• Prokaryotic • have simpler structures compared to eukaryotic organisms. • may be classified into three basic shapes: - coccus (pl. cocci) - bacillus (pl. bacilli) - spiral shaped or curved

SHAPES • spherical or round shaped organisms (e.g., Staphylococcus,Streptococcus)

SHAPES • Rod shaped organisms • e.g., Escherichia coli, Salmonella • Some may be very short, resembling elongated cocci called coccobacilli (e.g., Haemophilus influenzae)

SHAPES may show variations in their morphology

envelope serves to protect the bacteria from harsh environmental conditions.

• outermost covering of some bacteria • It is a gelatinous substance that is located external to the cell wall • composed of polysaccharide or polypeptide, or both.

GLYCOCALYX if it is strongly attached to the cell wall

GLYCOCALYX if it is loosely attached

• sometimes called the murein sacculus • Its principal component is PEPTIDOGLYCAN • It is MULTI LAYERED in GRAM POSITIVE bacteria • SINGLE LAYERED in GRAM NEGATIVE bacteria Functions: • provides rigid support • gives shape to the bacteria • It protects the bacteria from osmotic damage • plays an important role in cell division

Special components of gram positive cell wall • comprise major surface antigens of gram positive organisms • can elicit antibody response Functions: • for the attachment of the organism to the host cell (In some gram positive organisms such as Staphylococcus aureus) • provide tensile strength to gram positive bacterial cell walls.

Special components of gram positive cell wall • include neutral sugars • mannose, arabinose, rhamnose,and glucosamine • It also includes some acidic sugars • glucuronic acid • mannuronic acid

Special components of gram negative cell walls • BI LAYERED structure where the inner leaflet is composed of a LIPOPOLYSACCHARIDES (LPS). • It has special protein channels • allow the PASSAGE of small or low molecular weight hydrophilic substances • such as sugars and amino acids. • LPS has a complex glycolipid called LIPID A • responsible for its endotoxin activity • It is located in the outer leaflet of the outer membrane. • The inner core is a polysaccharide made up of REPEAT UNITS. • This repeat unit is also called the O ANTIGEN • which is unique for every species of bacteria

Special components of gram negative cell walls • to anchor the outer membrane to the peptidoglycan layer • stabilizes the outer membrane

Special components of gram negative cell walls • a fluid filled space between the outer membrane and the inner plasma membrane. Contains: • enzymes for the breakdown of large non transportable molecules into transportable ones • enzymes that serve to detoxify and inactivate antibiotics

Special components of gram negative cell walls • acid fast organisms - Mycobacterium tuberculosis • possess an outer layer that is LIPID RICH • cell wall is composed of large amounts of waxes that are known as MYCOLIC ACID • inner layer of the cell wall • is also made up of peptidoglycan but because the outermost layer is lipid rich, cell walls of acid fast organisms are HYDROPHOBIC. • reason why they CANNOT BE STAINED using the reagents used in gram staining. • The hydrophobic nature of their cell wall protects them from harsh chemicals • such as strong acids and detergents.

PROJECTING STRUCTURES • thread like structures • made up entirely of molecules of the protein sub unit flagellin. • They project from the capsule • organs for motility

4 TYPES OF FLAGELLA - single polar flagellum

4 TYPES OF FLAGELLA - A tuft of flagella at one end of the bacterium

4 TYPES OF FLAGELLA flagella at both ends of the bacterium

4 TYPES OF FLAGELLA flagella all around the bacterium

PROJECTING STRUCTURES • rigid surface appendages found on many gram negative bacterial • fine and short in comparison with flagella • Their structural protein sub units are called pilins FUNCTIONS: • may also function for motility • for adherence to cell surface (common pili) • attachment to another bacterium during a form of bacterial gene exchange called conjugation (sex pili)

PROJECTING STRUCTURES • are also called endoflagella • found in spirochetes(e.g., Treponema pallidum causing syphilis) • composed of bundles of fibrils, the structures of which are similar to flagella. • They arise from the ends of the bacterial cell and spiral around the cell. • The filaments rotate producing movement of the outer sheath of the spirochetes propelling them forward

PROJECTING STRUCTURES • Located beneath the cell wall • sometimes called the cell sac • because it encloses the cytoplasm of the cell. • is a selectively permeable membrane • allows for transport of selected solutes. • In aerobic organisms • the site of the electron transport chain • serves as the site of ATP production. • It therefore serves the function of the mitochondria, which are not found in prokaryotic cells. • contains the enzymes needed for the biosynthesis of DNA, cell wall components, and membrane lipids

INTERNAL STRUCTURE • Bacteria have no true nucleus that is surrounded by a nuclear membrane • Bacteria possess a single, circular, double stranded DNA

INTERNAL STRUCTURE • functions for cell division • It is also involved in the secretion of substances Produced by bacteria

INTERNAL STRUCTURE • function for protein synthesis. • Unlike eukaryotic ribosomes, bacterial ribosome is smaller (70S).

INTERNAL STRUCTURE • found in certain bacteria • serve for storage of food and energy (e.g., metachromatic granules of Corynebacterium diphtheriae or Much granules of Mycobacterium tuberculosis)

INTERNAL STRUCTURE • structures produced by many bacteria when they are placed in a hostile environment • composed of dipicolinic acid • confers resistance to heat, drying, chemical agents, and radiation • making it very difficult to destroy • The process of spore production is called sporulation • occurs when the environmental conditions are detrimental to the bacteria • When environmental conditions become favorable ▪It revert to their vegetative state through a process called GERMINATION • Some gram positive, but never gram negative, bacteria form