EXAM 3: Chapter 2- Part 1 Flashcards
Bacterial Cells Morphology
spherical
rod-shaped
comma-shaped
spiral
Pleiomorphic
spherical
coccus/cocci
rod shaped
bacillus/bacilli
comma shaped
vibrio/vibrios
spiral
spirillum/spirilla
What does pleiomorphic mean?
varied shape
What bacteria tend to be pleiomorphic?
bacteria that do not have a cells wall
Multicellular organization types
hyphae
mycelia
trichomes
hyphae
branching filaments of cells
mycelia
tufts of hyphae
trichomes
smooth, unbranched chains of cells
What organisms are trichomes specific to?
cyanobacteria
Size of bacteria
varies greatly
typically smaller then eukaryal cells
range: 0.1-10 um
surprisingly small bacteria-e xample
mycoplasma cells
are only 0.2 um in diameter (do not have a cell wall)
surprisingly large bacteria- examples
Thiomargarita namibiensis- up to 700 um in diameter
Epulopiscium fishelsoni- 200-700 um by 80 um
How do bacteria get so large?
forming symbiotic relationships
What is S/V ratio
surface to volume ratio
What does the S/V ratio mean
as the S/V ratio increases, nutrient uptake and diffusion of molecules becomes more efficient
Importance of S/V ratio?
As the cells get bigger the S/V ratio decreases
harder to support living
T/F Rod-shape have higher S/V ratio than Cocci
true
Cytoplasm
a gel-like liquid bounded by plasma membrane
components of cytoplasm
nucleoid region
plasmids
ribosomes
stew of macromolecules
inclusion bodies
What is the nucleoid region?
irregularly shaped region that is not membrane bound
takes up the most space
What organisms are nucleoid regions found in?
bacteria and archaea cells
What is located in Nucleoid region?
chromosomes and associated proteins- has supercoiling
nucleoid proteins
What are nucleoid proteins
proteins associated with DNA but not directly involved in transcription, translation, or synthesis
Examples of nucleoid proteins
binding proteins
proteins that regulate expression
Plasmids
may exist in many copies within the cell
inherited stably during cell division BUT can be lost
Why do some plasmids get lost during division?
occurs spontaneously
keeping a plasmid requires selective pressure from environment- no pressure= no plasmid
curing
Curing
particular chemical agents that prevent plasmids from dividing
How are plasma membranes classifies
mode of existence
spread
function
Copy numbers
low- 1-3 plasmids
medium- 4-20/30 plasmids
high- 100s of plasmids
Plasmid functional types (5)
conjugative plasmids
R plasmids
Col plasmids
Virulence plasmids
Metabolic plasmids
Conjugative plasmids
carry genes that require the cell to undergo conjugation
medium in size
low copy number
What is conjugation?
horizontal gene transfer
R plasmids
resistant in antibiotic-resistant plasmids
medium in size
low copy number
T/F a single plasmid can carry resistant to more than 1 antibiotic
TRUE
Col plasmids
encode col gene- responsible for the production of bacteriocins
small in size
medium in copy number
What are bacteriocins
proteins that kill other bacterium
Virulence plasmids
encode virulence factors that allow bacteria to cause disease
larger in size
Examples of virulence factors
toxins
adhesins
Metabolic plasmids
encode genes that allow addition of new metabolic pathways in cells
larger in size
ribosomes
“protein work bench”
used for protein synthesis
Why are ribosomes complex structures?
made up of RNA and protein
What is the Holoribosomal complex
large subunit and small subunit that we put together
Entire ribosome
bacterial/archaeal ribosomes: 70S
eukaryotic ribosomes is 80S
What is S?
Svedburg unit
sedimentation rate of molecule in a centrifuge; not additive
Bacteria and ribosomal rRNA
small subunit: total 30S- 16SrRNA
large subunit: total 50S- 23S and 5S rRNA
archaea/eukaryotic ribosomal rRNA
have an additional 5.8S in a large subunit
bacterial ribosome structure
30S/small subunit
- SSU proteins
- 16S rRNA
50S/large subunit
- 23S rRNA
- 5S rRNA
- LSU proteins
tRNA- spans both units
- carries an amino acid for translation
Inclusion bodies
granules of organic/inorganic material
common in all cells
some are enclosed by a single-layered membrane
Functions of inclusion bodies
storage of nutrients, metabolic end products, energy, and building blocks
other things
Two types of inclusion bodies
storage
micro compartment- used for things other than storage
Storage inclusion bodies
polyhydroxybutyrate granules
sulfur granules
microcompartment inclusion bodies
gas vesicles
carboxysomes
magnetosomes
ployhyrdroxybutyrate
carbon storage
sulfur granules
only found in bacteria that use sulfur products for electron acceptor in respiration
Gas vesicles
permeable to gas- allow bacteria to move up and down water column
found only in aquatic bacteria
Why do aquatic bacteria need to move in water column?
