8.2 cells

• Uni-cellular organism


  An organism made up of just one cell
• Uni-cellular organisms


  • They are not plants or animals as these are made up of lots of cells
  • They are adapted to carry out functions that in multi-cellular organisms are done by different types of cell
• Uni-cellular


  Consisting of a single cell
• Amoeba


  A uni-cellular organism that has no fixed shape
• Amoeba


  • Consists of a cell membrane filled with cytoplasm, with a nucleus inside that controls growth and reproduction
• Amoeba reproduction


  1. Splits itself into two cells, known as binary fission

  2. First the nucleus divides, then the cytoplasm divides to produce two identical cells
• Euglena


  A microscopic uni-cellular organism found in fresh water
• When a euglena doesn't have enough light


  It looks for other things to eat, such as bacteria and algae, by surrounding and engulfing them
• Euglena reproduction


  Reproduces by binary fission, like amoebas
• Amoeba and euglena reproduction


  Both reproduce by binary fission, splitting themselves into two identical cells
• Adaptations of uni-cellular organisms


  • Amoeba's ability to change shape to move, euglena's eyespot and flagellum to detect and move towards light
• Specialised cell


  Cells that have changed so that they are suited to carry out a particular job
• Nerve cell


  • Long and thin, have connections at each end where they can join to other nerve cells, allows them to transmit messages around the body
• Red blood cell


  • Transport oxygen around the body, contain haemoglobin, have no nucleus, disk-like shape increases surface area for carrying oxygen
• Sperm cell


  • Head and tail, swim rapidly to fertilise egg
• Leaf cell


  • Contains chloroplasts, where photosynthesis happens
• Components found in plant cells


  • Cell wall
  • Vacuole
  • Chloroplasts
• Cell wall


  Strengthens the cell and provides support, made of tough fibre called cellulose
• Vacuole


  Contains a watery liquid called cell sap, keeps the cell firm
• Chloroplasts


  Where photosynthesis happens, contain chlorophyll which traps energy from the Sun
• Chlorophyll and chloroplast both start with the prefix 'chloro-' meaning 'green'</b>
• Prefixes bio-, photo-, and micro- can give clues to the meaning of words
• Components of a cell


  • Nucleus
  • Cell membrane
  • Cytoplasm
  • Mitochondria
• Nucleus


  Controls the cell's activities
• Cell membrane


  Controls what comes in and out of the cell
• Cytoplasm


  Where chemical actions take place
• Mitochondria


  Where respiration occurs
• Leaf cells contain chloroplasts
• Root hair cells do not contain chloroplasts
• Plant and animal cells

  Have similarities and differences in their functions
• A microscope has an eyepiece lens and an objective lens that together magnify the object
• Total magnification

  Eyepiece lens magnification x Objective lens magnification
• Cells are the building blocks of life, the smallest units found in an organism
• Robert Hooke saw tiny room-like structures which he called cells when looking at a thin slice of cork under a microscope
• Observation

  Looking carefully and in detail at an object
• Steps to observe an object using a microscope

  1. Move stage to lowest position

  2. Place object on stage

  3. Select lowest magnification objective lens

  4. Look through eyepiece and turn coarse focus knob until object is seen

  5. Turn fine focus knob until object is in focus

  6. Repeat with higher magnification objective lens
• Uni-cellular organisms


  Organisms that consist of a single cell. Examples include bacteria, archaea, and protists.
• Autotrophic


  Refers to organisms that can produce their own food using light, water, and carbon dioxide. An example of an autotroph is a plant.
• Multi-cellular organisms


  Organisms that consist of multiple cells. Examples include plants, animals, and fungi.
• Photosynthesis


  The process by which some uni-cellular organisms, such as algae and cyanobacteria, produce their own food using light, water, and carbon dioxide. They use this organic matter for energy and growth.