Afamilial form of hypoparathyroidism is caused by a single point mutation in the gene encoding the preproparathyroid hormone. as a consequence of this point mutation, the signal sequence cannot be cleaved from the prepro-form of the mutant hormone. which statement below best describes the effect of this mutation upon synthesis of the preproparathyroid hormone? a) mrna encoding the mutant preproparathyroid hormone would accumulate in the nucleus and not be transcribed. b) the mutant preproparathyroid protein would not be targeted to the endoplasmic reticulum and thus would be translated by free ribosomes in the cytoplasm. c) the mutant preproparathyroid hormone would be incorrectly folded in the endoplasmic reticulum. d) the mutant preproparathyroid hormone would be inserted into the plasma membrane of the parathyroid cells. e) the mutant preproparathyroid hormone could not be stored in secretory vesicles, but instead would be secreted immediately following synthesis.

Mouse liver cells were homogenized and the homogenate subjected to equilibrium density-gradient centrifugation with sucrose gradients. fractions obtained from these gradients were assayed for marker molecules (i.e., molecules that are limited to specific organelles). the results of these assays are shown in the figure. the marker molecules have the following functions: cytochrome oxidase is an enzyme involved in the process by which atp is formed in the complete aerobic degradation of glucose or fatty acids; ribosomal rna forms part of the protein-synthesizing ribosomes; catalase catalyzes decomposition of hydrogen peroxide; acid phosphatase hydrolysis monophosphoric esters at acid ph; cytidylyltransferase is involved in phospholipid biosynthesis; and amino acid permease aids in transport of amino acids across membranes. a) name the marker molecule and give the number of the fraction that is most enriched for each of the following cell components: lysosomes; peroxisomes; mitochondria; plasma membrane; rough endoplasmic reticulum; smooth endoplasmic reticulum.

The first three phases of the cell cycle are collectively known as (1 point) play audio cellular respiration. telophase. mitosis. interphase.

Which of the following is not a symptom of desertification? a) decrease in salt content of the soil b) lowering of the water table c) reduced surface water d) increased soil erosion e) loss of native vegetation