Cell Structure and Function

These flashcards cover key concepts related to cell structures and functions, including organelles, transport mechanisms, and the distinction between prokaryotic and eukaryotic cells.

What is the primary function of ribosomes in cells?

Ribosomes synthesize proteins according to messenger RNA (mRNA) sequences.

What is the endomembrane system and its components?

The endomembrane system consists of membrane-bound organelles and components like the ER, Golgi complex, lysosomes, vacuoles, transport vesicles, nuclear envelope, and plasma membrane, working together to modify, package, and transport molecules.

What are vacuoles and their role in plant and animal cells?

Vacuoles are membrane-bound sacs; in plants, they maintain turgor pressure through nutrient and water storage, while in animals, they store cellular materials.

What is the function of chloroplasts?

Chloroplasts are specialized organelles in plants and photosynthetic algae that contain a double membrane and are the sites of photosynthesis.

What distinguishes rough ER from smooth ER?

Rough ER is associated with ribosomes and helps with protein synthesis, while smooth ER is involved in lipid synthesis and detoxification.

What is the function of the Golgi apparatus?

The Golgi apparatus modifies, packages, and sorts proteins and lipids for transport to their destinations.

How do mitochondria contribute to cellular respiration?

Mitochondria have a double membrane and are involved in aerobic cellular respiration, creating compartments for different metabolic reactions.

What are lysosomes and their importance in the cell?

Lysosomes are membrane-enclosed sacs containing hydrolytic enzymes that digest cellular waste and play a role in programmed cell death (apoptosis).

Describe the fluid mosaic model of cell membranes.

The fluid mosaic model describes the cell membrane as a dynamic structure with a mosaic of various components (phospholipids, proteins, cholesterol) that can move laterally within the layer.

What are the characteristics of phospholipids in the cell membrane?

Phospholipids have hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails, forming a bilayer that makes up the cell membrane.

Explain passive transport and give an example.

Passive transport is the movement of molecules across the membrane from high to low concentration without energy usage, such as in simple diffusion.

What is active transport and when does it occur?

Active transport requires energy to move molecules against their concentration gradient, such as with the sodium-potassium pump.

Define osmosis and its significance in cells.

Osmosis is the diffusion of water across a semipermeable membrane, crucial for maintaining cell turgor and overall water balance.

What is the purpose of endocytosis and exocytosis?

Endocytosis is the process of importing large materials into the cell, while exocytosis is the expulsion of materials from the cell using vesicles.

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotic cells are single-celled without a nucleus or membrane-bound organelles, while eukaryotic cells can be single-celled or multicellular and have a nucleus and organelles.

How did eukaryotic cells evolve according to the endosymbiotic theory?

Eukaryotic cells evolved from prokaryotic cells that formed symbiotic relationships with mitochondria and chloroplasts, which were once free-living prokaryotes.

What is the significance of surface area-to-volume ratio in cells?

The surface area-to-volume ratio affects a cell's ability to exchange materials; smaller cells have a higher ratio and are more efficient at transport.