Cells

• Cells


  The building blocks of every organism on the planet
• Organisms


  • Can be Prokaryotes or Eukaryotes
• Eukaryotes are organisms made up of eukaryotic cells- they are complex and include animal and plant cells
• A prokaryote is a prokaryotic cell, a single-celled organism
• Animal cells


  • Nucleus - containing genetic material that controls cell activities
  • Cytoplasm - where chemical reactions happen
  • Mitochondria - releases energy through respiration
  • Cell membrane - holds the cell together and controls what goes in and out
  • Ribosomes - involved in translation and protein synthesis
• Plant cell


  • Cell wall - rigid and made of cellulose to support the cell
  • Large vacuole - containing cell sap, a weak solution of sugar and salts, to maintain internal pressure to support the cell
  • Chloroplasts - where photosynthesis occurs, containing chlorophyll
• Bacterial cell

  • Chromosomal DNA - one long circular chromosome controlling the cell's activities and replication, is free in the cytoplasm
  • Plasmid DNA - small loops of extra DNA not part of the chromosome
  • Flagellum - a long hair-like structure that rotates to make the bacterium move.
• Bacterial cells have no nucleus
• Specialised Cells


  • Cells that are adapted to their function
• Egg Cells and Sperm Cells

  • They are specialised for reproduction
  • The nucleus of an egg cell and sperm cell only contain half the number of chromosomes that's in a normal body cell - they are called haploid
• Sexual reproduction


  Nucleus of an egg cell fuses with nucleus of a sperm cell to create a fertilised egg which then develops into an embryo
• Egg Cell


  • Contains nutrients in the cytoplasm to feed the embryo
  • Has a haploid nucleus
  • Straight after fertilisation, its membrane changes structure to stop any more sperm getting in to make sure the offspring end up with the right amount of DNA
• Egg cell

  • Haploid nucleus - contains half the number of chromosomes in a normal body so that when if is fertilised by the sperm, the DNA combine
  • Cytoplasm containing nutrients to feed the embryo
  • Jelly coat - hardens after fertilisation so that no more soerm can enter
• Sperm cells

  • Flagellum - swim to egg
  • Lots of mitochondria to provide the energy needed to swim to the egg
  • Acrosome - stores enzymes needed to digest through the membrane of the egg
  • Haploid nucleus
• Ciliates epithelial cells

  • Cilia - hair-like structures than move things along the surface of the cell