Study sheet: Cell Structure and Function

📋 Course Outline

1. Cellular Organization and Components
2. Organelle Membrane Classification
3. Plasma Membrane and Cytoplasm
4. Nucleus and Cytoskeleton
5. Mitochondrial Structure and Function
6. Endoplasmic Reticulum and Golgi
7. Lysosomes, Ribosomes, and Peroxisomes

📖 1. Cellular Organization and Components

🔑 Key Concepts & Definitions

• Cell : The basic structural and functional unit of living tissues, and human cells are eukaryotic.

★ Must-know

• The three major components are:
  • the plasma membrane
  • the cytoplasm
  • the nucleus

Further detail

• The plasma membrane encloses the cell, the cytoplasm contains organelles, and the nucleus stores genetic material and controls cellular activity.

💡 Memory Hook

PM–C–N: plasma membrane, cytoplasm, nucleus

📖 2. Organelle Membrane Classification

★ Must-know

• The membrane classes are:

  • no membrane
  • single membrane
  • double membrane

• Single-membrane organelles include:

  • the endoplasmic reticulum
  • the Golgi apparatus
  • lysosomes
  • peroxisomes
  • vesicles

Further detail

• Non-membrane-bound organelles include:
  • ribosomes
  • the cytoskeleton
  • centrioles

💡 Memory Hook

No membrane, single membrane, or double membrane determines organelle grouping

📖 3. Plasma Membrane and Cytoplasm

🔑 Key Concepts & Definitions

• Plasma membrane : Defines the cell periphery and is selectively permeable.
• Cytoplasm : The material between the plasma membrane and the nucleus, containing cytosol, metabolites, enzymes, inorganic ions, membranous organelles, and supramolecular structures.

★ Must-know

• The plasma membrane consists of a phospholipid bilayer with hydrophilic heads and hydrophobic tails; integral proteins span it, peripheral proteins lie on its surface, and carbohydrates attach to proteins or lipids as glycoproteins and glycolipids.

Further detail

• The cytoplasm supports organelles, provides the environment for many chemical pathways, and enables intracellular organization and transport.

💡 Memory Hook

A selective phospholipid boundary surrounds a watery, organized interior

📖 4. Nucleus and Cytoskeleton

★ Must-know

• The cytoskeletal elements are: microfilaments composed of actin, microtubules composed of tubulin, intermediate filaments composed of heterogeneous proteins

• The nucleus controls cellular activities, stores DNA, contains chromosomes, and supports DNA replication and RNA transcription.

• The cytoskeleton maintains cell shape, provides mechanical resistance, supports motility and contractility, enables intracellular movement, and participates in cell division.

Further detail

• The nucleolus supports ribosome production.

💡 Memory Hook

DNA control plus cytoskeletal support enables cellular organization and movement

📖 5. Mitochondrial Structure and Function

★ Must-know

• The mitochondrial outer membrane is smooth, while the inner membrane folds into cristae that increase the surface area available for ATP-producing reactions.

• The mitochondrial matrix contains enzymes for catabolic pathways, and major catabolic pathways occur there.

• Mitochondria produce ATP, the major energy-carrying molecule of cells.

Further detail

• Cytochrome c release from mitochondria contributes to programmed cell death, and mitochondrial function and damage influence cellular aging processes.

💡 Memory Hook

Cristae fold inward around an enzyme-filled matrix

📖 6. Endoplasmic Reticulum and Golgi

★ Must-know

📌 The endoplasmic reticulum is a membrane network extending from the nuclear envelope toward the plasma membrane; rough ER bears ribosomes, whereas smooth ER lacks them.

• Rough endoplasmic reticulum participates in protein synthesis, while smooth endoplasmic reticulum synthesizes phospholipids, cholesterol, and steroid hormones.

• The Golgi apparatus completes ER processing by maturing, modifying, packaging, and sorting synthesized proteins into vesicles for their destinations.

Further detail

• The sarcoplasmic reticulum stores and releases Ca²⁺ needed for muscle contraction.

💡 Memory Hook

ER synthesis → Golgi modification → packaging and sorting

📖 7. Lysosomes, Ribosomes, and Peroxisomes

🔑 Key Concepts & Definitions

• Lysosomes : Spherical, single-membrane-bound vesicles containing digestive enzymes called acid hydrolases.
• Ribosomes : Non-membrane-bound organelles composed of ribosomal RNA and proteins that translate messenger RNA and synthesize cellular proteins.
• Peroxisomes : Small, single-membrane-bound vesicles containing oxidative enzymes, including catalase.

📝 Essential Points

• Lysosomes digest proteins, polysaccharides, lipids, and nucleic acids, destroy some viruses and bacteria, and recycle damaged cellular material.

• Peroxisomes detoxify harmful substances, carry out β-oxidation of very-long-chain fatty acids, metabolize reactive oxygen species, break down selected amino acids and purines, and protect against destructive metabolic byproducts.

💡 Memory Hook

Ribosomes build, lysosomes digest, and peroxisomes detoxify

📊 Synthesis Tables

Organelle membrane classification

Class	Organelles
No membrane	Ribosomes; cytoskeleton; centrioles
Single membrane	Endoplasmic reticulum; Golgi apparatus; lysosomes; peroxisomes; vesicles
Double membrane	Nucleus; mitochondria