Scheda di revisione: Cell Structure and Function

📋 Course Outline

1. Cell Fundamentals and Components
2. Organelles and Cellular Functions
3. Movement Across Cell Membranes
4. Cell Cycle and Differentiation

📖 1. Cell Fundamentals and Components

🔑 Key Concepts & Definitions

• Cell membrane : a mostly lipid boundary containing proteins that regulates movement into and out of the cell and is selectively permeable
• Cytoplasm : a gel-like component containing the cytoskeleton and suspended organelles
• Nucleus : contains DNA and is separated from the cytoplasm by a nuclear envelope that protects DNA and controls movement

📝 Essential Points

• The three main cell components are:

  • the cell membrane
  • the nucleus
  • the cytoplasm

• Cells are the units of life, and they vary in size, shape, content, and function.

• Cells are controlled by genes, and different cells use different genetic instructions.

💡 Memory Hook

MNC: membrane, nucleus, cytoplasm

📖 2. Organelles and Cellular Functions

🔑 Key Concepts & Definitions

• Mitochondria : capture and release energy for the cell through cellular respiration, and their amount varies among different cells

★ Must-know

• Ribosomes are found on the rough endoplasmic reticulum and in the cytoplasm, where they carry out protein synthesis.

• The endoplasmic reticulum transports molecules, participates in protein synthesis, helps identify bad proteins, and communicates with other organelles, especially the cell membrane.

• The Golgi apparatus further processes and refines proteins, packages them, and forms vesicles that can fuse with the cell membrane.

Further detail

• Lysosomes break down various molecules, while peroxisomes are sac-like structures containing enzymes that speed up chemical reactions.

• Microtubules and microfilaments make up the cytoskeleton and perform various specialized functions.

• The centrosome is used during cell division, cilia move fluid over a cell surface, flagella enable cell movement, and vesicles move material in sac-like structures.

💡 Memory Hook

A cell as a factory: ER transports, ribosomes build, Golgi packages, and mitochondria supply energy.

📖 3. Movement Across Cell Membranes

📝 Essential Points

• Passive movement includes:

  • simple diffusion
  • facilitated diffusion
  • osmosis
  • filtration

• Active movement includes:

  • active transport
  • endocytosis
  • exocytosis

💡 Memory Hook

Passive movement follows the gradient without energy, whereas active movement uses cellular energy.

📖 4. Cell Cycle and Differentiation

★ Must-know

📌 Cell differentiation is the process by which cells become different types with specific functions, whereas apoptosis is cell death.

• 🔄 The cell cycle proceeds through:

  1. interphase
  2. prophase
  3. metaphase
  4. anaphase
  5. telophase

• During interphase, the cell grows and prepares by replicating its DNA material.

• During metaphase, chromatids line up in the middle of the cell and spindle fibers attach to the chromosomes.

• During anaphase, spindle fibers pull chromatids apart so they become individual chromosomes, while the cytoplasm divides and a cleavage furrow begins to pinch the cell.

• During telophase, chromosomes complete their separation and the cell continues pinching inward to form a nuclear envelope for two cells.

Further detail

• New cells are formed by old cells, and a cell can continue through the same process of cell division.

• During prophase, centrosomes produce centrioles that move apart, the nuclear membrane disappears, spindle fibers appear, and chromatids become visible.

💡 Memory Hook

Interphase → prophase → metaphase → anaphase → telophase

📊 Synthesis Tables

Passive and Active Membrane Movement

Category	Processes	Main distinction
Passive movement	Simple diffusion; facilitated diffusion; osmosis; filtration	Movement category distinct from active movement
Active movement	Active transport; endocytosis; exocytosis	Includes cellular transport into or out of the cell