Chapter 12, Problem 20A

Summary Introduction

To hypothesize:

The importance for DNA to have multiple origins of replication

Introduction:

The process by which DNA in the chromosome is copied is called DNA replication. During replication each strand serves as a template to synthesize new DNA molecule. Replication of DNA produces two identical molecules from one. Eukaryotic cells have many origins of replication whereas a prokaryotic cell has only one origin of replication.

Answer to Problem 20A

Multiple origins of replication in a eukaryotic cell ensure that a large chromosome can be replicated quickly at one time.

Explanation of Solution

The given diagram shows a cell replicating in several areas. This is a feature of eukaryotes which have many origins of replication.

Eukaryotic DNA unwinds in multiple areas as DNA is replicated. Each individual area of chromosome replicates as a section. The section may vary in length from 10,000 to one million base pairs. This results in multiple areas replicating at one time along the large eukaryote chromosome. Multiple replication origins look like bubbles in the DNA strand. Replication also occurs faster if there are multiple origins of replication.