cell structure & function (Mod 5-8 quiz)

At the end of DNA replication, the sister chromatids are held together by the: a. kinetochores b. securins c. cohesins d. histones

c. cohesins

Which of the following will not cross a cell membrane (not even very slowly) without assistance from a channel or transporter? a. Small nonpolar molecule b. Small, uncharged polar molecule c. Ions d. Large, uncharged polar molecule

C. Ions

Which of these is a process by which cells harvest the energy stored in food molecules; usually accompanied by the uptake of O2 and release of CO2? a. Cellular Respiration b. Glycolysis c. Oxidative Phosphorylation d. Photosynthesis

a. Cellular Respiration

Which of the following choices reflects the appropriate order of locations through which a protein destined for the plasma membrane travels? a. ER → Golgi → plasma membrane b. Golgi → lysosome → plasma membrane c. ER → lysosome → plasma membrane d. lysosome → endosome → plasma membrane

a. ER → Golgi → plasma membrane

Which of the following statements is true? a. GTP-binding proteins are active when bound to GTP, and inactive when bound to GDP. b. GDP is phosphorylated to form GTP by a GAP in order to active GTP-binding proteins. c. GEFs promote hydrolysis of GTP to GDP d. Protein phosphatases add phosphate groups to proteins.

a. GTP-binding proteins are active when bound to GTP, and inactive when bound to GDP.

Which of the following statements about microtubule organizing centers is FALSE? a. Microtubules emanating from the centrosome have alternating polarity such that some have their plus end attached to the centrosome while others have their minus end attached to the centrosome. b. Basal bodies serve as the microtubule organizing centers for cilia. c. Centrosomes typically contain a pair of centrioles, which is made up of a cylindrical array of short microtubules. d. Centrosomes are the major microtubule-organizing center in animal cells.

a. Microtubules emanating from the centrosome have alternating polarity such that some have their plus end attached to the centrosome while others have their minus end attached to the centrosome.

Which of the following is true of photosynthesis? a. Photosynthesis takes place in two stages: the light reactions and the light-independent (or dark) reactions. b. ATP and FADH are products of Stage 1 of photosynthesis, which go on to be consumed in Stage 2 of photosynthesis. c. Electrons transferred along Photosystem II and then Photosystem I are eventually donated to O2 as the final step. d. Photosynthesis takes place in the inner chloroplast membrane.

a. Photosynthesis takes place in two stages: the light reactions and the light-independent (or dark) reactions.

Which of the following statements about the endoplasmic reticulum (ER) is FALSE? a. Proteins to be delivered to the ER lumen are synthesized on the smooth ER. b. The ER membrane is contiguous with the outer nuclear membrane c. Steroid hormones are synthesized in the smooth ER. d. The ER is the major site for new membrane synthesis in the cell.

a. Proteins to be delivered to the ER lumen are synthesized on the smooth ER.

Which of the following statements is true? a. Vesicles resulting from pinocytosis are small, whereas vesicles resulting from phagocytosis are relatively larger to accommodate large particles such as bacteria. b. During constitutive exocytosis, selected proteins are diverted into secretory vesicles where the proteins are stored until an extracellular signal stimulates their secretion. c. Regulated exocytosis continually supplies the plasma membrane with newly synthesized lipids and proteins. d. Pinocytosis takes place in some specialized cell types, whereas phagocytosis happens in all eukaryotic cells.

a. Vesicles resulting from pinocytosis are small, whereas vesicles resulting from phagocytosis are relatively larger to accommodate large particles such as bacteria.

A major distinction between the connective tissues in an animal and other main tissue types such as epithelium, nervous tissue, or muscle is the: a. amount of extracellular matrix in connective tissues. b. ability of connective-tissue cells such as fibroblasts to change shape. c. ability of connective tissues to withstand mechanical stresses. d. numerous connections that connective-tissue cells make with each other.

a. amount of extracellular matrix in connective tissues.

Which of the following does not occur during M phase in animal cells? a. growth of the cell b. condensation of chromosomes c. breakdown of nuclear envelope d. attachment of chromosomes to microtubules

a. growth of the cell

Both multicellular plants and animals have: a. tissues composed of multiple different cell types. b. cells capable of locomotion. c. cells with cell walls. d. a cytoskeleton composed of actin filaments, microtubules, and intermediate filaments.

a. tissues composed of multiple different cell types.

Which of the following is an ancient enzyme that was likely an early development in the evolution of energy-generating systems? a. 3-phosophoglycerate transferase b. ATPase c. Rubisco d. Pyruvate dehydrogenase

b. ATPase

Which of the following statements about actin filaments is true? a. Actin filaments, similar to microtubules, are composed of actin dimers. b. Actin filaments are found in the cell in microvilli, contractile bundles, lamellipodia, filopodia, and contractile rings. c. Actin filaments, similar to intermediate filaments, do not have a polarity to their structure. d. Actin filaments can only be found in the cell in bundles of filaments.

b. Actin filaments are found in the cell in microvilli, contractile bundles, lamellipodia, filopodia, and contractile rings.

Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called a. passive transport. b. active transport. c. free diffusion. d. facilitated diffusion.

b. Active Transport

Which of the following statements is true about the role of enzymes in the oxidation of sugars: a. Enzymes lower the energy released from the reaction b. Enzymes allow reactions to proceed in a stepwise manner at appropriate temperatures for the cell c. An enzyme must be able to function in all steps of cellular respiration in order to be involved d. Without enzymes, the oxidation of sugar will produce AND capture the same amount of energy

b. Enzymes allow reactions to proceed in a stepwise manner at appropriate temperatures for the cell

Which of the following statements is true? a. G-protein coupled receptors only bind to monomeric G proteins. b. Ion-channel-coupled receptors are often found on neurons and muscle cells. c. All enzyme-coupled receptors must bind to an associated enzyme to become activated d. All receptors are located on the cell surface of a target cell.

b. Ion-channel-coupled receptors are often found on neurons and muscle cells.

Which statement is true regarding mitochondria? a. Mitochondria remain in the same location throughout the life of the cell. b. Mitochondria can be either small and round in shape or long continuous tubules. c. Mitochondria never divide or fuse. d. All cells have roughly the same number of mitochondria.

b. Mitochondria can be either small and round in shape or long continuous tubules.

Which of the following statements is TRUE? a. Aquaporin channels are found in the plasma membrane, and allow the rapid passage of water molecules and small ions in and out of cells. b. Most ion channels are gated, which allows them to open and close in response to a specific stimulus, rather than allowing the constant, unregulated flow of ions. c. The ion selectivity of a channel depends solely on the charge of the amino acids lining the pore inside the channel. d. Gap junctions are large pores that connect the cytosol to the extracellular space.

b. Most ion channels are gated, which allows them to open and close in response to a specific stimulus, rather than allowing the constant, unregulated flow of ions.

Which of the following statements is true? a. Nuclear import is powered by hydrolysis of GDP to GTP. b. Proteins destined for mitochondria and chloroplasts must translocate across two membranes, requiring close proximity of the two membranes during this process. c. The signal recognition particle binds to the mitochondrial signal sequence and enables proteins to embed in the membrane. d. Proteins destined for the nucleus are marked by a nuclear localization signal which binds in the cytosol to the nuclear basket.

b. Proteins destined for mitochondria and chloroplasts must translocate across two membranes, requiring close proximity of the two membranes during this process.

Which of the following statements about the regulation of Cyclin-Cdk complexes is true? a. Ubiquitylation of cyclin leads to the destruction of its Cdk partner b. Ubiquitylation of cyclin is mediated by the Anaphase Promoting Complex/Cyclosome (APC/C) c. Wee1 removes inhibitory phosphates from the cyclin-Cdk complex immediately upon its formation d. Cdc25 is responsible for addition of inhibitory phosphates to the cyclin component of the cyclin-Cdk complex.

b. Ubiquitylation of cyclin is mediated by the Anaphase Promoting Complex/Cyclosome (APC/C)

During sexual reproduction, novel mixtures of alleles are generated. This is because: a. a diploid individual has two different alleles for every gene. b. during meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene. c. every gamete produced by a diploid individual has several different alleles of a single gene. d. in all diploid species, two alleles exist for every gene.

b. during meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene.

The plasmodesmata in plants are functionally most similar to which animal cell junction? a. tight junction b. gap junction c. desmosome d. adherens junction

b. gap junction

Which of the following statements about the cytoskeleton is FALSE? a. The cytoskeleton is made up of three types of protein filaments. b. The cytoskeleton controls the location of organelles in eukaryotic cells. c. Covalent bonds between protein monomers hold together cytoskeletal filaments. d. The cytoskeleton of a cell can change in response to the environment.

c. Covalent bonds between protein monomers hold together cytoskeletal filaments.

Which of the following observations is NOT a true statement supporting the theory that mitochondria are descendants of prokaryotic ancestors? a. Mitochondria have ribosomes. b. Chemiosmotic coupling happens similarly in plasma membranes of mitochondria, bacteria, and archaea. c. Mitochondria are found within bacteria and archaea. d. Mitochondria have DNA based genomes.

c. Mitochondria are found within bacteria and archaea.

Which of the following statements is true? a. All enzyme-coupled receptors are receptor tyrosine kinases. b. Receptor tyrosine kinases remove phosphate groups from the tyrosine amino acids of proteins. c. Receptor tyrosine kinases often dimerize upon binding of their ligand, resulting in their activation. d. Receptor tyrosine kinases often activate Ras directly by exchanging its GDP for GTP.

c. Receptor tyrosine kinases often dimerize upon binding of their ligand, resulting in their activation.

