Bio - 3.2 cell membrane

cells in different solutions

"ISO"- means the same *Equal at all times*

U-tubes

*Which side has more solute? -The right side *What happens to the water? -The water will move in the direction of more solute.

cell wall

-Found only in plant cells and bacteria cells -Main function: support

solutions

-Mixtures of substances -EX: Salt and Water, Sugar and Water (solute and solvent)

Exocytosis:

-Removing Large particles (watse) from the cell -Stuff "exists" the cell.*The membrane of a vesicle surrounds the material then fuses with the cell membrane. The contents are forced out of the cell.*

active transport

-Requires the cell to use energy _Proteins or pumps found in the membrane move Materials across.

Rule for Osmosis:

-Salt sucks -If the area outside the cell has more cells, then water will be sucked out of the cell.

Endocytosis:

-Taking *in* large molecules by the cell -*Phagocytosis* = *Phood*, taking in food particles -*Pinocytosis*= liquid substances *The membrane forms a pocket around a particle.The pocket then breaks loose from the cell membrane and forms a vesicle within the cytoplasm.*

Osmosis:

-The _diffusion of water_ across a membrane -The cell membrane is selectively permeable *in osmosis only water moves - not the solutes. It follows the same concentration gradient rule for all forms of passive transport*

*Osmosis* 1) Why is water moving toward the left side of the beaker? 2) Which side is hypertonic? 3) What is the solute?

1) Because water will move in the direction of more solute (more sugar molecules) 2)The left side of the beaker 3) Sugar

List two ways that active transport is different than passive transport.

1) Moves a solute from LOW concentration to HIGH concentration 2) requires ENERGY from the cell

Know the three types of passive transport and how molecules move down the concentration gradient.

3 types of passive transport are diffusion( Molecules tend to spread out), osmosis (only water moves - not the solutes. It follows the same concentration gradient rule for all forms of passive transport), and facilitated diffusion (from an area of higher concentration to lower concentration but because the solute is charged or too big, it will need a transport protein).

Hypo =

= LESS -Cell may _burst_ or organelles called "contractile vacuoles" remove excess water. *When a cell bursts from having too much water flow in, it is called cytolysis.*

Concentration gradient

A region along which the density of a chemical substance increases or decreases. Difference in the concentration of a substance from one location to another. A difference in the concentration of a substance across a distance.

Hyper = _More_

Cells will __shrink or die_, _plants wilt_. *Why is it dangerous to drink sea water?* Because you are putting that hypertonic solution in your stomach which it is going to draw all of the water out of the cells there which is not good. *Why does pouring salt on a slug kill it?* Because it pulls all of the water out of the slug. *When cells are in hypertonic solution, the cells lose water to the surrounding and shrink or shrivel. This is called plasmolysis.*

[ Equilibrium / Diffusion ] is the simplest type of passive transport.

Diffusion

How is facilitated diffusion different from diffusion? How are they similar?

Diffusion moves a solute from an area of high concentration to low concentration. In facilitated diffusion is still from an area of higher concentration to lower concentration but because the solute is charged or too big, it will need a transport protein.

Know the types of bulk (active) transport and how this brings materials into/out of the cell.

Endocytosis: it takes in large molecules into the cell using energy. Exocytosis: it removes large particles (waste) from the cell using energy

cell membrane

Gatekeeper -Regulates what comes in and out of the cell -Main components: proteins and phospholipids -(bilayer, proteins) phospholipids (phosphate head and fatty acids) It is selectively permeable which allows certain things into and out of the cell.

If there is a concentration gradient, substances will move from an area of high concentration to an area of [ equal / low ] concentration.

LOW

Define homeostasis

Maintaining a stable internal environment. *Homeostasis is the cell/organism's actions that maintain a balance.*

Compare passive transport and active transport.

Passive transport is when molecules move from an area of high concentration to an area of low concentration without the need to use energy. While, active transport is when molecules move from an area of low concentration to an area of high concentration using energy.

Explain what happens when you place a bag full of starch (solution) into a solution of iodine.

The bag that is full of starch is selectively permeable which means that the iodine solution will get into the starch bag causing the bag to change color ( it turns it from white to dark purple, because iodine is an indicator of starch.)

