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Test Bank Molecular Biology of the Cell 6th Edition, by Bruce Alberts MOLECULAR BIOLOGY OF THE CELL, SIXTH EDITION CHAPTER 1: CELLS AND GENOMES Grade A 1. Scientists discover more than ten thousand new species of living organisms every year. What is shared between all these organisms? A. They ...

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  • August 8, 2023
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  • 2023/2024
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Test Bank Molecular Biology of the Cell 6th Edition, by Diffusion is a spontaneous process driven by the thermal
Bruce Alberts energy of randomly moving molecules, and normally
MOLECULAR BIOLOGY OF THE CELL, SIXTH EDITION does not require energy expenditure by the cell. For the
CHAPTER 1: CELLS AND GENOMES Grade A other mentioned processes, free energy is required. If a
cell “dies,” these processes would stop or get out of
1. Scientists discover more than ten thousand new control, but small molecules would still diffuse.
species of living organisms every year. What is
shared between all these organisms? 5. Which of the following would you NOT expect to
A. They are made of cells whose nuclei enclose their find in a bacterial cell?
DNA. A. Swimming using flagella
B. They obtain their energy from sunlight. B. Having a cell wall around the plasma membrane
C. They produce and use adenosine triphosphate C. ATP production in mitochondria
(ATP). D. Protein production on the ribosome
D. Their genome contains at least 1000 genes. E. Sexual exchange of DNA with other bacteria
E. All of the above.
Bacterial cells do not have membrane-enclosed
All living organisms are made of cells. However, only a organelles such as mitochondria.
minority of them are eukaryotes with defined cell nuclei.
Not all cells obtain their energy directly from sunlight. 6. To trace family relationships between distantly
However, regardless of the energy source, the main related organisms such as humans, algae, bacteria,
energy currency used by all known living cells is ATP. and archaea, one should compare their genomes in
Some prokaryotic genomes contain only a few hundred regions …
genes. A. that evolve rapidly
B. that have a higher mutation rate
2. All cells … C. that code for proteins
A. have membrane transport proteins D. where mutations are hardly tolerated
B. synthesize proteins on the ribosome E. where most mutations are selectively neutral
C. replicate their genome by DNA polymerization
D. transcribe their genetic information by RNA Highly conserved genes that code for optimized,
polymerization. essential, protein or RNA molecules should be studied to
E. All of the above trace family relationships across distant taxa. Mutations
in these regions (such as the genes that code for
All living cells replicate their DNA by the same overall ribosomal RNAs) are usually eliminated, making the
mechanism of templated polymerization. They also sequence recognizable even after billions of years of
transcribe the genetic information into RNA form using evolutionary history.
the same mechanism. Translation of this informationinto
protein form is mediated by the ribosome in all cells. 7. Laboratory strains of the modelorganism
Additionally, all cellular membranes have membrane Escherichia coli that are resistant to antibiotics are
transport proteins that control the flow of material very often used in research laboratories as well as in
through the membranes. the biotechnology industry. If cultures of such
bacteria were allowed to contaminate the
3. Imagine a segment of DNA (within a gene) encoding environment uncontrollably, it is possible that at
a certain amount of information in its nucleotide some point, pathogenic bacteria such as Neisseria
sequence. When this segment is fully transcribed meningitidis (which causes meningitis and can cause
into mRNA and then translated into protein, in death, especially inchildren) could acquire the same
general, … antibiotic- resistance gene, causing a meningitis
A. the protein sequence would carry more information outbreak that is difficult to treat. In this scenario,
compared to the DNA and mRNA sequences, which of the following mechanisms is a more likely
because its alphabet has 20 letters source of the antibiotic-resistance gene in N.
B. the protein sequence would carry less information meningitidis?
compared to the DNA and mRNA sequences, A. Random new gene generation
because several codons can correspond to one B. Intragenic mutation
amino acid C. Gene duplication
C. the amount of information in the mRNA sequence is D. DNA segment shuffling
lower, because the mRNA has been transcribed E. Horizontal gene transfer
using only one of the DNA strands as the template
D. the amount of information in the mRNA sequence is Horizontal gene transfer is common in bacteria and can
higher, because several mRNA molecules can be result in the acquisition of new antibiotic-resistance
transcribed from one DNA molecule genes by pathogenic bacteria.

