Bio I PAP Notes

In terms of tonicity, if “B” has a higher solute concentration compared to another solution “A”, then “B” is considered hypertonic to “A”. This means that water would move from “A” to “B”

Animal vs Plant cells have different names for states of tonicity:

  • Animal Isotonic= normal, best one

  • Animal hypotonic= lysed (same as cytolysis)

  • Animal hypertonic= shriveled

  • Plant isotonic= flaccid

  • Plant hypotonic= turgid

  • Plant hypertonic= plasmolyzed (water gone)

Hypertonic: A solution with a higher solute concentration than another solution (more solute outside, so the water leaves shriveling up the cell)

Isotonic: Solutions with equal solute concentrations (amount of solute and water moving is equal)

Hypotonic: A solution with a lower solute concentration than another solution (more solute inside the cell, so water will flood into the cell.. plants find this good)

Cytolysis: HYPOTONIC solution (lower to higher concentration outside the cell), water moves in which causes the cell to SWELL and potentially burst if excessive water

Osmosis: the movement of WATER (from high to low concentrations) across a semipermeable membrane. Water will move to only places that have the most solute concentration. It involves the tonicity states (applies to cells mainly)

Plasmolysis: HYPERTONIC solution (higher to lower concentration outside the cell), water leaves which causes the cell to SHRINK and the cell membrane to pull away from the cell wall

Passive Transport: requires no energy, occurs due to natural concentration gradient, molecules move from high concentration to low (DOWN the gradient)

  • Diffusion: simple, high to low concentration, movement of small molecules across a selectively permeable membrane (e.g. oxygen)

  • Simple Diffusion: allows direct transport of molecules across the cell membrane

  • Facilitated Diffusion: occurs via transmembrane proteins like carrier proteins, channel proteins, aquaporins

  • Osmosis: diffusion of WATER across a selectively permeable membrane, occurs because of course of water moving fast

  • Osmotic Pressure: the pressure exerted on a plasma membrane in solution

Active Transport: requires ATP to move molecules against gradient, low to high concentration

  • Endocytosis: cell surrounds and takes material INTO the cytoplasm

  • Exocytosis: expulsion or secretion of large or a bulk of materials from a cell (EXIT)

  • Protein Pump: transmembrane proteins that actively move ions against the gradient of concentration against membranes

Turgor pressure: How firm the cell gets (with plants, it’s how rigid the cell wall is).

  • If it’s hypotonic, lots of water, the cell wall/turgor pressure will be high and full

  • If it’s isotonic, equal distribution, for plants it will wilt (which can still be revived)

  • If it’s hypertonic, no water in the cell because it’s left it, then the turgor pressure is low and it dies

  • The cell wall can only remain rigid with water inside the cell, if it’s high it’ll stay the way, if not it won’t hold up