1. 1.2 Ultrastructure of cells

2. 1.2 Ultrastructure of cells
Understandings
Prokaryotes have a simple cell structure without compartments
Eukaryotes have a compartmentalized cell structure
Prokaryotes divide by binary fission
Electron microscopes have a much higher resolution than light microscope
Nature of Science
Developments in scientific research follow improvements in apparatus: the invention of electron microscopes led to greater understanding of cell structure
Applications
The structure & function of organelles within exocrine gland cells of the pancreas
The structure & function of organelles within palisade mesophyll cells of the leaf
Skills
Drawing the ultrastructure of prokaryotic cells based on electron micrographs
Drawing the ultrastructure of eukaryotic cells based on electron micrographs
Interpretation of electron micrographs to identify organelles & deduce the function of specialized cells

3. Discoveries due to electron microscopes in 1930’s
Nature of Science: Developments in scientific research follow improvements in apparatus: the invention of electron microscopes led to greater understanding of cell structure.
Discoveries due to improved light microscope in 1850’s
Discoveries due to electron microscopes in 1930’s
Bacteria
Chromosomes
Mitosis & meiosis
Fusion of gametes
Organelles within cells
Images of things as small as 0.2μm
More intricate details of chloroplasts & mitochondria
Existence of ribosomes, lysosomes, & ER
Images of things as small as μm

4. Understanding: Electron microscopes have a much higher resolution than light microscopes Resolution = the ability of a microscope to distinguish 2 separate points as 2 separate entities Naked eye can see things 0.1mm (100μm or 100,000 nm) as separate objects
Light Microscope
Electron Microscope
* Max resolution = 0.2 μm (200 nm)
even if you keep increasing the magnification (limited by wavelength of visible light), you would just get a blurry image
Max mag on light scope = 400x
Reveal structure of cells
Can see bacteria
Resolution = μm (1 nm)
200X higher than light scope
Use beams of electrons with shorts wavelengths, so higher magnification will have higher resolution
Reveal ultrastructure of cells
(ultra = high definition/extreme)
Can see viruses

5. Understanding: Prokaryotes have a simple cell structure without compartments
Pro = before
Karyon = nut or kernel
Prokaryote = before a nucleus (no nucleus)
Cell membrane
Cell wall – protects, maintains shape, prevents bursting, made of peptidoglycan, extracellular
All cytoplasm
One organelle = ribosomes (70S size, S = Svedberg unit)
DNA in middle of cytoplasm in “nucleoid” (nucleus-like)
DNA is “naked” = not associated with proteins (so appears lighter than cytoplasm, which has proteins (enzymes))
DNA usually one circular piece

6. Name the parts!

7. Understanding: Prokaryotes divide by binary fission
Binary fission = asexual reproduction
DNA replicates
The 2 DNAs move to opposite ends of cell
Division of cytoplasm

8. Bacterial conjugation = exchange of genetic material http://youtu

9. Skill: Draw the ultrastructure of prokaryotic cells based on electron micrographs

11. Escherichia coli http://www.cellsalive.com/cells/bactcell.htm

12. Understanding: Eukaryotes have a compartmentalized cell structure
Eu = true
Karyon = nucleus
Instead of one continuous structure, cell is divided into compartments
Compartments are single or double membranes
Compartments = organelles = little organs with specific functions
Advantages:
enzymes & substrates can be localized to one area so more concentrated
Harmful substances can be compartmentalized in a lysosome
pH can be compartmentalized in one organelle
Organelles can move around cell, carrying contents

13. Skill: Draw the ultrastructure of eukaryotic cells based on electron micrographs

14. Let’s practice!

25. Application: The structure and function of organelles within exocrine gland cells of the pancreas Gland cells = cells that secrete (release) substances thru cell membrane
Endocrine glands
Exocrine glands
Have no ducts
secrete hormones directly into bloodstream
Have ducts
Secrete substances into a duct that carries them somewhere else
(Pancreas cells secrete digestive enzymes thru duct into small intestine)

26. What organelles are needed in a pancreas exocrine gland cell?

27. Application: The structure and function of organelles within palisade mesophyll cells of the leaf. What organelles are needed for photosynthesis?

28. Skill: Interpret electron micrographs to identify organelles and deduce the function of specialized cells.
ferguson/unit-1-cells/1-2-ultrastructure-of-cells