Exam 1: Cells and Genomes

Based on the variation of genome size and gene number in the organisms presented in the following graph, which organism has the highest number of genes per unit length of their genome? (Note the logarithmic scale.)

Indicate if each of the following descriptions matches messenger RNAs (M), ribosomal RNAs (R), or transfer RNAs (T). Your answer would be a four-letter string composed of letters M, R, and T only, e.g. RRRT. ( ) They contain codons. ( ) They contain anticodons. ( ) They are (covalently) attached to amino acids. ( ) They are at the core of a complex that carries out protein synthesis.

Out of nearly 5000 protein-coding gene families, there is a set of nearly 300 conserved gene families that are found in species from all domains of life. When one looks at the general functions assigned to these gene families, it is found that …

A virus …

Mitochondria and chloroplasts are thought to have evolved from free-living aerobic bacteria that were engulfed by an ancestral anaerobic cell and established a mutually beneficial (symbiotic) relationship with it. Which of the following statements is NOT true about these organelles?

To trace family relationships between distantly related organisms such as humans, algae, bacteria, and archaea, one should compare their genomes in regions …

It is a model organism used to study various cell processes such as regulation of the eukaryotic cell cycle. Mutants are available for every gene in its exceptionally small genome. It can live indefinitely in either a haploid or a diploid state. Which of the following describes this organism?

Which of the following processes that happens inside a cell DOES NOT normally require consumption of free energy by the cell?

Scientists discover more than ten thousand new species of living organisms every year. What is shared between all of these organisms?

Laboratory strains of the model organism Escherichia coli that are resistant to antibiotics are very often used in research laboratories as well as in the biotechnology industry. If cultures of such bacteria were allowed to contaminate the environment uncontrollably, it is possible that at some point, pathogenic bacteria such as Neisseria meningitidis (which causes meningitis and can cause death, especially in children) could acquire the same antibiotic-resistance gene, causing a meningitis outbreak that is difficult to treat. In this scenario, which of the following mechanisms is a more likely source of the antibiotic-resistance gene in N. meningitidis?

In the following paragraph, fill in the blanks (indicated by numbers) with either Archaea (A), Bacteria (B), or Eukaryotes (E). Your answer would be a three-letter string composed of letters A, B, and E only, e.g. ABE. "Methanococcus jannaschii is an anaerobic thermophilic microbe that belongs to the domain ... (1) and is found in extreme environments such as hydrothermal vents. It lives at temperatures near the boiling point of water and at pressures over 200 times higher than at sea level. Its genome sequence, identified in 1996, revealed that most of its metabolic processes are similar to those in ... (2), while its genetic machinery is more similar to that of ... (3)."

Which of the following is NOT true regarding the tree of life?

It is a model organism used to study various eukaryotic cell and developmental processes such as cell division and cell death. Its hermaphrodite adult is composed of exactly 959 somatic (non-germ) cells, the lineage of each of which has been worked out with great precision. It is approximately 1 mm long. Which of the following describes this organism?

Which of the following groups of living organisms has the highest variation in haploid genome size?

Indicate if each of the following descriptions matches lithotrophic (L), organotrophic (O), or phototrophic (P) organisms. Your answer would be a four-letter string composed of letters L, O, and P only, e.g. LLPP. ( ) They feed on other living organisms or their organic products. ( ) They are responsible for the current oxygen-rich atmosphere of the Earth. ( ) They are all known to be prokaryotic. ( ) They are the primary energy converters in hydrothermal vents in the ocean floor.

All cells in a multicellular organism have normally developed from a single cell and share the same genome, but can nevertheless be wildly different in their shape and function. What in the eukaryotic genome is responsible for this cell-type diversity?

Indicate if each of the following descriptions matches RNA (R) or DNA (D). Your answer would be a five-letter string composed of letters R and D only, e.g. RDDRR. ( ) It is mainly found as a long, double-stranded molecule. ( ) It contains the sugar ribose. ( ) It normally contains the bases thymine, cytosine, adenine, and guanine. ( ) It can normally adopt distinctive folded shapes. ( ) It can be used as the template for protein synthesis.

Which of the following would you NOT expect to find in a bacterial cell?

A mutation in the cdc28 gene in the budding yeast Saccharomyces cerevisiae causes cell-cycle arrest, giving rise to unbudded cells that look like "dumbbells." Treatment of wild-type cells with nocodazole, a drug that destabilizes some cytoskeletal polymers, leads to a similar phenotype. Based only on these observations, which statement is true regarding cdc28?

Indicate if each of the following statements is true (T) or false (F). Your answer would be a five-letter string composed of letters T and F only, e.g. FFTFF. ( ) Animals ultimately depend on bacteria for fixation of the atmospheric nitrogen. ( ) If one finds animals in an isolated ecosystem, there should be photosynthetic organisms in that ecosystem as well. ( ) Carbon fixation can be carried out by bacteria only. ( ) All eukaryotes are organotrophs. ( ) Compared to eukaryotic cells, prokaryotes show greater biochemical diversity.