Lecture | Bacterial Genetics, Metabolism, & Structure Flashcards
Lacks nuclear membrane and Belongs to the prokaryotes
Bacteria
DNA : complexed with RNA
Prokaryotes
Prokaryotes exist as “?” Where it is highly coiled & mixed with rna, poly amines, & other proteins
Nucleoid
DNA exist as a definite structure known as the nucleus
Eukaryotes
DNA is linear
Eukaryotes
DNA is circular
Prokaryotes
DNA sequence that encodes specific product ➡️ RNA or protein
Gene
All the genes in an organism
Genome
Genome that is organized into discrete elements
Chromosome
Extensively folded and twisted to within bacterial cell. Also termed as “supercoiled”
Bacterial chromosomes
Exists as a double-stranded closed, circular macromolecule
Bacterial chromosomes
Extrachromosomal elements that replicate and encode information.
Plasmids and transposable elements
Double stranded, closed, circular autonomously replicating extrachromosomal
Plasmids
Determinant of antimicrobial resistance or unique metabolic process
Plasmids
Unable to replicate independently and do not exist as a separate entities
Jumping genes/transposons
Pieces of DNA that move from one genetic element to another, from plasmid to chromosome or vice versa
Transposable elements
Process by which transposons are REMOVE from one genomic location and INSERTED unto another location
Transposition
2 types of transposable elements
Simple transposon and composite transposon
Limited to containing the genes that encode information required for movement from one site in the genome to another
Insertion sequence
Cassettes (grouping of genes) flanked by insertion sequences
Composite transposons
Internal gene embedded in the insertion sequence encodes for an accessory function
Antimicrobial resistance
Capable of replication independently of the host chromosome
Episome
Process of making a copy of DNA
Replication
Converting the copy of DNA into mRNA
Transcription
Produce proteins, amino acids, polypeptide are produced from the copy of mRNA
Translation
Specific sequence of approximately 300 base pair is recognized by
Initiation proteins
Site of active replication
Replication fork
Replication fork extends to 2 bidirectional fork until they arrived at ?
Terminous
termination of replication occurs when the replication fork?
meet
Replication time
20 to 40 minutes
Processing of information encoded in genetic elements that result to production of biochemically functional molecules—> RNA & protein
Gene expression
Overall process of gene expression in composed of?
Transcription and translation
Input: DNA
Output: RNA (mRNA, tRNA, rRNA)
Transcription
- Sense strand
- RNA polymerase
- Polycistronic
Transcription
One of the 2 DNA strands that encodes for a functional gene
Sense strand
Enzyme central to the transcription process
RNA polymerase
mRNA molecules that result from transcription process
Polycistronic
proteins are involved in a single or closely related cellular function
Polycistronic mRNA
Cluster is under the control of a single of a single promoter sequence
Operon
Undergo structural alterations during temperature change
RNA thermosensor and riboswitches
Serves as antisense RNA and small regulatory RNA that bind to mRNA sequences to suppress and alter gene expression
RNA thermosensor and riboswitch
Input: mRNA
Output: Protein
Codon-anticodon
Translation
Involves protein synthesis
Translation
triplets of nucleotide bases
codon
each codon is specific for how many amino acid
single amino acid
Carries the 1 anticodon
tRNA
begins with the association of ribosomal subunits, mRNA, formylmethionine (f-met) tRNA , and various initiation factors
initiation
carries the initial amino acid of the protein to be synthesized
formylmethionine (f-met) tRNA
Involves tRNAs and a host of elongation factors that mediate the sequential addition of amino acids
Elongation
final step in translation, occurs when the ribosomal A site encounters a stop or nonsense codon
Termination
Posttranslational modification occurs in
golgi apparatus
A process where proteins undergo modification such as folding and enzymatic trimming
Posttranslational modification
Regulation and control of gene expression
Genetic control
Also known as genetic control
Transcriptional regulation
Involves the direct interactions with genes and their ability to be transcribed to mRNA
Genetic control
3 mechanism of Genetic Diversity
1) Mutation
2) Genetic recombination
3) Genetic exchange between bacteria
Change in organisms genotype
Mutation
Induced by mutagen (chemical/physical factors)
Mutation
Having a donor and recipient bacterial cell. There is an exchange with DNA segment of the recipient’s genome
Recombination
In genetic recombination, to create a new DNA strand the 2 bacteria must be be homologous, also called as
Homologous recombination
Organism’s ability to undergo recombination depend on the acquisition of “foreign “ DNA from donor cell
genetic exchange
3 mechanisms by which bacteria physically exchange DNA
Transformation, transduction, & conjugation
Involves recipient cell uptake of naked (free) DNA released into the environment when another bacterial cell dies and undergoes lysis
Transformation
Bacteria that are able to uptake naked DNA in surroundings; able to undergo transformation
Competent bacteria
Transformation & recombination plays a major role in the development of
Antibiotic resistance and gene dissemination
Via transformations and recombination:
Development of antibiotic resistance and dissemination of genes encode factor essential to an organism’s ability to cause
Disease
Bacteriophages
Virus capable of infecting bacteria
Process occurs between 2 LIVING cells, cell-cell contact, and requires MOBILIZATION of the donor’s chromosome
Conjugation
Sex pilus originates from the donor and establishes a conjugative bridge that serves as
Conduit for DNA transfer from donor to recipient
Plasmids and transposons may be transferred through
Conjugation
All cellular processes required for the organism’s survival and replication
Bacterial metabolism
It is essential to:
1. Understand bacterial interaction with human host cells
2. Mechanisms bacteria use to cause disease
3. Basis of diagnostic microbiology
Bacterial metabolism
Utilization of metabolic pathways
Involved in acquisition of nutrients from environment, production of precursor metabolites, and energy production
Fueling
Acquisition of Nutrients can enter the cell by what type of diffusion
Simple diffusion
Precursor metabolite are produced through 2 central pathways such as
EMP pathway and TCA cycle
EMP pathway is considered the major pathway in the conversion of
Glucose to pyruvate
Use by many members of enterobacteriaceae family that occurs under —?— environment
Anaerobic environment
Enterobacteriaceae family are fermenters or not?
