BIO2581 Section 10

During an endosymbiotic event, a nucleomorph engulfs an alpha-proteobacterium. How many total genomes are present during the feeding stage, and how many genomes are present after transfer of control, respectively?

• 5, 4
• 3, 4
• 5, 5
• 4,3
• 5, 3

Which of the following results is not true regarding mutations caused by ionizing radiation?

• a) Gamma rays are a form of ionizing radiation
• b) Causes single-strand DNA breaks
• c) Cosmic rays are a form of ionizing radiation
• d) Can dislodge electrons
• e) None of the above

Ras is a protein that may exist in either a GTP-bound form, or a GDP-bound form. When binding GTP, it possesses the ability to facilitate cell growth. However, when the GTP is hydrolyzed into GDP, cell growth no longer occurs. Which of the following Ras-related mutations is most likely to be considered an oncogene, in the context of cancer genetics.

• A replicative transposon inserts itself into the promoter of gene encoding for Ras.
• A null mutation in the Ras-encoding gene.
• Ras can no longer hydrolyze GTP.
• Once Ras is bound to GDP, it undergoes a conformational change that prevents it from binding GTP indefinitely.
• A nonsense mutation that occurs relatively early in the DNA coding sequence of Ras.

A patient has a heterozygous mutation in a tumor suppressor gene. The mutant allele produces no functional protein, and the remaining normal allele is unable to fully prevent tumor formation. This pattern of inheritance suggests that the mutation contributes to cancer through:

• Haplosufficiency
• Haploinsufficiency
• Dominant-negative mutation
• Gain-of-function mutation
• none of the above

You have found a mutant allele, practice1, that causes a decrease in function when heterozygous and a loss of function when homozygous. You are sure that this allele is either a dominant negative or a null allele. Which of the following is the best way to determine which it is?

• A) Test a gain of function variant of the allele and, if the phenotype is the opposite of an organism homozygous for practice1, then it is a null allele.
• B) Test the wild type phenotype for the organism.
• C) Test the phenotype of the organism when heterozygous for a recessive loss of function allele.
• D) Assume haplosufficiency based on the organism's phylogenetic tree.
• E) None of the above would work

When a non photosynthetic eukaryote engulfs a photosynthetic eukaryote how many genomes are present in the non-photosynthetic eukaryote before phagocytosis, directly after phagocytosis and after gene loss?

• 4, 5, 3
• 2, 3, 2
• 2, 5, 3
• 2, 5, 4
• 2, 5, 2

Which of the following statements about transposons is false?

• A) Transposons can move within the genome via a "cut-and-paste" mechanism or a "copy-and-paste" mechanism.
• B) The movement of transposons can contribute to genetic diversity by creating mutations, rearrangements, and changes in gene expression.
• C) Transposons are only found in prokaryotes and are absent in eukaryotes.
• D) Retrotransposons move through an RNA intermediate, which is reverse-transcribed into DNA before integration into the genome.
• n/a