9.11 Genetic Mutation

Which of the following is an example of a silent mutation? -A base-pair substitution that does not cause a change in the amino acid sequence -A base-pair substitution that causes a stop codon to form -A base-pair substitution that causes an amino acid substitution -A substitution of one gene for another in a chromosome

A base-pair substitution that does not cause a change in the amino acid sequence

What type of mutation causes sickle cell anemia?

A missense mutation

Which type of mutation causes phenylketonuria?

A nonsense mutation

How does a point mutation affect the protein that is coded for by a gene?

A point mutation can cause a different amino acid to be coded for, changing the structure of a particular protein.

How is the sample in amniocentesis obtained?

A sample of amniotic fluid is obtained via a syringe inserted through the abdomen and into the uterus.

A point mutation leads to the substitution of the codon "CCC" instead of "CCU". The mutation has no effect on the polypeptide chain. What type of mutation is involved?

A silent mutation.

Which of the following is a disadvantage of chorionic villi sampling? -It carries a relatively high rate of miscarriage compared to other methods of fetal testing. -It cannot be done until late in a pregnancy. -Karyotyping cannot be performed with the cells obtained through chorionic villi sampling -It is only a visual examination of the fetus, no cells are tested.

A. It carries a relatively high rate of miscarriage compared to other methods of fetal testing.

All of the following are advantages of using amniocentesis for fetal diagnosis except: -Amniocentesis can be used to detect Tay-Sachs. -Amniocentesis can be performed in the 14th or 15th week of pregnancy. -Amniocentesis can detect spinal bifida. -Amniocentesis can be used to detect Down syndrome.

B. Amniocentesis can be performed in the 14th or 15th week of pregnancy.

Which of the following is a cause of frameshift mutations? -Amino acids joining together in a random order -DNA strands within a chromosome breaking and joining back together. -RNA not translated properly. -Chromosomes separating during meiosis

B. DNA strands within a chromosome breaking and joining back together.

Which of the following terms does not describe a type of mutation caused by a base-pair substitution? -Silent mutation -Translocation -Nonsense mutation -Missense mutation

B. Translocation

Which statement below describes a point mutation? -A change in the entire gene on a chromosome -A change in the number of chromosomes in an organism -A change in a single nucleotide in a gene -A change in the number of genes on a chromosome

C. A change in a single nucleotide in a gene

Which of the following statements is the best definition of a missense mutation? -A base-pair substitution that causes no phenotypic effects, due to the several codons that code for each amino acid -A base-pair mutation that has no phenotypic effects due to the several amino acids that correspond to each codon -A base-pair substitution that causes a premature stop in protein production -A base-pair substitution that causes one amino acid to be substituted for another

D. A base-pair substitution that causes one amino acid to be substituted for another

Amniocentesis has many advantages as a method of fetal testing. It also has some disadvantages. Which of the following is not a disadvantage of amniocentesis? -Amniocentesis cannot be performed until the 14th or 15th week of pregnancy. -Amniocentesis results take several weeks to be produced. -Amniocentesis is an invasive procedure. -Amniocentesis is readily available to at risk families.

D. Amniocentesis is readily available to at risk families.

Which of the following are potential advantages in using the technique of amniocentesis versus chorionic villus sampling? -Amniocentesis can test for problems like spina bifida that chorionic villus sampling cannot. -Amniocentesis can be performed earlier in fetal development than chorionic villus sampling. -The risk of miscarriage in amniocentesis is lower than for chorionic villus sampling. -Both A and C.

D. Both A and C

Which of the following statements is TRUE? -A point mutation results when there is a change in at least two nucleotides on the DNA strand. -Sickle cell anemia results when the amino acid glutamic acid is substituted for valine in the polypeptide chain for hemoglobin. -A minimal error in an amino acid sequence has no effect on protein structure or function. -If one nucleotide in a codon is changed a point mutation will result.

D. If one nucleotide in a codon is changed a point mutation will result.

Which of the following is not true of ultrasound as a tool for fetal testing? -There is no risk to the fetus or the mother. -It is a non-invasive procedure. -It can be used to detect anatomical abnormalities. -It can be used to determine chromosomal abnormalities

D. It can be used to determine chromosomal abnormalities

Is a mutation in which three base pairs are inserted always more severe than a mutation in which one base pair is inserted? Why or why not?

Is a mutation in which three base pairs are inserted always more severe than a mutation in which one base pair is inserted? Why or why not?

Which type of mutation would cause the synthesis of a full-length protein with a different structure from the normal protein?

Missense mutation

Why do most point mutations in humans have no effect on phenotype?

Most point mutations occur in portions of the DNA that do not code for proteins.

How can some point mutations in coding regions have no effect on the amino acid sequence that is formed?

Several different nucleotide sequences can code for the same amino acid.

The procedure called __________ is similar to amniocentesis, but may be performed earlier in pregnancy.

chorionic villus sampling

True or false? A frameshift mutation is also known as a missense mutation.

false

A __________ mutation results when one or two nucleotide pairs are inserted into the DNA molecule.

frameshift

An example of a type of genetic mutation is

inversion, deletion, translocation.

True or false? A frameshift in a gene specifying for an enzyme usually results in a loss of enzyme activity.

true

True or false? Nonsense and frameshift mutations may both result in nonviable protein products.

true

The disease sickle cell anemia occurs when the amino acid __________ replaces the normally occurring amino acid __________.

valine, glutamic acid