MCB 410 Quiz 1

Which pair of values best fills in the blanks in this statement: On average, eukaryotic cells are _____ times longer and have _____ times more volume than prokaryotic cells. -10, 1000 -100, 300 -10, 200 -2, 10

-10, 1000

Considering a human neuron and a human epithelial cell lining the gut, which of the following statements is most likely false? -Because they are both human cells, the identity and amounts of individual proteins are identical in both cells. -Many cellular processes in both the neuron and epithelial cell are likely to have counterparts in cells of the eukaryotic single-celled yeast, Saccharomyces cerevisiae. -In both cells, the expression of genetic information requires transcription and translation. -In both cells, individual proteins function as catalysts, receptors, transcriptional regulators and motors, and can have structural roles.

-Because they are both human cells, the identity and amounts of individual proteins are identical in both cells.

What information can a researcher obtain from Western blot analysis of a target protein? -The percentage of total cellular protein represented by the target protein. -The relative abundance of the target protein in untreated cells versus drug-treated cells. -The in vivo size of the target protein. -Both the in vivo size of the target protein and the percentage of total cellular protein it represents. -Both the in vivo size of the target protein and its relative abundance in untreated versus drug-treated cells.

-Both the in vivo size of the target protein and its relative abundance in untreated versus drug-treated cells.

Referring to Figure 4-54 in Essential Cell Biology 5th ed, which of the following is NOT true of intracellular condensates: -Intracellular condensates are present only in diseased cells and have no biological function in normal cells. -Intracellular condensates are thought to form by "phase separation" of non-covalently interacting macromolecules. -Intracellular condensates can encompass both RNA and protein molecules. -The nucleolus is an example of a functional intracellular condensate.

-Intracellular condensates are present only in diseased cells and have no biological function in normal cells.

Which of the following was NOT true of the study by Simeone et al (2003) presented in Discussion 1: -Levels of a-actin correlated with increased resistance to the chemotherapeutic agent fenretinide. -Several breast cancer cell lines had increased levels of the HER2 protein relative to MCF-7 cells. -The MCF-7 breast cancer cell line was successfully engineered to overexpress the HER2 protein. -Increased levels of the HER2 protein were correlated with lower levels of fenretinide-induced apoptosis.

-Levels of a-actin correlated with increased resistance to the chemotherapeutic agent fenretinide.

Which of the following statements is TRUE? -Gel electrophoresis separates proteins based on the number of alpha-helices and beta-sheets they contain. -Phosphorylation of serine residues can alter protein function. -The amino acids in the interior of a protein do not interact with the ligand and therefore play no role in selective binding of the protein to the ligand. -Antibodies are Y-shaped and are composed of a single polypeptide chain.

-Phosphorylation of serine residues can alter protein function.

Which statement is NOT true about the event's conclusions from studies during the mid-1800s surrounding the discovery of cells? -Scientists concluded that new cels arise from he growth and division of previously existing cells. -Cells came to be known as the smallest universal building block of living organisms. -Scientists concluded that new cells can form spontaneously from the remnants of ruptured cells -Light microscopy was essential in demonstrating the commonalities between plant and animal tissues.

-Scientists concluded that new cells can form spontaneously from the remnants of ruptured cells

An enzyme acts on a tyrosine residue in a target protein to create a binding site for the SH2 domain. This enzyme is most specifically ... -a nuclease -a synthase -a phosphatase -an isomerase -a kinase

-a kinase

Prokaryotic cells do not possess -RNA -replication machinery -ribosomes -membrane bilayers -a nucleus

-a nucleus

A single type of antibody: -might recognize and bind to a specific glycolipid. -is produced by a sub-population of B cells in mammals. -is composed of two heavy chains and two light chains. -can itself be recognized by other antibodies. -all of the above

-all of the above

Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of species called "model organisms." Which of the following characteristics are useful in an organism chosen for use as a model in laboratory studies? -amenability to genetic manipulation -ability to grow under controlled conditions -rapid rate of reproduction -all of the above

