2.1.1 Cell Structure

• What is the image from a light microscope called?

  Photomicrograph
• Labelled Microscope

  A) eyepiece

  B) body tube

  C) arm

  D) stage

  E) coarse focusing knob

  F) fine focusing knob

  G) Base

  H) Light Source

  I) Diaphragm

  J) Stage Clips

  K) Objective Lenses

  
• Magnification is the number of times larger an image appears compared to the size of the object
• Resolution is the clarity of an image.
• Magnification = Image Size / Actual Size
• 4 advantages of light microscopes

  1. Cheap
  2. Easy to use
  3. Can view whole, living organisms
  4. Portable
• 2 disadvantages of light microscopes:

  1. Limited resolution -> due to the long wavelength of light
  2. Cannot view internal structures
• Laser Scanning Microscopes scan the object point to point and a computer compiles the image
• 3 advantages to laser microscopes:

  1. Depth selectivity
  2. 3D image
  3. Can view whole, living organisms
• What is depth selectivity?

  The microscope can focus on structures at different depths
• 3 disadvantages of laser microscopes

  1. Expensive
  2. Slow as relies on a computer
  3. May cause photodamage to cells
• In Transmission Electron Microscopes (TEM) the electrons pass through the specimen.
• In Scanning Electron Microscopes (SEM) electrons bounce off of the specimens surface.
• 5 disadvantages of TEMs:

  1. 2D image
  2. Greyscale
  3. Expensive
  4. Requires training to operate
  5. Dead specimen -> as viewed in a vacuum
• 2 advantages of SEMs:

  1. 3D images
  2. False colour can be added
• 3 disadvantages of SEMs:

  1. Expensive
  2. Requires training to operate
  3. Dead specimen -> viewed in a vacuum
• How is contrast provided in an electron micrograph?

  Specimens are coated in heavy metals. Denser areas absorb more electrons, providing contrast.
• Why do we stain specimens?

  Makes structures visible and increases contrast which makes them appear clearer when viewed with a microscope
• Stains

  A) lipids

  B) red

  C) cytoplasm

  D) pink

  E) Iodine

  F) starch granules

  G) yellow

  H) DNA

  I) red

  J) Methylene Blue

  
• What is the role of the diaphragm of a microscope?

  To control how much light is shining on the sample from below
• Labelled Eukaryote

  A) membrane

  B) rough endoplasmic reticulum

  C) nucleolus

  D) nucleus

  E) smooth endoplasmic reticulum

  F) lysosome

  G) ribosome

  H) nuclear envelope

  I) golgi apparatus

  J) cytoplasm

  K) mitochondria

  
• Labelled Nucleus

  A) Nucleolus

  B) Chromatin

  C) Nucleoplasm

  D) Nuclear Pore

  E) Nuclear Envelope

  
• Chromatin is DNA wrapped around histone proteins. It coils into chromosomes before cell division.
• Labelled Prokaryote

  A) cell wall

  B) plasmid

  C) pili

  D) cytoplasm

  E) flagellum

  F) ribosomes

  G) nucleoid

  
• Pili allow bacteria to adhere to each other or to host cells
• Organelles are components of cells which perform specific functions
• What type of cell contains membrane-bound organelles?

  Eukaryotes
• Prokaryotes contain what type of ribosomes?

  70s
• Eukaryotes contain what type of ribosomes?

  80s
• Where is the genetic material in prokaryotes?

  Nucleoid and Plasmids
• Bacterial cell walls are made out of what?

  Peptidoglycan
• Plant cell walls are made out of what?

  Cellulose
• What are the energy stores of prokaryotes?

  Starch Granules

  Oil Droplets
• Organelles of the Nucleus

  A) genetic material

  B) controls

  C) ribosome synthesis

  D) separates

  E) mRNA

  F) steroid hormones

  
• The nucleolus has no membrane
• What is the endoplasmic reticulum?

  A network of membranes containing fluid-filled cavities called cisternae. It is continuous with the nuclear membrane.
• Does the SER contain ribosomes?

  No
• Functions of Organelles

  A) movement

  B) modifies

  C) packages

  D) hydrolytic enzymes

  E) foreign

  F) aerobic respiration

  G) protein synthesis

  H) surface area

  I) protein synthesis

  J) lipids

  K) structure

  L) microtubules

  M) spindle fibres

  N) photosynthesis

  O) movement

  P) surface

  Q) controls

  
• In protein modification:

  • adding sugar -> glycoproteins
  • adding lipids -> lipoproteins
  • folding into 3D shape
• After proteins are packaged they are either:

  1. Stored in the cell
  2. Transported to the plasma membrane to be incorporated into it or moved outside the cell