Which of the statements below about intermediate filaments is true? a. They easily disassemble. b. They can be found in only the nucleus. c. They can be anchored to the plasma membrane at a cell-cell junction. d. Each filament is about 10 μm in diameter.

c. They can be anchored to the plasma membrane at a cell-cell junction.

During fertilization in humans: a. several sperm pronuclei compete in the cytoplasm to fuse with the egg nucleus. b. only one sperm binds to the unfertilized egg. c. a wave of Ca2+ ions is released in the fertilized egg's cytoplasm. d. a sperm moves in a random fashion until it encounters an egg.

c. a wave of Ca2+ ions is released in the fertilized egg's cytoplasm.

Induced pluripotent stem (iPS) cells: a. cannot yet be used to generate organoids. b. can differentiate into a greater variety of adult tissues than embryonic stem cells. c. can be created by the expression of a set of key genes in most somatic cell types, including cells derived from adult tissues. d. require a supply of donor egg cells, as is the case for embryonic stem cells.

c. can be created by the expression of a set of key genes in most somatic cell types, including cells derived from adult tissues.

Which of the following are true statements about skeletal muscle fibers? a. Skeletal muscle fibers are large multinucleated cells b. Skeletal muscle fibers include a specialized portion of the endoplasmic reticulum called the sarcoplasmic reticulum c. Each skeletal muscle fiber will include many myofibrils within its cytoplasm. d. All of the above

d. All of the above

Which of the following is an example of endocrine cell signaling? a. A membrane-bound signal molecule binds to a receptor on a neighboring cell b. A secreted signal acts locally in the extracellular fluid to influence nearby cells. c. A neurotransmitter binding to a receptor on a target cell at a synapse d. A secreted signal is available to interact with cells in the whole body via the bloodstream

d. A secreted signal is available to interact with cells in the whole body via the bloodstream

Which of the following statements is true? a. Clathrin remains on the outside of a vesicle for its entire journey from origin to destination. b. Transport vesicles only deliver lipids to the cell surface. c. Vesicle fusion to its destination organelle requires adaptin molecules on the vesicle to bind to Rab on the destination membrane. d. All transport vesicles in the cell must have a v-SNARE protein in their membrane.

d. All transport vesicles in the cell must have a v-SNARE protein in their membrane.

Which of the following statements about stem cell niches is false? a. The Paneth cell serves as a stem cell niche for the stem cells of the mammalian intestine. b. Wnt signaling is required for a functional stem cell niche in the mammalian intestine. c. Dr. Judith Kimble identified the first stem cell niche in an animal, which relied on Notch signaling. d. Paneth cells are not required for maintenance of the stem cells in the mammalian intestine.

d. Paneth cells are not required for maintenance of the stem cells in the mammalian intestine.

Which of the following statements is true? a. An N-terminal NLS is necessary, but not sufficient to trigger protein sorting to the nucleus b. Stop transfer sequences for ER transport are cleaved from a single pass transmembrane protein once the protein is embedded in the membrane c. A nuclear localization signal at the 3' end of an mRNA, will trigger nuclear import of that mRNA d. Signal sequences governing protein transport can be as short as 3 amino acids long

d. Signal sequences governing protein transport can be as short as 3 amino acids long

What would be the most obvious outcome of repeated cell cycles consisting of S phase and M phase only? a. The cells would not be able to replicate their DNA. b. The mitotic spindle could not assemble. c. The cells would get larger and larger. d. The cells produced would get smaller and smaller.

d. The cells produced would get smaller and smaller.

During recombination: a. sister chromatids undergo crossing-over with each other. b. the synaptonemal complex keeps the sister chromatids together until anaphase II. c. one crossover event occurs for each pair of human chromosomes. d. chiasmata hold chromosomes together.

d. chiasmata hold chromosomes together.

Which of the following is not a type of epithelium? a. squamous b. cuboidal c. columnar d. hexagonal

d. hexagonal

Ras is a GTP-binding protein that is often defective in cancer cells. A common mutation found in cancer cells causes Ras to behave as though it were bound to GTP all the time, which will cause cells to divide inappropriately. From this description, the normal Ras gene is a/an: a. oncogene. b. gain-of-function mutation. c. tumor suppressor. d. proto-oncogene.

d. proto-oncogene.

Which of the following is required for the secretion of neurotransmitters in response to an action potential? a. neurotransmitter receptors b. voltage-gated K+ channels c. Na+-K+ pumps d. voltage-gated Ca2+ channels

d. voltage-gated Ca2+ channels

Which of the following statements about the structure of microtubules is FALSE? a. Microtubules are built from protofilaments that come together to make a hollow structure. b. The two ends of a protofilament are chemically distinct, with α-tubulin exposed at one end and β-tubulin exposed at the other end. c. Within a microtubule, all protofilaments are arranged in the same orientation, giving the microtubule structural polarity. d. α-Tubulin and β-tubulin are covalently bound to make the tubulin dimer that then assembles into protofilaments.

d. α-Tubulin and β-tubulin are covalently bound to make the tubulin dimer that then assembles into protofilaments.