BIOL 1030H Lecture Notes - Lecture 9: Copy-Number Variation, Elastase, Elastin
13 May 2018
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Genetic Variation
Genotype-by-Environment Interactions
●Normal
○The a1AT gene encodes an enzyme that inhibits the function of elastase, an
enzyme that breaks down elastin in the lung.
○Normal lung elasticity is maintained by a balance between elastin production and
destruction
●Smoking
○Cigarette smoking reduces the activity of a1AT, decreasing inhibition of elastase
and leading to increased elastin breakdown.
○Emphysema results from too much breakdown in the lung, which can result from
cigarette smoking…
●Mutant
○Individuals who are homozygous for the PiZ allele produce a1AT with reduced
activity, leading to increased elastin breakdown in the lung.
○…or homozygous PiZ mutations.
Beneficial Mutations
●For HIV to invade a T cell, it must interact with a CD4 receptor and a CCR5 co-receptor.
Restriction Fragment Length Polymorphism (RFLP)
●A restriction enzyme cleaves both DNA samples at all of the sites it recognizes,
producing fragments of different lengths. Following electrophoresis, the gels show the
position of the fragments to which the probe hybridizes
●Number and position of bands indicate the genotype.
Copy Number Variation (CNV)
●In copy number variation, the size of the duplicated or deleted region can include one or
more complete genes.
Document Summary
The a1at gene encodes an enzyme that inhibits the function of elastase, an enzyme that breaks down elastin in the lung. Normal lung elasticity is maintained by a balance between elastin production and destruction. Cigarette smoking reduces the activity of a1at, decreasing inhibition of elastase and leading to increased elastin breakdown. Emphysema results from too much breakdown in the lung, which can result from cigarette smoking . Individuals who are homozygous for the piz allele produce a1at with reduced activity, leading to increased elastin breakdown in the lung. For hiv to invade a t cell, it must interact with a cd4 receptor and a ccr5 co-receptor. A restriction enzyme cleaves both dna samples at all of the sites it recognizes, producing fragments of different lengths. Following electrophoresis, the gels show the position of the fragments to which the probe hybridizes. Number and position of bands indicate the genotype.
