Bacteria Flashcards
What are some common morphology of bacteria?
coccus - spherical
bacillus - rod
spirillum - spiral
pleiomorphic - varied shapes
Eukaryotes are __________ than most Prokarya
larger
What are the advantages to a high surface-volume ratio?
- greater rate of nutrient/waste exchange
- higher metabolism
- faster growth
- faster evolution
Where are very small cells common?
Marine environments
What is the largest part of bacterial cells?
the nucleoid region
How does DNA compress within the nucleoid?
- cations to shield negative charges
- positively charges proteins
- supercoiling
How does bacteria maintain its shape?
Bacterial cytoskeleton
What is MreB?
a protein that is a homolog of actin
What is FtsZ?
a protein that is a homolog of tubulin
Define Cell Envelope
The layers that surround the cytoplasm of cells (membrane, wall, outer membrane)
The cell membrane is a __________ barrier, Not a ____________ barrier
permeability, structural
rigidity in cells can be caused by:
fluidity in cells can be caused by:
saturated fatty acid tails in the membrane.
unsaturated fatty acid tails in the membrane.
How does h2o cross the membrane?
aquaporin protein channels (osmosis)
What is facilitated diffusion?
- materials move through protein channels using concentration gradient
- does NOT use ATP
What is co-transport?
Form of active transport (uses ATP)
Define protein secretion
- shipping proteins outside the cell
- uses ATP energy
How do nutrients get through Gram-positive bacterial cell walls?
Large pores in the matrix
How do nutrients get through Gram-negative bacterial cell walls?
Porins and TonB proteins in outer membrane
Name and describe the 4 main flagella arrangements
Monotrichous - one flagella at pole
Amphitrichous - a flagella at each pole
Lophotrichous - many flagella at pole
Peritrichous - many flagella all over cell body
Flagella are composed of three basic pieces:
- Filament of multiple flagellin proteins
- Hook protein that connects filament to basal body
- Basal body (disk-like structure that turns filament like a propellor)
How do cells move their flagella?
Proton motive force (PMF)
Define chemotaxis
Chemoreceptor proteins temporarily sense changes in attractants and repellants
Describe methods of nonflagellar activity
Gliding motility - smooth sliding over surface (cyanobacteria)
Twitching motility - jerky movement using pili
Actin in host cells causing bacterial propulsion into adjacent cells
What are adherence molecules?
pili, pilin protein fibers, other proteins that allow cells to stick to surfaces
Define stalk
Extension of cell envelope that provides extra surface area for nutrient absorption (good for low-nutrient environments)
What are capsules?
- Thick layer of polysaccharides that surround cells and provide protection, help bacteria form biofilm, and enhance survivability (found on many pathogens)
- Found in Gram-positive and Gram-negative cells
What are S-layers?
- Array of interlocking proteins that most likely protect against predation or infection
- Found in Gram-positive, Gram-negative, and archaeal cells
