DNA Replication

DNA Replication

By David Fink

Match

Examine Model 2.

Number the steps below in order to describe the replication of DNA in a cell.

• Hydrogen bonds between nucleotides break.

• Strands of DNA separate.

• Free nucleotides are attracted to exposed bases on the loose strands of DNA.

• Free nucleotides are attracted to exposed bases on the loose strands of DNA.Hydrogen bonds between nucleotides form.

1

2

3

4

• 1

• 2

• 3

• 4

Multiple Choice

Locate the DNA helicase on Model 2.

What type of biological molecule is DNA helicase?

• Carbohydrate

• Protein

• Lipid

• Nucleic Acid

Open Ended

Locate the DNA helicase on Model 2.

What is the role of DNA helicase in the replication of DNA?

Multiple Choice

What rule is used to join the free nucleotides to the exposed bases of the DNA?

• The Rule of Threes

• Conservation of Energy

• Diffusion goes from high concentration to low concentration.

• The Base Pairing Rule

Open Ended

This type of replication is called semi-conservative replication. Considering the meaning of these words

(semi—half; conserve—to keep), explain why DNA replication is called semi-conservative.

Open Ended

DNA molecules can be tens of thousands of base pairs in length. Mistakes in DNA replication lead to mutations, which may or may not be harmful to an organism. How does semi-conservative replication help prevent mutations during DNA replication?

Draw

The proportions of the bases are consistent within a species; however they do vary between species. Using the base-pair rules, complete the following table to show the percentage of each type of base in the five different organisms.

Multiple Choice

According to Model 3, what term refers to loose DNA inside of a nucleus?

• nucleolus
• centromere

• chromosome
• chromatin

Multiple Choice

During what part of the cell cycle is the DNA in a cell’s nucleus replicated?

• G1

• S

• G2

• M

Multiple Choice

During what part of the cell cycle is the DNA in a cell condensed into chromosomes?

• G1

• S

• G2

• M

Draw

Replicated chromosomes are often illustrated as an X shape to match how they look in real life just before cell division.

Draw a circle around the diagram that correctly shows an original set of homologous chromosomes (grey) and their sister chromatids (black).

Open Ended

What structure holds the two sister chromatids together as they prepare for cell division?