Through The Cell Membrane

Question 1

Describe the passability of the cell membrane

Answer 1

Flexible and fluid and allows a unicellular organism to move through it

Question 2

Describe the functions of the cell membrane

Answer 2

Selectively permeable, meaning it controls what enters and exits the cell to maintain an internal balance called homeostasis. Provides protection and support for the cell. Allow cell recognition. Provide anchorage sites for filaments of the cytoskeleton. Provide a binding site for enzymes. Interlocking surfaces bind cells together. And it envelops the cytoplasm

Question 3

Describe the structure of the cell membrane

Answer 3

Amphipathic phospholipid bilayer. Proteins embedded in membrane act as anchors and tunnels for transporation

Question 4

Describe the fluid mosaic model of the cell membrane

Answer 4

Fluid because individual phospholipids and proteins can move around freely within the layer like a liquid. Mosaic because of the pattern produced by the scattered molecules when the membrane is viewed from above

Question 5

Describe the permeability of the cell membrane

Answer 5

Cell membranes have pores in it. Semipermeable, the structure helps it be selective: materials that are soluble in lipids can pass through the cell membrane easily. Small molecules and hydrophobic molecules such as O2, CO2, and H2O also move through easily. Ions and hydrophilic molecules larger than water and large molecules such as proteins do not move through the membrane on their own

Question 6

What are the types of transport across cell membranes?

Answer 6

Passive and active transport

Question 7

What are the types of passive transport?

Answer 7

Diffusion, facilitated diffusion, and osmosis. The cell does not use energy

Question 8

What are the types of active transport?

Answer 8

Protein pumps, endocytosis, and exocytosis. The cell uses energy

Question 9

Describe passive transport

Answer 9

Cell uses no energy, molecules move randomly, molecules spread out from an area of high concentration to an area of low concentration

Question 10

Describe diffusion

Answer 10

The random movement of particles from an area of high concentration to an area of low concentration. Diffusion continues until all molecules are evenly spaced out (equilibrium is reached). At this point, the molecules will continue to move around but stay spread out

Question 11

Describe osmosis

Answer 11

The diffusion of water through a selectively-permeable membrane from high concentration to low concentration. Water is so small and there is so much of it the cell can’t control its movement through the cell membrane

Question 12

What types of solutions can be created when the cell is not in equilibrium?

Answer 12

Isotonic, hypotonic, hypertonic

Question 13

Describe an isotonic solution

Answer 13

The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. As a result, water moves equally in both directions and the cell remains the same size. The net movement of water is zero, or in dynamic equilibrium

Question 14

Describe a hypotonic solution

Answer 14

The intracellular fluid has a higher solute concentration than the extra cellular fluid. As a result, water moves from the ECF into the ICF. The cell swells and bursts open leading to cytolysis. Some water still leaves the solute but little.

Question 15

Describe a hypertonic solution

Answer 15

The extracellular fluid has a higher solute concentration than the ICF. As a result, water moves from the INCF into the ECF, and the cell shrinks leading to plasmolysis

Question 16

What word describes the bursting of a cell due to an excess of water in the ICF?

Answer 16

Cytolysis

Question 17

What word describes the shrinking of a cell due to a lack of water in the ICF?

Answer 17

Plasmolysis

Question 18

How do bacteria and plants deal with osmotic pressure?

Answer 18

Bacteria and plants have cell walls that prevent them from overexpanding. In plants the pressure exerted on the cell wall is called turgor pressure

Question 19

How do protists deal with osmotic pressure?

Answer 19

A protist like paramecium has contractile vacuoles that collect water flowing in and pump it out to prevent them from overexpanding

Question 20

How do animals deal with osmotic pressure?

Answer 20

Animal cells are bathed in blood. Kidneys keep the blood isotonic by removing excess salt and water. Saltwater fish pump salt out at their specialized gills so they do not dehydrate

Question 21

Describe facilitated diffusion

Answer 21

Diffusion of specific particles through transport/tunnel proteins found in the membrane

Question 22

Describe transport proteins

Answer 22

Selective proteins that only let certain molecules cross the membrane. They transport larger or charged molecules such as glucose or amino acids

Question 23

Describe channel proteins

Answer 23

They are embedded in the cell membrane and have a pore for materials to cross

Question 24

Describe carrier proteins

Answer 24

They can change shape to move materials from one side of the membrane to another. Some carrier proteins do not extend through the membrane, they bond and drag molecules through the lipid bilayer and release them on the opposite side