UWORLD Cellular Biology

A scientist discovers a new unicellular organism. Initial analysis reveals that the organism lacks a nucleus and any membrane-bound organelles. Which of the following features would further classify this organism as an archaeon rather than a bacterium?

Which of the following is a key difference in the genetic material of prokaryotic and eukaryotic cells?

A researcher is studying gene expression in both prokaryotic and eukaryotic cells. What significant difference would the researcher observe in the mRNA processing of these two cell types?

A scientist examines two bacterial samples: one Gram-negative and one Gram-positive. Which statement accurately describes the difference between these bacteria?

A virologist is studying a newly discovered virus that infects human cells. The virus lacks a phospholipid bilayer. How would this virus MOST likely enter the host cell?

A researcher is studying the lytic and lysogenic cycles of a bacteriophage. What is a key distinction between these two cycles?

A retrovirus uses reverse transcriptase to integrate into the host genome. If a researcher inhibits eukaryotic Polymerase II (Pol II), which type of virus replication would remain unaffected?

Researchers are investigating a disease caused by a novel infectious agent. They determine that the infectious agent is composed solely of protein and lacks any nucleic acid. What type of agent is MOST likely responsible for the disease?

A plant pathologist is investigating a disease affecting a crop of tomato plants. They discover that the infectious agent is a small, circular RNA molecule without a protein coat. What type of infectious agent is MOST likely causing the disease?

A researcher is studying gene expression in bacteria and observes that several genes are transcribed together on a single mRNA molecule. What is the MOST likely genetic structure responsible for this observation?

A scientist is studying the expression of a particular gene and observes that when a specific protein binds to a DNA sequence near the gene, transcription is inhibited. What type of regulatory protein is MOST likely involved in this process?

A researcher is examining the expression of a specific gene in response to various transcription factors. The researcher observes that the binding of a transcription factor to its target DNA sequence does not always result in increased gene expression. Which of the following conclusions is MOST accurate?

A researcher wants to quantify the amount of a specific protein in a cell lysate. Which of the following techniques would be MOST appropriate for this purpose?

A neurobiologist is studying the propagation of prion diseases. Which of the following techniques would be MOST appropriate for detecting prions in brain tissue samples?

A researcher aims to generate multiple copies of a specific gene for downstream experiments. Which of the following molecular biology techniques would be MOST suitable for this purpose?

A researcher is studying the structure and dynamics of a plasma membrane. Which of the following statements BEST describes the movement of transmembrane proteins within the membrane?

A scientist investigates the composition of lipid rafts in a cell membrane. They discover these rafts are enriched in cholesterol. What effect do lipid rafts not have on the cell membrane?

A researcher is studying the transport of various molecules across a cell membrane. Which type of molecule requires transport proteins to cross the membrane?

A cell biologist is examining the transport of glucose into a cell. They observe that glucose transport requires energy input from the cell. What type of transport mechanism is MOST likely responsible for glucose uptake in this scenario?

A researcher is investigating the acidification of endosomes within a cell. Which of the following mechanisms is directly responsible for lowering the pH inside endosomes?

A cell biologist is studying the uptake of a specific protein by cells in culture. They observe that the protein binds to receptors on the cell surface, triggering its internalization. What type of endocytosis is MOST likely responsible for this protein uptake?

A researcher is observing a cell engulfing a large bacterium. What cellular process is the cell utilizing?

A researcher is studying the uptake of extracellular fluid by cells. They observe that cells are constantly taking in small droplets of fluid, without any specific receptor binding involved. What type of endocytosis is MOST likely occurring?

A researcher is tracking the movement of endosomes within a cell. What cytoskeletal element do endosomes travel along, and what is their destination?

During endocytosis, which organelle does an endosome not directly interact with when trafficking cargo?

A researcher compares the electron transport chain (ETC) location in prokaryotic and eukaryotic cells. Where is the ETC located in prokaryotes?

Under anaerobic conditions, how do prokaryotes and eukaryotes differ in their metabolic strategies?

Which of the following cellular processes does NOT require spindle fibers?

Which of the following statements about viruses is correct?

A researcher observes that a virus enters a cell by injecting its DNA through a tail sheath, while the rest of the viral structure remains outside. What type of virus is likely being studied?

How can enveloped and nonenveloped viruses differ? Select the MOST accurate.

What is/are an obligate component(s) of all viruses?

Which one of the following is present in both prokaryotic and eukaryotic cells?

Which description is TRUE of Encapsulins?

While observing cells under a microscope in Biology 101 lab, one student states, "That cell is prokaryotic because it does not have membrane-bound organelles." A second student adds, "That cell is definitely Archaea." What is the flaw, if any, in their statements?

Which of the following genetic characteristics is UNIQUE to prokaryotes?

If an alien life form was discovered that was shown to be prokaryotic, could it also be a virus?

