Introduction to Cells

Study Notes

Cells are fundamental units of structure and function in all living organisms.
All living things are made of cells, and they arise only from preexisting cells through division.
Key functions: store information, generate energy, adapt to movement, sense environmental changes, reproduce, and maintain homeostasis.

Prokaryotic Cells:
- Size: generally less than 10 µm.
- Lack a true nucleus; DNA is circular and not protein-bound.
- No membrane-bound organelles; all functions occur in cytoplasm.
- Unicellular organisms only, reproduce asexually via binary fission.
Eukaryotic Cells:
- Size: typically 10-100 µm.
- Have a true membrane-bound nucleus and multiple linear DNA strands associated with proteins.
- Contain various membrane-bound organelles.
- Can be unicellular or multicellular; reproduce sexually or asexually through mitosis and meiosis.

Three Main Regions:
- Cell Membrane: Protects the cell’s interior, regulates transport of substances, facilitates cell communication, and serves as an attachment for cytoskeleton and other cells.
- Nucleus: Largest organelle, functions as control center, houses genetic material (chromatin and chromosomes), and is involved in ribosome synthesis.
- Cytoplasm: Encloses organelles and is site for metabolic activities.

Organelles are specialized structures with distinct functions, essential for cellular operations.
Membranous Organelles: Endoplasmic reticulum, mitochondria, Golgi apparatus, lysosomes.
Non-Membranous Organelles: Ribosomes, cytoskeletal structures.

Functions in modifying, sorting, and packaging proteins and lipids for transport.
Has a structure consisting of flattened membrane sacs (cisternae).
Functions in receiving products from the ER and dispatching them as vesicles.
Faulty Golgi function can lead to diseases like muscular dystrophy, diabetes, and certain cancers.

Known as the cell’s powerhouse; responsible for energy production through cellular respiration.
Structure includes a smooth outer membrane, a folded inner membrane, and a matrix containing enzymes for ATP production.
Contain their own circular DNA and ribosomes, allowing them to self-replicate.
Play a significant role in cellular aging and can cause muscular dysfunction through mutations.

Enzymatic organelles containing enzymes for lipid metabolism and detoxification.
Break down fatty acids and harmful compounds while producing hydrogen peroxide (H2O2), which is neutralized by catalase.
Disorders can include X-linked adrenoleukodystrophy and Zellweger syndrome due to dysfunctional enzymes.

Organelles are crucial in various metabolic pathways and for the maintenance of cellular health.
Disorders of organelles can result in severe health consequences, emphasizing the need for proper functioning of cellular systems.