This image explain what is a structure

Cells are the fundamental building blocks of all living organisms. They are the smallest unit of life capable of performing all life processes. Every organism, from a tiny bacterium to a massive oak tree, is made of cells. Organisms can be unicellular, consisting of a single cell, or they can be multicellular, composed of billions of specialized cells. The study of cells is known as cell biology or cytology. Robert Hooke was the first scientist to discover cells in 1665. He observed a thin slice of cork under a microscope and saw box-like structures. He named these structures 'cells' because they looked like the rooms monks lived in. Over time, scientists developed the Cell Theory to explain the nature of cells. The Cell Theory states that all living things are made of one or more cells. It also states that cells are the basic units of structure and function in living things. Furthermore, the theory says that all cells come from pre-existing cells through division. Despite their small size, cells are highly organized and complex structures. Every cell contains genetic material in the form of DNA. DNA holds the instructions for all cell activities. Within the cell, several structures called organelles perform specific jobs. The nucleus is the control center of the cell, holding the genetic material. The cytoplasm is a jelly-like substance that fills the cell and surrounds the organelles. The cell membrane acts as a protective barrier and controls what enters and leaves. Plant cells have an additional rigid cell wall for support and structure. They also contain chloroplasts, which use sunlight to make food through photosynthesis. Ribosomes are responsible for making proteins. The endoplasmic reticulum is involved in protein and lipid synthesis. The Golgi apparatus modifies, sorts, and packages proteins for delivery. Mitochondria, often called the powerhouses of the cell, generate energy through cellular respiration. Lysosomes contain enzymes to break down waste materials and cellular debris. Vacuoles store water, nutrients, and waste products, and are much larger in plant cells. The cytoskeleton provides the cell with shape and internal organization. Cell division is essential for growth, repair, and reproduction. There are two main types of cell division: mitosis and meiosis. Mitosis creates identical body cells for growth and repair. Meiosis produces gametes, such as sperm and egg cells, with half the genetic material for sexual reproduction. Cell communication allows cells to send and receive signals to coordinate functions. Stem cells are unique cells that can develop into many different types of cells. Cancer occurs when cells divide uncontrollably and form tumors. In summary, cells are the essential building blocks that make all life possible.