Biochemistry of the Genome Flashcards

A set of vocabulary flashcards covering the discovery of DNA as genetic material, the structure and function of DNA and RNA, gene expression, and chromosomal organization based on Chapter 10 lecture notes.

Blending Theory of Inheritance

The belief that the process of inheritance involved a blending of parental traits that produced an intermediate physical appearance of the offspring, where original parental traits were lost or absorbed.

Gregor Mendel

Researcher who crossed true-breeding violet and white flower plants, observing that the $F1$ generation all had violet flowers and the $F2$ generation had a ratio of approximately three-quarters violet to one-quarter white flowers.

Chromosomal Theory of Inheritance

Proposed in the late 1800's after biologists visualized chromosomes replicating and condensing into distinct X-shaped bodies during meiosis.

Acetabularia

A single-celled alga measuring $2-6\,cm$ with a cap, stalk, and nucleus-containing foot, used by Hämmerling to conclude that genetic information for regeneration is found in the nucleus.

Beadle and Tatum

Researchers who used irradiated and nonirradiated mold spores to propose the one gene–one enzyme hypothesis based on arginine biosynthesis mutants.

One gene–one enzyme hypothesis

The conclusion that each mutant was defective in a different gene encoding a different enzyme in a specific metabolic pathway.

S. pneumoniae

A bacterium used by Griffith to show that a transforming principle could pass from a heat-killed pathogenic S strain to a live nonpathogenic R strain.

Oswald Avery, Colin MacLeod, and Maclyn McCarty

The research team that experimentally determined the transforming principle identified by Griffith was DNA.

Martha Chase and Alfred Hershey

Researchers who separately labeled DNA and proteins of the T2 bacteriophage to confirm that DNA is the genetic material responsible for phage production.

Nucleotides

The monomers of nucleic acids, each composed of a sugar called deoxyribose, a phosphate group, and a nitrogenous base.

Purines

A category of nitrogenous bases in DNA that possess two rings, consisting of adenine and guanine.

Pyrimidines

A category of nitrogenous bases in DNA that possess a single ring, consisting of cytosine and thymine; thymine is unique to DNA.

Phosphodiester bonds

Bonds that form between the phosphate group at the $5'$ carbon of one nucleotide and the hydroxyl group of the $3'$ carbon of the next nucleotide.

James Watson and Francis Crick

The scientists who, in $1953$, proposed the double helix model for the structure of DNA.

Antiparallel

The orientation of the two DNA strands where the direction of one strand is opposite to the other, defined by the numbering of the carbons ($1$ through $5$) in the sugar molecules.

Complementary nitrogenous bases

Bases on the interior of DNA that form hydrogen bonds to hold the two strands together.

Denaturization

The process where the DNA double helix is separated into single-stranded DNA through exposure to heat or chemicals.

Renaturation

The process where single-stranded DNA is allowed to reanneal through cooling or the removal of chemical denaturants.

mRNA

Short, unstable, single-stranded RNA that serves as an intermediary between DNA and protein synthesis.

rRNA

Stable RNA molecules composing $60\%$ of a ribosome's mass that ensure proper alignment and catalyze peptide bond formation.

tRNA

Short ($70-90$ nucleotides) stable RNA that carries the correct amino acid to the site of protein synthesis.

Genotype

The full collection of genes held within a cell, which remains constant.

Phenotype

The set of genes being expressed at any given point in time, which determines a cell's activities and observable characteristics and may change in response to environmental signals.

Constitutive Genes

Genes that are always expressed, often referred to as housekeeping genes necessary for basic cellular functions.

DNA supercoiling

The process by which DNA is twisted to fit inside the cell, often involving proteins like topoisomerases.

Chromatin

The combination of DNA and its attached proteins, such as histones.

Gyrase

A specific topoisomerase found in bacteria and archaea that helps prevent the overwinding of DNA during replication.

Noncoding DNA

DNA that does not code for proteins, representing up to $98\%$ of the eukaryotic genome but only about $12\%$ of the prokaryotic genome.