BACTE LEC (BACTERIAL GENETICS AND PATHOGENECITY)

genetics

• study of genes, genetic variations, and heredity in organisms

heredity (inheritance)

• passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction

genotype

• the genetic information

phenotype

• the observable traits

chromosome

• package of DNA with part or all of the genetic material of an organism

DNA (Deoxyribonucleic acid)

• the molecule that carries genetic information for the development and functioning of an organism

nucleotide

• the basic building block of the nucleic acids DNA and RNA

• made up of nitrogenous base, sugar molecule, po4 group

genes

• basic unit of hereditary

• sequence of nucleotides in DNA that is transcribed to produce a functional RNA

bacterial chromosome

• haploid genome, single set of chromosomes

• single, circular double stranded DNA (ssDNA)

• carry the genetic information needed for reproduction

plasmids

• extrachromosomal, self-replicating gene elements

• smaller than bacterial chromosomes

• non essential

• controls: antibiotic R, production of toxins, synthesis of bacterial virulence factors

bacteriophage

• also known as phage

• viruses that infect and replicate only in bacterial cells

• consists principally of proteins plus nucleic acid (DNA or RNA, but not both)

• consist of double stranded dna, single stranded dna, or rna

• encode functions required for replication in bacteria

• enhance bacterial pathogenicity by: transferring genes encoding toxins, duplicating the virulence factors, changing the regulatory sequences controlling bacterial virulence genes

transformation

• direct uptake, incorporation and expression of exogenous genetic material from its surrounding

• process of horizontal gene transfer by which some bacteria take up foreign genetic material from the environment

transduction

• process by which a virus genetic material from one bacterium to another

• bacteriophage

conjugation

• the transfer of genetic material between bacterial cells by direct cell-to-cell contact by a bridge-like connection between two cells

• takes place through pilus

• parasexual mode of reproduction in bacteria

bacterial mutation

• change in the nucleotide sequence and can create new cellular functionalities or lead to the dysfunction of others

• occur spontaneously or by exposure to mutation-inducing agents

• result from errors during DNA replication

silent mutation

• the mutation changes the original codon into another codon that codes for the same amino acids

missense mutation

• when a mutation in the sequence causes a codon to code for a different amino acid

nonsense mutation

• a mutant stop codon replaces a wild-type codon, terminating translation resulting in a shortened protein

mutagens

• can be physicaln chemical or biological

uv, radiation

• physical

reactive oxygen species, alkylating agents

• chemicals

transposons (bet species)

• biological

bacterial cell wall

• defines the shale of the bacteria

• some components responsible for pathogenicity: m protein and mycolic acid

• main constituent: peptidoglycan

• part of gram stain reaction

cytoplasmic membrane

• fluid phospholipid bilayer that encloses the bacterial cytoplasm

• selective permeable membrane

• site of energy production

endospores

• dormant, tough and non-reproductive structure produced by the bacteria during unfavorable conditions

• resting cell, resistant to high temperature, desiccant and chemical agents

• composed of calcium and dipicolinic acid

capsule

• increase in virulence by preventing pagocytosis

• antigenic

• demonstrating by staining method (india ink)

• form colonies which are often slimy

pili

• aka fimbriae

• proteinaceous, filamentous polymeric organelles expression on the surface bacteria

• somatic (attachment)

• sex (sexual conjugation)

• helps bacteria to adhere to host cell

flagella

• hair like appendage that protrudes from the surface of bacteria that is use for locomotion

• locomotion (25 deg celsius)

• non motile (37 deg celsius)

adherence factors

• pili

• use to adhere to host cells

antiphagocytic factors

• capsules, m chon, mycolic acid

enzymes

• coagulase

• fibrinolysin

• hyaluronidase

• IgA1 protease

toxins

• endotoxin

• exotoxin