During an experiment, you are measuring mRNA levels of Gene A and Gene B. The genes are adjacent to each other in the genome, are located downstream from the same promoter, and are transcribed together. What is TRUE of the level of their respective mRNA transcripts?

How does PCR differ from Northern Blot?

If the function of endosomes was inhibited in a human cell, how would that affect phagocytosis?

If a protein is destined to be embedded in the plasma membrane, which of the following organelles must it pass through during its synthesis and processing?

A researcher is studying protein trafficking in a eukaryotic cell and blocks the function of the Golgi apparatus. What is the MOST likely consequence for proteins normally secreted via exocytosis?

A cell biologist is examining cells under a microscope and observes the formation of kinetochores. What phase of the cell cycle is the cell MOST likely in?

How does meiosis in eukaryotic cells differ from binary fission in prokaryotic cells regarding the resulting daughter cells?

Which of the following mechanisms describes how chromosome number could decrease in a cell line without a loss of genetic information?

How do transposons affect the genome?

Which component of the bacterial flagellum is responsible for generating the torque that rotates the flagellum?

What is the function of the hook in the bacterial flagellum?

A researcher discovers a mutation in a eukaryotic cell line that disrupts the function of the rough ER. How would this mutation MOST likely affect protein synthesis?

A researcher is studying the effects of different mutations on cell division. They identify a mutation that prevents proper chromosome segregation during meiosis. Which of the following cellular structures is MOST likely affected by this mutation?

Which of the following distinguishes proteolysis in prokaryotes from proteolysis in eukaryotes?

What is the function of the filament in prokaryotic cells?

A researcher identifies a genetic element within a eukaryotic genome that can move to different locations but cannot form infectious viral particles. Which type of element is this MOST likely to be?

How does the absence of a nucleus in prokaryotic cells affect mRNA translation?

A researcher is studying a virus that infects bacteria. The researcher observes that the virus lacks an envelope. Which of the following is LEAST likely to be a component of this virus?

A scientist discovers a new infectious agent. After analysis, they find that the agent consists only of a small, circular RNA molecule and lacks a protein coat. What type of agent is this MOST likely to be?

Which of the following cellular structures exhibits different compositions in prokaryotic and eukaryotic cells?

How does the inheritance of genetic material differ fundamentally between prokaryotes and eukaryotes?

A researcher is studying the metabolic processes in a facultative anaerobic bacterium. Under anaerobic conditions, which of the following adaptations would MOST likely allow the bacterium to continue producing ATP?

Which of the following is a direct consequence of the compartmentalization achieved by membrane-bound organelles in eukaryotic cells?

A cell biologist is studying protein secretion in prokaryotes. Where would signal sequence proteins be directed for eventual export from the cell?

Which of the following is a critical function that the spliceosome performs in eukaryotic cells?

How can prions propagate diseases?

A researcher is studying a virus and determines that the virus's genetic material is single-stranded RNA. When introduced into a cell, the viral RNA is immediately translated into viral proteins. What type of genome does this virus MOST likely have?

A researcher is studying gene expression and observes that multiple ribosomes are translating a single mRNA molecule simultaneously. What is the name of this structure, and in which type(s) of cells does it occur?

Which cellular component is exclusively found in eukaryotic cells and is NOT present in prokaryotic cells?

What is one reason why viruses are excluded from cell theory?

A researcher uses Northern blotting to analyze gene expression in a cell culture. What type of molecule is being detected and quantified using this technique?

During which phase of mitosis do the chromosomes condense and become visible as chromatids?

A researcher is investigating the composition of a cell's plasma membrane. Which of the following components is ALWAYS present?

How does gene cloning differ from Northern blot in molecular biology applications?

Which of the following BEST describes the function of encapsulins in prokaryotic cells?

A researcher performs a Western blot on a sample from a patient with a suspected prion disease. What is the MOST likely purpose of this experiment?

Imagine a newly discovered virus lacks reverse transcriptase, integrase, and any kind of envelope proteins. What is the MOST accurate conclusion?

A researcher investigates bacterial cells and discovers that they lack histones. Which of the following is a valid conclusion?

Which of the following eukaryotic cellular locations is MOST analogous to the prokaryotic plasma membrane in terms of ATP production?

Telomeres are specialized structures found at the ends of eukaryotic linear chromosomes. What is the MOST likely reason telomeres are not present in archaeal chromosomes?

A researcher is comparing the genome organization of a bacterium, a eukaryotic cell, and a virus. Which of the following statements accurately describes a key difference they would observe?

A scientist is studying a newly discovered microbe. Initial analysis reveals that the microbe has a circular chromosome and lacks a nuclear membrane. Further analysis to classify the microbe reveals the presence of ether-linked lipids in its membrane. To which domain does this microbe MOST likely belong?

A researcher is investigating the evolutionary relationships between different organisms. They note that archaea, like eukaryotes, have genes that contain introns, a feature absent in bacteria. Which of the following conclusions is MOST supported by this observation?

