osmosis and tonicity Flashcards
What do all cells need to live?
Obtain nutrients and get rid of waste
What are some examples of nutrients a cell needs and why?
Water needed for chemical reactions and oxygen needed for cellular respiration
Simple diffusion
Moving molecules from high to low concentration
Does simple diffusion require energy?
No
Is simple diffusion active or passive transport?
Passive
Examples of things that do simple diffusion across the cell membrane
Oxygen, carbon dioxide, lipids, steroids
Facilitated diffusion
Using proteins to move molecules from high to low concentrations through the cell membrane
Example of facilitated diffusion
Osmosis
Does facilitated diffusion require energy?
No
Is facilitated diffusion an example of active or passive transport?
Passive
Examples of substances that require facilitated diffusion?
Large, charged, polar molecules
What kinds of molecules can go through the cell membrane with simple diffusion?
Small, nonpolar molecules
What kinds of proteins are involved in facilitated diffusion?
Integral proteins
What do integral proteins do?
Transport things into the cell
What’s one example of an integral protein and its function?
Aquaporins transport H2O to the cell
Active transport
Molecules move from low to high concentrations using ATP
Does active transport require energy?
Yes
Endocytosis
Bringing larger molecules into the cell using a vesicle
Exocitosis
Removing large molecules using a vesicle
Phagocytosis
Cell eating, example of endocytosis
Pinocytosis
Cell drinking, example of endocytosis
Tonicity
Ability of water to move into solutions with a high concentration of solute
3 different environments a cell can be in
Isotonic, hypotonic, hypertonic
Isotonic
Equal amounts of solute and water in a solution
Movement in a isotonic solution
No net movement, but there is movement
Hypotonic
More water and less solute in solution
Movement in a hypotonic solution
Water will move into cell (think hippo, big, takes in water)
What can happen because of a hypotonic solution to plant cells?
Becomes turgid
Turgid
Cell membrane pushes against cell wall
What can happen because of a hypotonic solution to animal cells?
Cells could lyse or burst
Hypertonic
Less water, more solute in solution (hyper, crazy, wants more of the cool solute)
Movement in a hypertonic solution
Out of cell
What can happen because of a hypertonic solution to plant cells?
Plasmolysis
Plasmolysis
Cell membrane shrinks because it’s losing water
What happens because of a hypertonic solution to animal cells?
Crenation
Crenation
Shriveling up of cell
Explain how a paramecium osmoregualtes (5 steps)
1) Normal paramecium
2) Uses a contractile vacuole and ATP to pump in positive hydrogen ions
3) Lots of solute (H+) and less water in the paramecium creates a hypertonic solution
4) Due to the high solute concentration within the cell, water wants to get in
5) Water then fills the cell, wants to go from high to low outside the cell
If the contractile vacuole is broken…
Water keeps coming in, so you can’t make a hypertonic solution and the cell will lyse/burst
How do freshwater fish osmoregulate?
- Freshwater is hypotonic (more water, less solute)
- A lot of water is entering their bodies through osmosis, so they need salts to counteract this
- Fish gills have active transport pumps to pump in sodium ions
Freshwater fish urine
Diluted because they have so much water in their bodies that they need to get rid of and their bodies retain the solute. They pee a lot because they have a lot of water storage.
How do saltwater fish osmoregulate?
- Live in a hypertonic environment, more solute less water
- Need to get rid of the salt from their bodies and hold on to the water needed for chemical reactions
- Gills have active transport pumps to pump out the salts
- They have concentrated urine because of the large amounts of solute and little water in their bodies
Diuretic
Hormone that makes you urinate
ADH antidiuretic
Hormone that makes you not urinate
How does the ADH antidiuretic hormone work?
It tells the kidneys to make aquaporins, water transport proteins, to reabsorb the water
If there was no ADH or if the aquaporin structure was broken/disfunctional, what would happen?
Humans can suffer from dehydration
What is water potential?
A measure of how water moves in a solution
How does water move in regard to water potential?
High water potential to low water potential
What are the two variables that affect the osmosis and movement of water?
Pressure and solute concentration
What is pressure potential?
Physical force
How does water move in regard to pressure?
Moves in the direction of the pressure (if pressure is directed to the right, water is moving to the right)
In an open container, pressure potential is:
0
What is solute potential?
How much solute is in a solution
How does solute affect water?
Water is attracted to solute
What is the solute potential of pure or distilled water?
0
When you add solute, what happens to the solute potential of a solution?
Solute potential decreases and you get negative values (less than 0)
Water potential =
Pressure potential + solute potential
What is the water potential sign called?
Psi
There is less solute in the cell than in the surrounding solution. Will water move into or out of the cell? Why?
Water will move out of the cell because there is a high water potential in the cell and low water potential outside the cell. High -> low water potential
Solute potential =
iCRT
What does the i in the iCRT fo
Ionization constant
i for NaCl
2
i for sugars/sucrose
1
Passive transport with regards to the concentration gradient
Down the concentration gradient
Active transport with regards to the concentration gradient
Against the concentration gradient
What’s an example of active transport?
The sodium potassium pump, where 3 Na+ ions go out and 2 K+ ions come into the cell
Cell originally has a mass of 82 grams. After 10 minutes, it has a mass of 75 grams. What kind of solution is it?
Hypertonic because water is exiting the cell, and therefore mass is decreasing
+ 15% Change
Hypotonic
- 15% Change
Hypertonic
Organisms try to be…
Isotonic
Greatest pressure potential =
Hypotonic