Department of Cancer and Cell Biology Principles of Cell Biology for Engineers I 20-MECH-871       Section 023    Call # 307631 Sarah Pixley Univ. of Cincinnati College of Medicine Department of Cancer and Cell Biology

Dr. Pixley (UC) 513-558-6086

NSF funded Engineering Research Center: Revolutionizing Metallic Biomaterials Partners: North Carolina A&T State Univ.; Univ. of Pittsburgh; Univ. of Cincinnati (Engineering & Medical Schools) Global Partner: Hannover Medical School, Germany Outreach Partners: California State Univ., Los Angeles; Edmunds Community Col., WA; Guilford County Community Col., NC Global Outreach/Cultural Partner: Indian Institute of Technology, Madras, India

What is a Cell? The cell is a glorified soap bubble! So, what is the difference? http://repairstemcell.wordpress.com/2009/02/11/first-ever-bubble-girl-cured/ http://images.google.com/images?hl=en&um=1&q=cell+biology&sa=N&start=63&ndsp=21

Cells defy Entropy!

& a bunch of organelles (Structural & Functional Compartmentalization) A typical animal cell & a bunch of organelles (Structural & Functional Compartmentalization) Cytoplasm (cytosol+ Organelles) Size : 10- 100s mm Lodish 5e

The basic structure of the cell membrane is a phospholipid (fat) bilayer: two layers of lipid (fat) molecules. Figure 1-12 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)

Lipids with a polar head group (hydrophilic) (red ovals) and one fatty acid tail (hydrophobic) (red stick) form “cone” shapes and form micelles in water. Lipids with two fatty acid tails have an effective “cylinder” shape and form bilayers. Figure 10-7 Molecular Biology of the Cell (© Garland Science 2008)

Figure 2-22 Molecular Biology of the Cell (© Garland Science 2008)

Figure 10-8 Molecular Biology of the Cell (© Garland Science 2008)

But it is a long way from a simple lipid bilayer to the cell! Let’s get going! Figure 1-30 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)

Cellular world Prokaryotic - No nucleus, simple organization (ex: bacteria) Eukaryotic - well-defined nucleus and other organelles (ex: yeast, fly, mammals, etc….) In all cases: cellular contents are surrounded by a lipid bilayer called: The unit membrane = plasma membrane = cell membrane

(building block: DNA) Structure of a Prokaryotic Cell chromosome E-Coli (1-2 mm) Lodish 5e

Electron micrograph of a bacterium Lodish 5e

Membrane bilayer Plasma membrane Chromosome (building block: DNA) Structure of an Eukaryotic Cell Membrane bilayer Plasma membrane Chromosome (building block: DNA) ribosome cytosol Size : 10- 100s mm Lodish 5e

Electron micrograph of an eukaryotic cell Lodish 5e

Let’s look at Sizes! Figure 21-20 Molecular Biology of the Cell (© Garland Science 2008)

25 µm 100 µm Figure 21-21 Molecular Biology of the Cell (© Garland Science 2008)

Figure 9-1 Molecular Biology of the Cell (© Garland Science 2008)

Figure 9-2 Molecular Biology of the Cell (© Garland Science 2008)

Visualizing Cells Microscopy: Light microscopy (LiteM): In theory, resolution limit is ~0.2 µm = 200 nm, but practical limit is ~0.4 µm. Resolution: you can distinguish 2 points (not 1) if they are 0.2 µm apart. Regular microscopy: uses regular light sources Confocal microscopy: uses laser light sources Electron microscopy (EM): practical limit of resolution: ~0.1 nm. “Light” source: electrons Transmission EM: electrons go through specimen Scanning EM: electrons bounce off surfaces of structures

LiteM Figure 9-3b Molecular Biology of the Cell (© Garland Science 2008)

Stained (after fixation) Unstained (live) Nucleus Cells B A LiteM Two cells in B are packed with pigment granules in their cytoplasm, so you can see the entire cell. Otherwise, you can only vaguely see nuclei.

Procedures to visualize unstained (live) cells differential interference (Nomarski) conventional phase-contrast LiteM

LiteM

Hematoxylin and Eosin (H&E) dyes staining Hematoxylin and Eosin (H&E) Hematoxylin is a positively charged blue dye, that will bind to negatively charged (acidic) cell structures (e.g. DNA, RNA). Structures that bind hematoxylin are referred to as basophilic (base dye-loving (philic)). Eosin is a negatively charged red/pink dye, that will bind to positively charged (basic) cell structures (e.g. proteins, mitochondria). Structures that bind eosin are referred to as acidophilic ( acidic dye-loving).

Hematoxylin and Eosin (H&E) Nuclei (blue) Cytoplasm (red/pink) LiteM

Cytoplasm (red/pinkish) Whole Cell LiteM Nuclei (blue)

Immunofluorescence More complicated (more details later in course). Basically: Use the immune system to find molecules (antibodies) that bind to just one cell type or just one protein, organelle or type of molecule in a cell. Fix a fluorescent molecule on the binding molecule (antibody with attached fluorescent molecule). Use a light microscope, but to visualize the fluorescence, add filters that only let one wavelength of light through to your eye or the camera (you only see the color put out by the fluorescent molecule). You can combine 2 or more colors in one view.

Immunofluorescence Microscopy This is ONE cell! Blue = nucleus Green = the microtubules inside the cell (cytoskeleton) Red = the microfilaments inside the same cell. LiteM Figure 16-1 Molecular Biology of the Cell (© Garland Science 2008)

Electron microscopy transmission electron microscopy (TEM) scanning electron microscopy (SEM) SEM TEM

TEM In TEM, proteins and DNA/RNA Appear dark. Most fatty substances Are washed out and appear light. No colors at the EM level.

TEM

TEM Ergastoplasm (old name) is now called: endoplasmic reticulum (ER). Shown is rough ER (RER)

SEM

SEM LiteM TEM unstained Figure 9-50 Molecular Biology of the Cell (© Garland Science 2008)