A scientist is examining a cell under a microscope and observes several key features: the absence of membrane-bound organelles, a single circular chromosome, and a cell wall made of pseudopeptidoglycan. To which domain does this cell MOST likely belong?

A researcher is investigating the process of DNA replication in a newly discovered organism. They observe that the organism's DNA is circular and contains a single origin of replication. Which of the following conclusions can be drawn from this observation?

A researcher is studying the energy production mechanisms in a bacterium and a eukaryotic cell. They observe that the bacterium generates ATP through the electron transport chain (ETC) located on its plasma membrane, while the eukaryotic cell's ETC is located in the mitochondria. What implication does this difference have for ATP production?

You are studying the evolution of different life forms and observe that bacteria, archaea, and eukaryotes all have different ribosomal structures. Which of the following statements BEST explains the significance of these differences?

A researcher isolates a new infectious particle from a patient. Initial tests show that the particle contains nucleic acids but no ribosomes. Which of the following could most accurately describe this particle?

A researcher performs an agar diffusion test on a bacterial culture. The culture was transformed with a plasmid containing a gene of interest and an ampicillin resistance gene. Three antibiotic disks were placed on the agar: tetracycline (T), chloramphenicol (C), and ampicillin (A). Which of the following results would be expected?

A researcher isolates an infectious agent from a patient’s blood. The pathogen lacks a phospholipid bilayer but contains nucleic acids. Which of the following is the most likely identity of the pathogen?

A researcher analyzes mitochondrial DNA from human cells. Which of the following characteristics would be expected in mitochondrial DNA, based on the endosymbiotic theory?

Scientists propose a prokaryotic organism acquired a gene from a eukaryotic host through symbiosis. Which of the following would most strongly challenge this hypothesis?

Which cell type can serve as the DNA donor during bacterial conjugation?

A researcher deletes a gene (pixR) from a bacterial plasmid known to carry antibiotic resistance (R plasmid). Which of the following BEST describes the resulting phenotype of these bacteria?

Which of the following best describes bacterial transformation?

Which of the following best describes bacterial transduction?

Which of the following events could reduce chromosome number in a eukaryotic cell without losing genetic information?

Which of the following statements is TRUE regarding cellular and viral envelopes?

Which of the following characteristics is unique to viruses and NOT found in prokaryotic or eukaryotic cells?

Which host cell structure is least involved in the assembly of an enveloped virus?

Which of the following statements best describes bacterial conjugation?

A researcher is classifying bacteria based on their morphology. Under a light microscope, they observe three distinct bacterial shapes: spherical, rod-shaped, and spiral-shaped. Which of the following correctly matches each bacterial shape with its classification?

A researcher is studying the effects of different pH levels on bacterial survival after antibiotic treatment. The experiment measures bacterial colony-forming units (CFUs) at pH 7 and pH 4, plotting results on a logarithmic scale. The null hypothesis states that pH has no effect on bacterial survival. Which of the following graphical results would best support the null hypothesis?

A researcher is studying the effect of a genetic mutation on the ability of Salmonella typhimurium to move toward host cells. The expression levels of two key genes, fljB and fliC, which code for flagellar proteins, were analyzed in mutant bacteria compared to wild-type (WT) bacteria. The results show that fljB and fliC expression decreased by a factor of 0.3 in the mutant strain, with a p-value of 0.02. The expression of chemotaxis-related genes remained unchanged (p = 0.20).

Based on this data, what is the most likely outcome for the mutant bacteria?

A researcher studies the impact of a genetic mutation on bacterial chemotaxis by measuring the expression of key flagellar and chemosensation genes. The results show that flagellar gene expression is significantly decreased (p < 0.05), while chemosensation gene expression remains unchanged (p > 0.05). What is the most likely effect of this mutation on bacterial movement?

Which of the following organisms are classified as eukaryotic cells?

A researcher is studying two newly discovered viruses. Virus A binds to fluorescent antibodies targeting capsid proteins, while Virus B does not. Based on this information, which conclusion is MOST likely correct?

Some retroviruses become retrotransposons due to mutations that prevent them from forming infectious viral particles. Which type of mutation would most likely cause a retrovirus to function as an autonomous retrotransposon rather than an infectious virus?

A researcher discovers a mutation in a retrotransposon that prevents it from moving to new locations in the genome. Which of the following mutations is MOST likely responsible for this loss of mobility?

A researcher is studying a retrotransposon that normally moves between different regions of the genome via an RNA intermediate. A mutation is introduced that prevents the retrotransposon from integrating into a new genomic location. Which of the following mutations is MOST likely responsible for this defect?

Which of the following genetic features is found in some viruses but never in eukaryotic cells?

Which of the following statements correctly differentiates positive-sense (+ssRNA) and negative-sense (-ssRNA) RNA viruses?