Mississippi Science GEN.1B

GEN.1B is a cluster heading. These are the individual standards under it.

• GEN.1B.1

  Compare and contrast various proposed models of DNA replication (i.e., conservative, semi-conservative, and disruptive). Evaluate the evidence used to determine...

• GEN.1B.2

  Develop and use models to illustrate the mechanics of DNA replication.

• GEN.1B.3

  Microscopically observe and analyze the stages of the cell cycle (G1-S-G2-M) to describe the phenomenon and identify methods at different cell cycle checkpoints...

01

What Students Need to Do

Students model how each DNA strand guides a new strand. They use DNA density results to compare three copying models. They examine microscope images and explain how cells check for errors before dividing.

02

What Mastery Looks Like

Students show strand separation and matching bases, with one old and one new strand in each copied molecule. They use results from two rounds of copying to reject the conservative and dispersive models. They distinguish interphase from mitosis in microscope images and explain how proofreading and checkpoints limit errors.

03

Common Misconceptions

Students may think both original strands stay together or that old and new DNA mix within each strand. They may claim they can see G1, S, and G2 separately in ordinary microscope images, though all three look like interphase. Some think checkpoints repair every error themselves, rather than pausing the cell so repair can happen.

04

How to Assess It

Show one intermediate DNA density band after one round of copying, then intermediate and light bands after two rounds. Ask students to sketch the copied DNA, rule out the other two models, and name one checkpoint that could stop a cell with damaged DNA.

1. 01

   Use colored paper strips for old and new strands; have pairs unzip a DNA ladder and build two molecules using base-pair rules.

2. 02

   Show one intermediate band after round one and intermediate plus light bands after round two; ask which copying models fail and why.

3. 03

   Use onion root tip slides to tally interphase and mitosis, then match G1, S, G2, and M checkpoint cards to error cases.

4. 04

   Present a skin cell with UV-damaged DNA; ask whether the G1 checkpoint should pause division for repair or let it continue.

• GEN.1A

  Students will demonstrate that all cells contain genetic material in the form of DNA.

• GEN.2B

  Students will determine the causes and effects of mutations in DNA.

• BIO.3C

  Students will construct an explanation based on evidence to describe how the structure and nucleotide base sequence of DNA determines the structure of proteins ...

• FB.4

  Students will demonstrate an understanding of how genetic information is transferred from parent to offspring.