Biology Chapter One

• Nucleus


  Controls the activities of the cell, contains genetic material
• Animal cells


  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
  • Chloroplasts
• Cytoplasm


  Where most of the reactions take place, jelly of the cell
• Cell membrane


  Controls the passage of substances in and out of the cell
• Mitochondria


  Site of respiration, energy is released
• Ribosomes


  Where proteins are synthesised (made for photosynthesis), protein synthesis
• Chloroplasts


  Contain chlorophyll, site of photosynthesis, absorb light
• Cell wall


  Strengthens the cell, made of cellulose
• Permanent vacuole


  Filled with cell sap to make the cell turgid
• Plant cells


  • Cell membrane
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Chloroplasts
  • Vacuole
  • Nucleus
  • Cell wall
• Not all plant cells have chloroplasts - not present in root cells as they do not receive any light
• Prokaryotic cells (bacterial cells)

  • Cell wall
  • Cytoplasm
  • Cell membrane
  • Plasmids
  • DNA (circular loop)
  • Ribosomes
  • Pili
• Bacterial cells have different shapes, but they are prokaryotic cells
• The roles of mitochondria and chloroplasts are taken over by the cytoplasm in prokaryotic cells
• Plasmids allow bacterial cells to move genes from one cell to another
• DNA in a bacterium is found in the cytoplasm as a circular loop
• Flagella


  A tail-like structure that moves the bacterium
• Eukaryotic cells


  Animal, plant and fungal cells
• Typical plant cell is about 0.1 mm in diameter, animal cell is 0.02 mm in diameter, prokaryotic cells are smaller at 0.002 mm long
• Units used to describe cell and sub-cellular structure size


  • Centimetre
  • Millimetre
  • Micrometre
  • Nanometre
• Light microscope


  • Developed in late 16th century
  • Used for hundreds of years
  • Specimen can be alive
  • Cheap
  • Anyone can use
  • Magnification up to 1000-2000x
  • Can't see internal structures
  • Limited resolution
  • Not much space needed
  • Uses light and rays
• Electron microscope


  • Recently invented
  • Magnification up to 2,000,000x
  • Can see internal structures
  • Technology can improve
  • Specimen is dead
  • Expensive
  • Only highly trained scientists can use
  • Lots of space needed
  • Uses beams of light energy
• Viewing cells under a microscope

  1. Plug in microscope

  2. Peel off transparent piece of onion, place on slide, add iodine, cover slip

  3. Swab inside of cheek, smear on slide, add methylene blue, cover slip

  4. Place specimen on stage

  5. Adjust height of stage with coarse focus until image is visible

  6. Fine tune image with fine focus wheel

  7. Draw what you see, add scale line
• Chromosomes


  Found in the nucleus, made of DNA, contain genes that control the development of different characteristics
• In body cells, chromosomes are found in pairs - one from each parent
• Humans have 23 pairs of chromosomes
• Mitosis and the cell cycle

  1. DNA is copied and new chromosomes are made

  2. Cell grows and makes new sub-cellular structures

  3. Chromosomes line up along the centre of the cell

  4. Nucleus divides

  5. Cytoplasm divides to give two new identical daughter cells
• Mitosis


  A type of cell division that leads to growth or repair
• Cell cycle


  A series of changes that cells go through
• Stem cells


  • Unspecialised or undifferentiated cells that can divide to make different types of cells
  • Found in developing embryo, umbilical cord, some organs and tissues
• Types of stem cells

  • Embryonic stem cells
  • Adult stem cells
• Embryonic stem cells

  Left over after IVF, wide range of applications, many available
• Adult stem cells


  Better to use than embryonic, cannot give consent, long term effects unknown, cannot treat as many diseases, risk of injection
• Using stem cells for treatment

  1. Stem cells removed from body

  2. Cells stimulated to divide

  3. Stem cells cultured

  4. Stem cells removed and injected back into patient
• Plant meristems


  Plant stem cells found at new tips of roots and stems, in buds, in xylem and phloem tissues
• Uses of plant meristems


  • Produce clones of plants quickly
  • Protect rare species from extinction
  • Make large numbers of identical plants with special features
• Diffusion


  The net movement of particles from an area of higher concentration to an area of low concentration until they are evenly spread out
• Particles move randomly and spread out during diffusion
• Many substances move into and out of cells across the cell membranes by diffusion
• Diffusion


  A passive process that does not require energy