What role does the cell membrane play in maintaining homeostasis?

The cell membrane selects what will come into the cell or be released by the cell through passive and active transport and keep a balance in the cell/organism.

Explain what happens to gummy bears when placed in a salt solution and tap water.

The gummy bears will shrink (decrease in size) when placed in a salt solution and tap water because there is more salt molecules in the saltwater than in the gummy bears. The water of the gummy bears will move towards the salt solution causing the gummy bears to shrink.

Diffusion

The movement of molecules from an area of high concentration to an area of low concentration. -Molecules tend to spread out _In the water and in the air! __Requires no energy!

Why is the sodium-potassium pump considered an active transport? Which direction are the sodium and potassium bing pumped? How many sodiums are being pumped? How many potassiums are being pumped?

The sodium-potassium pump moves 3 sodiums and 2 potassiums from areas of low concentration to areas of high concentration requiring energy from the cell.

Describe what happens to the cell membrane of patients with cystic fibrosis and resulting symptoms. Also understand why this is an example of active transport.

Within the cell membrane, there are a few proteins that are specialized in transporting ions against the concentration gradient via active transport. We know that chloride ions are fewer in the cell than in the outside of the cell, so active transport is needed to transport chloride ions from a low concentration to a higher concentration. In Cystic Fibrosis, chloride channel proteins are dysfunctional and cannot allow chloride ions to get out of the cell. (The chloride ions get trapped into the cell) Therefore, a buildup of chloride ions would be the result, leading to a high solute (salt) concentration with low water potential inside the cell. So, water will diffuse across the cell membrane from outside the cell into the cytoplasm via osmosis. The ever-increasing volume of water will cause the cell to swell and make the mucus outside the cell less hydrated (thickier, stickier). Cystic fibrosis patients have a defect in the protein that pumps ions against the concentration gradient. When this malfunctions, thick mucus builds up.

Particle movement from an area of lower concentration to an area of higher concentration

active transport

When energy is required to move materials through a cell membrane

active transport

Transport protein that provides a tube-like opening in the plasma membrane through which particles can diffuse

carrier protein

Transport protein that changes shape when a particle binds with it

channel protein

Organelles that collect excess water inside the cell and force water out are called[ diffusion organelles / contractile vacuoles ]

contractile vacuoles

When molecules move from areas of high concentration to areas of low concentration (passive transport)

diffusion

Process by which a cell takes in material by forming a vacuole around it

endocytosis

The cell membrane forms around another substance, for example, how the amoeba gets its food

endocytosis

The process of taking material into the cell by infolding of the cell membrane is called [ endocytosis / exocytosis ]

endocytosis

Is used during active transport but not passive transport

energy

Both endocytosis and exocytosis require:

energy from the cell

When the molecules of one substance are spread evenly throughout another substance to become balanced

equilibrium

A vacuole membrane fuses (becomes a part of) the cell membrane and the contents are released

exocytosis

Process by which a cell expels (exits) wastes from a vacuole

exocytosis

In [ facilitated / molecular ] diffusion, membrane proteins help molecules move across the membrane.

facilitated

A form of passive transport that uses transport proteins

facilitated diffusion

A solution that causes a cell to swell is called a [ hypertonic / hypotonic ] solution.

hypotonic

Equilibrium

is reached when molecules are evenly spread throughout a space.

Semipermeable

membranes that allow some substances through but not others. Some substances can pass directly through the cell membrane by passive or active transport

Diffusion, Osmosis and Facilitated Diffusion all require:

no energy

The diffusion of water through a cell membrane

osmosis

The diffusion of water through a selectively permeable membrane is called [ osmosis / diffusion ].

osmosis

Particle movement from an area of higher concentration to an area of lower concentration (diffusion)

passive transport

The movement of substances through the cell membrane without the use of cellular energy

passive transport

The direction of water movement across the cell membrane depends on the concentration of free water[ molecules / solutions ].

solutions

Used to help substances enter or exit the cell membrane

transport protein

bulk transport

transports large molecules and solid clumps of materials by movements of the cell membrane. The process by which large particles and macromolecules are transported through plasma membranes. Inc. exocytosis and endocytosis

Facilitated diffusion moves substances down their concentration gradient [ with / without ] using the cell's energy.

without