Bacterial Genome

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- Complete set of genetic material present in a bacterium. - It is typically composed of a single, circular, double-stranded DNA molecule.

Bacterial Genome

Some bacteria may have linear genomes or additional smaller circular DNA molecules called

Plasmids

Size and Structure of Bacterial Genome: • Varies widely, ranging from about ___ million base pairs (Mb) to over 10 Mb, depending on the species.

0.5

In Genome Terminology, Mb = MEGABASE, which held __ million bases.

Bacterial Genome is composed of:

Adenine, Cytosine, Guanine, Thymine

Genomic Content:

Genes, Operons, Plasmids

Bacterial genomes contain a high density of ____ with relatively little noncoding DNA compared to eukaryotic genomes. Most of the DNA is involved in coding for proteins.

Genes

Groups of genes that are transcribed together from a single promoter and typically function in related pathways.

Operons

Small, circular DNA molecules that replicate independently. It can carry genes that confer advantages, such as antibiotic resistance.

Plasmids

Genetic Variations:

Horizontal Gene Transfer (HGT), Mutations

can occur during DNA replication, leading to genetic variation within bacterial populations.

Mutations

Spontaneous mutations can occur during ___ replication, leading to genetic variation within bacterial populations.

DNA

Bacterial genome is replicated from a single origin of replication (OriC) in a bidirectional manner, ensuring that the entire genome is duplicated before cell division.

Replication

Bacterial genome is replicated from a single ________ in a bidirectional manner, ensuring that the entire genome is duplicated before cell division.

OriC (Original Replication)

A regulation that is tightly regulated, often in response to environmental

Gene Expression

Regulation can occur at various levels, including transcriptional control via repressors and activators.

Gene Expression

The compact and efficient nature of bacterial genomes, combined with the ability to rapidly acquire new genetic material through HGT (Horizontal Gene Transfer).

Adaptability

It allows bacteria to adapt quickly to changing environments, including the development of antibiotic resistance.

Adaptability

It allows bacteria to adapt quickly to changing environments, including the development of antibiotic resistance.

Adaptability

These are DNA sequences that can move within or between genomes, playing a crucial role in bacterial evolution and adaptability.

Mobile Genetic Elements

• These are small, circular, double-stranded DNA molecules that exist independently of the bacterial chromosome. • Replicates autonomously within the bacterial cell

Plasmids

A function of plasmids that often carry genes that can be beneficial to the host bacterium, includes virulence factors, antibiotic resistance genes and metabolic enzymes.

Gene Transfer

Plasmids, that can transfer themselves from one bacterium to another through a process called

Conjugation

Types of Plasmids

F Plasmids, R Plasmids, Virulence Plasmids

Carry genes responsible for the formation of pili (structures that connect two bacteria during conjugation).

F Plasmids

Carry antibiotic resistance genes, making bacteria resistant to specific antibiotics

R Plasmids

Contain genes that increase the pathogenicity of the bacterium.

Virulence Plasmids

Also known as "jumping genes," are DNA sequences that can move from one location to another within the genome, including the chromosome, plasmids, and other genetic elements.

Transpoons

Transpoons functions:

Genetic Mobility, Horizontal Gene Transfer

Transposons can disrupt genes, alter gene expression, and promote genetic diversity.

Genetic Mobility

By moving between different genetic elements, transposons can facilitate the transfer of genes between different bacteria or between different parts of the same genome.

Horizontal Gene Transfer

Types of Transpoons

Insertion Sequences (IS elements), Composite Transposons, Complex Transposons

The simplest form of transposons, consisting only of the genes necessary for transposition (e.g., transposase enzyme).

Insertion Sequences (IS elements)

These consist of two IS elements flanking additional genes, often antibiotic resistance genes

Composite Transposons

Carry additional genes (such as antibiotic resistance genes) in addition to those required for transposition.

Complex Transposons

Small, mobile genetic elements that can carry one or more genes, usually including an antibiotic resistance gene.

Gene Cassettes

- Genetic elements that can capture gene cassettes through a site-specific recombination system. - Provides a sitespecific recombination system that allows the insertion and excision of gene cassettes.

Integrons

Gene Cassettes Functions:

Gene Capture and Expression

A change in the DNA sequence of an organism. In bacteria, it can occur naturally during DNA replication or be induced by environmental factors such as UV radiation or chemicals.

