eläinsoluun

An animal cell is the basic structural and functional unit of all animal tissues. It is a eukaryotic cell, meaning it has a true nucleus and membrane-bound organelles. Unlike plant cells, animal cells lack a cell wall, chloroplasts, and a large central vacuole.

Key components of an animal cell include the nucleus, which contains the genetic material in the form of DNA. The cytoplasm is the jelly-like substance that fills the cell and surrounds the organelles. Within the cytoplasm are various organelles, each with specific functions. Mitochondria are often referred to as the "powerhouses" of the cell because they generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy. The endoplasmic reticulum, both rough and smooth, is involved in protein synthesis and lipid metabolism. The Golgi apparatus modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles. Ribosomes are responsible for protein synthesis. Lysosomes contain digestive enzymes that break down waste materials and cellular debris. Peroxisomes are involved in metabolic processes, including the breakdown of fatty acids.

The outer boundary of the animal cell is the plasma membrane, a selectively permeable barrier that controls the passage of substances into and out of the cell. Animal cells can vary greatly in size and shape depending on their specific function within the organism. For example, nerve cells are elongated to transmit signals, while muscle cells are specialized for contraction.