-all of the above

Proteins... -are chains of amino acids linked together by peptide bonds -can interact specifically with other molecules in the cell -can increase the rate of chemical reactions within cells -can be covalently modified by phosphorylation or ubiquitination -all of the above

-all of the above

Noncovalent interactions... -hold together individual monomers in polypeptide and nucleic acid macromolecules -are critical for interactions between macromolecules -are so "weak" that they are not important in cells -are only important in prokaryotic cells which do not have intracellular membranes

-are critical for interactions between macromolecules

The world of prokaryotes is divided into two domains (bacteria and archaea), each as different from each other as from eukaryotes. Select the observable characteristic that BEST separates archaea from bacteria. -are photosynthetic organisms -are found in extremest harsh environments -DNA is not transcribed into RNA -thrive in anaerobic conditions

-are found in extremest harsh environments

Referring to Figure 1-8 and the accompanying text in Essential Cell Biology 5th ed, electron microscopy: -is used to observe living cells. -has lower resolution than light microscopy. -can be used to visualize large ribonucleoprotein complexes, such as ribosomes. -is not capable of distinguishing between mitochondria and other organelles, such as lysosomes.

-can be used to visualize large ribonucleoprotein complexes, such as ribosomes.

Referring to Figures 4-46 and 4-47 in Essential Cell Biology 5th ed, covalent modification of the "tumor suppressor" protein p53: -can control p53 degradation -changes the amino acid sequence of p53 -does not involve protein kinases -does not vary between different cell types or under different conditions

-can control p53 degradation

Living systems are incredibly diverse in size, shape, environment, and behavior. It is estimated that there are between 10 million and 100 million different species. Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive. Which of the following can be described as the smallest living unit? -cell -organelle -protein -DNA

-cell

In the western blotting technique: -proteins are separated by gel electrophoresis and stained with a dye -gel-separated proteins that have been transferred to a membrane are probed with a specific antibody -proteins are separated by gel electrophoresis; primary antibodies recognize the largest protein and secondary antibodies recognize the smallest protein. -secondary antibodies catalyze the transfer of a fluorescent molecule to the target protein.

-gel-separated proteins that have been transferred to a membrane are probed with a specific antibody

Which of the following is a macromolecular assembly that is not enclosed by an intracellular membrane? -ribosome -mitochondrion -Golgi apparatus -lysosome -nucleus

-ribosome

The variation in the physical characteristics between different proteins are influences by the different overall amino acid compositions, but an even more important characteristic is the unique amino acid _____ which determines the _____ of the protein. -number, cellular location -peptide bond, resistance to denaturation -sequence, three-dimensional shape -number, molecular weight

-sequence, three-dimensional shape

The correct folding of proteins is necessary to maintain healthy cells and tissues. The presence of unfolded proteins are associated with the neurodegenerative disorders Alzheimer's disease, Huntington's disease, and Creutzfeldt-Jakob disease (the specific faulty protein is different for each). What happens to these disease-causing unfolded proteins? -they are extensively phosphorylated -they form structured filaments -they bind a different target protein -they form protein aggregates

-they form protein aggregates

Scientists discover thousands of new species of living organisms every year. What is most likely to be true about these newly discovered organisms? -their DNA is found within a membrane-bound compartment. -they can be easily maintained in the laboratory. -they produce and use adenosine triphosphate (ATP). -they contain mitochondria. -their genes and encoded proteins are entirely different from those in known organisms.

-they produce and use adenosine triphosphate (ATP)

Which of the following statements regarding microscopic observation of cells is FALSE? -electron microscopes have greater resolution than light microscopes -traditional light microscopes can be used to view individual protein molecules within cells -the limit of resolution of traditional light microscopes is approximately 200nm -ribosomes can be viewed using an electron microscope

-traditional light microscopes can be used to view individual protein molecules within cells

The central dogma provides a framework for thinking about how genetic information is used to produce structural and catalytic components of the cell.According to the central dogma, information flows from DNA to RNA and from RNA to protein via cellular processes known as ___________ and _____________. -transcription;translation -replication; translation -translation;transport -replication;transcription

-transcription, translation