1. 1.2 Ultrastructure of Cells
Prokaryotes and Eukaryotes

2. Prokaryotic Cells “primitive cells”
cells that lack membrane-bound organelles
ie: no nucleus, no mitochondria, no vacuoles, etc
Ex: bacteria (ie E. Coli) – found in soil, water, on your skin, in your intestine
Ex: blue green algae

3. Prokaryotes organisms that are made of prokaryotic cells.
Most prokaryotes are unicellular, such as bacteria, however, they can be multicellular too, such as blue green algae

4. Blue- Green Algae
E. coli

5. Prokaryote Cell Structure

6. Prokaryote Cell Structue

7. Prokaryote Cell Parts CELL SURFACE MEMBRANE / PLASMA MEMBRANE:
Thin layer composed of phospholipids
Controls the entry/ exit of substance via active or passive transport
Selectively permeable

8. Prokaryote Cell Parts CELL WALL:
Rigid to semi-rigid wall surrounding the plasma membrane.
Contains pores to allow passage of materials in and out of the cell.
The Cell wall supports the cell and provides shape

9. Prokaryote Cell Parts SLIME CAPSULE:
Protective outside layer, found outside the cell wall
Also known as “surface layer” or the “S-layer”
Protects the cell from environmental dangers
Contains proteins and or glycoproteins

10. Prokaryote Cell Parts Cytoplasm: The “inside” of the cell
Contains cytosol (fluid of the cell)
Contains the enzymes (biological catalysts) for catalyzing chemical reactions of metabolism
Contains ribosomes and naked DNA
No membrane bound organelles!

11. Prokaryote Cell Parts NUCLEOID:
Region of the prokaryotic cytoplasm where genetic information is found (1 main chromosome and plasmids)
The 1 chromosome is made of NAKED DNA
This means that the DNA is not bound to proteins (like histones)
This reduces the amount of space they take up
Usually circular

12. Prokaryote Cell Parts PLASMID: Small, circular, naked, DNA
Smaller, and contains less information than the chromosome.
Found in the nucleoid region

13. Prokaryote Cell Parts Mesosome:
Indentation in the cell membrane of bacteria
Unknown function, produced by chemical fixation techniques.

14. Prokaryote Cell Parts RIBSOSOME: Made of RNA and proteins
Makes proteins
Less dense than eukaryotic ribosomes

15. Prokaryote Cell Parts FLAGELLUM:
threadlike, motile proteins structures and are used for locomotion
Cell may have none, 1, or several

16. Prokaryote Cell Parts PILI (plr) / PILUS (singular):
Thin protein tubes found outside the plasma membrane and extend out from the slime capsule
Attachment Pili
Have sticky ends that allow it to attach to surfaces (i.e. another cell)
Conjugation Pili (Sex Pili)
Longer
Build a bridge between 2 bacterial cells allowing for exchange of DNA (conjugation)

17. Prokaryotic Reproduction
Prokaryotic cells divide asexually by binary fission (similar to mitosis)
They duplicate their chromosome (their circular DNA) and then split in half (each new daughter cell gets half the cytoplasm and 1 chromosome)

19. Since binary fission is a form of asexual reproduction, the daughter cells produced are identical to the original parent cell.
Conjugation (with the help of conjugation pili) allows for genetic variation – allows for a new combination of DNA

21. Annotate and Identify Structures from and electron micrograph of E
Annotate and Identify Structures from and electron micrograph of E. Coli
ribosome
Nucleoid region (DNA, plasmid)
Cell wall
cytoplasm
Plasma membrane
No visible slime capsule in this diagram

22. PILUS
SLIME LAYER

23. Metabolic Activity of Prokaryotic Cells
Photosynthesis: light + CO2 + H2O  C6H12O6 + O2
Nitrogen Fixation: Convert nitrogen from an unusable from to a usable form
Fermentation: convert organic substances into simpler substances (ie sugar into ethanol)

