Question

Які функції клітинних мембран? Яка речовина входить до складу клітинної оболонки?

Answer 1

Функціями клітинної мембрани є: 1) транспортна (обмін речовин, енергії та інформації з навколишнім середовищем через біліпідний шар, білкові канали тощо); 2) метаболічна (ферментні білки беруть участь у процесах взаємоперетворення речовин та енергії); 3) рецепторна (рецепторні білки в мембранах
2 запитання

складається переважно із полісахаридів, які залежно від їх ролі поділяють на речовини скелета та речовини матриксу. Скелетом К. о. вищих рослин є целюлоза (клітковина), молекули якої зібрані в тоненькі волоконця-мікрофібрили, які створюють каркас, скелет або арматуру К.

Answer 2

Functions of Cell Membranes

Cell membranes have several important functions in a cell. Some of the key functions of cell membranes include:

1. Selective Permeability: Cell membranes regulate the movement of substances into and out of the cell. They have selective permeability, which means they allow certain molecules to pass through while restricting the passage of others. This helps maintain the internal environment of the cell and control the exchange of materials with the external environment.

2. Transport: Cell membranes facilitate the transport of molecules across the membrane. This can occur through various mechanisms such as passive diffusion, facilitated diffusion, and active transport. These processes ensure the movement of essential molecules, ions, and nutrients into the cell and the removal of waste products.

3. Cell Signaling: Cell membranes play a crucial role in cell signaling. They contain receptors that can bind to specific signaling molecules, such as hormones or neurotransmitters. When these molecules bind to their receptors on the cell membrane, they initiate a series of intracellular signaling events that regulate various cellular processes.

4. Cell Adhesion: Cell membranes are involved in cell adhesion, which is the process by which cells stick together. This is important for maintaining the structural integrity of tissues and organs. Cell adhesion molecules on the cell membrane allow cells to interact with each other and form tight connections.

5. Cell Recognition: Cell membranes are responsible for cell recognition and identification. They contain specific molecules, such as glycoproteins and glycolipids, that act as markers to distinguish one cell from another. This is important for immune responses, tissue development, and cell communication.

Composition of Cell Membrane

The cell membrane, also known as the plasma membrane, is composed of various components. The main components of the cell membrane include:

1. Phospholipids: Phospholipids are the primary structural components of the cell membrane. They have a hydrophilic (water-loving) head and hydrophobic (water-repelling) tails. The arrangement of phospholipids forms a lipid bilayer, with the hydrophilic heads facing outward towards the aqueous environment and the hydrophobic tails facing inward, creating a barrier.

2. Proteins: Proteins are embedded within the lipid bilayer of the cell membrane. They have various functions, including transport of molecules across the membrane, cell signaling, and cell adhesion. Some proteins span the entire membrane (integral proteins), while others are attached to one side of the membrane (peripheral proteins).

3. Cholesterol: Cholesterol molecules are present in the cell membrane and help maintain its fluidity and stability. They are interspersed between the phospholipids and regulate the fluidity of the membrane.

4. Carbohydrates: Carbohydrates are attached to lipids (glycolipids) or proteins (glycoproteins) on the outer surface of the cell membrane. These carbohydrate chains form the glycocalyx, which plays a role in cell recognition and cell-cell interactions.

It's important to note that the specific composition of cell membranes can vary depending on the type of cell and its function. Different types of cells may have additional components or modifications to the basic structure described above.