DNA Replication and Telomeres in Eukaryotes

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Why did Meselson and Stahl label the DNA strands with a heavy isotope of nitrogen (15N)?

To support the semiconservative model (correct)

To study the function of Telomerase

To prevent DNA replication

To understand the process of chromatin disassembly

How did Meselson and Stahl's experiments support the semiconservative model of DNA replication?

By producing DNA with only 14N in both rounds of replication

By producing only heavy isotope-labeled DNA strands

By showing that DNA replication proceeds in one direction only

By eliminating the dispersive and conservative models (correct)

What is the role of origins of replication in DNA replication?

They prevent DNA elongation

They assist in the reassembly of histones

They bind to histones to facilitate replication

They separate the two DNA strands (correct)

In eukaryotes, why are there hundreds or thousands of origins of replication on a single chromosome?

To ensure faster replication of large eukaryotic chromosomes (A) Signup and view all the answers

Why is it essential for histones to be disassembled and reassembled during DNA replication in eukaryotes?

To allow DNA polymerase to replicate DNA bound to histones (D) Signup and view all the answers

What is the function of topoisomerases like gyrase in DNA replication?

To break, swivel, and rejoin DNA strands ahead of replication forks (D) Signup and view all the answers

What is the function of telomeres in eukaryotic chromosomes?

Delay the erosion of genes near the ends of DNA molecules (A) Signup and view all the answers

Why is the shortening of telomeres hypothesized to be the cellular basis for aging?

Immortal cells like stem cells have constant telomere length (C) Signup and view all the answers

Which enzyme is responsible for catalyzing the lengthening of telomeres in germline cells?

Telomerase (C) Signup and view all the answers

What is the purpose of circular chromosomes in prokaryotes?

Allow for more efficient DNA replication (C) Signup and view all the answers

How do telomeres differ from other parts of the chromosome?

They are dispensable and do not code for proteins (C) Signup and view all the answers

What role does telomerase play in protecting organisms according to the text?

Limits the number of cell divisions (C) Signup and view all the answers

What is the main function of DNA polymerase in DNA replication?

Adding nucleotides to the free 3' end of the new DNA strand (C) Signup and view all the answers

Which enzyme is responsible for sealing Okazaki fragments together in DNA replication?

DNA ligase (B) Signup and view all the answers

Why does repeated replication of linear eukaryotic chromosomes produce shorter DNA molecules with uneven ends?

Telomerase continuously extends the telomeres during replication (A) Signup and view all the answers

What is the term used to describe the complex that includes all components needed for DNA replication?

Replisome (A) Signup and view all the answers

Which model describes the lagging strand of DNA folding into a loop during replication?

Trombone model (D) Signup and view all the answers

In which type of chromosomes does the usual replication machinery provide no way to complete the 5' ends?

Linear chromosomes (C) Signup and view all the answers