Cell Structure of prokaryotes in the domains Bacteria and Archaea, and Eukarya Flashcards
Prokaryotes differ from eukaryotes in ____ and _______
Elaborate
size and simplicity
- most are smaller
- most lack internal membrane systems
- and no internal phospholipid bilayer membranes
prokaryotes are divided into 2 taxa, the domains are…
Bacteria and Archaea
pictures on slides 4-6
:)
Morphology is…
the cell shape
what are the 3 major cell morphologies?
- ) Coccus (pl. cocci): spherical or ovoid
- ) Bacillus (Rod; pl. Bacilli)): cylindrical shape
- )Spirillum: spiral shape
* *Many variations on basic morphological types
diplococci (s., diplococcus) arrangement is….
pairs
streptococci arrangement is…
chains
staphylococci arrangement is…
grape like clusters
tetrads arrangement is…
4 cocci in a square
sarcinae arrangement is…
cubic configuration of 8 cocci all perpendicular to each other
the 5 Cocci are….
diplococci streptococci staphylococci tetrads sarcinae
What are the 3 Bacilli? describe
Diplobacilli- 2 bacilli
Streptobacilli – chains of bacilli
Pallisade – several parallel cells along long axis
describe the shape and arrangement of Bacilli (s., bacillus)
- rods
* coccobacilli – very short rods
describe the shape and arrangement of Vibrios
resemble rods, comma shaped
describe the shape and arrangement of Spirilla (s., spirillum)
rigid helices
describe the shape and arrangement of Spirochetes
flexible helices
describe shape and arrangement of Mycelium
network of long, multinucleate filamentous cells
describe shape and arrangement of Pleomorphic
organisms that are variable in shape
online definition: ability of some bacteria to alter their shape or size in response to environmental conditions
describe shape and arrangement of Archaea
pleomorphic, branched, flat, square, other unique shapes
What are the advantages of being a small cell?
Small cells have more surface area relative to cell volume than large cells (i.e., higher S/V)
- This allows greater nutrient exchange per unit cell volume
- Thus, small cells tend to grow faster than larger cells
*Slide 18 has a picture
Cellular organisms less than__ in diameter are unlikely
0.15 µm
_________tend to contain small cells (0.2–0.4 µm in diameter
Open oceans
starting from the outside going on, what are the 4 parts of the Prokaryotic Cell Structure?
1) Structures exterior to the cell wall
2) Cell Wall
3) Cell membranes
The three above together are also referred to as the cell envelope; there are differences in the cell envelope between Archaea and Bacteria
4) Structures within cell membrane
**Slides 21 and 22
describe prokaryote cell membranes (2)
- Absolute requirement for all living organisms (all 3 domains)
- Some prokaryotes (both domain Bacteria and Archaea) also have internal membrane systems (but these are different from the internal membrane systems in eukaryotes)
what are 5 functions of the cell membrane in all 3 domains? describe each function
- ) Maintains cell’s integrity - Vital barrier that separates cytoplasm from environment (if no cell membrane, no cell)
- ) Regulates transport - highly selective permeable barrier
- ) Energy metabolism in prokaryotes (not eukaryotes)
- ) Protein attachment
- ) Receptors for detection of and response to chemicals in surroundings
describe the Fluid Mosaic Model of Membrane Structure (all domains) (2)
- ) Membrane somewhat fluid, somewhat solid
- ) Lipid bilayers with floating proteins
- amphipathic (having both hydrophilic and hydrophobic parts) lipids
- polar ends (hydrophilic – interact with water)
- non-polar tails (hydrophobic – insoluble in water)
- membrane proteins
describe the Domain Bacteria Cell Membrane (2) and describe
- ) General structure:
- phospholipid bilayer plus proteins (6–8 nm wide) ; no sterols, but +/- hopanoids or other molecules
- Contain both hydrophobic and hydrophilic components - ) Fatty acids point inward to form hydrophobic environment; hydrophilic portions remain exposed to external environment or the cytoplasm
**slides 28-31
what are 2 types of membrane proteins? describe them
this is not naming specific proteins
Peripheral
-loosely connected to membrane on cytoplasmic side
-easily removed
Integral
-amphipathic:embedded within membrane and project -outward or inward
-carry out important functions
-may exist as microdomains
proteins that completely cross the membrane from one side to the other are called what?
Transmembrane proteins
describe the outer surface of cytoplasmic membrane
can interact with a variety of proteins that bind substrates or process large molecules for transport
describe the inner surface of cytoplasmic membrane
interacts with proteins involved in energy-yielding reactions and other important cellular functions
what are 2 membrane strengthening agents? describe them
- ) Sterols
- Rigid, planar lipids found in eukaryotic membranes -Strengthen and stabilize membranes
- Only found in a very few prokaryotes (typically wall-less prokaryotes (ie, Mycoplasma)) - ) Hopanoids
- Structurally similar to sterols
- Present in membranes of many Bacteria
Saturation levels of membrane ______ reflect __________ such as _________
lipids; environmental conditions; temperature