The Molecular Basis of Inheritance Flashcards

These vocabulary flashcards cover the historical experiments and mechanical process of DNA replication and structure as presented in Chapter 16.

S strain (bacteria)

A strain of bacteria that is pathogenic and causes disease if injected into mice.

R strain (bacteria)

A non-pathogenic strain of bacteria that lacks an outer coating and does not cause disease alone.

Griffith experiment conclusion

R cells became S cells by picking up hereditary material from dead S cells, a process of transformation.

Avery experiment conclusion

Uptake of DNA, not protein, transformed the phenotype of R cells, identifying DNA as the hereditary material.

X-Ray Crystallography

A technique for finding the 3-D structure of crystallized molecules where X-rays are scattered to produce a shadow pattern; indicated DNA was a helix.

Chargaff's Base Content Rules

The percentage of $A$ equals the percentage of $T$, and the percentage of $G$ equals the percentage of $C$.

Base Pair (bp)

Two nucleotides from opposite strands H-bonded together; used as a unit of length along with kilo base pairs (kb).

Watson-Crick Base-Pairing Rules

$A$ hydrogen bonds with $T$ and $G$ hydrogen bonds with $C$; the nucleotides in a pair are complementary.

DNA Replication

The process of copying DNA during S phase where H-bonds are broken and each single strand serves as a template for a new strand.

Semi-conservative Replication

A model of replication where every DNA molecule is half old (template) and half new.

dNTPs (deoxynucleoside triphosphates)

Molecules that provide energy for replication through the hydrolysis of 2 $PO_4$ groups.

Origin of replication

The specific place in DNA where strands separate to begin the replication process.

Replication forks

The regions where DNA unwinds and synthesis of new strands occurs; two forks move in opposite directions from each origin.

Helicase

An enzyme that unwinds and separates the double helix.

Primase

An enzyme that begins synthesis by creating a short stretch of complementary RNA called a primer.

RNA primer

A short stretch of complementary RNA that provides the starting point for DNA synthesis.

DNA polymerase III

An enzyme that makes new DNA by adding nucleotides to the $3'$ end of the new strand, operating only in the $5'$ to $3'$ direction.

Leading strand

A new strand made continuously in one piece beginning at the origin, moving in the direction of the replication fork.

Lagging strand

A new strand synthesized discontinuously in sections because of the $5'$ to $3'$ activity constraints of DNA polymerase III.

DNA Pol I

An enzyme that replaces RNA primers with DNA nucleotides.

DNA ligase

An enzyme that completes gaps in the sugar-phosphate backbone by joining new DNA fragments.