Intro to Membranes + Bacterial Cell Structure Flashcards
What kind of movement is common in the phospholipid bilayer and why
Lateral movement, provides fluidity and flexibility. Flip-flop movement is rare because polar head is not stable in hydrophobic core
In high temperatures, there is _____ (more/less) room between phospholipids and the membrane permeability _______ (increases/decreases)
more, increases
In low temperatures, there is _____ (more/less) room between phospholipids and the membrane permeability _______ (increases/decreases)
less, decreases
How do membranes adapt to high & low temperatures
High: increase hydrocarbon tail length (increase hydrophobicity), decrease C=C bonds (they cause kinks, increase cholesterol content (stiffens/thickens membrane, increases hydrophobicity)
Low: Increase C=C bonds (“kick” apart), decrease tail length, increase cholesterol (acts as a spacer)
Non-polar amino acids are
hydrophobic
List substances from most permeable to least permeable
hydrophobic (np) molecules (O2, CO2, N2) -> small uncharged polar molecules (H2O, Glycerol, Ethanol) -> large uncharged polar molecules (glucose, sucrose) -> ions (Na+, K+, H+, Cl-)
How does passive transport work
Molecules flow from an area of high concentration to low concentration (water follows solute). Water undergoes passive transport by osmosis.
What is a risk when water rushes into the cell in animal cells
cells can burst (osmotic lysis)
What is a risk when water rushes out of the cell in animal cells
cells can shrink
Does facilitated diffusion require energy
no
Name the two forms of facilitated diffusion
Channel “tunnel” protein and carrier “revolving door” protein
Is facilitated diffusion specific
yes
Why perform active transport?
expel waste, concentrate nutrients in cell
Describe the sodium potassium pump
Sodium
Out
Potassium
In
Positive Out Negative In 3Na+ out 2K+ in
Define coupled transport, give an example
Energy released by one gradient is used to establish another gradient.
Sodium/Potassium pump is used to pull glucose up its gradient into the cell.
Explain exocytosis
Bulk transport out of the cell, proteins from golgi transported in vesicle that fuses with plasma membrane to secrete proteins
Explain Endocytosis/Phagocytosis
Bulk transport into the cell, non specific, vesicle forms from plasma membrane, transports to lysosome (digestive organelle)
Explain Receptor mediated endocytosis
Endocytosis of a specific ligand (anything that binds a receptor) placed in vesicle, receptors recycled, ligand goes to lysosome to be digested/recycled.
Bacteria HAVE:
fimbriae, cell membrane, cell wall, cytoplasm, flagella, ribosomes, DNA in nucleoid region
Bacteria DO NOT have:
Membrane bound organelles (eg. Golgi, ER, chloroplasts)
What is the motile structure of Bacteria, explain it
Bacteria flagellum: rotates like a corkscrew to allow movement, powered by H+ gradient
Basal apparatus anchors filaments into cell wall/membrane
What is peptidoglycan
structural polysaccharide
What is lipoteichoic acids role
link cell wall to membrane
Explain the differences between Gram negative and Gram positive bacterial cell walls
Positive: thick layer of peptidoglycan
Negative: thin layer of peptidoglycan, but has an outer membrane (but not a major permeability layer)
