Chapter 4 Summary

1. Microscope: An instrument that magnifies and visualizes very small objects, such as cells and microorganisms.
2. Light microscope: Uses visible light and lenses to magnify small objects, allowing observation of specimens like cells and tissues
3. Electron microscope: Use beam of electrons to achieve much higher magnification and resolution than light microscopes; allow detailed visualization of structures at the molecular and atomic levels
4. Scanning electron microscope: Used to see the details of cell surfaces
5. Transmission electron microscope: Used to see the details of a cell’s internal structures
6. Cell theory: All organisms are made of one or more cells; All the life functions of organisms occur within cells; All cells come from existing cells.
7. Prokaryotic cells: Simple cells lacking a nucleus and membrane-bound organelles (e.g. bacteria)
8. Eukaryotic cells: Complex cells containing a nucleus and membrane-bound organelles (e.g. plant and animal cells).
9. Plasma membrane: A selectively permeable barrier surrounding cells, controlling the passage of substances in and out
10. Phospholipid bilayer: Double-layered arrangement of phospholipids creating the fundamental structure of cell membranes.
11. Intracellular: Located or occurring inside a cell
12. Extracellular: Located or occurring outside a cell
13. Fluid Mosaic: A model describing the plasma membrane as a fluid structure composed of lipids, proteins, and carbohydrates that move freely within it
14. Cytoplasm: All cellular material inside the plasma membrane, excluding the nucleus
15. Cytosol: The fluid component of the cytoplasm
16. Cytoskeleton: Framework of protein fibres within cells that provides structural support
17. Extracellular matrix: A network of proteins and polysaccharides outside cells that holds cells together in a tissue
18. Flagella: Long, whip-like structures that extend from the plasma membrane and help in movement
19. Cilia: short, hair-like structures that extend from the plasma membrane and help in movement
20. Organelle: A specialized structure within a cell performing specific functions (e.g. mitochondria)
21. Nucleus: The cell’s control centre; contains the cell’s DNA
22. Nuclear envelope: Double-layered membrane surrounding the nucleus, protecting genetic material.
23. Nuclear pores: Channels in the nuclear envelope that regulate the passage of molecules between the nucleus and cytoplasm.
24. Nucleolus: A dense region within the nucleus where ribosomes are synthesized
25. Mitochondrion: Organelle responsible for producing cellular energy (ATP) through cellular respiration
26. ATP (adenosine triphosphate): The primary energy-carrying molecule cells use for metabolic processes
27. Endoplasmic Reticulum (ER): Membranous organelle involved in protein synthesis and lipid synthesis; composed of smooth ER and rough ER
28. Rough ER: Membranous organelle studded with ribosomes, which gives it a “rough” appearance; involved in protein synthesis
29. Smooth ER: Membranous organelle that looks smooth because it lacks ribosomes; makes lipids
30. Golgi Apparatus: Organelle that modifies, sorts, and packages proteins and lipids for transport within or outside the cell
31. Vesicle: Small sac-like organelle that stores and transports materials in the cell
32. Lysosomes: Vesicles containing digestive enzymes to break down foreign matter and dead cells
33. Centrioles: Organelles aiding in cell division by organizing microtubules in animal cells
34. Ribosomes: Sites of protein synthesis; composed of rRNA and proteins; found in cytoplasm or attached to rER
35. Cell wall: Provides structural support and protection to plant cells, fungi and some protists
36. Chloroplast: Organelle found in plant cells and some protists that conducts photosynthesis, converting light energy into chemical energy stored in glucose
37. Large central vacuole: Organelle in plant cells that stores water, nutrients, and waste products
38. Endosymbiotic Theory: Suggests that eukaryotic cells originated through a symbiotic relationship where one free-living cell engulfed another, leading to the development of organelles like mitochondria and chloroplasts
39. Passive Transport: Movement of substances across membranes without energy input; moving down a concentration gradient
40. Diffusion: Passive movement of molecules from high to low concentration until evenly spread out
41. Osmosis: Diffusion of water molecules across a membrane
42. Facilitated diffusion: Diffusion with the help of transport proteins
43. Transport proteins: Proteins that facilitate the movement of molecules across membranes
44. Homeostasis: A state in which stable conditions are maintained inside a cell or organism
45. Tonicity: Relative concentration of solutes in a solution outside a cell compared to inside; affects cell water movement
46. Hypotonic: A solution with a lower solute concentration causes water to enter cells and potentially cause swelling
47. Isotonic: A solution with equal solute concentration to the cell, maintaining equilibrium with no net water movement
48. Hypertonic: A solution with a higher solute concentration causes water to exit cells, potentially causing shrinkage
49. Active Transport: Movement of substances across membranes requiring energy input (ATP); moving substances against their concentration gradient
50. Sodium-Potassium Pump: Protein pump using ATP to actively transport sodium ions out and potassium ions into the cell, maintaining concentration gradients essential for cell functions
51. Vesicle Transport: Movement of materials inside membrane-bound vesicles, either into or out of a cell
52. Endocytosis: A type of vesicle transport that moves a substance into the cell
53. Phagocytosis: A type of endocytosis where large particles are engulfed; “cell-eating”
54. Pinocytosis: A type of endocytosis where cells ingest extracellular fluids and dissolved substances; “cell-drinking”
55. Exocytosis: A type of vesicle transport that moves substances out of the cell
56. Types of microscopes: light microscope, electron microscopes (scanning and transmission)
57. Who coined the term “cell”: Robert Hooke, after observing the structure of cork under a microscope in 1665
58. 2 basic types of cells: prokaryotic and eukaryotic
59. Characteristics of prokaryotic cells: evolved ~3.5 BYA; smaller, simple cells; most have cell walls; have a plasma membrane; no membrane-bound organelles; have a nucleoid; have ribosomes
60. Characteristics of eukaryotic cells: evolved ~2.1 BYA; larger, more complex; plant cells have cell walls while animal cells have an extracellular matrix; have a plasma membrane; have membrane-bound organelles; have a nucleus; have ribosomes
61. Why do cells remain small? Cells remain small and multiply to maintain efficient nutrient and waste exchange through their surface area-to-volume ratio.
62. What type of molecules pass through the phospholipid bilayer? Small hydrophobic molecules, because they are water-hating, like the interior of the membrane. Hydrophilic molecules cannot pass through without help
63. 3 types of passive transport: diffusion, osmosis, facilitated diffusion
64. Types of vesicle transport: Endocytosis (phagocytosis and pinocytosis) and exocytosis

OpenAI. (2025). ChatGPT. [Large language model]. https://chat.openai.com/chat
Prompt: Can you give me brief summaries of these key terms