Organelle Review

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 H 2 O 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 H 2 O outside cell; H 2 O moves in (Animal cells burst; Plant cells swell)

Hypertonic – high solutes/ low H 2 O outside cell; H 2 O 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 H 2 O Movement [H 2 O] Inside cell [H 2 O] Outside cell Isotonic [same] Hypotonic[Low][High] Hypertonic [High][Low] none Into the cell Out of the cell

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Osmosis State H 2 O Movement Solute [ ] Inside cell Solute [ ] Outside Cell Isotonic [Same] Hypotonic[High][Low] Hypertonic[Low][High] none Into the cell Out of the 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