1. Which of the following processes that happens inside a cell DOES NOT normally require consumption of free energy by the cell?
a. Replication of the genetic material
b. Import of nutrients from the environment
c.Diffusion of small molecules within the cell
d.Regulation of gene expression
e.Synthesis of enzymes that catalyze cellular reactions
2. Imagine a segment of DNA (within a gene) encoding a certain amount of information in its nucleotide sequence.When this segment is fully transcribed into mRNA and then translated into protein, in general,
a.the protein sequence would carry more information compared to the DNA and mRNA sequences, because its alphabet has 20 letters.
b.the protein sequence would carry less information compared to the DNA and mRNA sequences, because several codons can correspond to one amino acid.
c.the amount of information in the mRNA sequence is lower than DNA, because the mRNA has been transcribed using only one of the DNA strands as the template.
d.the amount of information in the mRNA sequence is higher than DNA, because several mRNA molecules can be transcribed from one DNA molecule.
3. In which of the following properties are the archaea more similar to eukaryotes than they are to bacteria?
a.size
b.microtubules and microfilaments
c.translation initiation
d.mode of cell division
e.both translation initiation and mode of cell division
4. Mitochondria are thought to have evolved from ancient bacteria. Which characteristics of a free-living bacteria have mitochondria lost over time?
a.an independent genome
b.ribosomes
c.phospholipid membranes
d.motility
e.ribosomes, phospholipid membranes, motility, and an independent genome
5. To trace family relationships between distantly related organisms such as humans, algae, bacteria, and archaea, one should compare their genomes in regions …
a. that evolve rapidly.
b. that have a higher mutation rate.
c. that code for proteins.
d. where mutations are hardly tolerated.
e. where most mutations are selectively neutral.
6. Gene duplication can give rise to homologous genes that are part of gene families. For example, there are six actin genes in the genome of most mammalian species. In humans, the ACTB gene, which encodes a cytoskeletal actin, is expressed ubiquitously, while ACTC1 is expressed mainly in cardiac cells. Although bacteria lack the eukaryotic cytoskeletal organization, the bacterial MreB gene bears recognizable sequence similarity to mammalian actin genes and codes for a protein that is similar to actin in structure and function. Which of the following statements is true about these genes?
a. ACTB is homologous to ACTC1 but not to MreB.
b. ACTB is orthologous to ACTC1 but not to MreB.
c. ACTB is paralogous to ACTC1 but not to MreB.
d. MreB is orthologous to ACTB but not to ACTC1.
e. ACTB is paralogous to both ACTC1 and MreB.
Quick Reply
