Molecular Biology of the Gene Material

Phages

Viruses that exclusively infect bacteria

Griffin

Scientist who found evidence of a transforming agent by mixing disease causing and non-disease phages, making non-disease phages pathogenetic

DNA

A double-stranded helix nucleic acid with deoxyribose sugar that is the organism’s genetic material, discovered by Watson and Crick

Nucleotide

The chemical units of nucleic acids, joined by a sugar-phosphate backbone

Semiconservative model

The model tah DNA replication follows, with the two DNA strands seperating, and each strand becoming a template for assembly of a complemetary strand from a supply of free nucleotides

DNA Polymerase

Enzyme that synthesiszes one daughter strand as a continous piece

DNA ligase

Enzyme that connects short pieces of a DNA strand

Transcription

Synthesis of RNA under the direction of DNA

Translation

Synthesis of proteins under the direction of RNA

Codon

Three nucleotide code sequence that specifies the specific protein to be built

Genetic code

Set of rules that dictates the amino acid translation of each mRNA nucleotide triplets

RNA polymerase

Enzyme that joins RNA nucleotides along strand of DNA, folloing base-pairing rules

Promoter

Nucleotide sequence that acts as a binding site for RNA polymerase and determines the start of transcrition

Terminator

DNA base that signals the end of the gene

Initiation

Beginning of RNA synthesis after RNA polymerase attaches to the promoter

Elongation

Stage of RNA synthesis where newly formed RNA strand grows

Termination

End of RNA synthesis with the RNA polymerase reaches the terminator

Messenger RNA

RNA that encodes amino acid sequences, conveys genetic messges from DNA to the translation machinery of the cell

Introns

Noncoding segments of RNA

Exons

Part of a gene that is expressed

RNA splicing

Process in which intron are spliced out, exons are spliced together, and a cap and tail are added to the ends of mRNA

Transfer RNA

RNA that is a folded molecule bearing an anticodon on on end and a specific amino acid attachement on the other, aids a ribosome that is attached to the mRNA to translate its message to a specific polypeptide

Anticodon

A nucleotide sequence complementary to a codon

Ribosome

Have binding sites for tRNA and mRNA, made of ribosomal RNA and proteins

Stop codon

Codon that signals the end of translation

Mutations

Changes in genetic information of a cell or virus, caused by errors in DNA replication or recombination, or by mutagens

Mutagens

Chemical agents that can cause mutations