Structure and Function Of Plasma Membranes (Chapter 5)

Question 1

What is the Membrane Structure?

Answer 1

-Phospholipids arranged in a bilayer
-Proteins and cholesterol inserted in the lipid bilayer

Question 2

What are the 4 components of a cell membrane?

Answer 2

• Phospholipid bilayer
  -Transmembrane proteins
  -Surface Proteins
  -Cell surface markers

Question 3

Phospholipids

Answer 3

-Glycerol , a 3- carbon molecule
-2 fatty acids attached to the glycerol (nonpolar and hydrophobic)
-Phosphate group attached to the glycerol (polar and hydrophilic)

Question 4

Facts about phospholipids and membranes

Answer 4

-Saturated fatty acids make the membrane less fluid than unsaturated fatty acids
-Long fatty acids make the membrane less fluid than short fatty acids.
-Most membranes also contain sterols that act as fluidity buffers.

Question 5

Simple diffusion is

Answer 5

An example of passive transport

Question 6

Facilitated Diffusion is

Answer 6

An example of Active transport

Question 7

What is Simple Diffusion?

Answer 7

No energy is required,and hydrophobic molecules move in response to their concentration gradient.

Question 8

The net diffusion of water across a membrane toward a higher solute concentration

Answer 8

Osmosis

Question 9

Osmotic Pressure is

Answer 9

The force needed to stop the osmotic flow

Question 10

Hypertonic, Hypotonic, and Isotonic

Answer 10

-Hypertonic solution has a higher osmotic force
-Hypotonic solution has a lower osmotic force
-Isotonic solutions have the same osmotic force.

Question 11

What is Facilitated Diffusion?

Answer 11

Molecules that cannot cross membrane easily may move through proteins.
-Channel Proteins
-Carrier Proteins.

Question 12

Usually specific to a particular ion or may be gated

Answer 12

Ion channels

Question 13

Can help transport both ions and other solutes, such as some sugars and amino acids AND must bind to the molecules they can transport.

Answer 13

Carrier Proteins

Question 14

What are the 3 different types of carrier proteins?

Answer 14

-Uniporters: move one molecule at a time
-Symporters: move two molecules in the same direction
-Antiporters: move two molecules in opposite directions

Question 15

What is Active Transport?

Answer 15

Requires energy - ATP is used directly or indirectly to fuel active transport
- Requires the use of highly selective carrier proteins

Question 16

This pump is an anti porter that moves 3 Na+ ions out of the cell and 2 K+ ions into the cell for each ATP that is hydrolyzed

Answer 16

Sodium - Potassium Pump

Question 17

What is Indirect (Secondary) Active Transport?

Answer 17

A symporter is used to pump a molecule against its concentration gradient, by using the energy released during the “downhill” movement of another molecule that was previously pumped against its concentration gradient.

Question 18

What are the types of Bulk Transport?

Answer 18

-Endocytosis: movement of substances into the cell
-Phagocytosis- cell takes in particulate matter
-Pinocytosis- cell takes in only fluid
-Receptor-mediated endocyotsis: specific molecules are taken in after they bind to a receptor.

-Exocytosis
-Movement of materials out of the cell
-Used in plants to export cell wall material
- Used in animals to secrete hormones, neurotransmitters