Study guide: Organisation des êtres vivants

📋 Course Outline

1. Unicellular and Multicellular Organisation
2. Cellular Specialisation
3. DNA Structure and Bases
4. Genes and Protein Production
5. Organelles and Extracellular Matrix

📖 1. Unicellular and Multicellular Organisation

📝 Essential Points

📌 A unicellular organism consists of one cell that performs all the functions necessary for life, whereas a multicellular organism contains several specialised cells that perform different functions.

• 🔄 The organisational hierarchy is:
  1. Cell
  2. Tissue
  3. Organ
  4. Organism

💡 Memory Hook

Cell → Tissue → Organ → Organism

📖 2. Cellular Specialisation

★ Must-know

• All cells of the same organism originate from one egg cell and initially possess the same genetic information, meaning the same DNA.

• Different gene expression allows cells with the same DNA to become specialised and perform different functions.

Further detail

• In a skin cell the tyrosinase gene is active, whereas in a liver cell the glucokinase gene is active.

💡 Memory Hook

Same DNA → different gene expression → different functions

📖 3. DNA Structure and Bases

🔑 Key Concepts & Definitions

• DNA: or deoxyribonucleic acid, consists of two strands wound into a double helix

📝 Essential Points

📌 In DNA, adenine pairs with thymine and guanine pairs with cytosine.

• DNA contains four bases:
  • adenine (A)
  • thymine (T)
  • guanine (G)
  • cytosine (C)

💡 Memory Hook

A-T and G-C

📖 4. Genes and Protein Production

🔑 Key Concepts & Definitions

• Gene: a portion of DNA containing genetic information

★ Must-know

📌 Genes are present in the cells of the same organism, but they are not necessarily all active.

• 🔄 An active gene leads to:
  1. information being used
  2. protein production
  3. a particular cellular function

Further detail

📌 An inactive gene contains information that is not used, so the corresponding protein is not produced.

💡 Memory Hook

Active gene → information used → protein produced → specific function

📖 5. Organelles and Extracellular Matrix

🔑 Key Concepts & Definitions

• Nucleus: contains genetic information
• Mitochondrion: enables the production of energy usable by the cell
• Extracellular matrix: a set of macromolecules, notably proteins and carbohydrates, that maintains cohesion between cells and contributes to tissue formation
• Chloroplast: carries out photosynthesis in plants
• Vacuole: notably stores waste products and various substances in plants

💡 Memory Hook

Nucleus stores information, whereas mitochondria produce usable energy

📊 Synthesis Tables

Cellular Structures and Functions

Structure	Main function
Nucleus	Contains genetic information
Mitochondrion	Produces usable energy
Chloroplast	Carries out photosynthesis in plants
Vacuole	Stores waste products and substances
Extracellular matrix	Maintains cell cohesion and contributes to tissue formation