^^Compartmentalization^^ in organelles allows for different metabolic reactions to occur in different places (giving them their own membranes to function).

Increases surface area
Prevents reactions from interfering with each other.
A lot of complex reactions are going on at the same time, so this allows for efficiency and to manage specific conditions necessary for certain reactions.
- Without this, everything would be occurring in the same place at the same time and it would be chaotic.

[[Unique cell components[[

Plants:

^^Chloroplasts^^
^^Central vacuole^^
- Animals have vacuoles too, but the central vacuole helps to maintain water balance and rigidity in a plant
^^Cell wall^^
^^Plasmodesmata^^

Animals:

^^Lysosomes^^
^^Centrosomes^^
^^Flagella^^
- sperms

[[Endomembrane Organelles[[

Note: ^^Metabolism^^ means to break things down.

^^Nucleus^^: Contains chromosomes (genetic info)

Enclosed by ^^nuclear envelope^^
Double membrane
- Contains pores
Regulates entry and exit of materials from the cell

^^Nucleolus^^: Dense region of the nucleus where ribosomal RNA (rRNA) is synthesized

Combined with proteins to form large/small units of ribosomes
Subunits exit via nuclear pores to be assembled
Ribosomes translate messages found in mRNA

^^Ribosomes^^: Synthesizes proteins

Composed of rRNA and protein
Found in cytosol and/or bound to ER or nuclear envelope
- Proteins produced here generally function within the cytosol (enzymes), free floating
Proteins produced in the ER/Nuclear envelope are secreted from the ribosomes
Rough ER is the one w/ ribosomes attached

Endoplasmic Reticulum: Network of membranous sacs and tubes; has membranes to help compartmentalize the cell

Dots = rough ER (ribosomes), no dots = smooth ER
- On Rough ER, the ribosomes make the proteins and the ER will transfer them out.
- Smooth ER contains no ribosomes and instead synthesizes lipids.

Golgi body: Contains flattened membranous sacs called cisternae (are not connected) and vesicles

Separates sacs from cytosol
Has directionality
- Cis face
- Receives proteins from ER
- Trans face
- Sends proteins back out into the cytosol post-modification to other locations or back to the membrane

Function: Sorts and sends out proteins to be transported to the lysosomes, plasma membrane, or to be secreted

Lysosome: Membranous sac with hydrolytic enzymes

Function:

Hydrolyzes macromolecules in animal cells
Authophagy: Lysosomes can recycle their own cell’s organic materials
- Allows the cell to renew itself
- EG: Breaking up nucleic acids into nucleotides to be reused

Peroxisomes: Similar to lysosomes, more specific class

Membrane bound metabolic compartments

Function:

Catalyzes reactions that produce hydrogen peroxide (H₂O₂)
- Peroxisome (peroxide).

Vacuoles: Large vesicles; Pockets used for organizing cellular substances and creating reaction chambers

Stem from ER and Golgi, more selective in transport
Multipurpose

Types:

Food vacuole
- Formed via cell eating (phagocytosis) and then are digested by lysosomes
Contractile vacuole
- Maintains water levels
Central vacuole
- Only in plants

Energy organelles

Mitochondrion: Site of cellular respiration

Structure of double membrane:

Outer is smooth
Inner has folds called cristae
- Divides mitochondria into two internal compartments and increases surface area
- Intermembrane: Space between inner/outer
- Mitochondrial matrix: Enclosed in inner membrane
- Location where Krebs cycle occurs
  - Has enzymes that catalyze ATP
- Contains mitochondrial DNA and ribosomes
More mitochondria = more metabolic activity
- EG: Cells that move/contract; have to do a lot of work, needs more ATP (muscles)

Chloroplasts: Specialized organelles in photosynthetic organisms

Performs photosynthesis
Contains chlorophyll (green)
Double membrane has:
- Thylakoids
- Membranous sacs that can organize into stacks called grana
- Light dependent reactions
- Stroma
- Fluid around thylakoids
- Location for Calvin cycle.
Contains:
- DNA
- Ribosomes
- Enzymes

*both organelles have the same building blocks

Misc.

Cytoskeleton: Network of fibers throughout cytoplasm

Gives structural support, especially in animal cells
Anchors organelles
Not found in all cells

Endosymbiosis Theory:

A prokaryote enveloped a eukaryote and instead of consuming it, it remained inside of itself.
The prokaryotic cell would provide food molecules and energy.
The eukaryotic cell would provide oxygen and a safe region for the eukaryotic cell to exist.
Prokaryotic cell eventually lost independent function and evolved into the mitochondria/chloroplasts.
They became one functional organism

Evidence: (boils down to the similarities between the types of cells)