1. Prokaryotic and Eukaryotic Cell Structure
And a Little Taxonomy too!

2. Taxonomy The science of classification of living organisms.
So we can identify and understand relationships between organisms.

3. Linnaean System First developed by Carolus Linnaeus (1707-1778).
Method of classifying things in a hierarchical structure from most general to most similar.
Binomial System (2 names)
Domain
Kingdom (most general)
Phylum or Division
Class
Order
Family
Genus
Species
Ex. Eschericia coli
or E. coli

4. Classification
Domains constitute a level of classification above the kingdom.
Domains are further subdivided into kingdoms etc.

5. The 3 Domains Prokaryotes Eukaryotes 1. Archaea 2. Bacteria 3. Eukarya
- animals
- plants
- algae
- protozoa
- fungi
Prokaryotes
Eukaryotes

6. 5 Kingdoms
Based on similar morphology, geographic distribution, and if multicellular, the ability to interbreed.
Bacteria

7. Bergey System Another system for classifying Prokaryotes.
Still use kingdom, division or phylum, class, order, family, genus, species.
Classification based on similar morphological and biochemical characteristics.

8. Eukaryotic and Prokaryotic Cells
How are they different and
how are they the same?

9. What Is a Cell? It is the fundamental unit of all living matter.
Has all characteristics of life.
Can live independently of other cells.

10. All Cells Have the Following:
Enzymes
A protein that speeds up a chemical reaction.
DNA – deoxyribonucleic acid
A large molecule that stores genetic information.
RNA – ribonucleic acid
A large molecule involved in protein synthesis.
ATP – adenosine triphosphate
The main energy currency of a cell.
Amino Acids
Proteins are composed of basically the same 20 amino acids.

11. Eukaryotic Cell Structure
Possess membrane-bound organelles.
10-30µm in diameter.
Eukaryote = “true nucleus”
Their DNA is enclosed by a double membrane.

12. Eukaryotic Cell Structure
Cell Membrane
Phospholipid (fatty chain with a phosphate) bi-layer with different types of proteins interspersed.
Separates inside of cell from external environment.
It has selective permeability.
Only certain things can get in and out.
Other organelle membranes are similar in structure.

13. Cell Membrane

14. Eukaryotic Cell Structure
Nucleus
Controls the functions of the cell (“the control center).
Nuclear membrane – surrounds nucleus.
Nucleoplasm – gelatinous matrix.
Chromosomes – linear DNA molecules and proteins.
Gene – specific DNA segment on the chromosome that contains the information for making a gene product, usually a protein.
Nucleolus – where rRNA is made and is used to make a structure called ribosomes.

15. Eukaryotic Cell Structure
Cytoplasm
A semi-fluid, gelatinous, nutrient matrix.
Contains storage granules and cell organelles.
Most of cell’s metabolism occurs.
Often called the cytosol.

16. Eukaryotic Cell Structure
Endoplasmic Reticulum (ER)
An irregular maze of spaces enclosed by a membrane.
“Assembly Line”
Rough ER
Contains ribosomes
Involved in making proteins
Smooth ER
Does not contain ribosomes
Involved in lipid metabolism (fat storage)

17. Eukaryotic Cell Structure
Ribosomes
Are important in protein synthesis.
Are found in the Rough ER.

18. Eukaryotic Cell Structure

19. Eukaryotic Cell Structure
Golgi Complex
“packaging plant.”
Stacks of flattened, membranous sacs.
Completes and packages newly formed proteins and lipids.
Packages them so that they are ready for storage within the cell or outside of the cell.

20. Eukaryotic Cell Structure
Lysosomes
“garbage disposal system”
1 µm diameter
Contain lysozyme and other enzymes that break down foreign material.
Particles may enter cell by phagocytosis.
Also involved in programmed cell death called autolysis or apoptosis.
Peroxisomes
Membrane-bound vesicles that generate and break down hydrogen peroxide (a dangerous and highly reactive chemical).
Used to break down lipids (fats) and destroy toxic molecules.

21. Eukaryotic Cell Structure
Mitochondria
“the power plant of the cell”
0.5 – 1 µm in diameter, 7 µm in length
Where ATP (adenosine triphosphate) is formed.
ATP is the energy currency of the cell.
ATP is formed during a reaction called cellular respiration.
ATP is formed from our food sources.

22. Eukaryotic Cell Structure

23. Eukaryotic Cell Structure
Plastids
Site of photosynthesis.
Contain photosynthetic pigments.
Photosynthesis – converting light energy into a source of chemical energy for organism.
Chloroplasts – type of plastid that contains chlorophyll.
Chlorophyll – a green photosynthetic pigment.

24. Eukaryotic Cell Structure - Plant Cell
micro.magnet.fsu.edu/cells/plants/plantmodel.html

25. Eukaryotic Cell Structure
Cell Wall
External structure that provides rigidity, shape, and protection.
May be composed of cellulose, pectin, lignin, chitin, and some mineral salts.
Usually simpler than prokaryotic cells.

26. Eukaryotic Cell Structure
Plant Cells
Cells stained green (DNA) and red (keratin)
Illustration by Robert Hooke (c.1665)
askabiologist.asu.edu/.../rhooke.html

27. Cell Walls Cell Walls Absent Present Animals Plants Protozoa Algae
Mycoplasma species (type of bacteria)
Present
Plants
Algae
Fungi
Most Bacteria

28. Eukaryotic Cell Structure
Flagella
An organelle of movement.
Long, thin structure that moves like a whip to propel organism through liquid environment.
Can be found in some species of protozoa, spermatozoa, and algae.
Cilia
Organelle of locomotion.
Usually short, hair-like structures that beat in coordinated, rhythmic movement.
Can be found in some species of protozoa and types of cells that line respiratory tract.

