<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
Dismiss
Skip Navigation

3.2: DNA Structure and Replication

Difficulty Level: At Grade Created by: CK-12
Atoms Practice
Estimated2 minsto complete
%
Progress
Practice DNA Structure and Replication
 
 
 
MEMORY METER
This indicates how strong in your memory this concept is
Practice
Progress
Estimated2 minsto complete
%
Estimated2 minsto complete
%
Practice Now
MEMORY METER
This indicates how strong in your memory this concept is
Turn In

Does DNA copy itself?

Yes, your DNA needs to copy itself every time a new cell is created. The new cell needs to have DNA exactly like the rest of your cells. Otherwise, that cell might malfunction. That's why it's important that the process of copying DNA, called DNA replication, is very accurate.

DNA Replication

DNA must replicate (copy) itself so that each resulting cell after mitosis and cell division has the same DNA as the parent cell. DNA replication occurs during the S phase of the cell cycle, before mitosis and cell division. The base pairing rules are crucial for the process of replication. DNA replication occurs when DNA is copied to form an identical molecule of DNA.

The general steps involved in DNA replication are as follows:

  1. The DNA helix unwinds like a zipper as the bonds between the base pairs are broken.
  2. The two single strands of DNA then each serve as a template for a new stand to be created. Using DNA as a template means that on the new strand, the bases are placed in the correct order because of the base pairing rules. As a template strand is read, the new strand is created. If ATGCCA is on the "template strand," then TACGGT will be on the new DNA strand.
  3. The new set of nucleotides then join together to form a new strand of DNA. The process results in two DNA molecules, each with one old strand and one new strand of DNA.

This process is known as semiconservative replication because one strand is conserved (kept the same) in each new DNA molecule (Figure below).

DNA replication occurs when the DNA strands “unzip,” and the original strands of DNA serve as a template for new nucleotides to join and form a new strand.

Vocabulary

  • DNA replication: Making an identical copy of the cell's DNA.
  • semiconservative replication: Describes the DNA replication process in which half of a newly created DNA molecule is from the parent DNA, and the other half is newly synthesized DNA.

Summary

  • During DNA replication, the DNA helix unwinds and the two single strands of DNA then each serve as a template for a new stand to be created.
  • DNA replication is semi-conservative: the new DNA molecule consists of half of the parent DNA molecule.

Practice

Use the resource below to answer the questions that follow.

  1. What protein molecules does DNA wrap around to form a nucleosome?
  2. What makes up chromatin?
  3. When can you see chromosomes in a cell? Explain your answer fully.
  4. Are both strands of DNA copied continuously during replication? Why do you think cells follow this procedure?

Review

  1. Describe how DNA is replicated.
  2. Explain why DNA replication is sometimes called semiconservative.

    Notes/Highlights Having trouble? Report an issue.

    Color Highlighted Text Notes
    Please to create your own Highlights / Notes
    Show More

    Vocabulary

    DNA replication

    Making an identical copy of the cell's DNA.

    semiconservative replication

    Describes the DNA replication process in which half of a newly created DNA molecule is from the parent DNA, and the other half is newly synthesized DNA.

    Image Attributions

    Show Hide Details
    Description
    Difficulty Level:
    At Grade
    Grades:
    7 , 8
    Date Created:
    Nov 29, 2012
    Last Modified:
    Aug 30, 2016
    Files can only be attached to the latest version of Modality
    Please wait...
    Please wait...
    Image Detail
    Sizes: Medium | Original
     
    SCI.LSC.323.L.1
    Here
    Add Note
    Please to create your own Highlights / Notes