Basic plasma membrane
List 4 types of macromolecules found in plasma membrane and describe functions of
each molecule
cholesterol, phospholipids, carbohydrates, and proteins
what are the components of the extracellular matrix (ECM) and what does it do?
provides structural support, communication, and anchoring
consists of collagen, proteoglycans, and integrins
what is diffusion and what are its types and what do those types mean for gradient, protein used, and energy
movement down gradient + simple - down; no protein; no energy; facilitated - down; either channel or carrier protein; no energy, and active transport - up; carrier protein; ATP used
3 stages of potassium pump cycle
1) building and phosphorylation - 3 Na+ (inside), ATP -> ADP + P, cytoplasm, transport protein
2) Sodium release and potassium binding - 3 Na+ (out), extracellular fluid, K+ binding
3) Dephosphorylation and reset - 2 K+ ions released into cytoplasm, P released, K+ moving in, cytoplasm
What is receptor-mediated endocytosis
this type of endocytosis uses specific receptors to take in certain molecules like cholesterol
what is a fluid mosaic
fluid = lipids move laterally within the bilayer
mosaic = diverse proteins embedded like tiles within the lipid sea
name the cell-cell junction types and functions
gap - channels between animal cells + rapid communication, adhering - anchor cells via filaments + structural stability, tight - seal membranes + prevent leakage, plasmodesmata - channels in plant cell walls + transport & communication
what is concentration gradient
difference in solute concentration
What is the membrane potential
the voltage difference across a cell’s plasma membrane, created by the uneven distribution of ions inside and outside the cell, inside is negative, outside is positive
What is phagocytosis
This type of endocytosis is often called 'cell eating' and is used by white blood cells to engulf bacteria.
Does the fluid membrane become more or less flexible when: temperature drops, more unsaturated tails in phospholipids, or when cholesterol is present?
less, less, cholesterol presence stabilizes fluidity
what is the cytoskeleton and what are its 3 main roles
network of protein fibers + support shape, movement, and transport
what is passive vs active transport
movement of molecules across a membrane from an area of high to low concentration which does not require energy, active transport requires energy
chemical gradient + electrical gradient = ?
what is it?
Chemical gradient → ions want to move from high → low concentration, Electrical gradient → ions are pulled toward the side with the opposite charge
adding these gives you the electrochemical gradient, which determines how ions move — for example, Na⁺ wants to move into the negatively charged, lower-sodium inside of the cell
What is pinocytosis
This process is known as 'cell drinking,' where the cell takes in droplets of extracellular fluid.
Rank easy to hard for the following molecules to pass through the phospholipid bilayer (without any proteins) and why
water, glycerol, glucose, O2, and H+/Cl-
non-polar molecules pass easily while non-polar molecules take time or need channels
types of cytoskeleton fibers, their description and function
microfilaments(actin) - thin; under membrane + shape & movement, intermediate filaments - durable; keratin + strength & anchor organelles, microtubules - hollow; tubulin + transport & mitotic spindle
what is osmosis
passive movement of water molecules across a semi-permeable membrane from lower to higher solute concentration to equalize concentration
What is cotransport and where does its energy come from
in animal cells cotransport uses the movement of sodium ions down their concentration gradient to power the movement of glucose against its gradient through the same protein, energy comes from sodium-potassium pump (uses ATP)
What is receptor-mediated endocytosis?
This highly specific endocytosis process uses receptor proteins to capture particular molecules, like LDL cholesterol.
explain what each membrane protein does briefly:
transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to the cytoskeleton or extracellular matrix
transport - moves ions or molecules, enzymatic activity - speeds up reactions, signal transduction - relay messages via receptors, cell-cell recognition - glycoproteins identifying cells, intercellular joining - form junctions, attachment - anchors cell membrane
plasma membrane labeling game 100% 5 times
yaaay
what are isotonic, hypertonic, and hypotonic? relate these to turgid, flaccid, and plasmolysis and the cell type
isotonic - equal in solute concentration + flaccid, hypertonic - higher solute concentration outside + plasmolysis, hypotonic - lower solute concentration outside + turgid
plant cells can have a turgid, flaccid, or plasmolysis state
what are lysosomes
These tiny organelles act as the cell’s cleanup crew, using digestive enzymes to break down waste and worn-out parts.
What is endocytosis
this process allows a cell to take in large materials or fluids by engulfing them in vesicles formed from the plasma membrane.