Biology 1201A Lecture 3: Lecture 3 Jan 12 Membranes Passive Transport BIO

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yellowcod194

12 Jan 2016

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Document Summary

Composed of a selectively permeable phospholipid bilayer. Proteins embedded or attached to the membrane perform membrane functions transport, signaling, etc. Fully saturated bound to maximum number of hydrogen. Hydrophobic effect of non-polar tails and polar heads. Structure is favored because it is the lowest energy state. Membrane fluidity influenced by type of fatty acid and temperature. As temperature drops the random motion of lipids slows down. Fluidity lost at a certain point gelling. More unsaturated molecules will have a lower gelling point the membrane. Keeping membrane fluid is essential to cell function. Organisms can regulate the degree of fatty acid unsaturation. Desaturases can introduce double bonds to saturated fatty acids. Allows organisms to respond to temperature changes in the environment. Not too viscous, not too fluid of. Similar to lipids, sterols also influence membrane fluidity. Like fatty acids hydrophilic interacts with aqueous hydrophobic interacts with membrane interior. Found in animals not in plants or prokaryotes.

Related Questions

Describe the two main differences between a passive and an active process of membranes transport. Also describe each of the 4 passive processes, and each of the 3 active processes.

byzantiummacaw28

1 Which of the following statements is false?

(a) CO₂ and O₂ can diffuse freely across the cell membranes.

(b) The differences in permeability between artificial lipid bilayers and cell membranes arise from variations in phospholipid content.

(d) Cells expend energy in the form of ATP hydrolysis to maintain ion concentrations that differ from those found outside the cell.

2 Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell?

(a) Na⁺

(b) K⁺

(d) Cl^â

3 Pumps are transporters that are able to harness energy provided by other components in the cells and drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________.

(a) active transport.

(b) free diffusion.

(d) passive transport.