Hello Keira,
I am sorry, I am not sure what happened. I remember specifically replying to your Forum post but it looks like maybe it did not upload.
1. Cell membranes are primarily organized around polarity and size. This STN molecule may look big but it actually is a planar molecule (all atoms lay in the same plane). A large molecule like glucose is around a ring so you know the atoms are in different planes. As for most non-polar molecules, you can assume they will diffuse through the membrane (anything with oxygen, carbon. Benzene is a larger molecule but it is more stabilized/planar than glucose, and it is non-polar so it will diffuse through the membrane. Endo/Exocytosis is the absorption or secretion of polar molecules through the cell membrane. Flu viruses, diphtheria, and cholera toxin all use receptor-mediated endocytosis pathways to gain entry into cells.
Alternatively, think about the following: all of the other answer choices just don't make any sense. This is a totally foreign molecule, so you just wouldn't expect there to be any corresponding receptors for active transport or receptor-mediated stuff.
2. Correct thought process with the DNA. DNA is just the map with all the possibilities, it does not reflect how much one particular protein will be expressed it just shows it has the possibility to express the protein! Your rationale is correct for rRNA. As for tRNA do not overcomplicate the topics. tRNA simply transfers amino acids to the ribosomes to help make the proteins, it would not actually be a reflection of the protein being made. For an analogy it is like saying you have the cake recipe in the kitchen (mRNA transcript) and a bunch of flours (amino acids from tRNA). You could possibly conclude what you might be baking based on the type of flour that is there, but the most reflective will be the recipe. Just know mRNA is a reflection of the proteins to be made.
3. Yes this is asking about post-translational modifications. "the translated polypeptide is cleaved" so you know translation already has happened. Post-translational modifications change the chemical nature of the polypeptide chain through alterations to amino acid residues. Post-translational modifications take place in the ER and include folding, glycosylation, multimeric protein assembly and proteolytic cleavage leading to protein maturation and activation. The endomembrane system is composed of the different membranes that are suspended in the cytoplasm within a eukaryotic cell. These membranes divide the cell into functional and structural compartments or organelles with the majority of protein modification occurring at the endoplasmic reticulum within the endomembrane system so it is more specific than just the cytoplasm.
4. because among the offspring of KkMm and Kkmm parents, the ones who lack a dominant K allele (necessary for hearing), or carry a dominant M allele (causes deafness) are deaf. Based on the Punnett square analysis, 10 out of 16 or 5/8 of all offspring are likely to be deaf. For these it is probably best to draw out the Punnett square if you have time. I just did a drawn out cross with the KkMm x Kkmm and 10/16 were in fact the fit for deafness to be certain. Your thought process with the M is wrong, only 1/4 will get (4/16). For the k gene you need capital K to hear.
5. The poly-A tail makes the RNA molecule more stable and prevents its degradation. Additionally, the poly-A tail allows the mature messenger RNA molecule to be exported from the nucleus and translated into a protein by ribosomes in the cytoplasm. Telomeres are the protective caps on the ends of the strands of DNA called chromosomes, which house our genomes. In young humans, telomeres are about 8,000-10,000 nucleotides long. They shorten with each cell division, however, and when they reach a critical length the cell stops dividing or dies. There is actually a phenomenon with age we get fewer telomeres, potentially exposing our DNA more to damage- maybe this is why older adults get more cancer. They act on different parts throughout the central dogma process.