of what makes the car go
 New models are based on the old model
e.g. model T  Taurus A Ford is a Ford! A
Basic Cell Structures
 All cells have:
 Cell membrane thin flexible
barrier around the cell.
 Function protect and support cell
allowing interaction with their
environment
 Cell wall strong supportive
layer around the cell membrane.
 Function support and protection
for cell.
Basic Cell Structures
cont.
 Some cells have a membrane
bound nucleus contains all
the cells genetic material (like a
blue print)
 Prokaryotes no membrane
 Eukaryotes membrane
 Cytoplasm liquid between cell
membrane and nucleus.
Are there different cell
types?
 YES!!!! There are two types:
 Prokaryotic cells
 Eukaryotic cells
End of 7-1
 Cell video
Cell structures 7-2
 Welcome to prokayotic and
eukaryotic cells!
 Hang on for the ride!
Prokaryotic Cell structures
You don’t need to know all this!
Prokaryotic Cells
 Features:
 Size is 1-10 µm.).
 Contains all basic cell structures
 All bacteria are prokaryotes
 E.g. E-coli
 No membrane bound nucleus
 Mostly Asexual reproduction
 No mitochrondria
 No cell division-budding or binary fission
 Cytoplasm present w/ ribosomes and inclusion
bodies protein syn. And carb., phosphate storage
etc.
Who has had to take
antibiotics?
 Did you feel better after 10
days?
 Did your Dr. or Mom have you
eat yogurt and cheese?
 Why?
 Antibiotics kills the good
bacteria that live in your body
 Yogurt and cheese replace the
good bacteria!
What does a prokaryotic
cell look like? 3 shapes
spirilla
Cocci
bacillus
You don’t need to know all this!
Eukaryotic cell
structures
Features of Eukaryotic
Cells
 Cell Wall to protect and support
cell-plants
 Plasma/cell membrane interacts
with cells exterior environment and
is the gateway for things
entering/leaving the cell.
 Animal cells don’t have wall plasma
membrane
 Plant cells do have wall cellulose
**pg 174**
Plasma Membrane
The plasma membrane is referred to as a Phospholipid bilayer,
 This bilayer surrounds the cell and designates what enters and leaves the cell
Plasma/Cell Membrane
Function
 The membrane is the gatekeeper
to the cell
 Embedded in the c. membrane are
different types of proteins
called protein receptors (you
don’t need to know this)
 They are specific in nature e.g.
protein receptor for insulin
 Two types integral and
peripheral
The Nucleus
 Function store house for DNA
and controls activities in the
cell
 You will find DNA:
 Chromatin uncondensed and
spread out through the nucleus
 Chromosomes condensed
chromatin into visible strands in
preparation for cell division
What’s the nucleus?
Chromatin in nucleus
Condensed chromatin =
chromosomes
What is the function of the
Nucleolus? It’s the cell’s
brain
 Function
produces
ribosomes (RNA
particles) used for
protein synthesis.
 How ribosomes
move out of the
nucleus to
positions on the
rough endoplasmic
reticulum where
they are critical
in
nucleolus
protein synthesis.
 http://www.tvdsb.on.ca/westm
in/science/sbi3a1/Cells/nucl
eus.htm
Cytoskeleton
• Cytoskeleton
function: maintains
cell shape and assists
with cell movementlike your bones
– Microtubules hollow
tubes of protein used in cell
division (centrioles), cilia
and flagella
– Microfilaments long thin
fibers that function in cell
movement and movement
of organelles
Cytoskeleton
Provides structure for the cell
Cytoplasm
 Consists of primarily of water
 Contains various organelles as
well as salts, dissolved gasses
and nutrients.
 Fluid that fills the cell
between the plasma membrane
and the nucleus
 It’s kind of gooey!
What’s next???!!
• ER…
• Two types of endoplasmic reticulum
– Rough synthesizes proteins for transport
within the cell.
• These proteins (cars) are transported to the Golgi
Apparatus
– Smooth synthesizes lipids and
phospholipids, modifies proteins further
Rough ER
 Function Acts as a conveyer
belt, transporting ribosomes
from the nucleus into the
cytoplasm
 cell including protein synthesis
 production of steroids
 storage and production of
glycogen and insertion of
membrane proteins.
Smooth ER
 Function synthesis of lipids,
phospholipids, fatty acids,
steroids and calcium storage
 Once these items are produced
they are sent to the Golgi
Apparatus-the cell’s UPS center…
• http://www.tvdsb.on.ca/westmin/science/s
bi3a1/Cells/endo.htm
Golgi Apparatus/UPS packaging
center
• Function modification, packaging and
storage of proteins from ER.