Mutation

A change in a single nucleotide base in the DNA sequence.

Point Mutation

No change in the protein product

Silent Mutation

A different amino acid is incorporated into the protein, potentially altering its function

Missense Mutation

The mutation creates a premature stop codon, leading to a truncated, usually nonfunctional protein

Nonsense Mutation

Addition or loss of nucleotide bases, which can result in a frameshift mutation, altering the reading frame of the gene and often leading to significant changes in the protein product.

Insertions and Deletions

A segment of DNA is duplicated, resulting in multiple copies of the same gene or sequence

Duplication

A segment of DNA is reversed within the chromosome.

Inversion

The process by which genetic material is exchanged between different DNA molecules, leading to the production of new combinations of genes

Genetic Recombination

Types of Mutations

Point Mutation, Silent Mutation, Missense Mutation, Nonsense Mutation

Types of Genetic Recombination

Transformation, Transduction, Conjugation

DNA is received from the environment by a bacterial cell. DNA integrates into the genome that led to genetic changes

Transformation

Transfer of bacterial DNA from one bacterium to another via a bacteriophage.

Transduction

Direct transfer of DNA from one bacterium to another through cell-to-cell contact. Usually, plasmid transfer is involved.

Conjugation

• They were first discovered in bacteria, where they serve as a defense mechanism against bacteriophages. • The bacteria produce these enzymes to recognize and cut foreign DNA at specific sites, thereby restricting the ability of the virus to replicate.

Restriction Enzymes

Encompasses all the biochemical processes that bacteria use to maintain life, grow, and reproduce

Bacterial Metabolism

The process by which bacteria acquire and convert nutrients into the basic building blocks and energy needed for cellular functions

Fueling

Bacteria obtain nutrients from their environment, which can include carbohydrates, proteins, lipids, and other organic or inorganic compounds.

Nutrient Uptake

Once inside the cell, nutrients are broken down through catabolic pathways to release energy and produce precursor metabolites. 

Catabolism

Glycolysis, Citric Acid Cycle, Fermentation, Respiration

Involves the use of energy derived from fueling processes (mainly in the form of ATP) to power various cellular activities. • ATP as Energy Currency • Reducing Power • Proton Motive Force

Energy Utilization

Refers to the anabolic pathways that convert precursor metabolites, energy (ATP), and reducing power (NADPH) into the macromolecules

Biosynthesis

The assembly of small building blocks, synthesized during biosynthesis, into larger macromolecules such as proteins, nucleic acids, and polysaccharides.

Polymerization

Protein Synthesis, DNA Replication, RNA Synthesis

SYNTHESIS OF BUILDING BLOCKS (BIOSYNTHESIS)

Amino Acids, Nucleotides, Fatty Acids and Lipids, Monosaccharides

The final stage of metabolism, where macromolecules are assembled into complex cellular structures and organelles.

Assembly

Respiration are two processes by which cells generate energy (in the form of ATP) from nutrients.

Aerobic, Anaerobic

The main difference between aerobic and anaerobic are the presence or absence of oxygen as the final electron acceptor in the electron transport chain.

True

The process by which cells convert glucose and oxygen into energy, carbon dioxide, and water.

Aerobic Respiration

The process by which cells generate energy in the absence of oxygen. Instead of oxygen, other molecules, such as nitrate, sulfate, or carbon dioxide, serve as the final electron acceptor in the electron transport chain.

Anaerobic Respiration

• With the absence of electron transport chain, some organisms proceed with _______ instead of respiration. • Pyruvate is converted into various end products such as lactic acid, ethanol, or other organic acids, regenerating NAD+ for glycolysis.

Fermentation

Refers to the metabolic pathways by which bacteria convert carbohydrates into energy and other cellular components

Carbohydrate Utilization

The specific type of carbohydrate utilization where lactose (a disaccharide composed of glucose and galactose) is fermented to produce energy.

Lactose Fermentations

A disaccharide composed of glucose and galactose

Lactose

LACTOSE UTILIZATION PATHWAY

Lactose Breakdown, Glucose Utilization, Galactose Utilization

LACTOSE FERMENTATION IN BACTERIA

Homolactic Fermentation, Heterolactic Fermentation

LACTOSE APPLICATIONS AND SIGNIFICANCE

Dairy Industry, Microbiological Testing, Lactose Intolerance

Therapeutic Index

Toxic Dose

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