1.3 and 1.4 Flashcards
Q: What are the main differences between eukaryotic and prokaryotic cells?
A: Eukaryotic cells have membrane-bound organelles, an organized nucleus with a nuclear envelope, complex locomotory and cytoskeletal structures, and chromosomes. Prokaryotic cells lack these features.
Q: How do plant and animal cells differ?
A: Plant cells have cell walls, plastids (such as chloroplasts), and a large central vacuole, which are absent in animal cells. Animal cells, on the other hand, have centrioles, which are usually absent in plant cells.
Q: What is the composition of the cell membrane?
A: The cell membrane is mainly composed of phospholipids arranged in a bilayer. It also contains cholesterol, proteins, and carbohydrates.
Q: What is the fluid mosaic model of the cell membrane?
A: The fluid mosaic model describes the cell membrane as a quasi-fluid structure where lipids can move laterally within the bilayer. It emphasizes the fluidity of the membrane, which is important for various cellular functions.
Q: How does the cell membrane transport molecules?
A: The cell membrane is selectively permeable and allows passive transport of molecules through simple diffusion and osmosis. Polar molecules require carrier proteins for facilitated transport. Active transport, which requires energy in the form of ATP, moves ions or molecules against their concentration gradient.
Q: What is the cell wall and what does it do?
The cell wall is a non-living rigid structure that forms an outer covering for the plasma membrane of fungi and plants. It:
* Gives shape to the cell
* Protects the cell from mechanical damage and infection
* Facilitates cell-to-cell interaction
* Provides a barrier to undesirable macromolecules
Q: What are the components of the cell wall in algae and other plants?
Algae have a cell wall made of:
* Cellulose
* Galactans
* Mannans
* Minerals like calcium carbonate
In other plants, the cell wall consists of:
* Cellulose
* Hemicellulose
* Pectins
* Proteins
Q: How does the cell wall change as a plant cell matures?
A: In a young plant cell, the primary wall is capable of growth. As the cell matures, the primary wall diminishes, and a secondary wall is formed on the inner side of the cell, towards the membrane.
What is the middle lamella?
The middle lamella is a layer mainly composed of calcium pectate. Its functions include:
* Holding neighboring cells together
* Acting as a glue between cells
Q: What are plasmodesmata?
Plasmodesmata are channels that traverse the cell wall and middle lamella, connecting the cytoplasm of neighboring cells. They allow communication and transport of materials between cells.
Q: Which organelles are part of the endomembrane system?
The endomembrane system includes:
* Endoplasmic reticulum (ER)
* Golgi complex
* Lysosomes
* Vacuoles
Q: Why are mitochondria, chloroplasts, and peroxisomes not part of the endomembrane system?
These organelles have distinct functions that are not coordinated with the functions of the endomembrane system organelles.
Q: What is the endoplasmic reticulum (ER)?
The endoplasmic reticulum is a network of tiny tubular structures in the cytoplasm that divides the intracellular space into two compartments:
* Luminal (inside the ER)
* Extra luminal (cytoplasm)
Q: What is the difference between rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER)?
RER has ribosomes attached to its outer surface, while SER appears smooth without ribosomes. Functions of RER include:
* Protein synthesis
* Secretion
SER is involved in lipid synthesis, including the synthesis of lipid-like steroidal hormones in animal cells.
Q: What is the structure of mitochondria?
- Mitochondria are double membrane-bound structures.
- They have an outer membrane and an inner membrane.
- The inner membrane has foldings called cristae.
- The inner compartment of mitochondria is filled with a dense substance called the matrix.
- The outer membrane forms the boundary of the mitochondria.
- The cristae increase the surface area of the mitochondria.
