Bio Chapter 3 Cell Structure and Function
Essay by rssh • January 12, 2018 • Study Guide • 1,130 Words (5 Pages) • 964 Views
Unit 3 Cell Structure and Function
3.1 Cell Theory
All organisms are made of cells[pic 1]
- Principles of cell theory All existing cells are produced by other living cells
The cell is the most basic unit of life
- Prokaryotic cells and eukaryotic cells
Prokaryotic cell | Eukaryotic cell |
Doesn’t have a nucleus | Has a nucleus |
Doesn’t have membrane-bound organelles | Has membrane-bound organelles |
Usually unicellular | Usually multicellular |
-Shared characteristics: enclosed by a membrane, filled with cytoplasm, have DNA and ribosomes.
3.2 Cell Organelles
Name | Structure and components | Function | Others |
Cytoskeleton | Microtubules | Shape the cell, position and transport organelles, assist in cell division | --- |
Intermediate filaments | Give the cell its strength | ||
Microfilaments | Enable cells to move and divide | ||
Nucleus |
| Stores genetic information | --- |
Endoplasmic reticulum | An interconnected network of thin, folded membranes
| Accommodate the process of producing proteins and lipids | --- |
Ribosomes | --- | Use the information from DNA to link amino acids and form proteins | Studded on the ER or suspended in the cytoplasm |
Golgi apparatus | Closely layered stacks of membrane-enclosed spaces | Process, sort, package and deliver proteins | --- |
Vesicles | Small membrane-bound sacs | Transport proteins to the Golgi apparatus | Pinched off from the ER |
Mitochondria |
| Supply energy | |
Vacuole | Fluid-filled sacs | Store materials needed by a cell (e.g. water, food molecules, inorganic ions, enzymes) | Plant cells contain central vacuoles |
Lysosomes | Contain enzymes | Hydrolyze (break down) proteins, fats, polysaccharides and nuclear acids | Lysosomal enzymes work best in acidic environment inside lysosomes |
Centrosomes | Contain two centrioles perpendicular to each other |
| |
Cell walls | A rigid layer surrounding the cell | Gives protection, support and shape to the cell | Does NOT exist in animal cells |
Chloroplasts |
| Carry out photosynthesis | Does NOT exist in animal cells |
3.3 Cell Membrane
- Basic structure
Charged phosphate group[pic 2][pic 3][pic 4]
- Phospholipids Glycerol
Fatty acid chains —— Nonpolar “tail
-Phospholipids form double layers because the polar heads bond to water molecules in the fluid inside and outside the cell, while the nonpolar tails are attracted to each other and repelled by water.
2. Embedded substances: cholesterol, protein, carbohydrate chain, proteins, protein channels…
- Selective permeability (allowing some materials, but not all, to pass)
Pass | Don’t pass |
Small | Large |
Nonpolar | Polar |
Not charged | Charged |
-Function: enables a cell to maintain homeostasis in spite of the changing conditions outside the cell
- Transmission of chemical signals
1. Ligand: signal molecules that bind to the receptors
2. Receptors: proteins that detect a signal molecule and perform an action in response
-Intracellular receptors: bind to certain small signal molecules that cross the membrane
-Membrane receptors: bind to signal molecules outside the cell change shape cause molecules inside the cell to respond[pic 5][pic 6]
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