Lecture 4 Flashcards
Eukaryotic flagella
-Back-and-forth motion
-Microtubules
-Protein subunit is tubulin
Archaea flagella
Some archaea have archaella which are composed of protein subunits known as archaellins
Flagella details
-Anchored to the cell wall and membrane by the basal body consisting of ring proteins
•Gram- have 4
•Gram+ have 2
Flagellar anatomy
-The hook
-Basal body
-Ring structures
-Mot proteins
The hook
Rotating part of the flagella
Basal body
Internal part of the flagella
Ring structures
Ring proteins attached to flagella on membrane
Mot proteins
The Mot complex in the inner cell membrane controls the flow of protons to make ATP
-Movement of flagella propel by movement of ions(+) (proton motive force PMF) down gradient through Mot proteins (no energy-gradient)
Gliding motility
-Movement without propulsive structures like flagella
-Gliding bacteria are filamentous or rod-shaped
Two types of gliding mobility
- Ratcheting
- Slime jet
Intracellular actin based movement
L. Monocytogenes can move from macrophage to macrophage without exposure to the rest of the immune system by pushing the membrane of one cell into the next.
-process of crossing from macrophage through phagocytosis then destruction of vacuole and release into cell
-moves from cell to cell without exposure to extracellular space
Ex. Listeria monocytogenes
Intracellular Actin-Based Movement mechanism factors
-actin
-VASP
-Bacterial ActA
Actin
Actin is the most abundant protein in the cytoplasm of mammalian cells (10-20%) and involved in cell motility, cell division, vesicle movement, cell shape
VASP
VASP interacts with the fast (barbed end) of actin filament to promote elongation
Bacterial ActA
Binds VASP and is connected to the expanding end of actin
Axial filament
-Also called endoflagella
-embedded between the cell wall and outer membrane
-rotates like a corkscrew
Filamentous appendages
-flagella
-fimbriae
-pili
Fimbriae (short attachment pili, common pili)
-short bristle-like and numerous
-made of fibrillin
-fimbriae are filamentous proteins with adhesive tips that allow for attachment to surfaces and other cells, colonization, and resistance flushing
-Act as virulence factors in Escherichia, Staphylococcus, and Streptococcus
Pilus (pili)
-few in number (1-10)
-longer than fimbriae
-made of pilin
-sex pili: facilitate transfer of DNA FROM ONE CELL TO ANOTHER (conjugation)
Eukaryote vs prokaryote rRNA count
Eukaryote-18 rRNA
Prokaryote-16 rRNA
Ribosome
For protein synthesis (creation)
Bacteria vs Archaea genome size
Bacteria 0.6-8 million base pairs
Archaea 0.5-5.6 million base pairs
E. coli—5 million nucleotides
Human —3.3 billion nucleotides
Bacterial genetics
-DNA genome
•Single, circular chromosome
*some exceptions like vibrio cholera
-Haploid
-No introns (very rare)
-may have a plasmid
Plasmids
An extra chromosomal self-replicating piece of DNA that carries gene for a variety of functions but is not essential for cell growth
