Cell structure + transport

• What is the main focus of the topic "The world of the microscope"?

  It covers microscopy techniques, magnification, resolution, and calculations related to specimens.
• Why is it important to understand the units used for tiny specimens before observing them?


  Because most cells are too small to see without a microscope, and proper units help in measurement.
• What are the conversions between different units of length relevant to microscopy?


  • 1 km = 1000 m
  • 1 m = 100 cm
  • 1 cm = 10 mm
  • 1 mm = 1000 µm
  • 1 µm = 1000 nm
• When were the first light microscopes developed?


  In the mid-17th century.
• What is the maximum magnification of the best light microscopes?


  About ×2000.
• What is a key advantage of light microscopes?


  They are relatively cheap and can be used almost anywhere.
• What significant advancement did the electron microscope provide in the 1930s?


  It allowed biologists to see subcellular structures inside cells.
• What is the maximum magnification of an electron microscope?


  About ×2,000,000.
• What type of images do transmission electron microscopes produce?


  2D images with very high magnification and resolution.
• What is the resolving power of a light microscope?


  About 200 nm.
• What is the resolving power of a transmission electron microscope?


  About 0.2 nm.
• How do you calculate the magnification of a microscope?


  • Magnification = magnification of eyepiece × magnification of objective lens.
  • Example: If eyepiece is ×4 and objective is ×10, then overall magnification is ×40.
• If the eyepiece lens is ×4 and the objective lens is ×10, what is the overall magnification?


  $40$
• How do you calculate the size of a real object using magnification?


  Size of real object = size of image / magnification.
• If the image of a cell measures 1 mm at a magnification of ×40, what is the actual diameter of the cell?


  $25 \mu m$
• What does resolution in microscopy refer to?


  It is the ability to distinguish between two separate points.
• What is the resolving power of a scanning electron microscope?

  About 10 nm.
• What are the advantages and disadvantages of light and electron microscopes?


  Advantages of light microscopes:

  • Cheap and portable
  • Can view live specimens

  
  

  Disadvantages of light microscopes:

  • Lower magnification and resolution

  
  

  Advantages of electron microscopes:

  • High magnification and resolution

  
  

  Disadvantages of electron microscopes:

  • Expensive and require special conditions
• What is the average length of an animal cell?

  About 10-30 µm.
• What is the function of the nucleus in a cell?


  It controls all the activities of the cell and contains genes on chromosomes.
• What is the role of mitochondria in a cell?


  They are where aerobic respiration takes place, releasing energy.
• What is the average diameter of mitochondria?


  About 0.2-0.7 µm.
• What is the function of ribosomes in a cell?


  They are where protein synthesis takes place.
• What are the main structures found in animal cells?

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• What additional structures do plant cells have compared to animal cells?

  Cell wall, chloroplasts, and permanent vacuole.
• What is the function of chloroplasts in plant cells?


  They absorb light for photosynthesis.
• What is the role of the permanent vacuole in plant cells?


  It keeps the cells rigid to support the plant.
• What is the size range of plant cells?

  From 10 to 100 µm in length.
• What distinguishes eukaryotic cells from prokaryotic cells?


  Eukaryotic cells have a nucleus, while prokaryotic cells do not.
• What is the size range of prokaryotic cells?


  About 0.2-2.0 µm in length.
• What is the genetic material in prokaryotic cells like?


  It is a single DNA loop found free in the cytoplasm.
• What are plasmids in prokaryotic cells?


  They are extra small rings of DNA that code for specific features.
• What is the function of the slime capsule in some bacteria?


  It provides protection around the cell wall.
• What is the role of flagella in bacteria?


  They are used for movement.
• Why are bacteria important in the environment?


  They play crucial roles in nutrient cycling and decomposition.
• What is the significance of studying bacteria in microbiology?


  It helps us understand diseases and develop antibiotics.
• What is the average size of a bacterial cell?


  About 0.2-2.0 µm.
• How do bacteria reproduce?


  They reproduce asexually through binary fission.
• What is the importance of plasmids in genetic engineering?


  They are used to carry new genes into the genetic material of other organisms.
• What are the main differences between eukaryotic and prokaryotic cells?


  • Eukaryotic cells have a nucleus; prokaryotic cells do not.
  • Eukaryotic cells are generally larger than prokaryotic cells.
  • Eukaryotic cells have membrane-bound organelles; prokaryotic cells do not.