Chapter 3- cell structure and function

Glycocalyx functions

CAPSULE- When the bacterium is composed of organized repeating units of organic chemicals firmly attached to the cells surface the glycocalyx is called a capsule SLIME LAYER- water soluble loose glycocalyx is called a slime layer- biofilm - Provides protection from drying and being devoured it might also help attached cells to one another To the surfaces in the environment -protects cells from drying and can also play a role to help pathogens survive and cause disease - biofilm chemicals on bacterial capsules can be similar to chemicals normally found in the body preventing bodies immune system from reacting A.k.a. streptococcus pneumoniae PROTECTS FROM DESSICATION/ PHAGOCYTOSIS HELPS WITH ATTACHMENT

inclusions function

storage for nutrients, wastes, and cell products Inclusions include reserve deposits of lipids, starch, or compounds containing nitrogen, phosphate, or sulfur. Inclusions called gas vesicles store gases. No DNA in inclusion

bacterial endospores

most resistant, only extreme heat or chemical treatment destroys them bacterial endospore is a dormant structure. Endospores are unique dormant structures formed by some Gram-positive organisms, notably Clostridium and Bacillus species. Endospores should not be confused with reproductive "spores" of fungi. An endospore is formed due to environmental stress such as nutrient limitations. The 8-10 process forms a thick structure around the DNA cells and is not metabolizing. Can remain alive for decades Exist in suspended animation Live in boiling water

conjunction pili

rigid, tubular structures used by prokaryotes to pass DNA from cell to cell

Mycolic acid (waxy lipid)

A cell wall component that can prevent phagocytosis Mycobacterium species are Gram-positive organisms which contain mycolic acid (a waxy lipid) in up to 60 percent of their cell wall. These organisms with mycolic acid are considered acid fast bacteria based on their appearance following the acid fast staining technique. Mycolic acid helps cells survive desiccation and are often more resistant to chemicals and antibiotics.

phospholipid bilayer membrane

A double layer of phospholipid molecules (each molecule consisting of a phosphate group bonded to two fatty acids) that is the primary component of all cellular membranes. inside is hydrophilic outside is hydrophobic

integral membrane proteins

A protein embedded in the lipid bilayer of a cell. These are typicallly cell surface receptors, channels, or pumps. opposite of peripheral proteins that are loosely attached to the membrane on one side or other both proteins act as recognition proteins enzymes receptors carriers are channelsm

Plasmid

A small, circular section of extra DNA that confers one or more traits to a bacterium and can be reproduced separately from the main bacterial genetic code.

archea flagella differ from bacteria flagella

Archaeal flagella are 10-14 nm in diameter, which is about half the thickness of bacterial flagella. Archaeal flagella lack a central channel; therefore, they grow with the addition of subunits at the base of the filament rather than at the tip. The proteins making up archaeal flagella share common amino acid sequences across archaeal species. These are very different from the amino acid sequences common to bacterial flagella. Sugar molecules are attached to the filaments of many archaeal flagella, a condition that is rare in bacteria. Archaeal flagella are powered with energy stored in molecules of ATP, whereas the flow of hydrogen ions across the membrane powers bacterial flagella. Archaeal flagella rotate together as a bundle both when they rotate clockwise and when they rotate counterclockwise. In contrast, bacterial flagella operate independently when rotating clockwise.

archea vs bacteria

Archaeal ribosomal proteins dffer from those in the ribosomes of bacteria. Archaea ribosomal proteins are more similar to the ribosomal proteins of eukaryotic organisms. Scientists further distinguish archaea from bacteria in that archaea use different metabolic enzymes to make RNA and use a genetic code more similar to the code used by eukaryotes. Both archaea and bacteria have glycocalyces, which are similar to those of prokaryotes. Furthermore bacteria and archaea are similar in size and shape of their DNA.

peptidoglycan

Cell wall of prokaryotes, but NOT ARCHAEA. Made of a sugar polymer and polypeptide. Peptidoglycan of the bacterial cell wall is found in varying amounts in both Gram-positive and Gram-negative cells. Bacterial cell walls are composed of peptidoglycan, a complex polysaccharide. Peptidoglycan in turn is composed of two types of regularly alternating sugar molecules, called N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM), which are structurally similar to glucose. Millions of NAG and NAM molecules are covalently linked in chains in which NAG and NAM alternate. These chains are the "glycan" portions of peptidoglycan. Gram-positive bacterial cell walls have a relatively thick layer of peptidoglycan. Gram-negative cell walls have only a thin layer of peptidoglycan.

Cilia

Cilia are not found in prokaryotic cells. Prokaryotes use structures such as the flagella for motility. Cilia are shorter and more abundant than flagella and are used for motility in eukaryotes.

gram positive and gram negative toxicity

Gram-positive bacterial cell walls also contain unique chemicals called teichoic acids. Some teichoic acids are covalently linked to lipids, forming lipoteichoic acids that anchor the peptidoglycan to the cytoplasmic membrane. Gram-negative bacterial cell walls contain an outer membrane. The inner leaflet of the outer membrane is composed of phospholipids and proteins, but the outer leaflet is made of lipopolysaccharide (LPS). LPS is a union of lipid with sugar. The lipid portion of LPS is known as lipid A. The erroneous idea that lipid A is inside Gram-negative cells led to the use of the term endotoxin.

Lipopolysaccharide

Lipopolysaccharide is significant because it contains Lipid A, which is an endotoxin. The Lipid A portion of lipopolysaccharide is considered an endotoxin that may trigger fever, vasodilation, inflammation, shock, and blood clotting in humans. Killing large numbers of Gram-negative organisms within a short period of time releases large amounts of Lipid A, which may threaten the person more than the live bacteria. LPS is a phospholipid layer with sugars. Many of these sugars act as antigens and allow us to differentiate strains of bacteria. Plays an important role in endotoxic shock.

Flagella

Longhollow structures, Extending beyond the surface of the cell and its glycol calyx, help propel self through the environment spirokets have axial......? The long whip like portion is called the filament- flagella proteins can help identify many bacteria because of how specific they are filament inserts into a hook connects filament to basal body basal body Is made up of rod two rings (gram-negative cell)or 4 rings (gram- positive cell) rotates 360° attached to plasma membrane

Glycocalyx structure

Some cells have a gelatinous, sticky substance that surrounds the outside of the cell. This substance is known as a glycocalyx (plural: glycocalyces), which literally means "sweet cup." The glycocalyx may be composed of polysaccharides, polypeptides, or both.

cell membrane

The cell membrane is selectively permable meaning that it allows certain substances across while preventing others from entering the cell. Membranes allow the cell to concentrate chemicals on one side of the membrane or the other. In the case of the electron transport system, hydrogen ions are concentrated outside of the cell membrane; when they flow into the cell through a special enzyme, ATP is generated.

Cell wall function and structure

The walls of algae are composed of a variety of polysaccharides or other chemicals, depending on the type of alga. These chemicals include cellulose, proteins, agar, carrageenan, silicates, algin, calcium carbonate, or a combination of these substances. Fungal cell walls are composed of chitin or other polysaccharides. Plant cell walls are composed of cellulose. Algal cell walls contain agar, carrageenan, algin, cellulose, or other chemicals. The cells of most prokaryotes are surrounded by a cell wall that provides structure and shape to the cell and protects it from osmotic forces. Energy generation occurs within the cytoplasm and across the cell membrane. SHAPE STRUCTURE PROTECTION FROM OSMOTIC FORCES

fluid mosaic model

a model that describes the phospholipid bilayer as fluid and proposes that integral membrane proteins float freely in the lipid bilayer