Cell Structure and Organisation
Cell Structure and Organisation
Basic Cell Theory
- All living organisms are composed of cells.
- The cell is the smallest unit of life.
- Cells come from the division of pre-existing cells.
Prokaryotic and Eukaryotic Cells
- Prokaryotic cells, such as bacteria, lack a nucleus and other membrane-bound organelles.
- Eukaryotic cells, found in plants, animals, and fungi, contain a nucleus and other membrane-bound organelles.
Cell Structure
- The nucleus contains the majority of a cell’s genetic material, DNA, which is organised into chromosomes.
- The mitochondria are the powerhouses of the cell, creating ATP in the process of cellular respiration.
- The endoplasmic reticulum and Golgi apparatus are involved in the production and transportation of proteins within the cell.
- Ribosomes, either free in the cytoplasm or attached to the endoplasmic reticulum, are the site of protein synthesis.
Cell Membrane
- The cell membrane is a semi-permeable barrier that controls the passage of substances in and out of the cell.
- It consists of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates.
- The cell membrane maintains cell integrity and carries out a variety of functions including transport, signal transduction, and cell adhesion.
Cell Organisation
- Tissues are organised groups of similar cells that work together to perform a specific function.
- Organs are composed of several types of tissues working in unison to perform specific tasks.
- Organ systems are groups of organs that work together to perform complex biological functions.
- Organisms are composed of multiple organ systems.
Plant Cell Structures
- Plant cells have additional structures not found in animal cells, including a cell wall, chloroplasts, and a large central vacuole.
- The cell wall gives structural support and protection to the cell.
- Chloroplasts are the site of photosynthesis, capturing light energy and converting it to chemical energy.
- The large vacuole serves multiple purposes, including maintaining turgor pressure within the cell and storage of waste products.
Cell Division
- Cells reproduce through a process known as cell division.
- In eukaryotes, this usually involves the stages of mitosis or meiosis.
- Mitosis, used for growth and repair, results in two identical daughter cells.
- Meiosis, involved in sexual reproduction, results in four genetically unique gametes.