Lecture 2-3 Structure and Function Flashcards
What is cell morphology?
Describes the shape, size, structure, and arrangement of microbial cells.
(Cocci, bacillus, rod, vibrio…)
Where are ribosomes located in microbial cells?
Cytoplasm
Where are chromosomal and extra DNA stored?
Nucleoid
Purpose of the cytoskeleton
comprising proteins analogous to eukaryotic cytoskeleton proteins
determines cell shape, aids in cell division, and contributes to intracellular organization.
What are the key components of microbial cell envelopes?
Capsule
S layer
Cell wall
Plasma membrane
- lipid bilayer, phospholipid
Describe the structure of the plasma membrane in microbial cells.
phospholipids
- amphipathic
(hydrophobic tails and hydrophilic heads)
Selectively permeable
allows small uncharged polar molecules
CO2, O2 urea
not allowed large charged non-polar
hopanoids
-rigidity
other proteins
integral membrane
peripheral
What is the significance of hopanoids in microbial membranes?
contribute to rigidity
Explain the process of diffusion in microbial cells.
net movement of molecules from a high concentration to a low concentration (PASSIVE PROCESS)
- Simple diffusion
-Facilitated diffusion - channel
-Facilitated diffusion - carrier
What is primary active transport in microbial cells?
ACTIVE TRANSPORT against gradient
Primary active transport
use of ATP as an energy source
mediated by transport proteins like ABC transporters.
Describe secondary active transport in microbial cells
ion gradients (e.g., Na+, H+) as an energy source.
It includes symporters and antiporters transporting molecules in the same or opposite directions
uniporter (one ion at a time)
symporter (one direction)
antiporter (opposite directions)
What is group translocation in microbial cells?
use high energy molecules like PEP
transferring phosphate groups to incoming sugars
Why do cells have cell walls?
protection from cell bursting (hypotonic environments) osmotic lysis
contributes to pathogenicity
resistance to toxic substances
Who developed the Gram staining technique, and what does it classify?
Han Gram
classifying purple as + and pink as -
distinguished between G + or - bacteria
Differentiate between Gram-positive and Gram-negative cell envelopes.
G +
-monoderm (one layer)
-thick peptidoglycan layer +cell wall
G -
-diderm
-cell wall
-thin peptidoglycan layer
What is the primary lipid in the outer membrane of Gram-negative cells?
Lipopolysaccharide (LPS)
dominant lipid in external leaflet of outer membrane
pathogenicity and restricting the entry of certain compounds.
contains:
- lipid A (endotoxin)
- Core polysaccharide
- O-antigen - pathogenicity
