1. EUKARYOTE CELL ULTRASTRUCTURE
© 2016 Paul Billiet ODWS

2. Primary Cell Structure
That which can be seen using the light microscope.
© P Billiet
Leaf cells Elodea viewed at x400
© 2016 Paul Billiet ODWS

3. Ultrastructure
Lehninger (1970) Biochemistry Worth
That which can be observed under the electron microscope.
Transmission electron micrograph (TEM) palisade leaf cell
© 2016 Paul Billiet ODWS

4. EUKARYOTE CELL ULTRASTRUCTURE
DIMENSIONS
MAIN FUNCTIONS
ORGANELLE
10 µm diameter
Cell division, protein synthesis
Nucleus
1.0 to 12.5 µm
Respiration pathways
Mitochondrion
5 to 10 µm diameter
Photosynthetic pathways
Chloroplast
0.5 to 3.0 µm diameter
Digestion, recycling & isolation
Lysosome
Cisternae: 0.5µm thick, l-3µm diameter
Secretion, reprocessing, lysosome synthesis
Golgi apparatus
26 to 56 nm thick
Support, Golgi apparatus synthesis
Endoplasmic Reticulum (ER)
20 nm diameter
Protein synthesis
Ribosome
© 2016 Paul Billiet ODWS

5. NUCLEUS (latin kernel)
TEM Nucleus of a rat hepatocyte
© 2016 Paul Billiet ODWS

6. NUCLEUS (pl nuclei)
10 µm
Usually spherical, occupying up to 75% of the cell volume.
© 2016 Paul Billiet ODWS

7. Protein: Up to 90%, HISTONES rich in basic amino acids.
NUCLEUS
Chemical composition
Protein: Up to 90%, HISTONES rich in basic amino acids.
Deoxyribonucleic Acid (DNA) about 20%
Ribonucleic Acid (RNA) 5 to 20%
Nuclei usually contain about 10% CHROMATIN = Histone + DNA = NUCLEOPROTEIN.
© 2016 Paul Billiet ODWS

8. Main site of DNA in eukaryotic cells
NUCLEUS
Functions
Main site of DNA in eukaryotic cells
Preservation, replication and expression of genetic information
It makes RNA for protein synthesis
It copies DNA for cell division.
© 2016 Paul Billiet ODWS

9. MITOCHONDRION (gk mitos = thread khondrion = granule)
TEM of mitochondrion from mouse kidney cell
© 2016 Paul Billiet ODWS

10. MITOCHONDRION (pl. mitochondria)
outer membrane
inner membrane
Mitochondrial envelope
Inter membrane space
Cristae
Inner matrix
1.0 to 12.5 µm
© 2016 Paul Billiet ODWS

11. MITOCHONDRION Pigments Cytochromes Functions
The mitochondria are closely associated with the pathways of respiration
These metabolic pathways are divided up and supported by the membranes
The inner membrane contains the enzyme necessary for the synthesis of Adenosine Triphosphate (ATP).
© 2016 Paul Billiet ODWS

12. CHLOROPLAST (Gk chloros = green plast = form or shape)
TEM chloroplast
botit.botany.wisc.edu/.../Chloroplast_EN.html
© 2016 Paul Billiet ODWS

13. CHLOROPLAST Grana Thylakoid membrane Frets outer membrane
inner membrane
Chloroplast envelope
Starch grains
Grana
Frets
Thylakoid membrane
Stroma
© 2016 Paul Billiet ODWS
5 to 10 µm

14. CHLOROPLAST
Pigments Mainly chlorophylls with carotenoids and others Function: Photosynthesis The metabolic pathways are closely associated with the membranes as in the case of the mitochondrion.
© 2016 Paul Billiet ODWS

15. Organelles and evolution
Both chloroplasts and mitochondria are double membrane bound
They involved in energy reactions
They contain extranuclear DNA and characteristic small ribosomes of their own
This has led biologists to believe that there may be some similarity in their origins in the cells of eukaryotes
The endosymbiotic theory.
© 2016 Paul Billiet ODWS

16. LYSOSOME
cellbio.utmb.edu/cellbio/lys2.jpg
© 2016 Paul Billiet ODWS

17. LYSOSOME
Not discovered by electron microscopy but by centrifugation and enzyme analysis
Not present in plant cells
Structure: Simple, spherical, single membrane bound
Lysosomes contain a large number of CATABOLIC enzymes.
© 2016 Paul Billiet ODWS

18. Enzymes found in lysosomes
SUBSTRATE
Acid phosphatase
Phosphate esters
Acid ribonuclease
RNA
Acid deoxyribonuclease
DNA
Glycosidases
Polysaccharides
Protease
Proteins and peptides
Lipase
Lipids
Phospholipase
Phospholipids
More than 40 types of enzymes are known to occur in lysosomes.
© 2016 Paul Billiet ODWS

19. LYSOSOME
Function
Digestion of compounds taken in by the cell by endocytosis
Recycling of material within the cell.
© 2016 Paul Billiet ODWS

20. GOLGI APPARATUS © 2016 Paul Billiet ODWS
© 2016 Paul Billiet ODWS

21. GOLGI APPARATUS
Golgi vesicles transport the materials from one cisterna to the next
Cisternae are flattened sacs
Transport vesicles bring material from the endoplasmic reticulum to the entry face
Golgi vesicles take transformed materials from the exit face to their destination
© 2016 Paul Billiet ODWS

22. GOLGI APPARATUS Functions Processing and packaging
Synthesising lysosomes to contain the potentially dangerous catabolic enzymes
Producing secretory vesicles e.g. mucus
Making more plasma membrane.
© 2016 Paul Billiet ODWS

23. ENDOPLASMIC RETICULUM (ER)
© 2016 Paul Billiet ODWS

24. ENDOPLASMIC RETICULUM (ER)
Rough ER
Smooth ER
Transport vesicles
Lumen which can occupy up to 10% of the cell volume
Membranes
© 2016 Paul Billiet ODWS

25. ER Functions Difficult to extract intact
ER starts the biosynthetic pathways that form many protein and lipid molecules in the cell
These continue in the Golgi apparatus
Rough ER has ribosomes attached to it as opposed to Smooth ER
The proteins made on rough ER will eventually be secreted outside the cell.
© 2016 Paul Billiet ODWS

26. RIBOSOME © 2016 Paul Billiet ODWS
© 2016 Paul Billiet ODWS

27. RIBOSOME NOT membrane bound Found both in prokaryotes and eukaryotes
The subunits are synthesised separately in the nucleolus of the nucleus of eukaryotes.
Large ribosome subunit
Small ribosome subunit
© 2016 Paul Billiet ODWS

28. RIBOSOME Distribution in the cytoplasm single free-floating
attached to rough ER
linked together as a POLYRIBOSOME or POLYSOME
Function: Protein synthesis
Chemical composition Protein + RNA = a nucleoprotein.
© 2016 Paul Billiet ODWS

29. The relationship between organelles
Nucleus ER
Golgi apparatus
Lysosome
Ribosomes
Endocytosis
Exocytosis
© 2016 Paul Billiet ODWS

30. The pancreas
© 2016 Paul Billiet ODWS

31. Pancreas exocrine cell
© 2016 Paul Billiet ODWS

32. Palisade mesophyll
© 2016 Paul Billiet ODWS

33. Palisade mesophyll cell
Palisade mesophyll wheat scale bar 2μm
© 2016 Paul Billiet ODWS