AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

DNA MAKES RNA MAKES PROTEIN

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
A molecule is observed traveling to the ribosome where it undergoes a change by releasing an attached subunit. Which may best describe this molecule?
A
DNA
B
mRNA
C
rRNA
D
tRNA
Explanation: 

Detailed explanation-1: -Structure of the ribosome The ribosome moves forward on the mRNA, codon by codon, as it is read and translated into a polypeptide (protein chain). Then, once translation is finished, the two pieces come apart again and can be reused.

Detailed explanation-2: -The tRNA is located in the ribosome’s first docking site. This tRNA’s anticodon is complementary to the mRNA’s initiation codon, where translation starts. The tRNA carries the amino acid that corresponds to that codon.

Detailed explanation-3: -During translation, these tRNAs carry amino acids to the ribosome and join with their complementary codons. Then, the assembled amino acids are joined together as the ribosome, with its resident rRNAs, moves along the mRNA molecule in a ratchet-like motion.

Detailed explanation-4: -tRNA molecules bind to the ribosome in a solvent-accessible channel at the subunit interface. Three binding sites for tRNA, called the aminoacyl site (A site), peptidyl site (P site), and exit site (E site), have been identified on both the large and small subunit (Fig. 1).

There is 1 question to complete.