Ch 13 & 16. Bacterial Genome and Genetic Variation

Central Dogma

Process of DNA to RNA to protein synthesis.

DNA Replication

Copying DNA using DNA polymerase enzyme.

Transcription

Process of synthesizing RNA from DNA template.

Translation

Synthesis of proteins from mRNA by ribosomes.

Transformation Test

Griffith's experiment showing genetic material transfer.

Avery-MacLeod-McCarty Experiment

Showed DNA is the transforming principle.

Hershey-Chase Experiment

Demonstrated DNA as genetic material using bacteriophages.

Bacteriophage T2

Virus used to study DNA and protein roles.

Nucleic acids

Polymers of nucleotides linked by phosphodiester bonds.

Nucleotides

Building blocks of nucleic acids, containing a base.

Nitrogenous bases

Components of nucleotides; include purines and pyrimidines.

Nucleoside

Base plus sugar, without phosphate group.

Nucleotide

Nucleoside with one or more phosphate groups.

Purines

Two-ring nitrogenous bases: adenine and guanine.

Pyrimidines

Single-ring nitrogenous bases: cytosine, uracil, thymine.

RNA

Single-stranded nucleic acid with ribose sugar.

DNA

Double-stranded nucleic acid with deoxyribose sugar.

Base pairing

Specific pairing of nitrogenous bases: A-T, G-C.

Hydrogen bonds

Weak bonds holding base pairs together in DNA.

RNA types

Includes rRNA, tRNA, mRNA, and others.

Polypeptides

Chains of amino acids forming proteins.

Peptide bond

Covalent bond linking amino acids in proteins.

Amino acids

Monomers of proteins, containing amino and carboxyl groups.

Primary structure

Sequence of amino acids in a protein.

Secondary structure

Local folding patterns, like alpha helices and beta sheets.

Tertiary structure

Overall 3D shape of a single polypeptide.

Quaternary structure

Assembly of multiple polypeptide chains in a protein.

Bacterial DNA replication

Circular DNA replication, bidirectional from oriC.

Codon

Three-nucleotide sequence on mRNA specifying an amino acid.

Start codon

AUG; signals the beginning of translation.

Stop codons

UAA, UAG, UGA; signal termination of translation.

Genetic code

Rules for translating mRNA codons into amino acids.

Molecular chaperones

Proteins assisting in the proper folding of other proteins.

Protein secretion

Movement of proteins from the cytoplasm to the outside.

Twin Arginine Translocation

System for moving folded proteins across membranes.

Type III secretion system

Injects proteins into host cells, aiding bacterial virulence.

Type IV Secretion System

Translocates proteins, mediates DNA transfer.

EHEC

Enterohemorrhagic Escherichia coli, causes severe diarrhea.

Pseudomonas aeruginosa

Opportunistic pathogen, resistant to many antibiotics.

Vibrio parahaemolyticus

Marine bacterium, causes gastroenteritis.

Mutations

Stable changes in DNA base sequences.

Point mutations

Alterations in a single DNA base.

Larger mutations

Include insertions, deletions, inversions, duplications.

Spontaneous Mutations

Errors during DNA replication, random changes.

Induced Mutations

Caused by external agents damaging DNA.

Ames Test

Assesses mutagenicity using bacteria and His media.

Auxotroph

Mutant requiring additional nutrients for growth.

Forward mutation

Changes in DNA leading to altered phenotype.

Reversion mutation

Restores original phenotype from mutant form.

SOS Response

Inducible repair system activated by DNA damage.

Horizontal Gene Transfer

Transfer of genes between organisms, not by reproduction.

Bacterial transformation

Uptake of free DNA by competent bacteria.

Bacterial transduction

Gene transfer via bacteriophages, general or specialized.

Bacterial conjugation

Direct transfer of DNA between bacteria via contact.

Bacterial Plasmids

Small, self-replicating DNA molecules in bacteria.

Hfr Conjugation

Transfer of chromosomal genes from Hfr cells.

Drug Resistance Genes

Genes conferring resistance to antibiotics, found on plasmids.

DNA Repair Mechanisms

Processes maintaining genome stability, including proofreading.