1. Components found only in Eukaryotic Cells
Rough Endoplasmic Reticulum (ER)
Folded membrane that forms compartments where newly synthesized proteins are processed (cut, joined, folded into their final shape)
Ribosomes bind to rough ER when they start to synthesize proteins that are intended to be exported from the cell – the proteins enter the ER directly from the ribosome

2. Components found only in Eukaryotic Cells
Smooth Endoplasmic Reticulum (ER)
Synthesis of lipids and steroids
Metabolism of carbohydrates and steroids
Regulation of calcium concentration
Drug/toxin detoxification
Attachment of receptors on cell membrane

3. Components found only in Eukaryotic Cells
Golgi Apparatus
Folded membranes form compartments that each contain different enzymes which selectively modify the contents depending on where they are destined to end up
Processes and packages macromolecules produced by the cell (e.g. proteins and lipids) – sent out as excretory vesicles “labeled” for their destination

4. Components found only in Eukaryotic Cells
Cytoskeleton
Network of long protein fibers (microtubules, actin filaments, and intermediate filaments)
Helps support cell shape and movement
transport organelles and vesicles throughout the cytoplasm to other areas within the cell
The cytoskeleton is stained green in this image (the nucleus is stained blue and the cell membrane is stained red)

5. Components found only in Eukaryotic Cells
Membranous Sacs
Excretory Vesicles
Carry products of protein synthesis to parts of the cell or to membrane to be excreted via exocytosis
Vacuoles
Store nutrients such as starch, glycogen, or fat
Take up most of space in many plant cells, full of water
Peroxisomes
In animal cells – full of enzymes that oxidize amino acids
In plant cells – full of enzymes that oxidize fat
In plant and animal cells – convert hydrogen peroxide to water
Lysosomes
Contain digestive enzymes
Fuse with vesicles and vacuoles containing food, cell refuse, captured bacteria, etc

6. Components found only in Eukaryotic Cells
Centrioles
Form centrosome and initiate formation of the mitotic spindle during cellular replication
Found in animal cells and some plant cells – not in higher plants or fungi
Composed of microtubules (like those in the cytoskeleton)

7. Components found only in Eukaryotic Cells
Mitochondrion (plural – Mitochondria)
Brakes down glucose (sugar) using oxygen to produce energy for the cell = cellular respiration
Many cells have only a single mitochondrion, whereas others can contain several thousand
Have own DNA and ribosomes

8. Photosynthetic Organelles
Chloroplasts (plant cells and photosynthetic protists)
Use light energy to convert atoms in water and CO2 (from air) into sugars and starches
Have double membrane (inner and outer)
Have own DNA and ribosomes
Grana (stacks of thylakoids) – where light energy is captured by chlorophyll and converted into chemical energy = photosynthesis
Stroma – fluid inside chloroplasts
Chlorophyll – light-absorbing pigment in thylakoids

9. Endosymbiotic Theory
Concept that mitochondria and chloroplasts are the result of years of evolution initiated by the endocytosis of bacteria and blue-green algae which, instead of becoming digested, became symbiotic

10. Endosymbiotic Theory
Concept that mitochondria and chloroplasts are the result of years of evolution initiated by the endocytosis of bacteria and blue-green algae which, instead of becoming digested, became symbiotic
Have their own DNA which resembles bacterial DNA
Have their own 70s ribosomes and produce their own proteins
Double membrane indicates they entered cell via endocytosis
Membrane composition strongly resembles Gram-negative bacteria
Divide within eukaryotic cell via binary fission (the way of bacteria)
Similar symbiotic relationships exist between organisms that are still distinct species from one another
Some evidence indicates that eukaryotic flagella and cilia may have originated as symbiotic bacteria as well

11. Evolution of Eukaryotes
Some protists lack mitonchondria which indicates that the eukaryote lineage evolved before the ancestral bacterial of mitochondria established a symbiotic relationship with early protists

12. Cell Walls Tough, rigid wall around cell membrane Functions:
Most prokaryotes
Eukaryotes: plants, algae and fungi only
Functions:
Prevents over-expansion when water enters the cell via osmosis
Structural support (otherwise cells would be spherical)
Protection

13. Cell Walls
Composed of cellulose and/or chitin in eukaryotes (only plant and fungi cells have cell walls in eukaryotes)

14. Other External Structures
Flagella
Creates movement in prokaryotes by rotating like a propeller
Whip-like movement in eukaryotes
Larger and more complex in eukaryotes - common in protozoa, found in some algae - only spermatozoa cells in humans
Positive chemotaxis – cell moves up concentration gradient
Negative chemotaxis – cell moves down concentration gradient
Phototaxis – cell moves towards (positive) or away from (negative) light

15. Other External Structures
Cilia (eukaryotes only)
Numerous on surface of cell
Beat in a coordinated pattern creating a wave of movement
Mostly occur in protozoa, but some human cells too (like those lining the respiratory tract)
Pili (prokaryotes only)
also known as fimbria
Hair-like appendage on bacteria that help the bacteria connect to other cells in order to exchange plasmids (DNA)