Biology 1001A Lecture Notes - Amphiphile, Eukaryote, Prokaryote

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30 Apr 2012
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Biology Lecture 2: Cell Biology
Water is polar; molecules attract.
Fatty acids are non-polar and insoluble in water.
Q. Why does mayonnaise separate?
o Mayo contains eggs that are “amphiphilic”, having both hydrophobic and hydrophilic
regions. Eggs are full of phospholipids (containing the hydrophobic and hydrophilic
regions).
Phospholipids have a polar region that is hydrophilic, and a non-polar region that is
hydrophobic.
Membranes are formed by lipid bilayers.
Clicker Question: Which of the following easily cross the membranes (without help)?
A. ATP
B. O2
C. Na + (ions, or charged molecules do not cross membranes by itself. They use channels.)
D. Glucose
Small, uncharged, polar molecules cross membranes easily (look at figure 5.12 in the textbook).
Over evolutionary time, membrane structure became very complex.
Unsaturated fats have kinks (double bonds), so they pack less well. Therefore in room
temperature they tend to be liquids.
Molecules that are saturated (have no double bonds) tend to be not very fluid at room
temperature.
Bacteria, Archaea, and Eukarya has a common ancestor. (Note: Archaea tend to associated with
extreme environments, therefore we are less prone to come across archeon cells).
Bacteria and Archaea are prokaryotic cells and do not have a nucleus.
Prokaryotic cells do not have membrane bound organelles.
What to know: Get familiar with the cell structure.
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