Cell Transport Flashcards
Why are cells small?
Small cells with larger SA:VOL ratios have less volume and MORE surface area so they can exchange the materials they need faster
Large cells with smaller SA:VOL ratios have MORE volume and LESS surface area so they exchange materials slower
this is why cells are small
Why is the cell membrane a fluid mosaic?
Because the proteins and phospholipids can move laterally in the membrane due to hydrophilic/hydrophobic properties
Simple diffusion:
Passive transport, moves with the concentration gradient and does not require anything to help it
Facilitated diffusion:
Passive transport, moves with concentration gradient but it is helped by a transport protein
Concentration gradient:
High —-> Low concentration
Major functions of cell membrane:
cell membranes decide what passes through it and moves into the cell and what cannot, decides what gets to leave the cell
- signaling abilities
Phospholipid structure role in cell membrane
two layers of lipids with a hydrophilic head and hydrophobic tail
tails face inwards towards each other this makes up phospholipid bilayer
phospholipid bilayer is where the cells have to go through
Proteins role in cell membrane
- Allow the cell to be recognized by other cells (receptor protein)
-transport materials across phospholipid bilayer (Transport protein)
Cholesterol role in cell membrane
- adds to membrane structure (fluidness)
- helps regulate movement of molecules across membrane
What can and cannot pass freely through the cell membrane?
Water, carbon dioxide, and oxygen can pass freely
What is diffusion?
hydrophobic molecules that are small can diffuse through the phospholipid bilayer without any help
What is osmosis?
The movement of water through a semipermeable membrane.
Water molecules can pass freely through the cell membrane.
- they move from high water conc. to low water conc.
- or the water moves from low to high concentrations of solutes
what is a solute?
substances like salt or sugar that are dissolved in a solvent
Hypertonic:
Higher solute concentration is hypertonic
Hypotonic
Lower solute concentration is hypotonic
Brownian Motion
The random movement of microscopic particles suspended in a liquid or gas, caused by collisions with molecules of the surrounding medium
Equilibrium
When concentration of solutes/solvents is equal on both sides of the cell membrane
Active Transport:
Requires energy (ATP)
Allows molecules to move against the concentration gradient (low to high instead of high to low)
Endocytosis
active transport
- large amounts of molecules or larger molecules fuse with the cell membrane and go into a vesicle in order to pass through the cell membrane
Exocytosis
Active transport
when the vesicle containing wastes moves the wastes out of the cell
what do cells do in an hypertonic solution?
The cell will shrivel and die because a the water in the cell moves from high to low concentration of water.
What do cells do in an hypotonic
the cell will swell because the water in the solution is moving into the cell because it is moving from a high to low concentration of water
What happens to cells in isotonic
they stay the same
What happens in a negative feedback loop?
The feedback counteracts the stimulus (Ex: the stimulus is high blood sugar and the feedback causes the blood sugar to get lower)
What happens in a positive feedback loop?
The feedback enhances/amplifies and/or continues going in the direction that the stimulus was going
Ex:
When the baby’s head presses against the cervix and that triggers a positive feedback loop with oxytocin and etc.
