AP Biology - DNA Replication

Double helix structure

DNA's twisted ladder shape

Directionality of DNA

DNA strands have a 5' to 3' orientation

Nucleotide

Building block of DNA

Numbering of carbons in a sugar

1' to 5'

Putting the DNA backbone together

Connecting the sugar-phosphate backbone of DNA

Anti-parallel strands

DNA strands run in opposite directions

Hydrogen bonds

Weak bonds between nitrogenous bases in DNA

Covalent phosphodiester bonds

Strong bonds between sugar and phosphate groups in DNA

Base pairing in DNA

Specific pairing of nitrogenous bases in DNA

Purines

Adenine (A) and Guanine (G) nitrogenous bases

Pyrimidines

Thymine (T) and Cytosine (C) nitrogenous bases

Replication of DNA

making a copy of a DNA molecule.

Unwind DNA

Separating the two strands of DNA

Helicase enzyme

Enzyme that unwinds DNA helix

Single-stranded binding proteins

Proteins that stabilize unwound DNA strands

Polymerase III

Enzyme that adds new bases to a DNA strand

Energy of Replication

DNA bases arrive as nucleosides. The extra phosphate groups split off to provide the energy for the endergonic synthesis of DNA.

Lagging strand

The DNA strand synthesized in short fragments

Okazaki fragments

Short DNA fragments on the lagging strand

Leading strand

The DNA strand synthesized continuously

Replication fork

The point where DNA strands separate

RNA primers

Short RNA sequences that initiate DNA synthesis

DNA polymerase I

Enzyme that removes RNA primers and replaces them with DNA

Chromosome erosion

Loss of bases at the ends of chromosomes

Telomeres

Repeating sequences at the ends of chromosomes

Telomerase

Enzyme that extends telomeres