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.