Transcript Protein Synthesis, Membrane properties, structure

Organelle Review
Plasma Membrane Surrounds The
Cytoplasm
Which contains
Golgi Apparatus Mitochondria
Ribosomes
Nucleus
Protein Synthesis and Secretion
• Ribosomes attach to the E.R. and make
protein
• Protein is then sent to the Golgi
Apparatus
• The G.A. packages it up and sends it off
to the Plasma Membrane where it can
be released from the cell.
Ribosomes –> E.R. –> Golgi A. –>
Plasma Membrane
Why do Organelles have
Folded Membranes?
• Provides a larger surface area
• Allows for cell processes to be more
efficient and effective
• Forms interconnected compartments
Basically it gives the organelle more space
to do work!
Are all Cells Created Even?
“How come plant cells have
chloroplasts, I want one of
those! That’s Booty!”
Only in Animal Cells
• Lysosomes – contains enzymes that
digest proteins, food, and other such
things.
• Centrioles – paired structure that
assists during cell reproduction
Only in Plant Cells
• Plastids –produces food for the cell
through a process called photosynthesis
(chloroplast, chromoplast, leucoplast)
• Cell Wall – protection and support
– Also found in algae, fungi, and bacteria
• Dictysomes – responsible for cell wall
formation (collection and packaging
center)
Bacterial Cells
(prokaryotic)
• Single Celled Organisms
• Lack a nucleus and other membrane
bound organelles
 Copy picture from board
Membrane Properties
• Gate Keeper – controls what enters
and leaves the cell (outer boundary)
• Selective Permeability – only certain
substances can cross the membrane
– Small vs. Large
– Neutral vs. Charged
Membrane Structure
• Lipid Bilayer – two layers of
phospholipids
acts as barrier and boundary
• Phospholipid – 2 fatty acid tails and a
phosphate head
• Tails are non polar, don’t like water
• Heads are polar, face inside and outside
of cell where water is
Membrane Structure Continued
• Cholesterol – bind and restrict
movement of lipid bilayer; allows for
strength and flexibility
• Proteins – some pass through bilayer,
while some are only on surfaces
– Function regulation, enzymes,
markers for chemicals, infection, and
recognition
Fluid Mosaic Model
Fluid - membrane is flexible
Mosaic - forms patterns on
the membrane surface
Membrane Function
Diffusion
Osmosis
Passive transport
Active transport
Endocytosis
Exocytosis
DIFFUSION
• Random movement of particles from
high concentration to low concentration
• [high] to [low]
• Diffusion occurs across membranes
until equilibrium (homeostasis) is
reached
• Dynamic equilibrium – particles are
evenly spread, equal [ ] , but still
moving
OSMOSIS
• Diffusion of H2O across a selectively
permeable membrane
• Osmotic conditions have 3 options:
Isotonic, Hypotonic, Hypertonic
How many of you have every killed a
plant? How?
Over watering or Under watering?
• Isotonic – same [ ] of solutes
inside as outside cell, not net
change
• Hypotonic – low solutes/ high H2O
outside cell; H2O moves in
(Animal cells burst; Plant cells swell)
• Hypertonic – high solutes/ low H2O
outside cell; H2O moves out
• Animal cell shrinks
• Plant cell contents shrink (loss of
turgor pressure)
Think… when you are hyper, you
want to move out of your seat!
Osmosis
State
Isotonic
H2O
[H2O]
Movement Inside cell
[H2O]
Outside
cell
none
[same]
[same]
Hypotonic
Into
the cell
[Low]
[High]
Hypertonic
Out of
the cell
[High]
[Low]
`
Osmosis
State
Isotonic
H2O
Solute [ ]
Movement Inside cell
Solute [ ]
Outside
Cell
none
[Same]
[Same]
Hypotonic
Into
the cell
[High]
[Low]
Hypertonic
Out of
the cell
[Low]
[High]
PASSIVE TRANSPORT
• No energy is required to move
particles through the cell’s plasma
membrane
• Facilitated Diffusion
– Protein required to move particles
through membrane
– Move down [ concentration]
gradient by random movement
– Channel proteins vs. carrier
proteins
– How glucose (sugar) enters the cell
ACTIVE TRANSPORT
• Move substances from [low] to [high]
• Requires:
– Cell to use energy
– Transport protein (pump) = each
pump is specific for a certain
substance
• 2/3 of your energy used to actively
transport Sodium and Potassium across
membranes
ENDOCYTOSIS (endo = in)
• Process in which the plasma membrane
engulfs substances from the
environment
• Pinocytosis – “cell drinking” large drops
of liquid.
• Phagocytosis – “cell eating” large
particles are engulfed into a vesicle for
digestion
– Ex: Amoeba’s and White Blood Cells
(Immunity)
EXOCYTOSIS (exo = exit)
• Process of removing large particle or
volumes of liquid
• Excretion – removal of waste
products
• Secretion – removal of cell products
needed elsewhere
• Requires vesicle and energy