Chapter 13: The Molecular Basis of Inheritance Flashcards
What does the term “transformation” refer to?
A change in genotype and phenotype due to the assimilation of external DNA by a cell.
What is the term that refers to viruses that infect bacteria?
Bacteriophages
How is a “virus” defined?
Little more than DNA (or sometimes RNA) enclosed by a protective coat, which is often simply protein.
DNA is composed of three components. What are they?
A nitrogenous (nitrogen-containing) base, a pentose sugar called deoxyribose, and a phosphate group.
The nitrogenous bases can be made of four different nucleotides. What are these 4?
Adenine, Thymine, Cytosine, and Guanine.
Chargaff analyzed the base composition of DNA from different organisms. What did he discover?
The base composition of DNA varies from one species to another.
What are Chargaff’s two rules?
1) the base composition varies between species
2) within a species, the number of A and T bases are roughly equal and the number of G and C bases are roughly equal.
What term can define how the two sugar-phosphate backbones run in opposite directions?
Antiparallel
Which two nitrogenous bases are purines?
Adenine and Thymine
Which two nitrogenous bases are pyrimidine?
Cytosine and Guanine
The pairs of nitrogenous bases in a DNA double helix are held together by…
hydrogen bonds.
When the two DNA strands are separated, each parental strand acts as a…
template for a new complementary strand
Define a Conservative Model of DNA.
The two parental strands reassociate after acting as templates for new strands, thus restoring the parental double helix.
Define a Semiconservative Model of DNA.
The two strands of the parental molecule separate, and each functions as a template for synthesis of a new, complementary strand.
Define a Dispersive Model of DNA.
Each strand of BOTH daughter molecules contains a mixture of old and newly synthesized DNA.