– Vesicles pinch off and fuse with sacs forming
a “golgi complex”
• These can be packaged products being shipped
out of the cell (secreted) or
• Enzymes in Golgi Ap. Attach carbs. and lipids to
proteins
• Packages full of digestive enzymes…
• http://www.tvdsb.on.ca/westmin/science/s
bi3a1/Cells/golgi.htm
Check for clarity-manufacturing
plant
Check for clarity…
Lysosomes
• Function demolition and clean up
team!!!
– Loysosomes:
• vesicles released by the golgi ap. that are full of
enzymes that break down carbs. Lipids and
proteins for recycling
• Digest bacteria engulfed by cell
• Digest/destroy worn out or diseased cells
• Enzymes so powerful they will destroy the cell
that made them if membrane is defective.
Mitochondria
• The powerhouse for the cell
• Contain some of their own DNA
• Maternally inherited (comes from egg
cell)
• Some evidence that mitochondria and
chloroplasts are descendents of
prokaryotic cells
• Formed a symbiotic relationship!
ATP produced in the mitochondria
to give the cells energy
http://www.tvdsb.on.ca/westmin/sci
ence/sbi3a1/Cells/mito.htm
Are we done yet??!!
• No! This is easy and
review for you…
• Chloroplasts use
sunlight to make
sugar/starch (food)
known as…..
• Photosynthesis!!!!
One more structure…
• Vacuoles in plants
and animal cells,
always in plant and
very large.
– Functions:
• Storage of water,
salts, proteins and
carbs.
• Provides support for
heavy structures like
flowers
• What is it we can’t
digest?
Yes, we’re done!
End of 7-2-end for genetics
• X-word puzzle
• View prepared slides of cells under
microscope
7-3 osmosis
 What is osmosis?
 Movement of water, gases and
other particles across the cell
membrane
Basis for osmosis.
 Solution solute (salt) and a
solvent (H20)
 Concentration mass (solute)
in given volume (solvent)
 E. g. 12 grams salt in 3 liters of
water
 12g/3 L 4 g/L or 4 grams per
liter
 Cytoplasm is a solution in the
cell
Osmosis
 Osmosisis the diffusion of
water through a selectively
permeable membrane
 Water can pass through the
membrane, sugar and other
molecules can’t
 Those molecules have to be assisted
osmosis
• Diffusion
movement across the
membrane that does
not require ATP or
energy.
– Water can diffuse
across the cell
membrane
– Water moves until
equilibrium has been
reached.
Osmotic Pressure
• What causes the
water to move?
– Moves from high H20
to low H20
– Body in fresh H20 lake
swells as H20 moves
in
– Body in GSL shrinks
as H20 leaves
Pressure!!!!
• As volume (space) decreases pressure
increases
– Think of a balloon
• Once there is no more room for gas (O2 or helium)
• It pops. Why?
– Space runs out for the gas to expand and take up space,
thus, as gas (substance) increases and volume (space)
decreases the rubber balloon pops due to pressure.
Substance/surface area to volume ratio
– Pressure is exerted on the rubber causing the balloon to
inflate.
Pressure!!!
• Why do cells experience pressure?
• Because the solutes/particles can’t diffuse
across the membrane
– This imbalance causes pressure between the
cell and it’s external environment
– And water moves because it can diffuse to
relieve pressure and create balance
 http://www.tvdsb.on.ca/westm
in/science/sbi3a1/Cells/Osmo
sis.htm
What do you think happened here?
Definitions for osmosis…
• Isotonic pressure
outside the cell is
equal to that within
the cell; solution has
equal amounts of
solutes and solvent
– Cell is normal size
– **water moves from
area of low solute
concentration to high
solute concentration**
Definitions for osmosis
• Hypertonic
solution cell’s
solute concentration
is lower than the
solute concentration
outside the cell
• Shrinks as H20
leaves the cell
• Body in GSL
Definitions for osmosis
• Hypotonic
solution
– cell’s solute
concentration is higher
than the solute
concentration outside
the cell
– The cell swells as H20
moves into cell
– Body in fresh water
lake
• http://www.tvdsb.on.ca/westmin/science/s
bi3a1/Cells/Osmosis.htm
Remember…
• Water moves from
an area of low
solute concentration
to high solute
concentration
• to find equilibrium
between the cell and
its external
environment
– Water is the
peacemaker!!
Facilitated diffusion
• Involves proteins
embedded in the cell
membrane
– Specific to molecule
• Sugars, salts and ions
– Does not require ATP
– Move from high to low
concentration
Active transport
• Requires ATP or energy
• These are pumps in the
cell
• Exocytosis the removal
of large materials form
the cell
• Endocytosis lg.
materials are ingested by
cell
– This process is called
phagocytosis
And we’re done!
• Video Osmosis and diffusion
• Egg and vinegar experiment
• Chap 7 questions 1- 25