Lecture 1. Basic Definitions and Nucleic Acids. Basic Definitions you should already know

Transcription

1 Lecture 1. Basic Definitions and Nucleic Acids Basic Definitions you should already know apple DNA: Deoxyribonucleic Acid apple RNA: Ribonucleic Acid apple mrna: messenger RNA: contains the genetic information(coding sequences for polypeptide) apple trna: transfer RNA: transfers amino acids during polypeptide synthesis of translating the information of mrna into polypeptide apple rrna: ribosomal RNA: plays structural and enzymatic role during translation (5S, 16S, 23S rrna) apple small RNA apple polypeptide: amino acids connected by peptide bonds all proteins are polypeptides 1

2 Basic Definitions you should already know apple genetics: study of organisms at the level of genes apple gene: region of DNA that encodes for protein, trna or mrna - gene encompasses promoter, ORF, and terminator apple ORF: Open Reading Frame: a region of the gene that contains the actual information for polypeptide (translated region) apple allele: different forms of a gene apple locus: a region in the genome of an organism Basic Definitions you should already know apple strain: a subdivision of species. All of the organisms in a strain are genetically identical to each other but not to other strains. apple mutation: change(s) in DNA sequence apple wild-type: refers to either a gene or a strain that does not have a known mutation. apple mutant: Duh! apple parent: refers to either a gene or a strain that served as the predecessor for a given mutant. apple genotype: genetic make up of an organism at the DNA level. apple phenotype: observable trait of the genotype. 2

3 Basic Definitions you should already know apple haploid vs diploid: haploid = one copy of chromosome apple merodiploid = partial diploid = diploid for only a portion of the genome apple prototroph: nutritionally non-deficient as long as basic substances (C, N, P, etc) are provided. apple auxotroph: nutritionally deficient (i.e.: aa auxotroph) apple promiscuous: refers to plasmids or enzymes that have a wide host or a substrate range. apple replication: refers to copying of DNA apple transcription: copying of DNA into RNA sequence apple translation: copying of RNA coding sequence into corresponding polypeptide Basic Definitions you should already know apple promoter: DNA sequence to which RNAP binds to start transcription apple RBS: ribosome binding site = complementary to the 3'-end of the 16S rrna to mediate binding of 30S ribosome in proper reading frame apple codon: three base (triplet) sequence of mrna that corresponds to a specific amino acid to be added to the polypeptide. apple reading frame: sequence of mrna (DNA also) that is read in triplets for translation into polypeptide apple nonsense codon: triplets for which there are no corresponding trnas - signals the end of the ORF. 3

4 Why Study Bacterial Genetics? apple Required - Hah! Not good enough of a reason. apple Haploid - only one copy of each gene (well, sort of) apple Asexual Reproduction - all progenies are clonal (well, sort of) apple Short Generation Time - less waiting to see results apple Bacterial Colonies on Agar - possible to screen a large number of cells for desired phenotype apple Easy to purify colonies - all clonal apple Easy to store apple Selections - won t go to jail for killing bacteria apple Relatively easy to manipulate - see all of the above + the rest of this semester Cellular Components 4

5 Amino Acids Nucleic Acid precursors 5

6 Sugars of Nucleic Acids Nucleic Acid Precursors Molecular Genetics of Bacteria, 2nd ed. Snyder and Champness, ASM Press 6

7 Synthesis of Nucleoside and Nucleotide Chain Elongation 7

8 Chain Elongation Molecular Genetics of Bacteria, 2nd ed. Snyder and Champness, ASM Press Hydrogen Bonding Between Bases 8

9 Antiparallel Nature of Double Helix Double Helix (Watson and Crick) 9