biology: cell bio

• Cells


  The basic unit of all living things
• Prokaryotic cells


  Cells that do not have a nucleus
• Eukaryotic cells


  Cells that have a nucleus where their genetic material is stored
• Eukaryotic cells


  • Larger and more complex than prokaryotic cells
• Eukaryotic cells


  • Animal cells
  • Plant cells
• Prokaryotic cells


  • Smaller and simpler than eukaryotic cells
• Prokaryotic cells


  • Bacteria cells
• Nucleus


  Houses genetic material (DNA) and controls cell activities
• Cytoplasm


  A gel-like substance where chemical reactions occur
• Cell membrane


  Controls what enters and exits the cell
• Mitochondria


  The site of aerobic respiration, which releases energy
• Ribosomes


  Where proteins are synthesised
• Rigid cell wall


  Composed of cellulose and provides support and structure
• Permanent vacuole


  Contains cell sap which is a storage for sugar and salts
• Chloroplasts


  The location of photosynthesis, contains chlorophyll to absorb light
• Animal cells


  Do not have cell walls or chloroplasts
• Animal cells


  Usually have smaller vacuoles compared to plant cells
• Bacterial cells


  Have a single circular strand of DNA instead of a true nucleus
• Plasmids


  Small rings of additional DNA found in some bacterial cells
• Differentiation


  The process where a cell transforms into a specialised cell for a specific job
• Differentiation


  • Involves the development of different subcellular structures for various functions
  • In animal cells, most differentiation occurs at an early stage as the organism develops
  • In mature animals' cells, the ability to differentiate is mainly used for repairing and replacing cells, such as skin or blood cells
  • Plants never lose their ability to differentiate
• Undifferentiated cells


  Stem cells
• Specialised Cells and Their Functions

  • Sperm Cells
  • Nerve Cells
  • Muscle Cells
  • Root Hair Cells
  • Phloem Cells
  • Xylem Cells
• Sperm Cells


  • Specialised for reproduction
  • Designed to deliver male DNA to female DNA
  • They have a long tail for mobility
  • They have many mitochondria for energy
  • The head is streamlined to make movement more efficient
  • The head contains enzymes that can digest through the membrane of the egg cell
• Nerve Cells


  • Specialised for sending electrical signals
  • Carry messages in the form of electrical signals across the body
  • They are long to cover more distance
  • They have branched connections called Dendrites to create a large network around the body
• Muscle Cells


  • Specialised for contraction
  • They are long, so they have space to contract
  • They are filled with many mitochondria to transfer energy for contraction
• Root Hair Cells


  • Specialised for absorbing water and minerals
  • Grow long "hairs" to increase surface area for absorption from the soil
  • Contain no chloroplasts as they are found underground and do not receive light for photosynthesis
• Phloem Cells


  • Specialised for transporting food substances
  • Cells are joined end to end to form tubes to transport food in plants
  • They have very few subcellular structures to help substances flow through easily
• Xylem Cells


  • Specialised for transporting water and minerals
  • Cells are joined end to end to form tubes to transport water and minerals in plants
  • They are hollow for easy flow
  • They are made up of dead cells strengthened with lignin
• Microscopes


  Tools that allow us to see the unseen world, revealing structures too small for the naked eye
• Types of microscopes


  • Light microscopes
  • Electron microscopes
• Light microscopes


  • Use light and lenses to magnify specimens, allowing us to see individual cells and large subcellular structures like nuclei
• Electron microscopes


  • Use electrons to form an image and can magnify much more than light microscopes, showing us the finer details of cell structures like mitochondria and chloroplasts
• Magnification


  How much larger the microscope makes the object appear
• Calculating magnification


  Microscope equation
• Standard form


  Used to handle very large or small numbers with microscopes
• Writing in standard form

  Move decimal point until one non-zero digit to left, then multiply by power of 10
• Power of 10 is positive if decimal point moved left, negative if moved right
• Microscope calculations


  Ensure units are consistent, know how to convert micrometers to millimeters
• Microscope calculation


  • Example calculation