Biology Chapter 9 quiz#1

Why did Janelle's doctors use gene therapy instead of gene editing to try to correct her sickle cell anemia?

Janelle received her infusion of new blood stem cells in late 2017, and CRISPR is not yet approved for human use.

Why do individuals who can trace their ancestry to sub-Saharan Africa, Saudi Arabia or central India seem to have a higher rate of sickle cell diagnosis than those who cannot trace their ancestry to these regions?

Malaria is caused by a parasite that is common to these regions and infects red blood cells, so having one sickle cell mutation provides protection against malaria infection.

Why would there be no evolution without mutations?

Mutations allow organisms to adapt to changes that occur in their environments, increasing the chances of survival if the mutation is beneficial.

Which statement describes the mechanism by which new alleles are formed?

Mutations can occur within existing genes, which brings about new allele variations.

What would be the impact of a genetic mutation that resulted in the production of only fetal hemoglobin and no adult hemoglobin?

No beta-globin subunits would be produced. Thus, the risk of sickle cell anemia would be eliminated.

What is an advantage of receiving a replacement organ grown from one's own cells versus receiving an organ transplant from a donor?

There is less chance of organ rejection, and there is no need to wait on a transplant list.

The table contains the DNA sequence for a segment of the human insulin gene as well as the same DNA sequence with a mutation. Original sequence ATG GAA TAA AGC CCT TGA ACC AGC Mutated sequence ATG GAA TAA ACC CTT GAA CCA GCA

deletion

Which type of DNA mutation results in a change in the reading frame of an mRNA?

deletion of a single nucleotide

An adult stem cell called a hematopoietic stem cell from bone marrow is most useful in treating a ______.

disorder affecting the development of blood cells.

DNA mutations can arise from uncorrected errors in DNA replication, inheritance, and

environmental insults.

The Chinese scientist who used CRISPR on human embryos stated that he was trying to

make the cells more resistant to HIV infection.

If an original DNA strand contained the sequence ATGCGTTCAGCGATT, but a mutation occurred such that it now read ATTCGTTCAGCGATT, what type of mutation would this be?

point mutation

When Manny Johnson received his stem cell therapy, the goal was to

stimulate the production of fetal hemoglobin instead of adult hemoglobin.

Gene therapy is defined as

the ability to fix a genetic mistake that an individual may be born with by inserting a healthy version of the specific gene into the individual's body.

What is a deletion mutation?

the loss of one or more nucleotide pairs in a DNA molecule

What is a substitution mutation?

the replacement of one nucleotide by another nucleotide in a DNA molecule

A cell with mutated DNA may not be able to produce proteins accurately. Which situations can lead to mutations in the DNA?

uncorrected DNA replication errors, chemicals in tobacco smoke, exposure to X‑ray radiation

Hematopoietic stem cells are _____ cells that develop into _____ cells.

undifferentiated; blood

How does an acquired mutation in a gene alter the function of a cell?

Base pair mutations in a gene are passed directly into mRNA via transcription.

Which events are potential effects of a point mutation within a protein coding gene?

A nucleotide is replaced with another nucleotide, but the amino acid sequence remains the same. A nucleotide is used in place of another, and the change results in a stop codon. An incorrect amino acid is placed in a protein, but it does not affect how the protein functions.

Using Infographic 8.8 (amino acid codon table), what would be the impact of a change in the DNA strand from the original sequence of ATGCGTTCAGCGATT to a mutated sequence of ATTCGTTCAGCGATT?

A stop codon would be introduced immediately and thus no protein would be produced.

What is an insertion mutation?

An additional nucleotide is inserted in the normal sequence, which lengthens the sequence

At which point does a mutation exert its potentially dysfunctional effects in a cell?

after a protein is produced