Photosynthetic organisms may need to move up if they aren’t getting enough light
may need to move up if oxygen diffusion is too low
Carboxysomes
Pulls CO2 off of oxygen for carbon fixation
only found in organisms that fix CO2
Magnetosomes
Allow the bacteria to ungergo magnetotaxis
usually found in anaerobic aquatic bacteria and cyanobacteria
contain iron
What is magneto taxis?
movement with magnetic field
bacteria aligns magnetosomes with Earth’s magnetic field
contain cytoskeleton elements to do this
Cytoskeleton
series of internal proteins
Roles of cytoskeleton
helps keep everything in cell
helps move things to correct locations within cell
contribute to organization of cell structure
used to build division septum during division
Types of cytoskelton proteins
Tubulin homologs- subunits of tubulin
- FtsZ
Actin Homologs- subunits of actin
- MamK
-MreB/Mbl
Intermediate filament homologs- mix of proteins
- CreS
Unique bacterial cytoskelton proteins
- ParA
- ParM
-ParR
FtsZ
functions in cell division
seen in bacteria and archaea
MamK
gives rod-shape
positions magnetosomes
MreB/Mbl
helps maintain cell shape
segregates chromosomes
localizes proteins
found in most rod-shaped bacteria
Cres
induces curvature of comma-shaped proteins
ParA
segregates chromosomes
ParA is chromosome-encoded form
ParM
involved in plasmid portioning during division
What are cytoskeletal proteins invovled in cell wall synthesis during division?
FtsZ and MreB
What happens if there is a mutation to FtsZ?
cell would not be able to make division in septum
cell would die
What happens if there is a mutation in MreB
monomers will still polymerize and form shape, but it would not stretch out
shape would be cocci instead of rod
cell can survive
What are cytoskeletal proteins involved in moving internal items
ParM and ParA and MamK
ParR
helps place plasmids during division
How do ParA, ParM, ParR work?
ParA acts as an anchor and tells ParM where to bring plasmids
They polymerize after plasmids anchor
ParR stretches out and pushes plasmids out
What happens if there is a mutation in MamK?
magnetosomes cannot line up
bacteria will not be properly oriented
T/F Not all cells have a plasma membrane
FALSE
cannot be a cell without a PM
What are the functions of PM?
encompasses the cytoplasm
selectively permeable- do not want to cut off internal environment
interacts with external environment- can adust internal in response to external
What does the fluid mosaic model mean?
fluid- phospholipids have lateral movement
mosaic- composed of proteins and sterile molecules; not just phospholipids
Features of plasma membrane
phospholipids
membrane proteins
Hapanoid
glycolipids
olgiosaccharides
hydrophobic alpha helix
Two types of membrane proteins:
- peripheral- do not span entire PM; not embedded
- integral- span length of PM; embedded
peripheral proteins
used mostly as sensors
loosely connected to PM and easily removed
make up 20-30% of membrane proteins
integral proteins
amphipathic
carbs often attached- act as sensors
lateral movement
may exist as microdomains
Microdomain
areas within the PM enriched with a particular protein
Structure of phospholipid
charged head group- hydrophilic and polar
glycerol- helps link tails to head
fatty acid tail- hydrophobic and nonpolar
Bacterial lipids are…
very dynamic
saturation levels reflect environmental conditions
T/F bacterial membranes lack sterols
TRUE
contain sterol-like molecules called hopanoids
Function of hopanoids
stabilize membrane across temperature ranges
higher temps have higher saturation- no kink/gaps
lower temps have lower saturations- more double bonds- less rigid
Structure of hopanoids
Hydroxyl group does not come off rings
sterol-hydroxyl group attached to the ring
How does PM get things in
Smaller non-charged molecules
- diffuse across readily
- EX: O2 and CO2
Polar small molecules
- aquaporins
- can pass right through tails but also use porins
- EX: H2O
Osmosis
What is osmosis?
flow of water across the PM towards the side of HIGHER solute concentrations