24. Eukaryotic Cells complex cells with membrane bound organelles
Ex: the cells that make up you! (and other animals)
Ex: plant cells
STRUCTURE: all eukaryotes contain:
Plasma membrane
Central nucleus with DNA
Membrane bound organelles in the cytoplasm

26. Eukaryotic Organelles
Plasma Membrane:
Outer surface of animal cells
Made of phospholipid bilayer
(usually double layer)
Controls the entry and exit of molecules

27. Eukaryotic Organelles
Nucleus:
Control center of the cell
Largest organelle
Surrounded by a double membrane (nuclear envelope)
Contains chromosomes – made of DNA and proteins
Nuclear Envelope:
Controls entry and exit of molecules
Contains nuclear pores (openings)

28. Eukaryotic Organelles
Chromosomes:
Contains hereditary info
Made of DNA and proteins
Nucleolus:
In center of nucleus
Makes ribosomes

29. Eukaryotic Organelles
Endoplasmic Reticulum:
Tubules fro transport and synthesis of large organic molecules
Often continuous with the nuclear envelope
RER – rough ER – has ribosomes
SER – smooth ER – makes carbs and lipids

30. Eukaryotic Organelles
Ribosomes:
Made of proteins and RNA
Site of protein synthesis
Lysosomes:
“suicide sac”
Contains digestive enzymes
breakdown of macromolecules
Digest worn-out cell parts/organelles
Digest pathogens
Can cause cell death if it breaks open (cell lysis) and releases enzymes

31. Eukaryotic Organelles
Mitochondrion:
Site of cellular respiration
Makes ATP (adenosine triphosphate) energy for the cell
Double membrane
Has its own DNA (mDNA)
Own ribosomes
Chloroplast:
Site of photosynthesis (makes sugar from light energy)
Has double membrane, own DNA, own ribosomes

32. Eukaryotic Organelles
Flagella:
Long microtubules strand
“whiplike” tail
For motility
Cillia:
Short microtuble strands

33. Eukaryotic Organelles
Golgi Apparatus/Golgi Body/Golgi Complex:
Looks like a stack of deflated balloons
Membranous sacs
“Packaging plant” of the cell
Packages cell products (ie: carbs and lipids)
Vacuoles:
Membrane bound organelles used for storage of water, wastes, and macromolecules

34. Eukaryotic Organelles
Cell Wall:
Rigid outer layer of plant cells
Made of cellulose
Plasmodesmata:
Gaps in cell walls
Create junctions between plant cells

35. Atypical Cells Striated Muscle Muscle Fibres (Muscle Cells)
Longer than typical cells (30mm opposed to <0.3mm)
Multiple nuclei

36. Atypical Cells Giant Algae
Ex Acetabularia, a unicellular organism, can grow to a length of 10 cm, despite having only 1 nucleus.
Usually organisms that large consist of several cells.

37. Atypical Cells Aseptate Hyphae Narrow thread like structure in fungi
Have a cell wall and membrane.
In aseptate fungi, the hyphae is an uninterrupted tube-like structure with many nuclei spread along it.

38. Animal vs Plant Cells ANIMAL CELL PLANT CELL No chloroplasts
No cell wall
Usually no large central vacuole
Carbohydrates stored as glycogen
Have lysosomes
Amorphic shape
Chloroplasts usually present
Cell wall present
Have large central vacuole
Carbohydrates stored as starch or cellulose
Generally lack lysosomes
Rigid shape, often with straight edges

39. Prokaryotic Cell vs Eukaryotic Cell
PROKARYOTES
EUKARYOTES
Do not have membrane bound organelles
Naked circular DNA (no proteins associated)
DNA in nucleoid region
RIBOSOMES: free floating in cytoplasm
No mitochondria; uses plasma membrane for respiration
Membrane bound organelles present
DNA wrapped around histone proteins
DNA within the nucleus
Ribosomes: attached to RER or free floating in cytoplasm
Has mitochondria for aerobic cellular respiration