3 Flashcards
(25 cards)
Microbial genetics
the study of inheritance and the variability of the characteristics of microorganisms
Information is stored in
chromosomes & plasmids
Phenotype
And genotype
P-the observable structural traits produced by the interaction of genes & environment
G-genetic “make-up” of the organism
Intergrons
Pieces of DNA that accumulate new genes
–They are specialized elements for the expression of antibiotic resistance genes.
Gene
The unit of genetic information or hereditary material contained in DNA molecule
Most genes have their protein-coding information interrupted by non-coding sequences called “…….”. The coding sequences are then called “……..”.
Introns and exons
Replication –
Transcription-
Translation –
Replication – new copy of DNA being made
Transcription-This is the process of making a copy of gene DNA to mRNA
Translation – mRNA read and protein produced
Transcription characteristics
The enzyme responsible for this process is RNA polymerase
Copies the gene is a 5‘→ 3’ direction
Gene transcription begins at a site called the Promoter & ends at another site called the Terminator.
Gene expression
The process by which a gene’s information is converted into the structures & functions of a cell by a process of producing a biologically functional molecule of either protein or RNA is made.
Gene expression is controlled …………. and …………….at various points in the sequence leading to protein synthesis.
by repressor or activator protein
Bacterial Chromosome
•Usually circular, super coiled, double stranded DNA molecule attached to cell membrane.
•Located/condensed into the nucleoid.
•No nuclear membrane.
•Replicate semi-conservatively – one DNA strand acts as template for the synthesis of the other; bi-directional
•Replication starts from a specific site – Origin of replication (Ori-C)
•The genome is haploid (only 1 chromosome per cell)
•Chromosome size differ between species
…… control the properties of organisms.
Genes
Plasmids are
Are extrachromosomal DNA elements capable of autonomous replication.
Characteristics of plasmid
Smaller but similar to chromosome
Circular except in B. burgdorferi which is linear
Inherited by daughter cells
Plasmid are commonly found in
Gram negative bacteria
Episome
a plasmid capable of integrating with the bacterial chromosome.
Plasmids can be removed from the host cell in the process called
Curing
Plasmids phenotypic characteristics
1.They are responsible for virulence (e.g. E. coli)
2.Antibiotic resistance
3.Production of antimicrobials (antibiotic, bacteriocins)
4.Metabolic pathway: Pseudomonas spp - catabolic activity for salicylic acid
5.They are specific to 1 or a few particular bacteria
Types plasmid based on function
Fertility plasmid (F factor)
Types of plasmid based on transfer properties
Additional
Transposons (Tn)
are sequences (segments) of DNA that can move around to different positions (b/n chromosome & plasmids) within the genome of a single cell
Transposons also called
Jumping genes
Disinfection and disinfectant
The destruction of pathogenic
Usually involves the removal of vegetative or non-endospore forming pathogens
Corrosive chemicals that are destructive to skin and mucous membrane
They are used where sterilization is not practicable
