1. 4-3: Cell Organelles + Features
Eukaryotic cells have many membrane systems
Divide cells into compartments that function together to keep a cell alive

2. Plasma Membrane (Factory Doors)
Location: surrounds the cell + its parts
Functions:
Controls the ease w/ which substances pass into and out of the cell - - known as selectively permeable
Separates internal rxns with external environment
Allows the cell to excrete wastes and interact with environment
Description: made of lipids + proteins

3. Membrane Lipids Major type – phospholipids
Hydrophilic (head) – Hydrophobic (tail)
Forms a lipid bilayer
Heads outward, tails inward
Contains sterols between the tails
Example: Cholesterol

4. Membrane Proteins
Function: transporting molecules through lipid bilayer
Two types:
Peripheral – located on both interior + exterior surfaces of C.M.
Integral – embedded into the bilayer

6. Fluid Mosaic Model
States that the lipid bilayer behaves like a fluid, not like a solid
Membrane proteins + lipids can move laterally within the bilayer
Watch

7. Nucleus (Main Office) Location: in the cytosol
Size: most prominent structure
Surrounded by a double membrane called nuclear envelope
Shape is maintained by skeleton – nuclear matrix
Filled with fluid known as nucleoplasm

8. Function: store hereditary information
Chromatin – combo. of DNA + proteins - - coils up to chromosomes for cell division
Production of RNA – which directs protein synthesis - - leaves through nuclear pores
Nucleolus – synthesis of ribosomes

9. Mitochondria (Electricity Generator)
Location: scattered throughout the cytosol
Size: Relatively large
Function: site of chemical rxns that transfer nrg from org. compounds to ATP
Responsible for producing 95% of nrg for a cell to function
Found in high #s in liver + muscles cells
Liver cells contain 2500 mitochondria/cell

11. Mitochondria (cont.) Surrounded by 2 membranes Mitochondria DNA
Outer membrane serves as a boundary between mitochondria + cytosol
Inner membrane has long folds called cristae, which increase surface area for chemical rxns to take place
Mitochondria DNA
Can reproduce own their own
Ancient invasion?
ENDOSYMBIOSIS

12. Ribosomes Function: Protein synthesis
Location: scattered throughout the cytosol or attached to endoplasmic reticulum
Made in nucleolus, completed in cytoplasm
NOT membrane bound – evolution (prokaryotic cells)
Size: relatively small + most numerous; made of protein + RNA
Function: Protein synthesis

14. Endoplasmic Reticulum (Assembly Line)
Location: within the cytosol, sometimes attached to the nucleus
Description: cisternae – membranous tubes + sacs
Function: Intracellular highway – a path for molecules to move from one part to another

16. Types of ER Rough ER – covered with ribosomes Smooth ER – no ribosomes
Produces phospholipids + proteins
Prominent in cells that export large amounts of proteins from the cell or use in cell membranes
Smooth ER – no ribosomes
Synthesis of lipids (cholesterol)
Synthesis of steroids in glands
Regulate calcium levels in muscles
Breakdown toxic substances in liver cells

17. Golgi Apparatus (Packaging Center)
Location: within the cytosol
Appearance: system of membranes; series of flattened sacs
Function: works with ER to modify proteins for transport from cell

18. Vesicles Lysosomes Made by Golgi Contain digestive enzymes
Small, spherical sacs
Classified by contents
Lysosomes
Made by Golgi
Contain digestive enzymes
breakdown proteins, nucleic acids, carbs, fats
Digests old cells (autolysis) or old organelles (autophagy)
**FYI - - involved in embryonic development
ex. Human hand

19. Vesicles Peroxisomes Glyoxysomes Abundant in liver + kidney cells
Neutralize free radicals (Oxygen ions), detoxify alcohol + other drugs
Break down fatty acids for nrg source
Glyoxysomes
Found in plant seeds
Help break down fats to supply embryo with food

20. Protein Synthesis Pathway
Proteins assembled by ribosomes on rough ER
Vesicles transport proteins to Golgi
Golgi modifies proteins + packages them in new vesicles
Vesicles release proteins outside cell (vesicles remain in cell to be used again)

21. Cytoskeleton Location: within the cytosol
Size: spans the entire length of cell – provides a framework
Functions:
Provide structure to maintain shape + size
Participates in movement of organelles in the cytosol

22. Components of Cytoskeleton
Microtubules – hollow tubes
Extend from a central point (centrosomes)
Form spindle fibers during cell division
Microfilaments – thread-like strands
Chains made of actin molecules
Cell movement + contraction of muscle cells
Intermediate filaments – rods
Anchor nucleus in place

23. Cilia + Flagella Cilia – short; present in large numbers
Location: extend from surface of cell
Appearance: hair-like organelles
Function: assist in movement
Cilia – short; present in large numbers
Propulsion through water
Ex. Nose + inner ear
Structure of cilia – cross section

24. Flagella – longer; less numerous
Common for only 1 flagellum to be present
Whips back and forth to propel cell
Ex. E. coli + sperm

25. Centrioles Two short cylinders of microtubules near nuclear envelope
Found in animal cells
Organize microtubules during animal cell division