Bio

• Cell


  Fundamental unit of life
• Robert Hooke


  Discovered the cell in 1665
• Robert Hooke observed a thin slice of cork under his microscope and found small box-like structures, which he called "cells"
• Unicellular organisms


  Organisms made up of only one cell
• Unicellular organisms


  • Amoeba
  • Chlamydomonas
  • Paramecium
  • Bacteria
• Multicellular organisms


  Organisms made up of many cells
• All multicellular organisms are developed from a single cell
• Cells produce cells of their own kind by cell division
• Multicellular organisms are made up of different types of cells
• Different types of cells in the body

  • Muscle cells
  • Blood cells
  • Nerve cells
  • Bone cells
  • Ovum
  • Sperm cells
  • Fat cells
• Shape and size of cells

  Depends on the function they perform
• Division of labor


  Different parts of the body perform different tasks
• Cell organelles


  Parts present inside the cell that help it perform its functions
• Cell organelles


  • Smooth endoplasmic reticulum
  • Rough endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
  • Mitochondria
  • Vacuoles
• Cytoplasm


  Semi-transparent jelly-like material inside the cell membrane, where many biochemical reactions take place
• Rough endoplasmic reticulum


  Protein factory, makes new proteins
• Smooth endoplasmic reticulum


  Fat factory, makes new fats
• Golgi apparatus


  Dispatch center, handles packaging and distribution of materials
• Mitochondria


  Powerhouse of the cell, produces energy from glucose
• Vacuoles


  Storage bags, store different materials
• Lysosomes


  Suicide bags, contain digestive enzymes and digest foreign materials
• Plastids


  Pigment stores, contain different pigments and help in photosynthesis (found only in plant cells)
• Cell organelles are membrane-bound structures that keep the chemical activities separate within the cell
• Cell organelles cannot be seen under a compound microscope, but can be seen under an electron microscope
• Plasma membrane


  Protects the inner components of the cell, controls the entry and exit of materials
• Diffusion


  Movement of gas molecules from high concentration to low concentration
• Osmosis


  Movement of water molecules from high concentration to low concentration through a semi-permeable membrane
• Active transport


  Transfer of other materials into the cell, requires energy
• Plasma membrane is made up of lipids and proteins, and can only be seen under an electron microscope
• Endocytosis


  Process by which amoeba and other organisms engulf food materials through their cell membrane
• Cell wall


  Rigid outer cover of plant cells, made up of cellulose
• Plasmolysis


  Loss of water from a living plant cell, causing the contents to shrink away from the cell wall
• Nucleus


  Covered by a nuclear membrane with pores, contains chromatin that becomes chromosomes during cell division
• Chromosomes


  Rod-like structures containing DNA and proteins, control the functioning of the cell
• Genes


  Functional segments of DNA that execute different tasks
• Prokaryotes


  Organisms whose cells lack a nuclear membrane and membrane-bound organelles
• Eukaryotes


  Organisms whose cells have a nuclear membrane and membrane-enclosed organelles
• Proteins and fats


  Materials used by cells in different ways
• Cell membrane


  Made up of proteins and lipids
• For the formation of new cell membrane during cell division


  Proteins and fats are required