, Viruses are not living cells but use the cellular machinery A significant fraction of the ubiquitous gene families
of their hosts to replicate their genetic material, which is across the three domains of life is involved in translation
made of DNA or RNA. They can act as vectors for and amino acid metabolism and transport. Other
horizontal gene transfer between cells of the same or metabolic processes such as carbohydrate and coenzyme
different species. Infection is followed by either lysis metabolism and transport also constitute a large subset.
(killing of the host cell) or the persistence of the viral This is only a rough sketch of the core ancestral gene set
genome in the host cell (which can last for many cell but is nevertheless informative.
generations).
12. Which of the following is true regarding Escherichia
9. Which of the following does NOT typically involve coli?
horizontal gene transfer? A. Most of our understanding about mitosis comes
A. Sexual reproduction in humans from studies on this model organism.
B. Bacteriophage infection of bacteria B. It is a rod-shaped bacterium that can only grow in
C. The evolutionary history of the eukaryotic cell the gut of humans and other vertebrates.
D. The accidental duplication of a small region of a C. Two strains of E. coli can differ by up to 0.1% in their
bacterial chromosome followed by cell division genomes.
E. Introduction of plasmids into bacteria in a D. E. coli strain K-12 encodes about 4300 proteins.
laboratory E. The E. coli (strain K-12) genome is about 430 million
nucleotide pairs long.
Introduction of genes into bacteria or eukaryotes by viral
infection or artificially in the laboratory are examples of E. coli is a prokaryotic model organism; although the
horizontal gene transfer, as is sexual reproduction discovery of many fundamental molecular mechanisms
between members of the same eukaryotic species. A were aided by studies using E. coli, the eukaryotic
great deal of horizontal gene transfer has occurred process of mitosis is best studied in simple eukaryotic
during the evolution of eukaryotic cells, such as in the cells. E. coli can be easily cultured in the lab in nutrient
process that led to the development of mitochondria media. Its genome of 4.6 million nucleotide pairs codes
for about 4300 different proteins. But this number is
10. Gene duplication can give rise to homologous genes reported for the K-12 strain. Other strains can be
that are part of gene families. For example, there are different in up to 50% of their genes, a significant
six actin genes in the genome of most mammalian diversity which has been explained by the process of
species. In humans, the ACTB gene, which encodes horizontal gene transfer.
a cytoskeletal actin, is expressedubiquitously, while
ACTC1 is expressed mainly in cardiac cells. Although 13. Which of the following is NOT true regarding the
bacteria lack the eukaryotic cytoskeletal tree of life?
organization, the bacterial MreB gene bears A. Most bacteria and archaea have 1000 to 6000 genes
recognizable sequence similarity to mammalian in their genomes.
actin genes and codes for a protein thatis similar to B. Eukaryotes are more similar to archaea than to
actin in structure and function. Which of the bacteria with respect to the proteins that act on
following statements is true about these genes? their DNA.
A. ACTB is homologous to ACTC1 but not to MreB. C. Most bacteria and archaea have genome sizes
B. ACTB is orthologous to ACTC1 but not to MreB. between one and ten million nucleotide pairs,
C. ACTB is paralogous to ACTC1 but not to MreB. whereas eukaryotic genomes can be millions of
D. MreB is orthologous to ACTB but not to ACTC1. times larger.
E. ACTB is paralogous to both ACTC1 and MreB. D. Archaeal species were thought to belong to the
eukaryotic world before sequence analysis placed
Gene duplication within a single genome results in them in a separate domain of life.
paralogous genes (such as E. Photosynthetic bacteria are thought to be the
human ACTB and ACTC1 genes), whereas other ancestors of the eukaryotic chloroplasts.
homologous genes that share direct ancestry are called
orthologs (in this case, some ancestor of MreB is Most prokaryotes have small genomes (106 to 107
presumably a distant actin ortholog). These genes all nucleotide pairs) and code for between 1000 and 6000
belong to the actin family. genes. Archaea are more similar to bacteria in their
metabolism, but more similar to eukaryotes with respect
11. Out of nearly 5000 protein-coding gene families, to their DNA replication, DNA repair, and DNA packaging
there is a set of nearly 300 conserved gene families proteins (archaeal histones). Before the comparison of
that are found in species from all domains of life. DNA sequences of highly conserved genes placed them
When one looks at the general functions assigned to in a separate domain, archaeal organisms were classified
these gene families, it is found that … as bacteria.
A. the majority of them function in cell-to-cell signaling

B. the majority of them are poorly characterized 14. A mutation in the cdc28 gene in the budding yeast

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