Lactase can be classified as which type of enzyme? O A. Isomerase O B. Hydrolase O c. Transferase OD. Oxidoreductase Which cells express lactase? O A. Enterocytes of the duodenal villi O B. Epithelial cells of the colon lining OC. Parietal cells of the stomach lining O D. Bile-producing hepatocytes of the liver One of the silent SNPs present in the Northwestern European haplotype that is associated with LP resides within the lactase gene. Genomic DNA and cDNA of the region containing this SNP in an LP heterozygous adult was sequenced. The sequence results are shown. ACGT ACGT 11 Genomic CDNA DNA The SNP resulted from what type of mutation? O A. Purine to purine OB. Purine to pyrimidine O c. Pyrimidine to purine OD. Pyrimidine to pyrimidine

Human Physiology: From Cells to Systems (MindTap Course List)
9th Edition
ISBN:9781285866932
Author:Lauralee Sherwood
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Chapter12: Body Defenses
Section: Chapter Questions
Problem 1SQE
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Cow's milk allergy (CMA) and lactose intolerance both result from
dietary exposure to cow's milk and are often confused.
CMA is caused by an abnormal inflammatory response to one or
more proteins in cow's milk. Although more than one mechanism
appears to be involved in generating this response, the antibody-
mediated response is the best understood. Development of the
antibody-mediated response occurs in two stages, the first being the
generation of an abnormal immune response during initial exposure to
milk proteins and the second being the generation of an inflammatory
response upon subsequent exposure. Symptoms of antibody-mediated
CMA may include hives and respiratory difficulty. Anaphylactic shock
rarely occurs but can be fatal if not treated immediately.
Lactose intolerance, also known as lactase deficiency, is a
condition that results from insufficient synthesis of the enzyme lactase,
which converts lactose into glucose and galactose. Although all healthy
newborns produce sufficient levels of lactase, two distinct phenotypes
exist in adults: lactase persistence (LP) (includes heterozygotes) and
lactase non-persistence (LNP). LP adults continue to produce lactase
into adulthood, whereas LNP individuals do not. It has been suggested
that the LP phenotype is the result of a mutation event that coincided
with the domestication of dairy animals thousands of years ago in
areas such as northwestern Europe and within some Afro-Arabian
nomadic populations. In Northwestern Europeans, sets of alleles
located closely together on the same chromosome (haplotypes)
associated with the LP phenotype contain several single nucleotide
polymorphisms (SNPs). However, only one appears to be directly
responsible for this phenotype; the others are silent. By comparison,
several different SNPs appear to be directly responsible for the LP
phenotype in Afro-Arabian LP-associated haplotypes.
Lactase can be classified as which type of enzyme?
O A. Isomerase
OB. Hydrolase
O C. Transferase
OD. Oxidoreductase
Which cells express lactase?
OA. Enterocytes of the duodenal villi
O B. Epithelial cells of the colon lining
OC. Parietal cells of the stomach lining
O D. Bile-producing hepatocytes of the liver
One of the silent SNPs present in the Northwestern European haplotype
that is associated with LP resides within the lactase gene. Genomic
DNA and cDNA of the region containing this SNP in an LP heterozygous
adult was sequenced. The sequence results are shown.
ACGT A CGT
Genomic
DNA
The SNP resulted from what type of mutation?
cDNA
O A. Purine to purine
O B. Purine to pyrimidine
OC. Pyrimidine to purine
OD. Pyrimidine to pyrimidine
Based on the information in the passage, the mutation that causes the
LP phenotype is most likely located in:
O A. an intron within the lactase gene.
O B. the coding sequence of the lactase gene.
O C. an enhancer sequence of the lactase gene.
O D. the stop codon at the end of the lactase gene.
Transcribed Image Text:Cow's milk allergy (CMA) and lactose intolerance both result from dietary exposure to cow's milk and are often confused. CMA is caused by an abnormal inflammatory response to one or more proteins in cow's milk. Although more than one mechanism appears to be involved in generating this response, the antibody- mediated response is the best understood. Development of the antibody-mediated response occurs in two stages, the first being the generation of an abnormal immune response during initial exposure to milk proteins and the second being the generation of an inflammatory response upon subsequent exposure. Symptoms of antibody-mediated CMA may include hives and respiratory difficulty. Anaphylactic shock rarely occurs but can be fatal if not treated immediately. Lactose intolerance, also known as lactase deficiency, is a condition that results from insufficient synthesis of the enzyme lactase, which converts lactose into glucose and galactose. Although all healthy newborns produce sufficient levels of lactase, two distinct phenotypes exist in adults: lactase persistence (LP) (includes heterozygotes) and lactase non-persistence (LNP). LP adults continue to produce lactase into adulthood, whereas LNP individuals do not. It has been suggested that the LP phenotype is the result of a mutation event that coincided with the domestication of dairy animals thousands of years ago in areas such as northwestern Europe and within some Afro-Arabian nomadic populations. In Northwestern Europeans, sets of alleles located closely together on the same chromosome (haplotypes) associated with the LP phenotype contain several single nucleotide polymorphisms (SNPs). However, only one appears to be directly responsible for this phenotype; the others are silent. By comparison, several different SNPs appear to be directly responsible for the LP phenotype in Afro-Arabian LP-associated haplotypes. Lactase can be classified as which type of enzyme? O A. Isomerase OB. Hydrolase O C. Transferase OD. Oxidoreductase Which cells express lactase? OA. Enterocytes of the duodenal villi O B. Epithelial cells of the colon lining OC. Parietal cells of the stomach lining O D. Bile-producing hepatocytes of the liver One of the silent SNPs present in the Northwestern European haplotype that is associated with LP resides within the lactase gene. Genomic DNA and cDNA of the region containing this SNP in an LP heterozygous adult was sequenced. The sequence results are shown. ACGT A CGT Genomic DNA The SNP resulted from what type of mutation? cDNA O A. Purine to purine O B. Purine to pyrimidine OC. Pyrimidine to purine OD. Pyrimidine to pyrimidine Based on the information in the passage, the mutation that causes the LP phenotype is most likely located in: O A. an intron within the lactase gene. O B. the coding sequence of the lactase gene. O C. an enhancer sequence of the lactase gene. O D. the stop codon at the end of the lactase gene.
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