exam 2 - study guide 5 Flashcards
(49 cards)
how do phospholipids interact with water
They don’t because water is polar and phospholipid layer is nonpolar
importance of sterols in the membrane
Provide rigidity, permeability, and structural integrity
cell types that contain sterols
common in eukaryotes, not common in prokaryotes
what type of molecule is a sterol
sterols are steroid molecules with a hydroxyl group attached to one of the rings
properties of membranes and mechanisms that substances cross the membrane
they key property is that it is selectively permeable and ions/materials pass through diffusion, osmosis, and active transport
active transport
uses ATP or proton motive forces to move substances
carrier protein moves substance from low to high concentration, against the chemical gradient
passive transport
does not require energy
includes simple diffusion (CO2 and O2), facilitated diffusion (permease carries substance), and osmosis.
functions of proteins
membrane proteins act as selective gate, sensor of environmental conditions, and as a fluid mosaic model.
endocytosis
substance coming into the cell
pinocytosis
small invaginations of cell membrane bring in liquid and liquid-dissolved substances.
phagocytosis
extensions of cell membrane that take up solid material
pmf
Proton motive force. Is harvested to drive cellular processes including ATP synthesis & some forms of transport and motility.
what are extracellular membrane vesicles
membrane-bound vesicles that facilitate communication, cargo transfer, and modify recipient cells functions.
secreted by most cells
proteins, lipids, nucleic acids, and sugars contain EMVs
what are ribosomes, composed of, function
Ribosomes are sites of protein synthesis in cytoplasm.
Composed of protein and rRNA. Small (30S) & large (50S) subunits come together to make a 70S ribosome in procaryotes. Ribosomes facilitate joining of amino acids. Eukaryotes are 80S.
what are chromosomes, composed of, procaryote properties, nucleoid, plasmids
Nuclear material
composed of nucleotides
chromosomes are single, covalently closed, and circular.
Nucleoid is a gel-like region with single circular double-standard DNA and packed tightly via binding proteins & supercoiling.
Plasmids are circular, supercoiled DNA smaller than a chromosome.
what are endospores, common genera of prokaryotes that form these, dipicolinic acid, resistant towards
form when nutrients are depleted in a cell’s environment
Bacillus and Clostridium
dipicolinic acid is a chemical compound that’s part of bacterial spores which aids in heat resistance
resistant to heat, desiccation, chemicals, UV light, and boiling water
How many hours does it take for a vegetative cell to complete sporulation and form a mature endospore (enter dormancy)? How long does it take for an endospore to exit from dormancy and return to vegetative growth
Takes around 8 hours to enter dormancy
minutes to 2 hours to exit dormancy
endospore formations
terminal, subterminal, central
circular or ellipsoid
non-deformed and deformed
How long can endospores remain dormant but remain viable/able to germinate if conditions are favorable?
They can remain viable for potentially hundreds or even millions of years
glycogen granules
storage units for glucose that are made of branched chains of glucose molecules.
polyphosphate granules
intracellular storage structures composed of a linear polymer of phosphate molecules.
polyhydroxyalkanoate granules
storage compartments in bacteria that contain carbon and energy.
extracellular polymeric substances (EPS)
usually polysaccharide sometimes protein secreted by some bacteria outside of cell wall; sometimes includes extracellular DNA. Protects against desiccation &/or chemical stress, nutrient accumulation, allow cell to adhere/stick to surface, protection form phagocytic eucaryotic cells.
biofilm
Polysaccharide-encased community with cell walls & channels that nutrients & wastes pass, cells communicate/coordinate by synthesizing & sensing chemical signals.
