Biology 1001A Lecture Notes - Amphiphile, Eukaryote, Prokaryote
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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
Phospholipids have a polar region that is hydrophilic, and a non-polar region that is
Membranes are formed by lipid bilayers.
Clicker Question: Which of the following easily cross the membranes (without help)?
C. Na + (ions, or charged molecules do not cross membranes by itself. They use channels.)
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
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.