Organelle Review

Golgi A pparatus M itochondr ia Ribosom es N ucleus

C ytoplasmWhich con tains

Plasm a M em brane Su rrounds T he

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 flexibleMosaic - forms patterns on

the membrane surface

Membrane FunctionDiffusionOsmosisPassive transport Active transportEndocytosisExocytosis

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

H2O

Movement

[H2O]

Inside cell

[H2O]

Outside cell

Isotonic [same] [same]

Hypotonic [Low] [High]

Hypertonic[High] [Low]

none

Into the cell

Out ofthe cell

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Osmosis

State

H2O

Movement

Solute [ ]

Inside cell

Solute [ ]

Outside Cell

Isotonic[Same] [Same]

Hypotonic [High] [Low]

Hypertonic [Low] [High]

none

Into the cell

Out ofthe cell

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