Nucleic Acids & DNA Polymerase

Nucleotide

Phosphate + sugar + nitrogenous base.

DNA nucleotide sugar

Deoxyribose.

RNA nucleotide sugar

Ribose.

DNA bases

A, T, G, C.

RNA uses what instead of thymine?

Uracil.

Phosphodiester bond

Covalent bond connecting nucleotides within one strand.

What holds complementary DNA bases together?

Hydrogen bonds.

DNA base pairing

A-T and G-C.

Antiparallel DNA strands

Two strands run in opposite 5′→3′ directions.

What is at a DNA strand's 3′ end?

A free 3′ OH.

DNA polymerase requires what three things?

Template, pre-existing 3′-OH, and dNTPs.

Can DNA polymerase start a strand from nothing?

No.

Where does DNA polymerase add a nucleotide?

To the existing 3′ OH.

Direction of DNA synthesis

5′ → 3′.

Why is DNA synthesized 5′→3′?

Polymerase adds nucleotides only to the 3′ end.

What is DNA's usual higher-order structure in this course?

Secondary double-helical structure.

Can RNA form tertiary structures?

Yes.

Can RNA form quaternary structures?

Yes.

Does DNA generally form tertiary structure in this course?

Generally no.

DNA polymerase proofreading

Correction of some errors during DNA synthesis.

Mismatch repair

Correction of replication errors remaining after replication.