Bacterial structure Flashcards
(23 cards)
What are the domains?
Bacteria
Archaea
Eucarya
What are the characterisitcs shared between bacteria and archae? What about eucarya?
Bacteria/Archaea are prokaryotes:
- >DNA stored in nucleoid
- > Lack of well-defined nucleus and cellular organelles
Eucarya are eukaryotes “true nucleus”
->cellular organelles
Bacteria are single celled prokaryotes with a specific cellular morphology, what are the 3 morphological categories?
Rods
Cocci
Spirillium
What is the bacterial cell wall predominantly comprised of?
Peptidoglycan
How to bacteria multiply?
Binary fission
What are the 2 ways in which archea are dissimilar to bacteria?
cell wall composition
proclivity for extreme environments
What are the qualities of the bacterial chromosome?
Circular, single, double stranded
super-coiled
located in nucleoid
What are the qualities of a bacterial plasmid?
- small, circular pieces of dsDNA
- Antibiotic resistance, toxin-producing
- Copies of plasmids can be transferred from one bacterium to another
(which accounts for the increasing frequency of antibiotic resistance)
What is the function of a prokaryotic ribosome and how does it differ from eukaryotic one?
- Site of protein synthesis
- 70S instead of 80S
What essential processes take place within the cytoplasmic (plasma) membrane of a bacteria?
Electron transport
Energy production
Bacterial plasma membrane are said to have be a fluid mosaic model. What does this mean?
The bacterial PM uses proteins to also serve as receptors but the proteins are not stationary in the fluid bilayer. Bc they’re constantly changing positions the cell membrane is known as a fluid mosaic model
What is the significance of the bacterial cell wall being comprised of peptidoglycan? What are the two major alternating subunits of peptidoglycan?
- Triggers immune system
- NAM & NAG
Within bacteria there are two basic cell wall structures which divide them up into 2 categories. What are these categories?
Gram positive
Gram negative
What are the steps of the Gram Stain?
Step 1: Crystal violet => Stains cells purple
Step 2: Iodine (mordant) => Cells remain purple
Step 3: Alcohol (decolorizer- this is the step that distinguishes gram(+) from gram(-)) => Gram (+) cells remain purple while gram (-) cells become colorless
Step 4: Safarnin (counterstain) => Gram (+) cells remain purple while Gram (-) cells now appear red
What is the prominent component of a gram (+) cell wall? What does this do to the overall polarity of the cell?
- Teichoic acid
- Negatively charged = cell negative polarity
In gram (-) cells the peptidoglycan layer is located between the outer membrane and the cytoplasmic membrane, what is this inbetween space known as?
Periplasmic space
In gram (-) cells there is the presence of the outer membrane which is comprised of what?
Lipopolysaccharides (LPS)
Within the LPS there is single feature which is known to be the detrimental characteristic of Gram (-) cells. What is it?
Endotoxin
LPS => Lipid A + O-specific polysaccharide side chain
Large of amount of LPS released into the blood stream from gram (-) bacteria can cause Diseseminated Intravascular coagulation or DIC. What does this do?
Inappropriate activation of the coagulation cascade and fibrinolysis
What are the two exceptions in bacteria which are unable to be gram stained? Why?
-Mycobacterium sp.
- Have a cell wall which has peptidoglycan intertwined with waxlike lipids of mycolic acids
- Must use “acid-fast” to identify
-Mycoplasma sp.
- Lack peptidoglycan cell wall
- incorporate steroids into their membrane
Coating the outside wall of bacteria is a substance known as glycocalyx (slime/capsule). Some allow bacteria to adhere to surfaces, developing communities known as what?
Biofilms
What are the 3 parts of a flagellum?
Filment => tail
Hook => connects tail to head
Basal body => Head (anchors flagellum to the cell wall and cytoplasmic membrane)
What are PILI?
Shorter and thinner than flagella, have a bunch of small adhesive extremities known as fimbriae
