Prokaryotic Cell Structures Flashcards
Which is simpler: prokaryotic or eukaryotic?
Prokaryotic (proteins, nutrients, and DNA)
What are the main components of a Prokaryotic cell?
-nucleoid
-cytoplasm
-cell envelope
-surface structures
What do prokaryotic cells not have?
a nucleus or other membrane bound organelles
nucleoid
a chromatin-dense area within the cytoplasm and contains the bacterial DNA
cytoplasm
the gel-like fluid inside the cell
cell envelope
complex multi-layered structure that protects the cell contents
surface structures
functional proteins on the cell surface
What are the two major types of bacteria?
- gram-positive (simpler)
- gram-negative (more complex)
What do all bacterial cell envelops consist of?
- cytoplasmic membrane
- cell wall
What is the main difference in structure between gram-positive and gram-negative?
gram-negative has an outer membrane
Composition of the Bacterial Inner Membrane
-cytoplasmic/inner membrane surrounds the cytoplasm
-bilayer: hydrophobic fatty acid “tails” and hydrophilic glycerol + phosphate + other functional groups
What are the hydrophobic and hydrophilic components of a bacterial’s inner membrane connected by?
ester linkage
What is the main function of the inner membrane?
selective permeability
What kind of components might disrupt the bilayer?
detergents
How does temperature affect the inner membrane?
-HEAT will make the bilayer more FLUID
-COLD will make the bilayer more RIGID
Composition of the Bacterial Cell Envelope
peptidoglycan
Main structures of peptidoglycan
- polysaccharide backbone
- tetrapeptide
polysaccharide backbone
-structural component of peptidoglycan
-rigid and provides strength
-2 modified glucose molecules connected by a beta (1,4) bond
tetrapeptide
-other structural component of peptidoglycan
-short peptide attached to N-acetylmuramic acid
Amino acids in peptidoglycan
L-alanine
D-alanine
D-glutamic acid
L-lysine/diaminopimelic acid (DAP)
Where are peptidoglycan layers crosslinked?
DAP and D-alanine
What inhibits the peptidoglycan layer crosslink?
penicillin
Who discovered penicillin?
Alexander Fleming
How does penicillin inhibit the peptidoglycan crosslink?
Penicillin binds to the penicillin binding protein and prevents the protein from forming the crosslink. Thus, bacteria cannot divide or repair the cell wall.
What are two possible ways that bacteria can become resistant to penicillin?
- Disrupt the binding protein (change binding site)
- Disrupt the penicillin
Who discovered lysozyme?
Alexander Fleming
What does lysozyme do?
-degrades cell walls
-used in many bacterial DNA extraction protocols to break open the cell walls and lyse the cells