Final answer:
Over 80% of our genome can be transcribed but not translated, which corresponds to non-coding regions that are used in the production of molecules like rRNA, a key component of ribosomes.
Step-by-step explanation:
The percentage of DNA in our genomes that can be transcribed but not translated is over 80%. This includes regions of DNA that are used to create non-coding RNAs (ncRNAs) such as ribosomal RNA (rRNA), transfer RNA (tRNA), and others that do not code for proteins. Therefore, the correct answer to the first question is 'a. Over 80%.'
The primary component of non-coding RNA in terms of cellular dry mass is rRNA. rRNA is a significant component of ribosomes, which are abundant in the cell. Hence, the answer to the second question is 'c. Ribosomes.'