Bacteria 1

How is bacteria classified?

Using microscopic, macroscopic, and biochemical characteristics

What are the staining properties used in bacterial classification?

Gram positive and negative

What are the shapes used in bacterial classification?

Cocci, bacilli, spirilla, fusiform, cluster, chains or pairs

How is bacterial respiration categorized?

Aerobic and anaerobic

What are the types of reproduction seen in bacteria?

Sporing and non-sporing

How are important subspecies groups identified in bacteria?

Based on immunological properties, biochemical characteristics, antibiotic susceptibility, phage typing, and direct genetic approach

What are serogroups and serotypes based on?

Bacterial cell wall, flagellar, and capsule antigens

What is phage typing used for in bacteria?

Identifying bacterial strains based on their susceptibility to specific bacteriophages

Give an example of how biochemistry characteristics can be used to identify different bacterial species

Certain strain of Streptococci aureus release beta-haemolysin (a toxin that causes lysis of RBCs)

What is PCR used for in bacterial classification?

to detect organism-specific sentinel (disease-causing) DNA sequence

What is the main component of the bacterial cell wall?

Peptidoglycan

What disrupts the synthesis of peptidoglycan in bacteria?

Beta-lactam and glycopeptide antibiotics

What is the function of the capsule in bacteria?

Protection against phagocytosis and determining virulence

What are the main components of Gram-positive cell walls?

Peptidoglycan layer, lipoteichoic acids (LTA)

What is the unique feature of Mycobacteria cell walls?

Outer layer contains complex lipids like mycolic acid with adjuvant activity

What are the main components of Gram-negative cell walls?

Thin peptidoglycan layer, lipopolysaccharides (LPS)

What are the properties of lipopolysaccharides (LPS) in Gram-negative bacteria?

O antigen (carbohydrate chain) and endotoxin (lipid A component)

What are flagella made of?

Flagellin protein

What is the function of pili in bacteria?

Attachment to host cell (common pili) or other bacteria (sex pili), transferring DNA material, and preventing phagocytosis

What is antigenic variation in pili?

Changes in the antigens to avoid immune recognition

How do bacteria take up nutrients?

Through small molecules across the cell wall

What can Gram-negative bacteria do with larger molecules?

Preliminary digestion in the periplasmic space.

What are the different nutritional requirements of bacteria?

Some require minimal nutrients like E. coli with glucose and inorganic salt, while others need complex media with organic compounds like Streptococci

What are the two types of bacterial respiration based on oxygen requirement?

Aerobic and anaerobic

What are the final products of aerobic respiration in bacteria?

38 ATP, CO2, H2O

What are the final products of anaerobic respiration in bacteria?

34 ATP, NH3, H2S, etc.

How do bacteria deal with potentially destructive reactive oxygen species?

By having oxygen detoxifying enzymes like superoxide dismutase, catalase, and peroxidase

How does the growth rate of bacteria relate to nutrient availability?

Bacterial growth and division depend largely on the availability of nutrients and genetic factors

What are the phases of the bacterial growth curve?

Lag phase, log or exponential phase, stationary phase, death phase

What are the characteristics of bacterial genomic DNA?

Circular, no introns, tightly coiled in a nucleoid, and can be extrachromosomal in plasmids

Where does bacterial DNA replication begin?

OriC: origin of replication

What enzymes are involved in unwinding and separating DNA strands during replication?

Helicases and topoisomerases like DNA gyrase

Why is accurate DNA replication important for bacteria?

DNA carries information defining cell properties and processes

What are the mechanisms that ensure accurate DNA replication?

Base selection, 3’-5’ exonuclease, mismatch repair

What is the majority of bacterial genes transcribed into?

mRNA, up to 98% in E. coli

Which ribosomal RNA species are produced from bacterial genes?

5S, 16S, 23S

What is the function of transfer RNA in bacteria?

Decoding mRNA into functional proteins

What influences the frequency of transcription initiation in bacteria?

DNA sequence of the promoter site, DNA supercoiling, presence of regulatory proteins

What is the role of the sigma factor in transcription?

It is a component of RNA polymerase important for promoter recognition

What are the two types of bacterial gene arrangements in terms of transcription?

Monocistronic and polycistronic

Why is polycistronic gene arrangement important in bacteria?

It ensures the simultaneous and correct synthesis of protein subunits for enzyme complexes or specific biological processes

How does gene expression regulation affect bacterial adaptation?

It helps bacteria adapt to changes in their environment and conserve metabolic energy

How can gene expression be altered in bacteria?

By changing the amount of mRNA transcription or the efficiency of RNA polymerase binding to the promoter site

What is positive gene regulation in bacteria?

It increases the rate of transcription by binding activator proteins to the operator site

What is negative gene regulation in bacteria?

It inhibits transcription by binding repressor proteins to the operator site

What is the role of regulons in gene regulation?

They involve the coordinated regulation of multiple genes by the same regulatory protein

How does translation occur in bacteria?

Ribosomes bind to specific mRNA sequences, start translation at the AUG codon, elongate the polypeptide chain, and terminate at the stop codon