Chapter 4 Cell Biology 2: Transport in Cells

4.1 Diffusion –Cell Bio 2

I. Molecules need to move in and out of cells

A. Because membranes allow some substances to cross or be transported more easily than others, they exhibit ______________________

1. carbon dioxide and oxygen cross easily because they are ___________ but _______________cannot because they are hydrophilic

2. ___________________ do not cross easily because they are too big (need help from ___________________)

4.1 Diffusion –Cell Bio 2

B. There are 3 main ways that molecules can pass through a phospholipid membrane:

1.

2.

3.

4.1 Diffusion –Cell Bio 2 C. _____________– small molecules move across a cell membrane from areas of ___________ concentration that ________________. There are 3 types:(the second 2 will be discussed in next section)

1. _________ - a process in which particles spread out evenly in an available space from an area of _______________________________________

a. This means that particles flow in the direction of their ___________________(high moves to the low area)

b. Eventually, the particles reach ____________ where the concentration of particles is the same throughout

4.2 Osmosis–Cell Bio 2 II. It is crucial for cells that water moves across

the plasma membrane

A. ____________ - a mixture of solute and solvent

1. the material that is being dissolved - ___________ ex. salt, sugar 2. the material that is doing the

dissolving - __________. ex. the solvent is usually _______

3. There are 3 types of solutions:

a. __________solution- indicates that the concentration of a solute is the same on both sides

b. __________ solution- higher solute concentration- cell _________ from water loss

c. __________ solution- lower solute concentration- cell ________ water

4.2 Osmosis–Cell Bio 2

Cells are being placed in each of these solutions: Watch what happens to the cells!

4.2 Osmosis–Cell Bio 2

B. _________ - a process where _______ moves across membranes from an area of __________________. _____________________________________

1. Osmosis will move water across a membrane down its concentration gradient until the concentration of solute (the particle) is equal on both sides of the membrane

2. When animal cells are in a ____________ solution, they shrivel and die. The plasma membrane in a plant cells pulls away from the cell wall through a process called __________________.

4.2 Osmosis–Cell Bio 2

3. Animal cells do best in an _________ environment and plant cells do best in a ______________ environment

C. ____________ pressure –the pressure of ______ in a cell and the main cause of plant support. Pressure is applied against the cell wall to keep it stiff (____________)

D. Controlling Osmosis 1. to prevent a single celled organism that

lives in water, from taking in too much water, a _________________________ helps to push out extra water.

Ex: ______________________

4.3 Facilitated Diffusion – Cell Bio 2 III. Many substances that are necessary for the

cell to live do not freely diffuse across the membrane

A. They require the help of specific ____________________ that transport a specific substance like sugars, amino acids, ions and even water

B. These proteins assist in _____________________, a type of _______ transport that does not require energy and carries material down a _____________________________

4.3 Facilitated Diffusion – Cell Bio 2 C. There are 3 types of transport proteins: 1. ______________ protein – allows

___________________________________ into the cell quickly

2. _________protein – opens a “gate” to allow a molecule that binds to it, in

ex. ___________________________ 3. ____________protein- is specific for

an ion, molecule or group of substances & and changes shape and releases it on the other side (_______________________________)

4.3 Facilitated Diffusion – Cell Bio 2

D. __________________– allows charged particles like ____________________________________________________, to pass through by using no energy

1. They allow the formation of a _____________________ between

the extracellular fluid and the cytosol

4.4 Active Transport – Cell Bio 2

IV. _______________– the use of energy (_____) to move a solute against its concentration gradient from _____________________ to maintain homeostasis

A. It requires the use of energy (__________ of passive transport – diffusion & osmosis)

Ex. Sodium-Potassium pump

4.5 Sodium-Potassium Pump– Cell Bio 2

V. ____________________– uses ATP during ________________ to allow charged particles of __________ to be exchanged for charged __________ across the plasma membrane (2 K+ into cell; 3 Na+ out)

- important for _______ cells

4.6 Exocytosis and Endocytosis – Cell Bio 2

VI. A cell uses two ways to move large molecules across membranes using _________ and ___________________

A. _____________________ is used to take in substances useful to the cell by capturing a particle and engulfing it with the cell membrane

1. Material to be transported is packaged within a _______________ that fuses with the membrane

4.6 Exocytosis and Endocytosis – Cell Bio 2 2. There are two kinds of endocytosis:

a. ______________ is engulfment of a _________________ by wrapping cell membrane around it, forming a ______________

b. _______________ cell membrane folds inward and __________ are taken in forming ______________

https://www.youtube.com/watch?v=InG6xF9D4EM&list=PLl13cwKLhxqQnW-_w88qSrq1hLKNdB-C1

4.6 Exocytosis and Endocytosis – Cell Bio 2

B. _______________ uses vesicles to send out big molecules, such as ______________________

1. newly made membrane ________ & ______ are moved on top the plasma membrane by exocytosis