During the mitotic cell cycle, the chromosomal DNA is replicated. The specific points in DNA molecules where replication is occurring are known as replication forks. A typical human chromosome has about 150 million base pairs of DNA. It takes about 1 hour to replicate the DNA of a typical human chromosome. The rate of replication using a single replication fork is approximately 50 base pairs per second. Approximately how many replication forks must occur in a typical human chromosome during DNA replication?

835

41700

50000

3000000

Biology

IGCSE&ALevel

CAIE

Exam No：9700_m24_qp_12 Year：2024 Question No：26

Answer:

Knowledge points:

6.1.1 describe the structure of nucleotides, including the phosphorylated nucleotide ATP (structural formulae are not expected)

6.1.2 state that the bases adenine and guanine are purines with a double ring structure, and that the bases cytosine, thymine and uracil are pyrimidines with a single ring structure (structural formulae for bases are not expected)

6.1.3.1 the importance of complementary base pairing between the 5' to 3' strand and the 3' to5' strand (antiparallel strands)

6.1.3.2 differences in hydrogen bonding between C–G and A–T base pairs

6.1.3.3 linking of nucleotides by phosphodiester bonds

6.1.4.1 the roles of DNA polymerase and DNA ligase (knowledge of other enzymes in DNA replication in cells and different types of DNA polymerase is not expected)

6.1.4.2 the differences between leading strand and lagging strand replication as a consequence of DNA polymerase adding nucleotides only in a 5 to 3 direction

6.1.5 describe the structure of an RNA molecule, using the example of messenger RNA (mRNA)

Answer:

Knowledge points:

Solution:

Related Question