Lesson

Purpose of the work:

• To study the main components of cells using microphotographs

Expected results:

After completing the work, students can:

•  develop teamwork skills
•  be able to analyze and summarize the information received
•  draw logical conclusions

Teacher’s Guide:

• The task is performed in groups of 3-4 people
• Before starting laboratory work, please read the safety rules by following the link:

• To download the worksheet, follow the link:

Theory

• Plasma membrane — separates the cell from the external environment and regulates the exchange of substances. It is semipermeable: allows only necessary molecules to pass inside and removes waste. Receptor proteins in the membrane are involved in signal transmission.
• Cytoplasm — a semi-fluid medium in which organelles are located. Most biochemical reactions occur here.
• Nucleus — stores genetic information in DNA molecules and controls all cellular processes.

Main organelles of the cell and their functions

• Nucleus
  The “control center” of the cell. Contains chromosomes made of DNA and proteins. Stores hereditary information that determines the structure and function of the organism. Regulates division, growth, and metabolism.
• Nucleolus
  Located inside the nucleus. Its main function is the synthesis of ribosomal RNA and the assembly of ribosomal subunits, which later move into the cytoplasm.
• Ribosomes
  Small non-membrane organelles composed of RNA and proteins. They may float freely in the cytoplasm or be attached to the rough ER. Function — protein synthesis.
• Endoplasmic Reticulum (ER)
  A network of membrane-bound tubules and channels connected to the nuclear envelope.
  • Rough ER — covered with ribosomes. Synthesizes proteins, which are transported to the Golgi apparatus.
  • Smooth ER — lacks ribosomes. Synthesizes lipids and carbohydrates and carries out detoxification.
• Golgi Apparatus
  Consists of stacked, flattened membrane sacs (cisternae). Functions:
  • sorting and modifying proteins and lipids from the ER;
  • packaging substances into vesicles;
  • forming lysosomes.
    It is often called the “post office of the cell.”
• Mitochondria
  Double-membrane organelles known as the “powerhouses of the cell.” Cellular respiration takes place inside them, producing ATP — the main source of energy for the cell. Cells with high energy demands (e.g., muscle or nerve cells) contain many mitochondria.
• Lysosomes
  Membrane-bound vesicles containing enzymes. They break down large molecules, destroy damaged organelles, and can digest invading bacteria. They are the “clean-up system” of the cell.
• Vesicles
  Small membrane-bound sacs. They transport substances within the cell and are involved in secretion (export of molecules). For example, they can carry proteins from the Golgi to the plasma membrane.
• Cytoskeleton
  Made of microtubules and microfilaments. Maintains the cell’s shape, aids in organelle movement, forms pseudopodia in amoebas, and plays a critical role in cell division (spindle formation).

Each organelle performs a specific function, but they all work together: the nucleus stores and transmits information, mitochondria provide energy, ER and Golgi synthesize and sort substances, ribosomes build proteins, while lysosomes and vesicles handle transport and recycling. As a result, the cell operates as a unified system.

Practical part