2. Prokaryotic Cells
Chapter 4

3. Prokaryotes
The first types of cells to develop evolutionarily were prokaryotes
The term prokaryote means “naked DNA”
Prokaryotes therefore, do not have a nuclear membrane surrounding their DNA

4. Prokaryotes
In fact, they have no membrane bound structures and are instead very simple in construction
Prokaryotes began, and continue to be, unicellular organisms
All bacteria are prokaryotes

6. Prokaryotes consist of the following structures:
Plasma Membrane – controls what enters and exits the cell
Sometimes has infoldings (called mesosomes) that increase the surface area of the membrane

7. Cell Wall – provides protection
Made of a protein/carbohydrate structure
Bacteria are identified based upon which of the two types of cell walls they have as based upon the Gram Stain Technique
Gram positive bacteria stain purple
Gram negative bacteria stain pink

8. Flagella – Tail-like structure that helps with locomotion
Pilli – Threadlike projections that help with attachment and sexual reproduction (through transfer of DNA)
Cytoplasm – clear, gelatinous fluid that takes up most of the space inside the cell and contains all necessary enzymes for metabolic processes

9. Ribosomes – Used for protein synthesis, which is a part of gene expression
Composed of two parts called the “heavy” and “light” pieces
Heavy and light pieces are 50s and 30s in size (s represents the svedburg unit)
Total measurement of prokaryotic ribosomes is 70s (doesn’t add up because s is not a measurement of size but sedimentation during centrifugation)

10. Nucleoid – Region where DNA can be found
In prokaryotes, DNA forms a closed loop
Many prokaryotes also have a smaller loop called a plasmid that contains a few genes and can be easily transferred to other cells

11. Prokaryotes

12. Conjugation Form of reproduction in some prokaryotes
2 prokaryotes attach to each other via the pilus and exchange genetic material.
Then go on to binary fission.
NOTE: Conjugation does not
create new prokaryotes!!
It recombines the DNA before
they go on to divide separately.

13. E. Coli infection

14. Prokaryotes Binary fission Method of reproduction in prokaryotes
Asexual form of reproduction in which a cell divides into two same size cells that are genetically identical

15. Eukaryotic Cells
Chapter 4

16. Eukaryotic Cells evolved after prokaryotes
The endosymbiotic theory states that eukaryotes came about when one prokaryote enveloped another

17. Eukaryotic Cells are much more complex than prokaryotes
Made up of smaller components with specialized functions called organelles

22. Eukaryotes Cell Organelles Nucleus – contains DNA
Ribosomes – create new proteins
Composed of a 40s and 60s unit which makes the ribosome overall to be 80s
Rough Endoplasmic Reticulum (Rough ER) – site protein synthesis
Called “rough” because it is studded with ribosomes

23. Smooth ER – site of lipid (fat) synthesis and storage
Lysosome – contains enzymes that break down cellular waste
Golgi Apparatus (aka Golgi Body) – packages and ships proteins (to other parts of the cell as well as outside of the cell)

24. Mitochondria – “powerhouse of the cells”; creates energy for the cell in the form of ATP
Cytoplasm – clear gelatinous fluid inside of the cell
Centriole – helps with cell division in animal cells

25. Chloroplast – found only in plant cells, this organelle is the site of photosynthesis
Cell Wall – found only in plant cells, this organelle gives support and structure to the cell
Plasma membrane – controls what enters and exits the cell

26. Microtubules and Microfilaments – linear protein structures that provide support for animal cells; sometimes aid in movement of cell organelles
Nucleolus – found within the nucleus, this organelle is in charge of creating new ribosomes
Vacuole – stores food, water, and/or waste; animal cells have multiple small ones while plant cells have one large vacuole for water storage only

27. Plant and animal cells are very similar but have a few distinct differences:
Plant Cells
Animal Cells
Cell Wall
One large vacuole
No centrioles
Has chloroplasts
Store energy as starch
No cell wall
Many small vacuoles
Has centrioles
No chloroplasts
Store energy as glycogen

28. Animal Cell Mix-Match Plant Cell Mix-Match
Plant Cell Mix-Match

29. 2.3.5

30. Roles of extracellular components:
Plant cell wall mantains cell shape, prevents excessive water uptake, and holds the whole plant up against the force of gravity
Animal cells secrete glycoproteins that integrate themselves in the plasma membrane
The glycoproteins help with support, adhesion and movement

31. Prokaryotes
Eukaryotes
No membrane bound organelles; DNA is in the cytoplasm (nucleoid region)
DNA is “naked”; has no associated proteins
No centrioles
No mitochondria
70s ribosome
All ribosomes are “free”
Cell wall is made of peptidoglycans
Multiple membrane bound organelles including the nucleus, which houses DNA
DNA is associated with proteins that help it to fold into chromosomes
Centrioles
Mitochondria
80s ribosome
Free ribosomes and ribosomes attached to the rough er
No cell wall or one made of cellulose

32. Comparing Prokaryotes and Eukaryotes