Cell Biology: Theory, Transport, and Structures
Cell Theory and Microscope Technology
1. Can cells appear spontaneously without genetic material from a previous cell?
No, cells do not appear spontaneously; they pass copies of their genetic material on to their daughter cells.
2. Compare and contrast a TEM and SEM.
In a TEM (Transmission Electron Microscope), electrons are transmitted through a specimen to a fluorescent screen. An SEM (Scanning Electron Microscope) is a modification that directs electrons over the surface of the specimen, producing a three-dimensional image.
3. Explain how the development and improvement of microscopes changed the study of living organisms.
Development in microscope technology has given scientists the ability to study cells in greater detail than early scientists ever thought possible.
4. Compare and contrast the structure and function of various types of microscopes.
- Optical Microscope: An optical microscope uses visible light and lenses to magnify an object.
- Non-optical Microscope: As they began studying cells, scientists needed greater magnification to see the details of tiny parts of the cell.
5. Describe the cell theory.
All organisms are made of one or more cells; the cell is the basic unit of life; and cells arise from previously existing cells, passing on their genetic material.
Plasma Membrane and Homeostasis
6. Differentiate the plasma membrane and the organelles.
- Plasma Membrane: Helps control what enters and leaves the cell.
- Organelles: Specialized membrane-bound structures that perform specific functions at the same time.
7. Describe the benefit of the bilayer structure of the plasma membrane.
The phospholipids are arranged tail-to-tail.
8. Identify the molecules in the plasma membrane that provide basic membrane structure, cell identity, and membrane fluidity.
Lipids and phospholipids.
9. Describe how the plasma membrane helps maintain homeostasis in a cell.
It allows nutrients into the cell and allows waste and other products to leave the cell.
Cellular Transport Mechanisms
10. Compare and contrast the three types of solutions.
- Diffusion: The movement and colliding of particles.
- Osmosis: The diffusion of water across a selectively permeable membrane.
- Isotonic: When the cell has the same concentration of water and solutes as its environment.
11. Compare and contrast active and passive transport across the plasma membrane.
- Active Transport: The movement of substances across the plasma membrane against a concentration gradient; requires energy.
- Passive Transport: A type of transport that does not require energy to move substances.
12. List and describe the types of allowed transports.
Active: Requires energy. Passive: Does not need energy.
13. Explain the role of the cell membrane during passive transport and active transport.
The cell membrane separates the inside of the cell from the environment.
14. Sketch a “before and after” diagram of an animal cell placed in a hypotonic solution.
Water moves into the cell, the pressure increases, and the plasma membrane swells.
15. Contrast how facilitated diffusion is different from active transport.
Facilitated diffusion uses proteins for entry, while active transport moves solutes both in and out.
Cell Structure and Organelle Functions
16. Summarize the structure and function of the cytoskeleton.
The structure is complex, composed primarily of the plasma membrane, microtubules, and microfilaments; the function is to support the cell.
17. Compare and contrast the cell walls of prokaryotic and eukaryotic cells.
- Prokaryotic: The cell wall surrounds the cell.
- Eukaryotic: A thick, rigid mesh of fibers that surrounds the outside of the plasma membrane, protecting the cell and giving it support.
18. Describe the role of the nucleus.
Produces ribosomes and stores DNA information.
19. Explain the role of lysosomes in cells.
They contain digestive enzymes for the breakdown of excess or worn-out cellular substances.
20. Justify the statement: “Cells are the most important part of all living organisms.”
They store DNA information for new generations and produce ribosomes.
21. Identify the role of the nucleus in a eukaryotic cell.
It is a membrane system of folded and interconnected channels that acts as the site for protein and lipid synthesis.
22. Summarize the role of the endoplasmic reticulum.
- Rough ER: Has ribosomes and produces more protein.
- Smooth ER: Has fewer ribosomes and makes lipids.