Download Cell Organelle Functions part 1

Cell Organelle Functions part 1
Eukaryotic cell structures:
1. Cell Membrane:
a. description-Thin semipermeable
membrane (selectively permeable)
def. Selective Permeability =
allows only certain materials to go into & out of cell
b. STRUCTURE: Bilayer (2 layers) of PHOSPHOLIPIDS
1) POLAR
Globular ends face INSIDE & OUTSIDE the cell (where H2O is found)
2) NONPOLAR
Straight tails face inside bilayer (to avoid H2O)
3) Protein molecules are embedded and float freely. That is why the membrane is
sometimes referred to as a “fluid mosaic model”
2. Cytoplasm – space within cell
* Cytosol = gel-like fluid that suspends organelles
3. Nucleus – controls all activities of cell
Three major parts:
a. Nuclear membrane/ envelope = allows certain materials into & out of nucleus
through pores
b. Nucleolus = makes ribosomes
c. DNA (chromatin) – hereditary info.
Organelles Part 2
4. Endoplasmic Reticulum (ER) – TRANSPORT materials from ribosomes to Golgi complex
a. Rough ER = ribosomes attached; makes & transports PROTEINS
b. Smooth ER = no ribosomes; makes & transports LIPIDS
5. Ribosomes – makes PROTEINS (directed by nucleus)
a. free floating in cytosol
b. attached to endoplasmic reticulum
6. Golgi apparatus (bodies) flattened sacs that– MODIFY, PACKAGES & SECRETES PROTEINS from the ribosomes
to be used inside & outside of cell
a. packages proteins into VESICLES [small bubbles]
7. Lysosomes –BREAK DOWN wastes, food & old cell parts using enzymes
8. Vacuoles – pouch that STORES water, food & some wastes
a. very LARGE in PLANT; small in animal cells
9.. Mitochondria – makes ENERGY (ATP) for cell
a. Has its own DNA
b. Completes the breakdown of glucose to carbon dioxide to make energy
c. Muscle cells need a lot of mitochondria for energy
d. Inner, folded membrane = CRISTAE
Important details:
Mitochondrion is called the "Powerhouse". It releases energy when bonds are broken.
The production of ribosomes begins in the nucleus, the rough ER takes the proteins from the ribosomes and transports
them where the golgi apparatus (golgi bodies) modify, package & package the proteins for storage or delivery to
outside the cell
Cell Organelle Functions
part 3
10. Centrioles –make spindle fibers in cell division
a. only in ANIMAL cells
Animal cells have many different methods of movement.
11. Cilia – short hair-like projections for MOVEMENT
12. Flagella – long, whip-like structure for MOVEMENT
Plant cells are basically rectangular in shape.
They look like a brick wall.
Plant cells have a cell wall to give it shape that is located outside the membrane.
13. Cell wall – rigid structure outside cell membrane for STRUCTURE, SUPPORT &
PROTECTION
a. made of CELLULOSE
b. Only in PLANT cells
14. Chloroplast – CONVERTS light energy to chemical energy (photosynthesis)
a. contain chlorophyll [pigment that captures light]
b. Only in PLANT cells
c. Makes sugar
from carbon dioxide
Active Transport
Cellular Transport (through cell mem.)
Why is the cell membrane “selective?”
HOMEOSTASIS!
= Maintains a stable environment (size) by controlling what enters & leaves.
Two Categories of Transport
Active (requires chemical energy)
versus
passive (does NOT require chemical energy)
Active Transport = pumping substances across membrane USING ENERGY (ATP)
* Molecules move from low/lesser to high/greater concentration
("Against" the concentration gradient)
Types of Active Transport
1. Endocytosis = move large amounts of materials INTO cell in VESICLES
a. Steps:
1) membrane folds in to form pocket
2) Pocket closes & pinches off inside cell to form vesicle
3) vesicle fuses w/ organelles to release contents
b. Two Types of Endocytosis:
1) Phagocytosis – LARGE particles (food) or whole CELLS (bacteria) into cell
2) Pinocytosis – large amounts of solutes/ fluids into cell
2. Exocytosis – releases large amounts of material OUT of cell in VESICLES
a. Steps:
1) Vesicle forms, travels to & fuses w/ cell mem.
2) Vesicle opens to outside & releases contents
Passive Transport
Types of Passive Transport
1. Diffusion – molecules move from HIGH to LOW concentration gradient and/or voltage gradient.
a. Moves small & nonpolar (uncharged) molecules
b. Uses pores or open channel proteins
c. Slow process
2. Facilitated Diffusion – moves molecules from HIGH to LOW conc.
a. Moves large & polar molecules
b. Uses CARRIER proteins
(pores/channels too small)
c. Faster than diffusion
3. Osmosis – movement of WATER from HIGH to LOW conc.
* H2O moves to area with MORE SOLUTES
a. Three Types of Solutions:
1) Hypotonic Solution = H2O
Hyp0ertonic Hs) moves out of cell and cells shrinks
moves INTO cell & CELL EXPANDS
2) Isotonic Solution = H2O moves INTO & OUT OF cell & cell stays NORMAL SIZE
Plants display turgor pressure
TURGOR PRESSURE = force of vacuole against cell membrane & wall
a) HIGH turgor pressure = very full vacuole; pushes all other organelles against the cell wall
*Plant stands & is rigid
b) LOW turgor pressure = vacuole not full; all organelles & cytoplasm shrink in from cell wall
* Cell loses its shape
* PLASMOLYSIS = wilting of plant