Question 1

The nervous system damage symptomatic of untreated PKU is due to

Accepted Answer

A)  too much phenylalanine being transported into nerve cells. 
B)  too few of the other seven neutral amino acids being transported into nerve cells. 
C)  accumulation of the breakdown products of phenylalanine in nerve cells. 
D)  none of these. 
E)  it is not clearly known.

Question 2

The study of genetic variations that affect people's responses to environmental chemicals is called _____________.

Accepted Answer

The answer of The study of genetic variations that affect...

Question 3

What is the nature of the genetic mutation that causes lactose intolerance?

Accepted Answer

A)  It is a dominant mutation that prevents lactase production. 
B)  It is a dominant mutation that causes a decline in adult lactase levels. 
C)  It is a recessive mutation that prevents lactase production. 
D)  It is a recessive mutation that causes a decline in adult lactase levels. 
E)  It is an X-linked mutation that prevents lactase production.

Question 4

Supertasters for the chemical PTC are ____________.

Accepted Answer

A)  homozygous dominant 
B)  heterozygous 
C)  homozygous recessive 
D)  either homozygous dominant or homozygous recessive 
E)  either homozygous dominant or heterozygous

Question 5

PKU is a recessive disorder. If a woman who has PKU has a child, what is the child's possible genotype?

Accepted Answer

A)  Homozygous dominant. 
B)  Homozygous recessive. 
C)  Heterozygous. 
D)  The genotype could be any one of these. 
E)  There is not enough information to determine the child's genotype.

Question 6

Certain traits in humans are incompletely penetrant, or show variations in expressivity. Can you suggest a biochemical explanation for these observations in such cases caused by a metabolic error?

Accepted Answer

The answer of Certain traits in humans are incompletely penetrant,...

Question 7

An essential amino acid is defined as one that is not produced by the body.

Accepted Answer

A) True 
 B)False

Question 8

Garrod called enzyme defects ____________________.

Accepted Answer

The answer of Garrod called enzyme defects ____________________....

Question 9

The uptake of neutral amino acids such as leucine, histidine, and valine is inhibited in brain cells of PKU individuals.

Accepted Answer

A) True 
 B)False

Question 10

The hemoglobin molecule

Accepted Answer

A)  has four subunits of two types. 
B)  has two subunits that can be formed from four types. 
C)  is involved in amino acid metabolism. 
D)  acts as a cell surface receptor. 
E)  is controlled by a single gene.

Question 11

What actually happens to the blood cells of people with sickle cell anemia that causes the cells to change their shape ("sickle")?

Accepted Answer

A)  Polymerization of hemoglobin molecules into long fibers. 
B)  Destruction of the hemoglobin molecules. 
C)  Loss of hemoglobin through leaky cell membranes. 
D)  Attachment of phosphate groups to the hemoglobin molecules. 
E)  Binding of methyl groups to the heme group of the hemoglobin molecule.

Question 12

PKU results from a failure to convert tyrosine to phenylalanine.

Accepted Answer

A) True 
 B)False

Question 13

The symptoms of alkaptonuria result from a build-up of ____________________ in the blood.

Accepted Answer

The answer of The symptoms of alkaptonuria result from a...

Question 14

Why must dietary therapy for PKU be instituted soon after birth?

Accepted Answer

The answer of Why must dietary therapy for PKU be...

Question 15

In most cases, mutations in metabolic pathways produce a recessive trait. Suggest how a mutation in a metabolic pathway might produce a dominant condition.

Accepted Answer

The answer of In most cases, mutations in metabolic pathways...

Question 16

Some success has been achieved in efforts to treat sickle cell disease by the process of ____________________.

Accepted Answer

The answer of Some success has been achieved in efforts...

Question 17

Large scale alterations of the amino acid structure in alpha globin are the cause of sickle cell anemia.

Accepted Answer

A) True 
 B)False

Question 18

Results from the study of globin variants indicate that

Accepted Answer

A)  all amino acid substitutions cause severe phenotypic effects. 
B)  the alteration of one amino acid can cause a genetic disease. 
C)  extended chains do not function to carry oxygen. 
D)  all mutations in globin are caused by changes in amino acids. 
E)  none of these is indicated.

Question 19

In Chapter 4, two forms of bleeder's disease (hemophilia A and hemophilia B) were described. Each is deficient in a clotting factor. What would you predict are the clotting capacities of a mixture of blood from these two disorders? Why?

Accepted Answer

The answer of In Chapter 4, two forms of bleeder's...

Question 20

The enzyme lactase splits the lactose molecule into ____________ and ____________.

Accepted Answer

The answer of The enzyme lactase splits the lactose molecule...

Exam 10: From Proteins to Phenotypes

The nervous system damage symptomatic of untreated PKU is due to

The study of genetic variations that affect people's responses to environmental chemicals is called _____________.

What is the nature of the genetic mutation that causes lactose intolerance?

Supertasters for the chemical PTC are ____________.

PKU is a recessive disorder. If a woman who has PKU has a child, what is the child's possible genotype?

Certain traits in humans are incompletely penetrant, or show variations in expressivity. Can you suggest a biochemical explanation for these observations in such cases caused by a metabolic error?

An essential amino acid is defined as one that is not produced by the body.

Garrod called enzyme defects ____________________.

The uptake of neutral amino acids such as leucine, histidine, and valine is inhibited in brain cells of PKU individuals.

The hemoglobin molecule

What actually happens to the blood cells of people with sickle cell anemia that causes the cells to change their shape ("sickle") ?

PKU results from a failure to convert tyrosine to phenylalanine.

The symptoms of alkaptonuria result from a build-up of ____________________ in the blood.

Why must dietary therapy for PKU be instituted soon after birth?

In most cases, mutations in metabolic pathways produce a recessive trait. Suggest how a mutation in a metabolic pathway might produce a dominant condition.

Some success has been achieved in efforts to treat sickle cell disease by the process of ____________________.

Large scale alterations of the amino acid structure in alpha globin are the cause of sickle cell anemia.

Results from the study of globin variants indicate that

In Chapter 4, two forms of bleeder's disease (hemophilia A and hemophilia B) were described. Each is deficient in a clotting factor. What would you predict are the clotting capacities of a mixture of blood from these two disorders? Why?

The enzyme lactase splits the lactose molecule into and .