Cell Quizzes

A: The prefix “lyso-” refers to the ability to dissolve or destroy molecules or cells.

B: The suffix “-some” refers to an organelle within a cell. The other suffixes all indicate a type of cell.

A: The choices with ATP are not true. While choice C refers to endocytosis.

C: Plasma proteins are found in the blood plasma. Not to be confused with the plasma membrane.

B: One function of membrane proteins is to receive (amino acid-based) hormones that cannot pass through the plasma membrane.

A: The phosphate end is hydrophilic (water soluble), while the lipid end is hydrophobic (insoluble in water).

B: The basic cell membrane lipid bilayer is composed of proteins and three main types of lipids: phospholipids, sphingolipids, and cholesterol. The approximate composition is 55% proteins, 25% phospholipids, 13% cholesterol, 4% other lipids, and 3% carbohydrates.

D: Peroxisomes contain oxidases capable of combining oxygen with_x000d_hydrogen ions derived from different intracellular chemicals to form_x000d_hydrogen peroxide (H2O2), a highly oxidizing substance used in_x000d_association with catalase, another oxidase enzyme present in large_x000d_quantities in peroxisomes. These enzymes oxidize and neutralize many_x000d_drugs and toxins that might otherwise be poisonous to the cell.

B: The suffix “-some” refers to small body or organelle within a cell.

A: Desmosomes (despite having the suffix “-some”) are not within the cell. They are structures that join adjacent plasma membranes to each other.

B: ATP is only produced within the mitochondria.

C: Chromatin makes up chromosomes.

C: Microfilaments occur inside the cell.

B: Mitochondria are often called the “powerhouses” of the cell and contain oxidative enzymes that permit oxidation of the nutrients, thereby forming carbon dioxide and water and at the same time_x000d_releasing energy. The liberated energy is used to synthesize “highenergy” ATP.

B: The plasma membrane is indeed made of two layers, but they are phospholipid (not glycoprotein) molecules.

D: Molecules that are soluble in water cannot pass through lipid (fat). So the phospholipids are a barrier. The functions described by B and C are performed by other molecules in the plasma membrane.

A: This is a basic function of mitochondria. All other answers are wrong.

C: The term “active” implies using energy (in the form of ATP) to move a molecule against its concentration gradient while the other processes are all passive.

A: This is the only correct answer. The others are not true.

B: The “pump” (or ATPase) transports Na+ out and K+ into the cell.

C: The suffix “-blast” indicates that the cell is immature.

B: The first stage of mitosis, the process by which the cell splits into two new cells, is called prophase_x000d__x000d_

C: ATP production is the function of mitochondria.

C: Most cells, except for fat cells, are composed mainly of water in a concentration of 70% to 85 %. After water, the most abundant substances in most cells are proteins, which normally constitute 10% to 20 % of the cell mass.

A: Facilitated refers to the role of the protein carriers. The other choices refer to diffusion, active transport and osmosis, respectively.

B: Na-K-ATPase pump regulate the cell volume and membrane integrity.

D: Gap junctions are present in electrically excitable cells, such as neurons, heart, and_x000d_smooth muscle. Indeed, gap junctions (electrical synapses) were first discovered in myocardium and nerve because of their properties of electrical transmission_x000d_between adjacent cells.

B: The inside of a cell is negative, while the exterior side of the membrane is positive. This difference in charge constitutes a difference in electrical potential (or voltage), known as the resting membrane potential. An action potential is generated when the membrane is stimulated and the potential reversed.

B: During metaphase, chromosomes are arranged on a plane (the metaphase plate) in the middle of the cell, attached to microtubules of the spindle

D: Remember the metaphase plate occupies the middle of the cell.

A: Both pinocytosis and phagocytosis involve movement of the plasma membrane. Pinocytosis involves invagination of the cell membrane, whereas phago cytosis involves evagination. Both events require the recruitment of actin and other cytoskeleton elements. Phagocytosis is_x000d_not spontaneous and is selective, being triggered by specific receptor-ligand interactions.

D: The cell is smallest structural unit that is deemed to be alive.

A: The pore diameter in the channel is estimated between 0.8 and 1.4 nm, which permits the passage of ions, sugars, amino acids, and other solutes with molecular weights up to about 1000 Da.

A: Autophagy is a housekeeping process by which obsolete organelles and large protein aggregates are degraded and recycled. Worn-out cell organelles are transferred to lysosomes by double membrane structures called autophagosomes that are formed in the cytosol.

D: The extracellular fluid has relatively high concentrations of sodium and chloride ions but lower concentrations of potassium and phosphate than the intracellular fluid.

B: Cholesterol is an amphipathic lipid and as such is an essential structural component of membranes, where it is important for the maintenance of the correct permeability and fluidity, and of the outer layer of plasma lipoproteins.

B: The cell “glycocalyx” is the loose negatively charged carbohydrate coat on the outside of the surface of the cell membrane. The membrane carbohydrates usually occur in combination with proteins or lipids in the form of glycoproteins or glycolipids, and the “glyco” portion of these molecules almost invariably protrudes to the outside of the cell.

A: Separation of the two chromatids of a chromosome occurs at anaphase. Choice D is cytokinesis and begins in late anaphase and continues into telophase

D: Meiosis produces sperm or egg so these must have half the complement of chromosomes (be haploid) to allow for the full complement to be present (and not more!) when sperm combines with egg.

A: Chromatin is DNA and the associated proteins so it pertains to genetic material.

C: One function of integral protein in the plasma membrane is to form channels to allow for the passage of ions.

B: Microtubule is a cytoskeletal protein, which maintains the size and shape of the cell. Microtubule may play a role in fine-tuning of locomotion.

C: Mitosis involves somatic cells. Meiosis refers to the production of the sex cells

A: The glycocalyx refers to molecules in the plasma membrane that have a carbohydrate chain attached (prefix “glyco-”).

B: Interphase is the time when the cell is performing its normal function and not dividing.

B: DNA replication occurs during the S phase of the cell cycle and precedes mitosis. Condensation of the chromosomes occurs during the prophase of mitosis. Fragmentation of the nuclear envelope occurs during the prometaphase of mitosis. The chromatids align at the equatorial plate during metaphase and separate into two complete sets of daughter chromosomes during anaphase.

C: DNA is double-stranded, while the “D” refers to “deoxy-”