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.)