BIOCH200 Lecture Notes - Lecture 2: Carbohydrate, Cytoskeleton, Peripheral Membrane Protein

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skycaribou653

10 Dec 2017

School

University of Alberta

Department

Biochemistry

Course

BIOCH200

Professor

Jonathan Parrish

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Document Summary

The structure of biological membranes: e(cid:454)plai(cid:374) (cid:449)h(cid:455) lipid (cid:271)ila(cid:455)ers are fluid, (cid:455)et sta(cid:271)le, stru(cid:272)tures. Lipids in the bilayer are not covalently bonded to each other, but are stabilized by hydrophobic interactions: state (cid:449)h(cid:455) the e(cid:454)a(cid:272)t di(cid:373)e(cid:374)sio(cid:374)s of a lipid (cid:271)ila(cid:455)er are (cid:448)aria(cid:271)le. The polar head groups have different dimensions, and the acyl tails also vary in length (16-20 carbons: describe how changes in fatty acid composition affect the fluidity of a biological membrane. More unsaturated fatty acids and shorter fatty acid chains increase fluidity of membrane. In colder temperatures, more unsaturated fatty acids and shorter fatty acids are incorporated in lipids. More saturated fatty acids and longer fatty acids decrease fluidity of the membrane. Abundance of these fatty acids in lipids in high temperatures: state the function of cholesterol in biological membranes. Cholesterol increases rigidity of the membrane, by limiting rotational movement of neighbouring acyl tails, thereby decreasing van der waals forces.

Related Questions

The lipid bilayer that makes up a cell membrane is composed of molecules like phospholipids that are synthesized from fatty acids. A phospholipid membrane undergoes a phase transition from solid-like to fluid-like when the temperature is raised above a melting temperature.
What can cause the melting temperature of a membrane to increase making it more solid-like at higher temperatures?
Select all that apply.

A. increasing the fraction of cis unsaturated fatty acids that make up the phospholipids

B. increasing cholesterol to disrupt the tight packing of the phospholipids fatty acyl chains

C. decreasing the fraction of saturated fatty acids that make up the phospholipids

D. increasing the fraction of saturated fatty acids that make up the phospholipids

E. decreasing cholesterol to increase the tight packing of the phospholipids fatty acyl chains

Which one of the following statements about lipids and biological membranes is incorrect?

A) Increased temperature can change the membrane from gel phase to fluid phase.

B) Membrane fluidity is affected by lipid composition but not by temperature.

C) Phospholipid bilayers are fluid.

D) For lipid movement, flex is faster than lateral shift.

E) Ions are not allowed to freely traverse a lipid bilayer.

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64. Which of these statements about fatty acids are false? A. The physical state of a triglyceride with three unsaturated fatty acid tails would be a clear liquid. B. Complex lipids that contain mainly unsaturated fatty acids are liquids (oils) at room temperature C. Its best to use fats with high melting points in our diet. D. A disadvantage of the ability of saturated fats to pack tightly is that tightly packed, saturated fats clog arteries as atherosclerosis 65. Trans fatty acids A. are formed when vegetable oil is hydrogenated (for solidification). B. are found in fried foods C. have an atypical shape that affects their chemical activity D. are not flexible and can adhere to surfaces E. should be avoided because they are composed of partially hydrogenated (partially hardened) oils F. are all of the above 66 Which of these statements about fatty acids are false? A. When plants and animals build fatty acids they make the trans forms. B. Food manufacturers found that foods like chips with the trans form have a longer "shelf life" C Natural cis fatty acids tend to turn rancid and spoil D Although natural cis fatty acids turn rancid and spoil, it is the cis form that is used by the body. E.The process of hydrogenation, in which hydrogens are added to unsaturated fats, produces a mixture of saturated fatty acids and standard and trans forms of unsaturated fatty acids 67. Good tips for reducing dietary fats are to A. use non-fat or low-fat dairy products and other products B use low-fat cooking methods C bake, roast, steam, broil, stir fry, microwave D. seldom have fried foods E choose lean cuts of meat, trim fat F. do all the above 68. Which of these statements about the properties of fatty acids are true? A. Melting point of all fatty acids increases with increasing hydrocarbon chain length (i.e increasing size) B cis double bonds prevent good alignment of molecules in unsaturated fatty acids leading to C Melting point of unsaturated fatty acid are lower than that of a saturated fatty acid with the D. The melting point of a saturated fatty acid is greater than that of an unsaturated fatty acid of poor packing same number of carbon atoms due to the presence of their double bonds the same chain length, because saturated fatty acid chains tend to be fully extended and to stack in a regular structure, thereby causing increased intermolecular attraction. E. all of the above 69. Freebie 70 Freebie

BIOCH200 Lecture Notes - Lecture 2: Carbohydrate, Cytoskeleton, Peripheral Membrane Protein

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