Biology, Eighth Edition (Raven)

Chapter 10: How Cells Divide

Bidirectional DNA Replication

What is semiconservative replication? DNA is double stranded molecule. Only one strand codes for proteins at any given point in the molecule. However, both strands are used during DNA replication. Each of the four bases in DNA (adenine, thymine, guanine, and cytosine) binds to a unique complementary base on the other strand. Therefore the base sequence on one strand determines the complementary sequence on the other strand. During DNA replication the two strand separate from one another and each strand has a new complementary strand built onto it. This form of replication is called semiconservative; each new DNA molecule is composed of one conserved strand from the original molecule and one new strand.

View the animation below, then complete the quiz to test your knowledge of the concept.



1.

The genetic material in bacteria is
A)double-stranded DNA.
B)double-stranded RNA.
C)single-stranded DNA.
D)single-stranded RNA.
E)either A or B
2.

DNA replication in bacteria begins at
A)a single origin and proceeds in one direction.
B)a single origin and proceeds in both directions.
C)two origins and proceeds in both directions.
D)many origins and proceeds in one direction.
E)many origins and proceeds in one direction.
3.

DNA replication is said to be
A)dispersive.
B)semi-conservative.
C)conservative.
D)liberal.
E)none the above
4.

DNA replication does not require a template.
A)True
B)False
5.

The bacterial chromosome is linear.
A)True
B)False
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