15. Gene Expression

Which of the following mutations would be most likely to have a harmful effect on an organism?a. a deletion of three nucleotides near the middle of a geneb. a single nucleotide deletion in the middle of an intronc. a single nucleotide deletion near the end of the coding sequenced. a single nucleotide insertion downstream of, and close to, the start of the coding sequence

Which of the following describes mutations? Select True or False for each statement.T/F Point mutations can occur in any DNA sequence.T/F Frameshift mutations can occur in any DNA sequence.T/F Neutral mutations depend on the degeneracy of the genetic code.T/F Deleterious mutations occur only in protein-coding sequences of DNA.

Which of the following describes mutations? Select True or False for each statement.T/F Point mutations can occur in any DNA sequence.T/F Frameshift mutations can occur in any DNA sequence.T/F Neutral mutations depend on the degeneracy of the genetic code.T/F Deleterious mutations occur only in protein-coding sequences of DNA.

Explain what's wrong with this statement: All point mutations change the genotype and the phenotype.

Explain what's wrong with this statement: All point mutations change the genotype and the phenotype.

Skin color is often one of the first traits people notice in each other. Studies in zebrafish uncovered a mutation that altered a transport protein and resulted in light-colored fish. This discovery led to the finding that the same gene in humans has a strong influence on skin pigmentation in many populations. The zebrafish mutation that reduced coloration created a null allele of the transport protein gene. Which of the following types of mutation would be most likely to create this null allele?a. a missense mutationb. a frameshift mutationc. a neutral mutationd. a silent mutation

A mutation in a single gene may cause a major change in the body of a fruit fly, such as an extra pair of legs or wings. Yet it probably takes the combined action of hundreds or thousands of genes to produce a wing or leg. How can a change in just one gene cause such a big change in the body?

Skin color is often one of the first traits people notice in each other. Studies in zebrafish uncovered a mutation that altered a transport protein and resulted in light-colored fish. This discovery led to the finding that the same gene in humans has a strong influence on skin pigmentation in many populations. The zebrafish mutation that reduced coloration created a null allele of the transport protein gene. Which of the following types of mutation would be most likely to create this null allele?a. a missense mutationb. a frameshift mutationc. a neutral mutationd. a silent mutation

A chemical called dioxin is produced as a by-product of some chemical manufacturing processes. This substance was present in Agent Orange, a defoliant sprayed on vegetation during the Vietnam War. There has been a continuing controversy over its effects on soldiers exposed to it during the war. Animal tests have suggested that dioxin can be lethal and can cause birth defects, cancer, organ damage, and immune system suppression. But its effects on humans are unclear, and even animal tests are inconclusive. Researchers have discovered that dioxin enters a cell and binds to a protein that in turn attaches to the cell's DNA. How might this mechanism help explain the variety of dioxin's effects? How might you determine whether a particular individual became ill as a result of exposure to dioxin?

Investigators examined the expression of transporter mRNA and protein produced in zebrafish homozygous for each of the alleles and obtained the results summarized here (+=present,−=absent). Does the allele associated with light color appear to be altering transcription ortranslation? Why?

A small portion of the human transport protein amino acid sequence is shown here. The upper sequence is associated with darker skin, and the lower sequence is associated with lighter skin. What DNA base-pair change created the light-skin form of the human protein from the gene that coded for the dark-skin form?

The allele of the human transport protein associated with lighter skin is found almost exclusively in people with European ancestry. The other common allele for darker skin, which appears to be the ancestral allele, is found in people with African ancestry. What is a plausible explanation for how the lighter-skin allele came to be so common in those with European ancestry?