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Biology 160 Exam 2 Study Guide
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Biology 160 Exam 2 Study Guide
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Biology 160 Exam 2 Study GuideChapter 6: Lipids, Membranes, and transport Biological Molecules: Lipids and Membranes Learning Outcomes ·Be familiar with related scientific terminology and chemical structure and properties of the various lipids.
·Compare and contrast the structures and functions of saturated and unsaturated fats. Describe how each affects the fluidity and permeability of the plasma membrane.
·Describe the role of cholesterol in biological systems- both in steroid hormone
production and how it affects the fluidity and permeability of the plasma membrane..
·Describe the molecular structure of phospholipids and the roles phospholipids play in cells.
Biological Molecules: Lipids and Membranes Questions 1.How are lipids defined? Are they made of discrete monomer units that are linked together to form massive polymers? What is a hydrocarbon?
a)Any organic substance that does not dissolve in water, but dissolves well in nonpolar solvents
b)Lipids include fatty acids, oils, waxes, steroids, and phospholipids
c)Lipids are not composed of discrete subunits like polysaccharides but are still macromolecules.
d)Lipids are primarily hydrocarbons CH2
a.No charge (nonpolar)
b.Energy source
c.Insulation in animals-
d.Cell membranes
e)Hydrocarbon chains in lipids are called isoprene – a five carbon compound that has only carbons bonded to hydrogens+
2.What is a saturated fat and what is an unsaturated fat? How are they different? How are they the same? Why is one solid at room temperature and why is one liquid?
a)Saturated fat
a.The hydrocarbon chain is a straight chain
b.Comes from animals
i.Butter, beeswax
c.Carbons are packed tightly together and form a solid
d.Has a carboxyl group at the end of the hydrocarbon chain
b)Unsaturated fat
a.The hydrocarbon chain has a bend in it (a double bond)
b.The bend does not allow the carbons to be packed tightly thus causing the fatty acid to be a liquid c.Comes from plants
i.Safflower oil
d.Unsaturated lipids may prevent heart disease and is good for your diet
e.Has a carboxyl group at the end of the hydrocarbon chain
c)The fluidity of sat. and unsat. fats depends on how long the hydrocarbon chain length
3.What is a triglyceride? How are the fatty acid tails linked to the glycerol molecule (what reaction takes place)? What linkage forms?
a)Triglyceride has 3 fatty acid tails, and provides energy storage and insulation in animals
b)Fats form through dehydration reactions
c)Ester linkages – join fatty acids
and glycerol to form a fat or phospholipid
4.What is a steroid and why are they considered to be a lipid? What is the function of cholesterol? Estrogen?
Testosterone? What is common to the structure of these molecules?
●Steroid is a group of lipids with 4 rings; defined as lipid because they
are made largely of carbon and hydrogen atoms, and they are water
insoluble. ●Cholesterol function: reduces membrane permeability by increasing the density of hydrophobic section; component of cell membrane and precursor to other steroids.
●Estrogen: responsible for the development of the female sex characteristics...
●Testosterone: responsible for the development of the male sex characteristics...
5.What is a phospholipid and why is it said to have a polar, hydrophilic head and
a nonpolar, hydrophobic tail? What is meant by amphipathic?
●A phospholipid consists of a hydrophilic head and a hydrophobic tail.
The head is polar and can interact with water, while the tail is
nonpolar (does not interact with water...only with each other).
●Amphipathic: When molecules have both hydrophilic and hydrophobic parts
6.What is a phospholipid bilayer? What is a micelle?
7.Discuss lipid bilayers and selective permeability. What molecules are able to cross the membrane easily? What molecules cross, but at a slower rate? What molecules are impermeable to the membrane and cannot cross at all (without a transport protein, at least!)? What types of experiments have provided us with the above information about membrane permeability? What is an artificial-
membrane experiment?
-Lipid bilayers: a double layer of regularly arranged phospholipid molecules that are widely accepted as forming the basic structure of cell membranes and other biological membranes.
-Liposomes: artificial, membrane-bound vesicles
-planar bilayers: artificial membranes
-Experiments:
-Artificial-membrane experiment:
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