AP BIOLOGY

Detailed explanation-1: -During transcription, a piece of DNA that codes for a specific gene is copied into messenger RNA (mRNA) in the nucleus of the cell. The mRNA then carries the genetic information from the DNA to the cytoplasm, where translation occurs.

Detailed explanation-2: -The eukaryotic nucleus therefore provides a distinct compartment within the cell, allowing transcription and splicing to proceed prior to the beginning of translation. Thus, in eukaryotes, while transcription occurs in the nucleus, translation occurs in the cytoplasm.

Detailed explanation-3: -The nuclear envelope of eukaryotic cells separates the nucleus and cytoplasm. It is thought to partition transcription and processing of messenger RNAs (mRNAs), which occur in the nucleus, from protein synthesis (translation), which is observed in the cytoplasm.

Detailed explanation-4: -Transcription occurs in the nucleus and not in the cytoplasm in eukaryotes because eukaryotes store the DNA in the nucleus. In prokaryotes, there is no nucleus and the DNA is in the cytoplasm. Thus, transcription can occur in the cytoplasm as well.

Detailed explanation-5: -The most prominent substructure within the nucleus is the nucleolus (see Figure 8.1), which is the site of rRNA transcription and processing, and of ribosome assembly.