Chapter 7

Question 1

Define Amphipathic

Answer 1

Having both a hydrophilic region and hydrophobic region

Exapmle: phospholipid

Question 2

Integral proteins

Answer 2

Proteins that penetrate the hydrophobic bilateral. Can be transmembrane (spanning the entire membrane) or only partially penetrate the membrane. On cytoplasmic side some proteins attach to cytoskeleton

Question 3

Peripheral proteins

Answer 3

Not embedded in the lipid bilateral. On extra cellular side certain proteins attach to extra cellular matrix.

Question 4

Protein function

Answer 4

Transport
Enzymatic activity
Signal transduction
Cell recognition
Intercellular joining
Attachment to cytoskeleton or extra cellular matrix (ECM)

Question 5

Protein transport (channel and carrier)

Answer 5

Channel:
Transmembrane proteins provide hydrophilic channel across membrane
Carrier:
Proteins will change shape to transport substances from one side to the other

Question 6

Signal transduction for protein

Answer 6

Protein will have binding site with a specific shape that fits the shape of a chemical receptor.

Question 7

Glycolipids and glycoproteins

Answer 7

Membrane carbohydrates that are short, branched chains containing fewer than 15 sugar units these are covanlently bonded to lipids.
Glycoproteins are the the same build but bonded to proteins.

Question 8

What is permeable with the lipid bilayer?

Answer 8

Any molecule small enough and nonpolar can permeate.

Molecules that are polar and hydrophilic can pass at a much slower speed.

Question 9

Transport protein (channel)

Answer 9

Channels function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane.

Question 10

Aquaporins

Answer 10

A transport channel proteins allowing the passage of water molecules through the cell membrane.

Question 11

Transport carrier proteins

Answer 11

The proteins will change shape and hold on to its passenger in a way that shuttles it across the cell membrane

Question 12

Diffusion

Answer 12

The movement of particles of any substance so that they spread out into the available space. All substances will diffuse down its concentration gradient

Question 13

Concentration gradient

Answer 13

In absence of other forces a substance will diffuse from where it is more concentrate to where it is less. No work must be done to make this occur.

Question 14

Passive transport

Answer 14

The diffusion of a substance across a biological membrane where the transportation doesn’t require energy spent

Question 15

Osmosis

Answer 15

The diffusion of free water across a selectively permeable membrane

Question 16

Isotonic

Answer 16

(iso=same) there is no net movement of water across the plasma membrane. Water diffuses across the membrane but at the same rate in both directions.

Question 17

Hypertonic

Answer 17

(hyper=more)

A cell in a hypertonic solution will lose water and shrike and die.

Question 18

Hypotonic

Answer 18

(hypo=less)
A cell in a hypotonic solution will allow water the enter the cell at a faster rate than it leave and the cell will swell and burst. In plant cells however this is merely a swelling of the cell as the cell walls can protect against bursting.

Question 19

Facilitated diffusion

Answer 19

When polar molecules and ions impeded by the lipid bilayer diffuse passively through the membrane with the help of transport proteins spanning the membrane.

Question 20

Gated Channels

Answer 20

Channel proteins that open and close in response to a stimulus

Question 21

Active transport

Answer 21

To pump a solute across a membrane against its concentration gradient requires work and the cell must expend energy

Question 22

Steps to a sodium-potassium pump

Answer 22

1) Cytoplasmic Na+ binds to pump is when protein has a high affinity for Na+ but taking on a certain shape
2) Na+ binding stimulates phosphorylation (ATP)
3) APT leads to a change of shape in the protein reducing its affinity for Na and releasing it
4) This causes the protein to take the shape with an affinity for K+ which binds on the extracellular side and release the phosphate group
5) the lost of the phosphate group restores the protein to original shape and lowers the K affinity
6) K+ is released and the affinity for Na+ increases again

Question 23

Exocytosis

Answer 23

A cell will secrete certain membrane molecules by the fusion of vesicles with the plasma membrane. When the vesicles membrane and plasma membrane come into contact, specific proteins rearrange the lipid molecules of the two bilayer a so that the membranes fuse. The contents of the vehicle spill out f the cells and the vesicle membrane becomes part of the plasma membrane.

Question 24

Endocytosis

Answer 24

Cells will take in molecules and particulate matter by forming new vesicles from the plasma membrane

Question 25

Ligand psych

Answer 25

Any molecule that binds specifically to receptor site on another molecule

Question 26

Phagocytosis

Answer 26

A cell engulfs a particle by extending pseudopod is (lip like) around it and packages it within a membrane sac

Question 27

Pinocytosis

Answer 27

The cell continually gulps droplets of extracellular fluid into tiny vesicles formed by unfolding of the plasma membrane

Question 28

Receptor-mediated Endocytosis

Answer 28

A type of pinocytosis that enables the cell to acquire bulk of quantities of specific substances by utilizing receptors on proteins on the extracellular side of the membrane.