뒤로Cell Structure & Function: Study Notes
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Cell Structure & Function
Introduction
Cells are the fundamental units of life, forming the basis of all living organisms. Understanding their structure and function is essential for comprehending biological processes at every level of organization.
The Four Big Ideas in Cell Biology
1. Evolution
All cells arise from pre-existing cells, creating an unbroken lineage that traces back nearly 4 billion years.
This continuity is a cornerstone of evolutionary theory, explaining the shared characteristics among all living things.
2. Energy & Homeostasis
Eukaryotic cells contain multiple, specialized organelles that cooperate to maintain the structure and functions necessary for life.
These organelles enable cells to regulate their internal environment (homeostasis) and efficiently manage energy.
3. Information & Signaling
Every cell contains DNA, which encodes the information required for all cellular structures and functions.
DNA may be enclosed within a nucleus (eukaryotes) or exist freely in the cytoplasm (prokaryotes).
4. Interactions & Systems
Cells interact with their environment and with each other, adapting to changing conditions through metabolic and signaling pathways.
These interactions are essential for the survival and function of multicellular organisms.
Types of Cells
Prokaryotic Cells
Prokaryotes include bacteria and archaea.
They lack membrane-bound organelles (such as a nucleus, mitochondria, or endoplasmic reticulum).
Genetic material is located in a region called the nucleoid.
Other features: cell wall, plasma membrane, ribosomes, sometimes flagella or pili.
Eukaryotic Cells
Eukaryotes include animals, plants, fungi, and protists.
They possess membrane-bound organelles, including a nucleus that houses DNA.
Two main types: animal cells and plant cells.
Plant cells have additional structures such as a cell wall, chloroplasts, and a large central vacuole.
Comparison Table: Prokaryotic vs. Eukaryotic Cells
Feature | Prokaryotic Cells | Eukaryotic Cells |
|---|---|---|
Membrane-bound organelles | No | Yes |
Nucleus | No (nucleoid region) | Yes |
Cell wall | Yes (most) | Yes (plants, fungi); No (animals) |
Size | 1–10 μm | 10–100 μm |
Examples | Bacteria, Archaea | Animals, Plants, Fungi, Protists |
Key Terms
Organelle: A specialized subunit within a cell that has a specific function, usually surrounded by its own membrane.
Nucleus: The membrane-bound organelle in eukaryotic cells that contains genetic material (DNA).
Cytoplasm: The region of the cell within the plasma membrane, including the cytosol and organelles (except the nucleus in eukaryotes).
Plasma membrane: The lipid bilayer that forms the outer boundary of the cell, controlling the movement of substances in and out.
Example: Bacterial vs. Plant vs. Animal Cells
Bacterial cells (prokaryotes): No nucleus, no membrane-bound organelles, usually have a cell wall.
Plant cells (eukaryotes): Have a nucleus, membrane-bound organelles, cell wall, chloroplasts, and large central vacuole.
Animal cells (eukaryotes): Have a nucleus, membrane-bound organelles, but lack a cell wall and chloroplasts.
Additional info: The images in the slides visually compare the internal structures of prokaryotic and eukaryotic cells, highlighting the presence or absence of organelles and the differences between plant and animal cells.
