Study Guide 5

Front 1

Describe the alpha helical structure of DNA. What are the three major components of
the DNA molecule?

Back 1

The sugar-phosphate backbones of each strand coil are located around the outside of the helix. Nitrogenous bases point toward center of helix. Hydrogen bonds between complementary bases hold the two strands together. (A (purine) with T (pyrimidine) makes two hydrogen bonds while G (purine) with C (pyrimidine) makes three hydrogen bonds)

Front 2

What are the four major structural features of DNA?

Back 2

1. DNA molecule itself is a double-stranded helix 2. Diameter is uniform 3. Twist is right-handed 4. Two strands run antiparallel

Front 3

The two strands of a DNA molecule are anti-parallel. What does that mean?

Back 3

They run in different directions

Front 4

What is the difference between the 3’ and 5’ end of a DNA molecule?

Back 4

3' contains the hydroxyl group end while 5' contains the phosphate group end

Front 5

What is Chargaff’s rule?

Back 5

A=T and G=C

Front 6

What is the difference between conservative, semi-conservative and dispersive
replication of DNA?

Back 6

a. Conservative: replication builds an entirely new double helix based on template of old helix
b. Semi-conservative: replication would use each parent strand as a template for a new strand
c. Dispersive: replication would use fragments of the original DNA molecule as templates for assembling two molecules

Front 7

What is a replication fork? What is the role of DNA polymerase?

Back 7

When DNA replicates in both directions from the origin, it forms 2 replication forks. They are DNA helicase (cases of proteins) that unwind the double helix, while DNA polymerase elongates both strands and catalyses the transcription of DNA.

Front 8

In what direction is DNA read?

Back 8

3'-5'

Front 9

In what direction is DNA written?

Back 9

5' to 3'

Front 10

Where does protein synthesis occur?

Back 10

In G1 or G2

Front 11

In what direction is mRNA read?

Back 11

5' to 3'