DNA Structure
What 3 structures make up a DNA molecule?
Phosphate group, deoxyribose sugar, and nitrogenous bases.
What are the 4 nitrogenous bases?
Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).
Before a cell divides, it must first do what?
Before a cell divides, it must first replicate its DNA.
Which enzyme unwinds the DNA by breaking hydrogen bonds?
Helicase (it breaks the hydrogen bonds).
Which strand is made continuously toward the fork?
The Leading Strand.
Which 2 structures make up the DNA "backbone"?
The phosphate group and the deoxyribose sugar.
What are the base-pairing rules for DNA?
Adenine pairs with Thymine (A-T) and Cytosine pairs with Guanine (C-G).
During which specific phase of the cell cycle does replication occur?
DNA replication occurs during the S phase of the cell cycle.
Which enzyme synthesizes short RNA primers to start the process?
RNA Primase (it creates the RNA primer).
Which strand is made in short segments?
The Lagging Strand.
What is the twisted ladder shape of DNA called?
The Double Helix.
Which two nitrogenous bases are classified as purines?
Adenine (A) and Guanine (G).
What does it mean that DNA strands are "antiparallel"?
It means the two strands run in opposite directions.
Which enzyme adds new DNA nucleotides to the primer?
DNA Polymerase III.
What are the short pieces of DNA on the lagging strand called?
Okazaki fragments.
What kind of bonds form the sugar-phosphate backbone?
Covalent bonds.
Which two nitrogenous bases are classified as pyrimidines?
Cytosine (C) and Thymine (T).
The Phosphate end of a DNA strand is always which end (3' or 5')?
The 5' end.
Which enzyme replaces RNA primers with DNA nucleotides?
DNA Polymerase I.
In which direction (using 5' and 3') is the leading strand made?
The 5' to 3' direction.
What kind of bonds bind the nitrogen bases together?
Hydrogen bonds.
Adenine always pairs with Thymine. How many bonds are between them?
Hydrogen bonds (specifically 2 for A-T and 3 for C-G).
The Deoxyribose sugar is always which end (3' or 5')?
The 3' end.
Which enzyme connects Okazaki fragments using phosphodiester bonds?
Ligase (Topoisomerase also helps relieve tension).
In which direction is the lagging strand made relative to the fork?
5' to 3', but in pieces opposite to the replication fork.