1.2 Ultrastructure of cells

Diana CarvajalAugust 2014

http://t2.gstatic.com/images?q=tbn:ANd9GcTB6YQWcF9pYillWplUSjwLeaYe9b6DpWQa5EnlY_oZHbJGcx_00w

http://explore.ecb.org/videos/VLC_file?TYPE=Image&P1=2080&REFERER=OTHER

Developments in scientific research follow improvements in apparatus—the invention of electron microscopes led to greater understanding of cell structure.

Microscopes!Electron microscopes have a much higher

resolution than light microscopes.

https://www.classzone.com/books/ml_science_share/vis_sim/chm05_pg19_microscope/chm05_pg19_microscope.swf http://web.biosci.utexas.edu/psaxena/MicrobiologyAnimations/Animations/Microscopy/micro_microscopy.swf

Relative sizes

1. Molecules (1nm). 2. Cell membrane thickness (10nm).3. Virus (100nm).4. Bacteria (1um).5. Organelles (less 10um).6. Cells (<100 um).7. Generally plant cells are larger than animal cells.

http://intranet.canacad.ac.jp:3445/BiologyIBHL1/550

nm = nanometer μm = micrometer

• Absence of organelles.• There is no true nucleus.• Some bacteria have flagellum.

Ultrastructure of E. coli.

Drawing of the ultrastructure of prokaryotic cells based on electron micrographs

Prokaryotes have a simple cell structure without compartmentalization.

(With naked DNA)

70S

What are the functions of these prokaryotic cell parts?

Binary fission:• Asexual method of reproduction.• The cells produced are genetically identical (clones).

Prokaryotes divide by binary fission

Drawing of the ultrastructure of eukaryotic cells based on electron micrographs.

1

2

3

4

5

6

7

8

Eukaryotes have a compartmentalized cell structure.

Eukaryotic cell

Which structures can you identify in this false-coloured TEM (transmission electron microscopy) image?

Electron micrographs of liver cells.

http://www.sciencephoto.com/media/214698/enlarge

Magnification x47,500 at 10X8 cm size.

http://www.sciencephoto.com/media/214698/enlarge

Magnification x47,500 at 10X8 cm size.

Nucleus

Nuclear membrane

mitochondria

endoplasmic reticulum (ER)

ribosomes

Electron micrographs of liver cells.

http://www.ucmp.berkeley.edu/alllife/eukaryotamm.html

What are the differences between prokaryotic and eukaryotic cells?

Comparison of prokaryotic and eukaryotic cells

Identify structures in electron micrographs of E. coli