1. All About Cells
A cell with its cytoskeleton by fluorescence microscopy

2. The Cell Theory
1. Cells are the fundamental unit of life. A cell is the “simplest collection of matter that can live”.
2. All current cells come from pre-existing cells.
3. Cells organize the metabolism of life and carry the genetic “blueprints” of life from one generation to the next.

3. Prokaryotic versus Eukaryotic Cells
Prokaryotic cells:
Nucleoid contains DNA, not a membrane-bounded nucleus
No membrane-bounded organelles
Eukaryotic cells:
Has a membrane-bounded nucleus which contains the DNA
Has membrane-bounded organelles
Both are full of cytoplasm
Both have a plasma membrane surrounding the cell

4. Prokaryotic Cell Cytoplasm with ribosomes
plasma membrane
Often have projections called pili to increase surface area
Flagella for locomotion

5. Prokaryotic Structure
Cytoplasm contains DNA (nucleoid) and ribosomes, as well as various chemicals
Surrounded by plasma membrane
May have pili to increase surface area and “stickiness”
May have flagella for movement

6. Prokaryotic Structure
Cell wall (a rigid structure important in classifying bacteria) made of a protein-sugar molecule
Some bacteria also have a capsule, a protective outer coating

7. Size difference between eukaryotic and prokaryotic cells
Bacteria on the human epithelial cell from the mouth of a human
Photo by Dr. Gary Kaiser

8. Overview of a Eukaryotic Cell
(characterized by membrane bound organelles)
nucleus
mitochondria
endomembrane
system
In plants, add a
cellulose cell wall and a
really big vacuole full of
water
plasma membrane

9. Nucleolus (where ribosomal RNA is made)
condensed DNA
Nucleus (surrounded by the nuclear envelope)

10. The Nucleus
nuclear pores

11. nuclear pores
The Nucleus
Connection between outer nuclear membrane and the endoplasmic reticulum
inner membrane of
nuclear envelope
nuclear pore
outer membrane of
nuclear envelope

12. nuclear pores
The Nucleus
Attached to the outer surface of the nuclear envelope and the endoplasmic reticulum are ribosomes
ribosomes

13. Ribosomes are the sites of protein synthesis in the cell
Ribosomes are composed of a type of RNA (ribosomal RNA or rRNA) and proteins – made in the nucleolus of the nucleus
Ribosomes are the sites of protein synthesis in the cell
Free ribosomes vs. Bound ribosomes

14. The Endomembrane System
A continuous internal membrane system that
includes the:
Outer membrane of the nuclear envelope
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Transport vesicles between ER and Golgi
Golgi apparatus
Transport vesicles between Golgi and plasma membrane
Lysosomes
Plasma membrane

15. The Rough and Smooth Endoplasmic Reticulum
Smooth ER
Transitional ER
Transport vesicle destined for Golgi apparatus
Rough ER

16. Functions of smooth ER and rough ER
Produce certain lipids (e.g., steroids)
Detoxifies drugs (has enzymes in its membranes that do this)
Rough ER
With bound ribosomes, produces proteins destined for secretion from cell or packaging in specialized organelles (e.g., lysosomes)
Makes new membranes (phospholipids and proteins are made and put together by the rough ER)

17. Golgi apparatus – a “refinery” or “processing plant”
Golgi apparatus – a “refinery” or “processing plant”. Proteins are processed and refined as they pass through on their way to final destination
Transport vesicle from transitional ER
cisternae (flattened membranous sacs)
Transport vesicle destined for plasma membrane, or to become a lysosome

18. Golgi are especially used to “refine” glycoproteins – proteins plus carbohydrate chains
Glycoprotein produced in ER
Refined as it passes through Golgi
Distributed in transport vesicles

19. Nematode Golgi apparatus
trans face – ‘shipping’
cis face – ‘receiving’
Flow of transport vesicles and proteins

20. The flow of membrane through the endomembrane system
Tracking an insulin molecule

21. 1. Insulin is produced by ribosomes on the rough ER
2. Enters the cisternae of the rough ER and moves inside the cisternae to the transitional ER

22. 3. Packaged into transport vesicles and transferred to cis face of the Golgi apparatus
4. Transport vesicles fuse to form first cisternae of Golgi apparatus

23. 5. Processed in Golgi apparatus as cisternae move through stack
6. Packaged into transport vesicles at the trans face of the Golgi apparatus and transported to plasma membrane

24. The entire process once again!

25. One additional organelle produced by the Golgi apparatus is the lysosome

26. Lysosomes Digestive organelles – sacs of digestive enzymes
Function at acidic pH inside lysosome

27. Lysosomes – digestive organelles – for intracellular digestion
Digesting food particles that are brought into cells
Digesting damaged mitochondria and other organelles