Q

QuestionAnatomy and Physiology

The origins of replication, DNA polymerases, and the leading strand are involved in building new strands of DNA. Part B Solution: The correct statement about DNA replication is: "The leading strand is built continuously, and the lagging strand is built in pieces." During DNA replication, the two strands of parental DNA are separated, and new strands are synthesized using the parental strands as templates. The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized in short, discontinuous stretches in the opposite direction. DNA ligase then seals the gaps between these stretches to form a continuous strand. Step 1: Identify the correct statement about DNA replication. - The lagging strand is built continuously. (Incorrect) - The leading strand is built continuously, and the lagging strand is built in pieces. (Correct) - The lagging strand is one of the strands of parental DNA. (Incorrect) - DNA ligase helps assemble the leading strand. (Incorrect) - The leading strand is one of the strands of parental DNA. (Incorrect) The leading strand is built continuously, and the lagging strand is built in pieces. Part C Solution: During DNA replication, a nucleotide with a complementary base pair will bind to an A nucleotide in the parental DNA. Since Adenine (A) forms a base pair with Thymine (T) in DNA, a T nucleotide will bind to an A nucleotide in the parental DNA. Step 1: Identify the nucleotide that will bind to an A nucleotide in the parental DNA. - T (Correct) - U - G - C - A T will bind to an A nucleotide in the parental DNA. Part D Solution: DNA ligase is the molecule that seals the gaps between the pieces of DNA in the lagging strand. DNA ligase is an enzyme that catalyzes the formation of a phosphodiester bond between the 3'-hydroxyl group of one nucleotide and the 5'-phosphate group of another, thereby joining two DNA fragments together. Step 1: Identify the molecule that seals the gaps between the pieces of DNA in the lagging strand. - DNA ligase. (Correct) - The replication fork. - DNA polymerase. - The leading strand. - RNA. DNA ligase seals the gaps between the pieces of DNA in the lagging strand. Part E Solution: The statement "The two strands of parental DNA are separated during DNA replication" is true. However, the statement "DNA ligase adds nucleotides to the lagging strand" is false. DNA ligase seals the gaps between the pieces of DNA in the lagging strand, but it does not add nucleotides. Step 1: Identify the false statement about DNA replication. - The lagging strand is made of a series of pieces that must be joined together to make a continuous strand. (True) - DNA ligase adds nucleotides to the lagging strand. (False) - DNA polymerase builds a new strand by adding DNA nucleotides one at a time. (True) - Because the two strands of parental DNA run in opposite directions, the new strands must be made in different ways. (True) - The two strands of parental DNA are separated during DNA replication. (True) The statement "DNA ligase adds nucleotides to the lagging strand" is false.