Cell Bio - DNA Structure & Replication

Semi-conservative

DNA replication occurs in this manner

Nucleotide

The building blocks of DNA; made up of the deoxyribose sugar, phosphate group, and nitrogen-containing base.

Guanine

What Adenine's shape most resembles

Chargaff's base-pairing rules and what that means in terms of concentration within a DNA molecule.

The base-pairing rules follow that adenine pairs with thymine and cytosine pairs with guanine. In a specific DNA strand, the concentrations of adenine and thymine were always about the same and the concentrations of cytosine and guanine were also always about the same. He concluded that since adenine and thymine concentrations were the same that they must, in fact, pair up. The same is true for cytosine and guanine. The concentrations of all four bases should be at 100%, with adenine and thymine having equal concentrations and cytosine and guanine having equal concentrations.

Interphase

A period between two mitotic or meiotic divisions during which the cell grows, copies its DNA, and synthesizes proteins

What the structure of DNA, called a double helix, resembles

A spiral staircase; a twisted ladder

How and why the bases pair up they way they do

Adenine pairs up with thymine; cytosine pairs up with guanine. Adenine and guanine have a two-ring structure. Cytosine and thymine have a one-ring structure. Adenine pairs with thymine and cytosine pairs with guanine so that the distance between the two chains is kept constant. If adenine paired with guanine, there would be a four-ring distance between the two strands. If thymine paired with cytosine, then there would have a two-ring distance, therefore making the distance variable. However, when a one-ring base pairs with a two-ring base, the distance remains constant.

Thymine

DNA is made up of 4 nitrogen-containing bases: adenine, cytosine, guanine, and this

Complementary strands

In a DNA molecule, these are joined at the nucleotides by hydrogen bonds between the nitrogen-containing bases.

DNA replication

Process in which unzipped DNA strands serve as templates for complementary strands; DNA strand is copied. Occurs during interphase of the cell cycle.

Nitrogen-containing bases

What the rungs of the double helix are composed of

Double helix

What the structure of DNA is called