BIO 120 Lecture Notes

Organelle: Tiny organ inside a cell responsible for specific functions.
Nucleus: Unofficial center of the cell; primary storage location of DNA.
Mitochondria: Known as the energy center; organelles that produce ATP through cellular respiration.
Cytoskeleton: Provides structural support to the cell; a network of protein filaments and tubules.
Centrioles: Essential for cell division; involved in organizing microtubules.
Endoplasmic Reticulum (ER): Involved in lipid and protein synthesis.
- Smooth ER: Lacks ribosomes; involved in lipid and steroid synthesis.
- Rough ER: Contains ribosomes; site of protein synthesis.
Lysosomes: Contain digestive enzymes that break down macromolecules; involved in waste processing.
Golgi Apparatus: Modifies, sorts, and packages proteins and lipids; often referred to as the “FedEx” of the cell.
Peroxisomes: Organelles that break down specific molecules, including fatty acids and amino acids.

Animal Cells:
- Have lysosomes and centrioles.
- Lack a cell wall.
Plant Cells:
- Have a cell wall, which provides structure and protection.
- Contain a central vacuole, that stores water and maintains turgor pressure.
- Possess chloroplasts for photosynthesis.

Defined as a specific set of organelles surrounded by membranes.
Organelles within this system have specific functions and work together continuously, ensuring efficient cellular processes.
- Vesicles: Transport materials between organelles; are described as vehicles.
- Budding: Process by which vesicles are formed by the membrane of an organelle.
- Merging: Process by which vesicles fuse with the membranes of organelles or the plasma membrane.

Defined as the process of exiting molecules from a cell; involves vesicles moving toward the plasma membrane.

Defined as the process of entering molecules into the cell; vesicles fuse with the membrane to facilitate transport.

Vesicles play a crucial role by fusing with the membranes of organelles or the plasma membrane to transport materials.
Transfer of genetic material (DNA, RNA) occurs through nuclear pores to the Endoplasmic Reticulum, where ribosomes synthesize proteins.

Composed of many membranes called Cisternae.
- Smooth ER: Engaged in the synthesis of lipids and steroids, no ribosomes present.
- Rough ER: Has ribosomes attached that synthesize proteins.
- Hepatic Cells: Involved in breaking down toxins and contain extensive networks of smooth and rough ER.

Functions to modify, package, and transport lipids and proteins; analogous to a shipping company.
Modification Methods:
- Glycosylation: The addition of carbohydrates to proteins; yields glycoproteins which serve protective functions.
- Glycolipids are also synthesized here.

Described as flexible, movable stomachs in cells that digest waste materials.
Maintain a constant internal pH (around 5) optimal for enzyme function.
- Contain transport proteins (proton pumps) that help maintain the acidic environment inside lysosomes.
Example: Tay-Sachs Disease results from lysosomes failing to break down waste effectively.

Large storage structures found within cells.
- Create osmotic pressure in plant cells, particularly through the central vacuole for water storage.
- Contractile Vacuole: Present in protists, such as Paramecium, to pump excess water out of the cell.
Phagocytosis: The process of engulfing and digesting food particles by the cell.
Pinocytosis: The process of ingesting extracellular fluid; it’s often referred to as “cell drinking.”

Mitochondria: The powerhouse of the cell, involved in energy production through aerobic respiration.
Chloroplasts: Involved in photosynthesis; found in plant cells.
Both mitochondria and chloroplasts are thought to have originated from ancient engulfed prokaryotic cells (Endosymbiotic Theory).

The cell functions as an integrated unit where no single component operates in isolation.
Continuous coordination among organelles is essential for the survival of cells and the overall organism.