DNA Structure and Replication

DNA Structure and Replication

Multiple Choice

DNA stands for:

• deoxyribonucleic acid

• dinitrogen acid

• double nucleic acid

• do not answer

Multiple Choice

Which of the following is not a DNA base?

• adenine (A)

• guanine (G)

• cytosine (C)

• histidine (H)

Multiple Choice

Nucleotides consist of all of the following except:

• a phosphate

• a sugar

• a base

• a nucleic acid

Multiple Choice

DNA is located in the _____ in eukaryotic cells.

• nucleus

• cytoplasm

• mitochondria

• ribosome

Multiple Choice

What is the backbone of DNA made of?

• sugar and phosphate

• nitrogen bases

• sugar and nitrogen bases

• phosphate and nitrogen bases

Multiple Choice

The shape of DNA is arranged as:

• a double helix

• one strand of nucleotides

• squiggly lines

• a single nucleotide

Multiple Choice

What are the correct base pair rules in DNA?

• A-T and C-G

• A-C and T-G

• A-G and C-T

• A-A, C-C, G-G, and T-T

Multiple Choice

What is the complementary strand to this DNA sequence: ATACCGCTG

• TATGGCGAC

• ATACCGCTG

• CGCAATAGT

• GCGTTATCA

Multiple Choice

What are the complementary bases that would pair with this DNA strand: CTAATGT

• GATTACA

• AGCCGTG

• CTAATGT

• TCGGCAC

1. DNA Helicase

Color Red

Function: Unzips the DNA for replication to begin.
Action: As the two strands of DNA part, they form a Y shaped structure called the replication fork. Two opposite forks extend away from a replication origin to create a replication bubble.
Type of molecule: Enzyme (-ase)

2. Topoisomerase

Color Yellow

Function: relieves tension
Action: Works ahead of helicase and cuts the sugar phosphate backbones of one or both DNA strands (by cutting the phosphodiester bonds) so that the double stranded DNA can untwist and relieve the tension.
Type of molecule: Enzyme (-ase)

3. SSBPs (Single Stranded Binding Proteins)

Color Purple

Function: Keeps the DNA strands from rejoining
Action: Bind to the single strands near the fork and prevent them from rejoining.





Type of molecule: Protein

4. RNA Primase

Color Blue

Function: Provides a jumping off point for DNA Polymerase III to build from
Action: Builds a small section of RNA called a primer on template strands



Type of molecule: Enzyme (-ase)

5. DNA Polymerase III

Color Green

Function: Primers
Action: Adds nucleotides starting at the end of RNA primers. Leading strand and lagging strand.





Type of molecule: Enzyme (-ase)

6. Nucleoside Triphosphates

Color Orange

Function: Stores Energy
Action: These are much like the typical DNA nucleotides, except that instead

of having one phosphate, they have three phosphates.



Type of molecule: triphosphate

7. Leading Strand

This is the newly synthesized DNA strand that is built in the same direction as the replication fork.

It is built continuously in one long segment and requires only one primer, (as well as one DNA Pol III, one DNA Pol I and one DNA ligase.)

8. Lagging Strand

This is the newly synthesized DNA strand that is built in the opposite direction as that of the replication fork.
It is built using short fragments of DNA called Okazaki fragments(discovered by husband and wife team – Reiji and Tsuneko Okazaki)

The lagging strand is built discontinuously, in fragments, away from the direction of the replication fork.

9. DNA Polymerase I

Color Black

Function: Once the RNA primers have done their job, they need to be replaced by the appropriate DNA nucleotides so that the newly synthesized DNA strands don’t have any RNA nucleotides in them.
Action: comes in and removes every RNA nucleotide in each

primer and replaces them with the appropriate DNA nucleotides.

Type of molecule:Enzye (-ase)

10. DNA Ligase

Color Brown

Function: attach together the Okazaki fragments.
Action: joins unattached sections of DNA by forming

phosphodiester bonds between them.





Type of molecule:

11. Exonucleases

Function: Repair
Action: functions that allow them to remove mismatched DNA nucleotides and replace them with the correct ones.





Type of molecule: