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quiz on this Friday, October 23!!


substance prepared from killed or weakened pathogens and introdeced into a body to produce immiunity


referring to the deadliness of a disease-causing agent


the transfer of genetic material from one organism to another; first observed by Griffith


a virus that infects bacteria

double helix

spiral-staircase structure characteristic of the DNA molecule


subunit of nucleic acids; consisting of a nitrogenous base, a sugar, and a phosphate group


five-carbon that is a component od DNA nucleotides

base-pairing rules

the rule stating that in DNA adenine on the strand always pairs with thymine on the opposite strand and guanine on one strand always pairs with a cytosine on the opposite strand


characterisic of nucleic acids in which the sequence of bases on one strand determines the sequence of bases on the other

DNA replication

the process of making a copy of DNA

DNA helicase

enzyme that breaks the hydrogen bonds between bases during DNA replication

replication fork

a Y-shaped point that results when a double helix of DNA separates so that it can be copied

DNA polymerase

enzyme that catalyzes the replication of DNA by adding complementary nucleotides

ribonucleic acid (RNA)

a type of nucleic acid involved in protein synthesis


nitrogen-containing base of RNA, complementary to adenine when RNA base pairs with DNA


stage of protein synthesis in which the information in DNA for making a protein is transferred to an RNA molecule

gene expression

two-stage processing of information encoded in DNA to produce protein

RNA polymerase

enzyme that adds and links complementary RNA nucleotides during transcription

messenger RNA

RNA copy of a gene used as a blueprint for the making of a protein during translation


a three-nucleotide sequence in DNA or mRNA that encodes an amino acid or signifies a stop signal

genetic code

sequence of nucleotides that specifies the amino acid sequence of a protein

transfer RNA

RNA moleule that temporarily carries a specific amino acid to a ribosome during translation


a three-nucleotide sequence on tRNA that recognizes a complementary codon on mRNA

ribosomal RNA

type of RNA molecule that plays a structural role in ribosomes


region of DNA that contols RNA polymerase's acess to a set of genes with related functions


segment of DNA that controls gene regulation in a set of genes with related functions in prokaryoyes

lac operon

gene system with a promoter; an operator gene, and three structural genes that control lactose metabolism


protein that binds to the operator in an operon to switch off transcription


segment of mRNA transcribed from eukaryotic DNA but removed before translation of mRNA into a protein


sequence of nucleotides on a gene that gets transcribed and translated

point mutation

mutation in which one or just a few of nucleotides in a gene are exchanged


stage of gene expression in which the gene information in mRNA is used to make protein

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