29. Eukaryotic Cell Structure
Paramecium – sp. Protozoa. Notice the cilia.
microbewiki.kenyon.edu/index.php/Paramecium
Euglena – sp. Protozoa. Notice the flagella.

30. Prokaryotic Cell Structure
More simple than eukaryotic cells.
Can perform all functions necessary for life.
Prokaryotes comprise all bacteria and archaeans.
Do NOT contain membrane-bound organelles.
Typical E. coli cell is about 1 µm wide and 2-3 µm long.

31. Prokaryotic Cell Structure
Bacterial Cell Wall
Provides rigidity, strength, and protection.
More complex than eukaryote cell walls.
Composed of peptidoglycan (polymer of sugars and amino acids)
Gram-positive bacteria
Thick layer of peptidoglycan with some other molecules.
Gram-negative bacteria
Thinner layer of peptidoglycan with an outer membrane composed of lipid macromolecules.
Genus Mycoplasma do not have cell walls.
Archaens have cell walls but not composed of peptidoglycan.

32. Prokaryotic Cell Structure
Cell Membrane
Similar to eukaryotic cells.
Contains proteins and phospholipids.
Selectively permeable.
It is very flexible and thin.

33. Prokaryotic Cell Structure
Glycocalyx
Thick, slimy, gelatinous material produced by the cell membrane and secreted outside the cell wall.
Some bacteria have it.
2 types of glycocalyx
1. Slime Layer
Is not highly organized or firmly attached to cell wall.
Allows bacteria to glide or slide along surfaces.
2. Capsule
Highly organized and firmly attached to cell wall.
Chemical composition allows scientists to determine different types of bacteria.
Prevent bacteria from being phagocytized by phagocytic white blood cells.
Can attach bacteria to a wide array of surfaces.

34. Prokaryotic Cell Structure
diverge.hunter.cuny.edu/~weigang/Lecture-syll.

35. Prokaryotic Cell Structure
Prokaryotic Chromosome
Single, long, supercoiled, circular DNA molecule.
Embedded in cytoplasm.
Found in nuclear region of cell.
Does not have a nuclear membrane.
Contains all the information for carrying out life processes.
Plasmids may also be found in prokaryotic cells.

36. Prokaryotic Cell Structure
Plasmid
Small, circular molecule of double-stranded DNA.
Not part of the chromosome.
Called extrachromosomal DNA.
Found in the cytoplasm.
May contain s genes.
Number varies per cell.

37. Prokaryotic Cell Structure
Cytoplasm
Semiliquid interior of cells.
Consists of water, enzymes, dissolved oxygen (in some bacteria), waste products, nutrients, proteins, carbohydrates, and lipids.
Everything necessary for its metabolic functions.

38. Prokaryotic Cell Structure
Cytoplasmic Particles
Ribosomes are found in the cytoplasm.
They are important in protein synthesis.
Some substances are stored in cytoplasmic granules.
Such as starch, lipids, sulfur, or iron.
The type of substance stored depends on the species of organism.

39. Prokaryotic Cell Structure
diverge.hunter.cuny.edu/~weigang/Lecture-syll.

40. Prokaryotic Cell Structure
Flagella
A mechanism for movement for some bacteria.
Bacteria can be classified and identified by the arrangement of their flagella.
Nonflagellated bacteria are usually considered to be nonmotile.
Although there are exceptions.
Pseudomonas fluorescens – aerobic soil bacteria.

41. Prokaryotic Cell Structure
Pili (Fimbriae)
Not associated with motility.
Thin, rigid, hair-like structure.
Arise in cytoplasm and extend through the plasma membrane, cell wall, and capsule (if present).
2 types of pili
1. Adhesins - allows bacteria to adhere to surfaces.
2. Sex pilus
Allows for the transfer of genetic material through a process called conjugation.
One bacteria attaches its sex pilus to another cell and transfers its genetic material to the other cell usually in the form of a plasmid.

42. Prokaryotic Cell Structure
Adhesin bacterial cell with pili (fimbriae) ultr23.vub.ac.be/.../fimbrialadhesion.html
Bacterial conjugation with sex pilus.

43. Prokaryotic Cell Structure
Spores (Endospores)
Bacterial spores called endospores.
Usually found in 2 genera: Bacillus and Clostridium.
Form through the process sporulation.
A copy of the chromosome and some cytoplasm is enclosed in a thick protein coat.
This occurs when moisture and nutrients are low.
Endospores are resistant to heat, cold, drying, and most chemicals.
If adequate conditions are present, the endospore can become an active bacteria.

44. Endospore Clostridium difficil forming an endospore.
Associated with antibiotic related diarrhea caused by toxins produced
Red structure is endospore forming.

45. Prokaryotic Cell Reproduction
Binary Fission
One parent cell splits to become 2 daughter cells.
This process produces a clone of the parent cell.
During this process, its chromosome is replicated in a process called DNA replication.
Generation time
The time it takes one parent cell to become 2 identical daughter cells.

46. Binary Fission

47. The End