AP BIOLOGY

LABORATORY REVIEW

MOLECULAR BIOLOGY

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Characteristics of transcription
A
makes a mRNA
B
makes a protein (polypeptide)
C
occurs in the nucleus
D
occurs at a ribosome
Explanation: 

Detailed explanation-1: -That’s because transcription happens in the nucleus of human cells, while translation happens in the cytosol. Also, in eukaryotes, RNA molecules need to go through special processing steps before translation. That means translation can’t start until transcription and RNA processing are fully finished.

Detailed explanation-2: -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-3: -Key points: It involves copying a gene’s DNA sequence to make an RNA molecule. Transcription is performed by enzymes called RNA polymerases, which link nucleotides to form an RNA strand (using a DNA strand as a template). Transcription has three stages: initiation, elongation, and termination.

Detailed explanation-4: -Transcription occurs in the nucleus whereas the major mRNA decay pathways operate in the cytoplasm. As synthesis and decay processes contribute equally to maintaining mRNA levels, it is quite likely that organisms have evolved a mechanism to coordinate events in the two compartments.

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.

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