honors - cells & insulin, membrane and transport 1112b
TRANSCRIPT
Cells: Honors Biology ~ Edgar
Leukocyte Extravasation
• Chemoattraction– Cytokines
– Cellular adhesion molecules on endothelial cells
• Rolling Adhesion– Selectin ~ carbohydrate
ligands
• Tight Adhesion– Juxtacrine signaling
– Immobilize leucocytes
• Transmigtation– chemotactic gradient
Cytokine:induce directed chemotaxis in nearby responsive cells
Cell Biology and Diabetes
Cells in the pancreas of a 1-week-old mouse that express the Ptf1a transcription factor gene are revealed in this photograph. The Ptf1a gene has been genetically engineered to express a bacterial enzyme that produces a dark blue color. In both mice and humans, Ptf1a is essential for formation of the entire pancreas, including insulin-secreting beta cells. By tracing the “cell lineage,” or family history, of Ptf1a-expressing cells, scientists hope to learn more about how to maintain—or restore—the function of beta cells. At top right is the sausage-shaped spleen (light orange), and at bottom is the duodenum.Photo by Fong Cheng Pan, Ph.D., research fellow, Department of Cell & Developmental Biology, Vanderbilt University. Courtesy of Christopher V. E. Wright, D.Phil.
Red arrows indicate Beta Cells
Proinsulin - Orange
Igf-1
Insulin-like growth factor 1
Looking good. The pancreas of a mouse after it was transplanted with human beta cells (left) looks similar to that of an animal that produces insulin normally (right).
CREDIT: Narushima et al., Nature Biotechnology
Brimming with b's. Newfound cells in the pancreas give rise to neurons (red) and insulin-producing b cells (green).CREDIT: SEABERG ET AL., NATURE BIOTECHNOLOGY
The full picture. Human ES cells can eventually give rise to cells that resemble pancreatic beta cells (labeled β).
Pulse Chase Experiment
mRNA Protein Localization
• Some cells make 10,000+ proteins.
• Typical Mammalian cell will contain a billion protein molecules
• How do cells get their proteins to their correct destinations and keep those molecules out of the wrong places?
Cell Membranes and Transport
Honors Biology ~ Edgar
Jmol
Harvard BioVisions
Sodium Potassium
Pump
Gramicidin
• Antibiotic for gram positive bacteria.
• Limited to topical application.
• Induces hemolysis at lower concentration then bacteria ….therefore no internal use.
Prediction: ion flow higher, the same or lower?
Passive Transport
Osmosis
Osmosis
Concept Check
• If a Paramecium were to swim from a hypotonic environment to an isotonic one, would the activity of its contractile vacuole increase or decrease? Why?
Concept Check• This diagram represents osmosis
of water across a semipermeable membrane. The U-tube on the right shows the results of the osmosis. What could you do to level the solutions in the two sides of the right hand U-tube?a) Add more water to the left hand side.
b) Add more water to the right hand side.
c) Add more solute to the left hand side.
d) Add more solute to the right hand side.
Answer
•This diagram represents osmosis of water across a semipermeable membrane. The U-tube on the right shows the results of the osmosis. What could you do to level the solutions in the two sides of the right hand U-tube?
c) Add more solute to the left hand side.
Vegetables in Sucrose Solutions
-30.00
-20.00
-10.00
0.00
10.00
20.00
30.00
0 0.2 0.4 0.6 0.8 1 1.2
Sucrose Concentration (Molarity)
Per
cen
t C
han
ge
in M
ass
(%)
Beet
Potato
Carrot