Chapter 3 Flashcards
Glycocalyx
Has two layers: thin and thick.
Thin: called a slime layer
Thick: called a capsule
What is Glycocalyx?
Slimy substance that adheres to the outside of the cell wall.
Functions of glycocalyx
1) Protects the cell from dehydration when the environment dries up.
2) Allows the bacteria to attach to the tissue which then can be invaded.
3) Protection against phagocytosis by WBC, increasing the survival of the cell in the body
Cell wall
Animals do not have a cell wall or any other comparable structure. Most bacteria except one has a cell wall (mycoplasma)
Functions of a cell wall
1) rigid structure maintains cell shape
2) provides protection from the environment
3) protection from osmotic pressure
Lysosomes
Found in tears, breaks down peptidoglycan
Gram positive cell wall
Thick, homogenous sheath of peptidoglycan, 20-80nm in thickness. 90% of the cell wall
Peptidoglycan is composed of?
Alternating glycan molecules and tetra peptide chains
Glycan molecule
Simple sugar, connected to an amino acid. Two types NAG and NAM glycan molecules.. Forms a mesh like structure
Tetra peptide chain
Contains teichoic acid.. Used as a structural material
Gram negative cell wall
More complex then gram positive, contains two layers.
1) periplasmic space
2) outer membrane
Periplasmic space
A region between the cell membrane and the outer layer. Composed of a layer of peptidoglycan and periplasm. Periplasm is a gel like material. Peptidoglycan is one layer thick and is much weaker than a gram positive cell wall
Outer membrane
Consists of a bilayer structure. One layer is composed of a phospholipids and other macromolecules. The second layer serves as a selective barrier only allows certain particles through
Lipopolysaccharides (LPS)
Can be toxic to the human body, because of this Lethal affect on the body, LPS are called endotoxins.. also forms an outer sheath of membrane
What is wrong with LPS being called endotoxins?
The membrane is the outer most surface not endo or “in” like the name states
Porin proteins
Small opening, Allows specific molecules to pass and will shut off when the cell is threatened. Pretty effective on stopping meds on getting through
Mycoplasma
Lack cell walls, pump NA+ ions out of the cell to keep tugor pressure equal inside and out. Prevents lysis from happening. Cell membrane is strengthened by adding cholesterol. Usually found in eukaryotic cells
Cell membrane
Composed of a phospholipid bilayer
Integral proteins
Mainly involved in transport
Carrier proteins
Bind to specific substances and transport them across the cell membrane
Channel protein
Opening which allows small, water soluble substances to go across the membrane
Functions of a cell wall
Serves as a barrier to molecules. Selectively permeable(prevents entrance or exit of certain molecules.)
Enzymes embedded within the cell membrane helps with?
Anabolic chemical reactions and catabolic pathways such as electron transport
Flagella
Long, thin, must be seen with a light microscope, rigid hair like appendages composed of protein.
Flagella rotate
360 degree at nearly 2000rpm. This rotation causes the cell itself to slowly spin in the opposite direction this provides a way for bacteria to locomote.
Composition of flagella
Filament- tube like structure (part you see, whip like)
Hook- the filament is inserted into the hook (outside of the cell wall)
Two rings- Hook inserts here, provides the anchor for the filament and the hook has one ring is attached to the cell membrane
Monotrichous
Single flagellum at one end of the cell o~~~~~
Amphitrichous
Single flagellum at each end ~~~~o~~~~
Lophotrichous
A tuft of many flagella at one end o~~~~~~~~~~~~~~~~~~~~~~~~
Peritrichous
Flagella located on many sides of the bacterial cell
~~~~o~~~~
Flagella present in
Spirilla- always have flagella
Bacilli- 1/2 of these have flagella
Coccus- not very many of these of flagella
Fimbriae
Short but numerous tubes composed of protein. Have a tendency to stick to surfaces and to other fimbriae.
Functions of fimbriae
Adhere to epithelial cells, allowing the cells to invade the tissues
Pilus
Long, less, numerous hollow, tubular structures. Found in gram negative bacteria and some gram positive bacteria. The long pilus tube links to the cytoplasm of one bacteria with the cytoplasm of another bacteria of the same species
Pilus functions
Used to exchange small amounts of circular DNA called plasmids between cells in a process called conjugation
Bacterial chromosome
A single, double stranded, circular piece of DNA. Found in the nuclear region of a bacterial cell
Plasmids
Very small, circular pieces of DNA that are NOT essential for bacterial growth and cell maintenance. Free floating, and are not attached to the cell membrane. Can embed themselves into a bacterial chromosome
Functions of plasmids
Can provide info. that can be helpful to survival but not essential..Resistant to drugs, productions of toxins, and production of enzymes
Conjugation
Transfer plasmids to other bacterial cells to convey additional resistance
Ribosomes
Is the only true organelle found within a prokaryotic cell, used in protein synthesis
Cytoplasmic inclusions
Small, membrane bound structures that will contain various substances
Various substances for cytoplasmic inclusions
Energy- rich organic substances, that are produced in times of need and when the environment is low in energy sources. Also contain gases used in buoyancy and floatations
Granules
Not membrane bound, areas within a cell that contains inorganic crystals. Stores important resources that are essential elements in building macromolecules
Who produces endo spores
Only some gram positive rods (species belonging to bacillus and clostridium)
When are endo spores produced?
When conditions become unfavorable for further bacterial growth and the survival of the bacteria is in question. The bacteria that produces endo spores will die.
Why are endo spores produced?
For survival, not reproduction
What is an endo spore?
Small, protected, dormant bacteria that will germinate under favorable growth conditions into a new bacterial cell. Genetically identical to the cell that produced it
Endo spores have three layers
Spore coat, cortex. And core
Spore coat
This outer layer provides a nearly impervious barrier to many chemicals
Cortex
Middle layer contains many calcium salts and dipicolinic acid, this keeps the core very dry
Core
Innermost layer contains the bacterial chromosome DNA
Di-
Two
Strep-
Long chains
Staph-
Irregular clusters
Genes (number)
3000-4000 in bacteria
25,000-30,000 in humans
