Structure and functions of cell

• Structure and functions of cell: Cells are the basic structural and functional units of life.
• They can be classified into two main types: prokaryotic cells (found in bacteria and archaea) and eukaryotic cells (found in plants, animals, fungi, and protists).
• Both cell types share some basic structures and functions, but eukaryotic cells are generally larger and more complex than prokaryotic cells.

Here are the main structures (organelles) and functions of a typical eukaryotic cell

Cell membrane (plasma membrane)

• A selectively permeable barrier that surrounds the cell, controlling the passage of substances in and out of the cell.
• It is composed of a phospholipid bilayer with embedded proteins.
• Function:
• Controls the movement of substances in and out of the cell, maintaining a balance of ions, nutrients, and waste products.
• It also mediates cell-to-cell communication and recognition.

Cytoplasm

• The gel-like substance within the cell membrane that contains organelles, enzymes, and other molecules required for the cell’s functions.
• It is the site of many cellular processes.
• Function:
• Provides a medium for cellular processes to occur, suspending organelles and facilitating the transport of molecules throughout the cell.

Nucleus

• The control center of the cell, which contains the cell’s DNA, organized into chromosomes.
• The nucleus is surrounded by a double-layered nuclear membrane and contains a nucleolus, which is involved in ribosome synthesis.
• Function:
• Contains genetic information (DNA) and regulates gene expression, controlling the synthesis of proteins required for cellular function, growth, and reproduction.
• It also houses the nucleolus, which produces ribosomes.

Endoplasmic reticulum (ER)

• A network of membranous tubules and sacs that play a crucial role in protein and lipid synthesis.
• The ER can be classified into two types:
  1. smooth ER (involved in lipid synthesis and detoxification)
  2. rough ER (studded with ribosomes and involved in protein synthesis).
• Function:
• Involved in protein synthesis (rough ER) and lipid synthesis (smooth ER).
• The rough ER is studded with ribosomes and produces proteins destined for secretion or incorporation into the cell membrane.
• The smooth ER produces lipids and detoxifies harmful substances.

Ribosomes

• Small structures made of protein and RNA that are responsible for protein synthesis.
• They can be found free-floating in the cytoplasm or attached to the rough ER.
• Function:
• Small structures made of protein and RNA responsible for protein synthesis.
• They can be found free-floating in the cytoplasm or attached to the rough ER.

Golgi apparatus

• A series of flattened, membrane-bound sacs that modify, package, and sort proteins and lipids for transport to their final destinations within or outside the cell.
• Function:
• Modifies, packages, and sorts of proteins and lipids for transport to their final destinations within or outside the cell.

Mitochondria

• The powerhouse of the cell, responsible for producing ATP (adenosine triphosphate), the cell’s primary energy source, through cellular respiration.
• Mitochondria have their own DNA and are believed to have originated from an endosymbiotic relationship with bacteria.
• Function:
• Produce ATP (adenosine triphosphate), the cell’s primary energy source, through cellular respiration.

Lysosomes

• Small, membrane-bound organelles containing hydrolytic enzymes that break down waste materials, cellular debris, and foreign substances.
• Function:
• Contain hydrolytic enzymes that break down waste materials, cellular debris, and foreign substances.

Peroxisomes

• Organelles that contain enzymes involved in various metabolic reactions, including the breakdown of fatty acids and the detoxification of harmful substances.
• Function:
• Contain enzymes involved in various metabolic reactions, including the breakdown of fatty acids and the detoxification of harmful substances.

Cytoskeleton

• A network of protein filaments that provides structural support, maintains cell shape, and aids in cell movement and division.
• The cytoskeleton consists of microtubules, microfilaments, and intermediate filaments.
• Function:
• A network of protein filaments that provide structural support, maintain cell shape, and aid in cell movement and division.
• The cytoskeleton consists of microtubules, microfilaments, and intermediate filaments.

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