QUIZ 6

If one human protein contains 400 amino acids, how many nucleotides need to be in the exons of the corresponding gene to properly code for it?

1200

The fruit fly (Drosophila melanogaster) has four pairs of chromosomes. How many chromosomes would you find in an unfertilized egg (female gamete or sex cell) of this species?

4

An addition or deletion of one or two base pairs in a gene sequence results in a __________ mutation

frameshift

In sickle cell anemia, a point mutation leads to a replacement of one amino acid in a hemoglobin molecule, in a unit responsible for transportation of oxygen. This and any other mutation in a gene that causes a change in the amino acid sequence in a polypeptide chain is known as a __________ mutation

missense

The purple flower of the F1 offspring of Gregor Mendel's parental generation crosses indicated that __________

purple color in flowers is dominant to white color

Which position in a codon shows the greatest degeneracy? In other words, if a change occurs in this codon position, it is less likely to change the amino acid that is specified relative to the other positions.

third position

A type of mutation in which a region of one chromosome is moved to a different chromosome is called __________

translocation

A mutation that results in a replacement of a purine with a pyrimidine is known as a __________ mutation

transversion

According to the figure, which of the following statements regarding base substitution mutation rates is FALSE?

In viruses, base substitution mutation rates increase with increasing genome size.

Which of Gregor Mendel's laws contradicts the blending theory of inheritance?

Mendel's first law, the law of segregation

In the 1850s and 1860s, Gregor Mendel bred pea plants and examined the way that traits were passed down across generations. His conclusions, although not accepted during his lifetime, established the foundation for the field of genetics. Of the choices listed, what is the most relevant summary of Mendel's conclusions?

The hereditary factors responsible for traits such as seed shape and flower color are inherited as discrete units.

The graph shows the distribution of fitness effects of Bacteriophage f1 mutants. Note that values greater than 1.0 indicate beneficial mutations, whereas values less than 1.0 indicate deleterious mutations. What is the best conclusion from this study?

The vast majority of the mutations had a deleterious effect, but some were beneficial.

Suppose that in wild rose plants, the A locus controls pigmentation of the flower petals. The A allele (for red flower coloration) is completely dominant to the a allele (for pale pink flower coloration). If purebred red-flowered plants were crossed with purebred pink-flowered plants, and their heterozygous offspring (the F1 generation) were grown so that such hybrids might be crossed among themselves, which of the following flower phenotypes might you expect in the F2 generation?

both red and pale pink roses (in a ratio of 3:1, respectively)

Gene expression in eukaryotes is strongly influenced by the local structure of the chromosome. In which of the following regions of a DNA molecule would you expect to find the highest levels of gene expression?

decondensed chromatin

One of the important facts learned from experiments in molecular genetics is that most amino acids can be encoded by more than one nucleotide triplet. For this reason, we say that the genetic code is __________

degenerate

A mutation resulting in deletion of a protein-coding gene will most likely have a ___________ effect on fitness.

deleterious

Why did the pre-Mendelian theory of blending inheritance pose a major challenge to Charles Darwin's theory of evolution by natural selection?

Blending inheritance would eliminate variation in a population.

In their experiment in 1943 using E. coli, Salvador Luria and Max Delbrück tested two alternative hypotheses. The random mutation hypothesis and the acquired inherited resistance hypothesis make different predictions about the distribution of resistant mutants that will be observed upon exposure to bacteriophage (viruses that can infect and kill E. coli). Which of the following predictions, if proven, would support the acquired inherited resistance hypothesis?

At the time of exposure to the phage, all E. coli cells will be phage-sensitive. The process of exposure to the phage will induce phage resistance in a small fraction of the bacterial cells.

Which of the following is TRUE regarding the difference between a DNA molecule and an RNA molecule?

DNA is a double-stranded molecule, whereas RNA is a single-stranded molecule.

Which of the following statements is FALSE?

Epigenetic information cannot be passed down across generations.