GCSE biology edexcel paper 1 topic 1

• Eukaryotes


  Cells that are complex and include all animal and plant cells
• Prokaryotes


  Cells that are smaller and simpler, e.g. bacteria
• Multicellular organisms contain lots of different types of cells (e.g. cells with different structures)</b>
• Specialised cells


  Cells that have a structure which makes them adapted to their function
• Egg cell


  • Carries the female DNA
  • Nourishes the developing embryo in the early stages
• Sperm cell


  • Has a long tail to reach the egg
  • Has lots of mitochondria to provide energy
  • Has an acrosome to digest through the egg cell membrane
  • Contains a haploid nucleus
• Ciliated epithelial cells


  • Have cilia (hair-like structures) on the surface
  • Function is to move substances in one direction along the surface of the tissue
• Prokaryotic cells are smaller and simpler than eukaryotic cells
• Eukaryotic cells are the cells that make up multicellular organisms
• Escherichia coli is an example of a prokaryotic cell (it's a single-celled organism)
• Subcellular structures


  The parts of a cell
• Subcellular structures of a cell

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• Nucleus


  • Contains genetic material that controls the activities of the cell
  • Genetic material is arranged into chromosomes
• Cytoplasm


  • Gel-like substance where most of the chemical reactions happen
  • Contains enzymes that control these chemical reactions
• Cell membrane


  • Holds the cell together and controls what goes in and out
• Mitochondria


  • Where most of the reactions for respiration take place
  • Respiration transfers energy that the cell needs to work
• Ribosomes


  • Involved in translation of genetic material in the synthesis of proteins
• Plant cells have all the bits that animal cells have, plus some things that animal cells don't have
• Cell wall


  • Made of cellulose
  • Supports the cell and strengthens it
• Ribosomes


  Involved in translation of genetic material in the synthesis of proteins
• Plant cells


  • Have all the bits that animal cells have
  • Plus a few extra things that animal cells don't have
• Rigid cell wall


  • Made of cellulose
  • Supports the cell and strengthens it
• Cell sap


  A weak solution of sugar and salts
• Large vacuole


  • Maintains the internal pressure to support the cell
• Chloroplasts


  • Where photosynthesis occurs, which makes food for the plant
  • Contain a green substance called chlorophyll
• Bacterial cells


  • Smaller than plant or animal cells
  • Have these subcellular structures
• Subcellular structures in bacterial cells


  • Chromosomal DNA (one long circular chromosome)
  • Ribosomes
  • Cell membrane
  • Plasmid DNA (small loops of extra DNA that aren't part of the chromosome)
  • Flagellum (a long, hair-like structure that rotates to make the bacterium move)
• Plasmid DNA

  • Contains genes for things like drug resistance, and can be passed between bacteria
  • Controls the cell's activities and replication
• Flagellum


  Can be used to move the bacteria away from harmful substances like toxins and towards beneficial things like nutrients or oxygen
• Cell structures - become a property developer...
• On this page are typical cells with all the typical bits you need to know. But cells aren't all the same - they have different structures depending on the job they do.
• Adaptions of egg cell

  Contains nutrients in cytoplasm to feed embryo

  Has a haploid nucleus

  After fertilisation, its membrane changes structure to stop any more sperm getting in - makes sure offspring has right amount of DNA
• Function of sperm cell is to transport the male’s DNA to the female’s egg.