Fermenters
Pathway notably use by gram-negative bacteria
Entner-Doudoroff pathway
EDP catalyzes the degration of
gluconate and glucose
In EDP, gluconate is phosphorylated, dehydrated, and converted into pyruvate leading to the production of
ethanol
aerobic process under production of metabolites
EDP
Alternative to EMP for carbohydrate metabolism
Pentose phosphate pathway
2 general mechanisms for ATP production
- Substrate-level phosphorylation
- Oxidative phosphorylation
High-energy phosphate bonds produced are donated to ADP to for ATP
Substrate-level phosphorylation
A primary intermediate that serves as the initial substrate to generate ATP
Pyruvate
Other pathways constitute to —?— which does not require oxygen and produce alcohol, acids, carbon dioxide and hydrogen
Fermentative metabolism
Involves electron transport system
Oxidative phosphorylation
Series of electron transfer from reduced carriers (NADPH2, NADH2, FADH2) to a terminal electron acceptor
Oxidative phosphorylation
Oxidative phosphorylation uses oxygen as the terminal electron acceptor
Aerobic respiration
Oxidative phosphorylation that use final electron acceptor
Anaerobic respiration
Use the precursor products in dozens of pathways to produce amino acids, fatty acids, sugars, nucelotide
Biosynthesis
A fundamental staining technique : bacterial identification schemes
Gram stains
Gram stain separates medically relevant bacteria into 2 general types
Gram+ and gram-
Counter stain in gram stain
Safranin
Gram negative bacteria gives off color
Pink to red
Gram positive bacteria gives off the color
Deep blue to purple
Bacterila identification starts with
Gram staining
All (most) cocci are positive, except
Neisseria, moraxella, veillonella
All (most) bacilli are gram negative, except
BANS CEL
Outermost structure
Cell envelope
Cell wall is composed of
Peptidoglycan
Outer membrane is a bilayered structure composed of
Lipopolysaccharide
Lipopolysaccharide gives the surface of gram-negative bacteria a?
Negative charge
Water filled structure that controls the passage of nutrients and other solute through outer membrane
Porins
Cell wall is referred to as peptidoglycan or
Murein layer
Gives bacterial shape and strength to withstand changes in environmental osmotic pressures
Cell wall
Cell wall of gram-positive bacteria contains
Teichoic acid
A layer that contains this makes cell more refractory to toxic substances
Mycolic acid
Bacteria with mycolic acid require unique staining procedures such as
Acid Fast stain
Consist of Gel-like substances that assist in capturing nutrients from the environment
Periplasmic Space/periplasm
Contains several enzymes involved in the degradation of macromolecules and detoxification of environmental solutes that enter through the outer membrane
Periplasmic space/periplasm
Vital to cellular metabolism
Cytoplasmic Membrane
Confers protection top of bacteria & allows bacteria to evade the immune system
Capsule
Facilitates and maintains bacterial colonization of biologic & inanimate surface through the formation of
Biofilms or “slime layers”
A biofilm may consist of a ? housed in a complex biochemical matrix
Monomicrobic /polymicrobic
Proteinaceous structure or hairlike
Fimbriae or pili
Serve as adhesion that helps bacteria to attach to animal host surfaces
Fimbriae or pili
1st step in establishing infection
adhesion of bacteria to animal host surfaces
The sex pilus is present only in cells that produce a protein referred to as
F factor
Responsible for bacterial motility
Flagella
Contains thousands of enzyme and is the site of protein synthesis
Cytosol
Under adverse physical and chemical conditions or when nutrients are scarce
endospore
able to form spore
sporulation
When cell transforms from an active to dormant metabolic and growing state, the cytosol will
Decrease
