Topic 2 - lipid bilayer (lec 3)

They can have single sugar units or strings of sugar

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Unformatted text preview: of sugar units. The small string of sugars are called oligosaccharides. You find them primarily with the carbohydrate extending to the outside of the cell. Those carbohydrate groups are most commonly used as signals or recognition signals. An example is the ABO blood groups. If u have type A blood or type B blood, you have different groups of carbs that are extending out off ur red blood cells. Those different groups function as antigens (recognition signals). Glycolipids single sugars or oligosaccharides antigens (e.g. ABO blood groups) Sterols (steroids) Derivatives of 4-ringed hydrocarbon skeleton Absent from prokaryotes Cholesterol (animals, some protists) Phytosterols (plants) Ergosterol (fungi) galactose fatty acid sphingosine fatty acid galactose glycerol fatty acid galactose e.g. Plant glycolipids Fig. 5.1 BIO 1140 – SLIDE 10 Glycolipids single sugars or oligosaccharides antigens (e.g. ABO blood groups) cholesterol Sterols (steroids) Derivatives of 4-ringed hydrocarbon skeleton Absent from prokaryotes Cholesterol (animals, some protists) Phytosterols (plants) Ergosterol (fungi) Purple pages F43 BIO 1140 – SLIDE 11 Hydroxal Group (Polar) 4 -ringedhydrocarbon skeleton (nonpolar) Fig. 5.8 Hydrocarbon tail (nonpolar) Test your knowledge... The lipid bilayer functions as a permeability barrier because... a. the lipids are held together by covalent bonds that prevent unwanted movement across the membrane. b. it is difficult for hydrophilic molecules to traverse the hydrophobic core of the lipid bilayer. c. the lipid bilayer is thick, so that the diffusion distance becomes too great for rapid transit across the lipid bilayer. d. the glycolipids of the lipid bilayer recognize and bind molecules that the cell wishes to exclude. e. None of the above Explain your answer. BIO 1140 – SLIDE 12 3) Sterols (steroids): Sterols are a particular type of steroid. Steroid as a group are characterized by the presence of a four ringed hydrocarbon skeleton. The four hydrocarbons are linked together. In the case of steriols in particular on t...
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This note was uploaded on 02/19/2014 for the course BIO 1140 taught by Professor Fenwick during the Winter '07 term at University of Ottawa.

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