Biol 251 chapter 4

• No nuclear membrane or nucleoli
• No organelles
• Gycocalyx - capsule or slime layer
• Cell wall (Bacteria - peptidoglycan call walls)
• Plasma membrane - carbohydrate & lacks sterols
• Cytoplasm - no cytoplasmic streaming
• 70s ribosome
• Single, circular chromosome (DNA)
• Lacks hitones
• Binary fission
• No sexual reproduction - transfer DNA only (conjugation)

• True nuclear consisting nuclear membrane and nucleoli
• Organelles (nuclei, lysosome, Golgi, ER, mitochondria)
• Glycocalyx present in some cells that have cell wall, when present cellulose (plant), fungi (Chitin)
• Plasma membrane (Lipopolysacchride) - sterols & carbohydrates that serve as receptors
• Cytoplasm - cytoskeleton (micro filaments, intermediate filaments, micro tubules), cytoplasmic streaming
• 80s ribosome and 70s in organelles (mitochondria)
• Multiple leaner chromosome with hitones
• Mitosis
• Meiosis

• Glycocalyx (meaning sugar coat) is substance that surround cells
• Bacterial glycocalyx is viscous, gelatinous polymer that is external to the cell wall an composed of polysaccharide, polypeptide, or both
• Capsule - firmly attached to the cell wall
• Slime layer - unorganized and loosely attached to the cell wall
• Capsules are important in contributing to bacterial virulence (the degree to which a pathogen cause disease)

• Capsule often protect phagocytic bacteria from phagocytosis by the ells of the host
• Bacillus anthrasis causes antrax, it is speculated that capsule may prevent it from being destroyed by phagocytosis
• Streptococcus pneumoniae cause phenomia when only the cells are protected by a polysaccharide capsule
• Uncapsulated S. pneumoniae cells cannot cause pneumonia and readily phagocytized

• Helps cells in a biofilm attach to their target environment and to each other
• Biofilm protects the cells within it, facilitates communication among them, and enables the cells to survive by attaching to various surfaces in their natural environment. Through attachment, bacteria can grow on diverse surfaces such as rocks in fast-moving streams, plant roots, human teeth, medical implants, water pipes, and even other bacteria
• Capsule protects pathogenic bacteria from phagoytosis - evading immune system
• Extracellular polymeric substance helps form biofilm

Eukaryotic cells, including animal cells, the plasma membrane is covered by glycocalyx, a layer of material containing substantial amounts of sticky carbohydrates. Some of those carbohydrates are covalently bonded to proteins and lipids in the plasma membrane forming glycoproteins and glycolipids that anchor the glycocalyx to the cell

Glycocalyx strengthens the cell surfaces, help attache cells together, and may contribute to cell to cellreconition

Antibiotics, such as penicillin, and cephalosporins, act against peptidoglycan cell wall and therefor do not affect human eukaryotic cells

Glycocalyx is substances surround bacteria cell wall composed of polysaccharide adn polypeptide. they are sticky and gelatinous. They form biofilm to attach surface,capsule & slime layer. Gylococalyx allows microbes to adhere the surface and form complex aggregation of cell. It's difficult to destroy even with antibiotics and may be found on the surface of medical equipment within the tissue.

• Evenly distributed over the entire surface of the cell. Fimbriae have a tendency to adhere to each other and to surface
• Neisseria gonorrheae, the causative agent of gonorrhea help microbes colonize mucous membranes
• E. coli, adhere to the lining of small intestine, where it cause a severe watery diarrhea

• Usually longer than fimbriae and only one or two per cell. 
• Pili involve motility and DNA transfer by conjugation pili (sex pili)

• Coccus (spherical) - diplococci, streptococci, staphylococci, tetrads, sarcine
• Bacillus (Rod shape) - single bacillus, diplobacilli, straptobacilli, coccobacilli
• Spiral - vibrios (curved rods), sprilla (helical shape like corkscrew, fairly rigid bodies), spirochete (helical & flexible)

• Consist many layers of peptidoglycan forming a thick rigid structure
• the space between the cell wall and plasma membrane of gram-positive bacteria is the plasmic space
• Granular layer, which is composed of lipoteichoic acid
• Cell walls of gram-positive bacteria contain teichoic acid which consist primarily of an alcohol (such as glycerol or ribitol) and phosphate

• Lipoteichoic acid - spans peptidoglycan layer and linked to the plasma membrane
• Wall teichoic acid - linked to peptidoglycan layer

• Cell walls of gram-negative bacteria consist of one or a very few layers of peptidoglycan and an outer membrane
• The peptidoglycan is bound to lipoproteins in the outer membrane and is the periplasm, a gel-like fluid in the periplasmic space of gram-negative bacteria, the region between the outer membrane and the plasma membrane 
• Gram-negative bacteria contain only small amount of peptidoglycan, they are more susceptible to mechanical breakage
• Outer membrane of the gram-negative cell consist of lipoprotien, phospholipids, and lipopolysaccharides
• Part of the permeability of the outer membrane is due to proteins in the membrane, called porins that form channels.

Porins permit the passage of molecules such as nucleotides, disaccharides, peptides, amino acids, vitiamin B12, and iron

• Lipid A - when gram-negative bacteria die, they release lipid A, which functions as endotoxin Lipid A responsible for the symptoms associated with infections by gram-negative bacteria such as fever dilation of blood vessels, shock, and blood clotting
• Core polysaccharide - structural, provide stability
• O polysaccharide - functions as antigen and is useful for distinguishing species of gram-negative bacteria

Polypeptide, NAG, NAM

• Protein synthesis
• 70s
• Located in cytoplasm

• Protein synthesis
• 80s 
• Located in cytoplasm, rough ER, nuclear envelpe, mitochondria, and chloroplast
• Chloroplast and mitochondria contains 70s ribosomes which indicates their evolution form prokaryotes

10-20 ribosomes often join together in a string like arrangement

• circular, singular
• DNA present in nucleoid
• No hitone
• Plasmid

• Chromosome protein hitone
• Linear double stranded DNA - multiple within nucleus
• Also found in mitochondria and chloroplast

• When essential nutrients are depleted, certain gram-positive bacteria, such as those of the genera Clostridium and Bacillus form specialized "resting"cell called endospore
• Endospores are hightly durable dehydrated cells with thick walls and additional layers
• When released into the environment, they can survive extreme heat, lack of water, and exposure to many toxic chemicals and radiation
• When endospore matures, the vegetative cell wall ruptures (lyses), killing the cell, and the endospore is freed
• The highly dehydrated endospore core contains only DNA, small amount of RNA, ribosome, enzymes, and few important small molecules. These cellular components are essential for resuming metabolism later
• Endospore-forming bacteria are problem in the food industry because they are likely to survive under processing and if conditions for growth occur, some species produce toxins and disease
• Extreme heat and pressure can kill endospore

• The process of endospore formation within a vegetative cell takes several hours and is known as sportulation
• Sportuation in bacteria is not means of reproduction. This process does not increase the number of cells

Newly replicated bacterial chromosome and a small portion of cytoplasm are isolated by an ingrowth of the plasma membrane

• An endospore returns to its vegetative state by a process called germination. 
• Germination is triggered by high heat, such as is used in canning or small triggering molecules called germinants