Chapter 7 (Test 2 Review) Flashcards
What types of molecules can pass through the membrane unaided? Why?
Small hydrophobic non-polar (selfsame) molecules can pass through the membrane rapidly. Water, despite being hydrophilic, can slip through the cracks due to its tiny size.
What types of molecules need transport proteins?
Transport proteins allow for the passage of small hydrophilic molecules across the plasma membrane. Water is transported via aquaporins.
What are the two physical methods for transport?
Active and Passive. Active transport requires energy to move something to an area of higher concentration whereas Passive transport requires no energy and moves the thing to an area of lower concentration.
What is diffusion?
Diffusion is the process whereby molecules evenly fill space. Take air rushing into a vacuum for example.
What is a concentration gradient?
The term “concentration gradient” refers to a gradient of concentration between an area of high concentration and an area of low concentration.
Typically substances diffuse down their concentration gradient.
What is the difference between passive and active transport?
Passive transport requires no energy and moves substances down their concentration gradient.
Active transport requires energy and moves substances against their concentration gradient.
What is osmosis?
Osmosis is the process whereby water diffuses through a membrane from an area of high concentration to an area of low concentration.
Imagine two buckets, one with a lot of rocks and a little bit of water, and the other with a small amount of rocks and a lot of water. You need the ratio of rocks to water to be equal, but you can’t move the rocks. Osmosis is moving the water from the little rocks lots of water solution with a (low rock-to-water ratio) to the bucket with a lot of rocks and little water (high rock-to-water ratio) so that the ratios of rocks to water are the same.
Define “Hypertonic”
The term “Hypertonic” refers to a difference between two substances. Instead of being a definite thing, it’s a comparative kind of word like “more than.”
Hypertonic basically means “more concentration in this than that.”
Define “Hypotonic”
The term hypotonic refers to a smallER (hypo) concentration of solution (tonic). Think of hypothermia: someone suffering from hypothermia has a smaller amount of heat than normal.
Define “Isotonic”
Isotonic means equal tonic. Two solutions are isotonic when they have the same concentration.
What happens when animal cells are placed in a hypertonic solution?
Animal cells in a hypertonic solution (a solution with MORE concentration than the cells’ concentration) will shrink as the water inside of the cell rushes out in an attempt to equalize the concentration outside of the cell.
Think of it like pressure: the more pressure outside of the cell, the more compressed the cell will be.
What happens to animal cells in a hypotonic solution?
Animal cells in a hypotonic solution (a solution with more concentration relative to the cell) will swell up and burst as water rushes INTO the cell in an attempt to equalize the solution (remember osmosis).
Think of it like pressure: the less pressure outside a balloon, the greater the balloon will expand to fill the available space.
What happens to plant cells in a hypertonic solution?
Plant cells in a hypertonic solution will shrivel up and die like a salted slug.
What happens to plant cells in a hypotonic solution?
If you fill up a big balloon in a room it won’t get bigger than the walls of the room. The plant cells will fill up but not burst because of their cell walls.
What is facilitated diffusion?
Facilitated diffusion is the process whereby diffusion is helped along by a port or channel.
