1. A Tour of the Cell

2. Tools of Biology Microscopes Light Microscope Electron Microscope
Scanning Electron Microscope
Transmission Electron Microscope

3. Tools Of Biology
Cell Fractionation – takes cells apart and separates organelles from one another
Done by centrifuge

4. Eukaryotes vs. Prokaryotes
Similarities between these two types of cells include:
Enclosed in plasma membrane that is filled with cytosol
Contain chromosomes that hold the genetic information for the cell
Have ribosomes that make proteins according to instructions from genes

5. Eukaryotes vs. Prokaryotes
Differences include:
Location of DNA: Eukaryote found in Nucleus; Prokaryote found in Nucleoid (not bound by membrane)
Eukaryotic cells have membrane bound organelles with specialized form and function; Prokaryotes do not
Eukaryotes tend to be larger in size (related to the functions that take place)

6. Eukaryotes vs. Prokaryotes
You will be required to draw and/or annotate pictures of E. coli and the liver cell as an example of these cell types.

7. Eukaryotes: Plants and Animals
Know the differences between plant, animal and prokaryote cell structure p81-83 in textbook

8. Eukaryotic Cell Parts
Nucleus – contains the genetic information within the cell; enclosed by the nuclear envelope
Nuclear envelope – double membrane (2 lipid bilayers) with pores to allow movement in and out of the nucleus
Nucleolus – dense region inside the nucleus where rRNA is synthesized using instructions from the DNA

9. Eukaryotic Cell Parts
Nuclear side of nuclear envelope contains the nuclear lamina which maintains the shape
Also evidence for a nuclear matrix

10. Eukaryotic Cell Parts Ribosomes Made of rRNA and protein
Carry out protein synthesis
Are found floating freely in the cytosol or attached to the ER or nuclear envelope
These ribosomes are structurally identical, but may perform slightly different jobs
Free floating tend to make proteins used within the cytosol
Bound tend to make proteins for membranes or that will be exported out of the cell (associated with ER)

11. Eukaryotic Cell Parts Endomembrane system
Tasks include synthesis and transport of proteins within and outside the cell; metabolism and movement of lipids; detox of poisons
Membranes of the system related through physical proximity or via vesicles
System includes: nuclear envelope (NE); ER (rough and smooth); GA; lysosomes; vacuoles; (sometimes plasma membrane)

12. Eukaryotic Cell Parts Endoplasmic Reticulum (ER)
Membrane continuous with the NE
Consists of smooth and rough ER
Smooth ER – not covered in ribosomes; synth. of lipids, metablism of carbs and detox of drugs and poisons
Rough ER – covered in ribosomes; produces many secretory proteins (insulin) and membrane proteins

13. Eukaryotic Cell Parts
Golgi Apparatus (GA) – proteins from the ER are modified, stored and then sent to another location
Polar sides known as cis and trans vary in membrane thickness and function

14. Eukaryotic Cell Parts
Lysosomes – a sac that holds digestive enzymes in animal cells
Lysosome membrane and enzyme made by rough ER and processed by GA
Plays role in phagocytosis and autophagy

15. Eukaryotic Cell Parts
Vacuoles – storage vesicles with a variety of functions
Food vacuoles
Contractile vacuoles – involved in maintaining homeostasis
Central vacuole - can hold cell sap, toxins, pigments

16. Eukaryotic Cell Parts
Mitochondria – Site of cellular respiration which generates ATP (usable energy) from fats and sugars
Is membrane bound, but not a part of the endomembrane system
Found in nearly all eukaryotic cells
Often have hundreds or thousands per cell
Composed of 2 membranes that create an outer cavity called the intermembrane space and an inner cavity called the mitochondrial matrix, which holds enzymes, mitochondrial DNA and ribosomes

17. Eukaryotic Cell Parts
Chloroplasts – photosynthetic organelle that holds the pigment chlorophyll
Built similarly to mitochondria: 2 membranes separated by an intermembrane space. Inside there are flattened sacs called thylakoids that can be stacked into grana. The stroma (fluid outside the thylakoids) contains the chloroplasts DNA, enzymes and ribosomes

18. Eukaryotic Cell Parts
Peroxisomes – similar to lysosomes, but are not a part of the endomembrane system
Contain enzymes that transfer hydrogen from various substrates to oxygen, producing hydrogen peroxide, but also contains enzymes that can break this down into water
Some aid mitochondria by breaking down fats into usable sizes, but also works in detoxification

19. Eukaryotic Cell Parts
Cytoskeleton – has a variety of roles including support, movement and regulation of biochemical activities.
Microtubules – shape and support the cell and help in organelle movement
Centrosomes and Centrioles – aid in cell division
Cilia and Flagella – aid in movement
Microfilaments – helps the cell bear tension and keep its shape (muscles)
Intermediate Filaments- Aid in bearing tension and reinforcing cell shape

21. Additional Structures
Cell Wall – protects cell, maintains shape and prevents excessive water uptake.
Found in plants, fungi, prokaryotes and some protists.
Primary Cell Wall – secreted by young plants; relatively thin and flexible to allow for growth
Adjacent cells are “stuck” together with a sticky polysaccharide called pectin in a space called the middle lamella
Secondary Cell Wall – a cell wall between the primary cell wall and plasma membrane often deposited in several layers (wood)

22. Additional Structures
The Extracellular Matrix (ECM)
Made of glycoproteins that form strong fibers on the exterior of the animal cell.
Glycoproteins are usually collagen or fibronectin
There are surface receptors imbedded in the plasma membrane called integrins
Integrins are used to communicate between the ECM and the cytoskeleton of the cell and are integral in changes to the cell inside and out

23. Additional Structures
Intracellular Junctions – cells are able to communicate with each other through these means
Plants
Plasmodesmata – a channel between two adjacent cells that creates a path through cell walls
Animals
Tight Junctions – neighboring cells are bound together by specific proteins (tight seal – ie. skin)
Desmosomes (anchoring junctions) – fasten cells together (muscles)
Gap Junctions (communicating junctions) – provide channels between cells