Chapter 4

Question 1

What is the phospholipid bilayer?

Answer 1

Contains hydrophilic (water loving) heads that face the inside and outside of the cell, and hydrophobic (water fearing) tails that face each other, away from the water

Question 2

What are the membrane proteins that are throughout the membrane?

Answer 2

Peripheral proteins which are associated with only one side of the membrane, Integral proteins which span the membrane and can protrude from one or both sides.

Question 3

What are glycolipids?

Answer 3

Lipids that are attached to carbohydrates and provide energy to the cell and aid in cell to cell communication.

Question 4

What are glycoproteins?

Answer 4

Cell recognition proteins that are attached to carbohydrates and can recognize when it is being invaded by pathogens and try to block. The carbohydrates help protein maintain proper shape and solubility.

Question 5

What are channel proteins and what do they do?

Answer 5

They are involved in the passage of solutes through the membrane and they may have a gate that opens in response to a signal. (Mostly for smaller molecules)

Question 6

what are cell recognition proteins?

Answer 6

The major histocompatibility complex glycoproteins are different for each person, so organ implants are difficult to achieve.

Question 7

What are receptor proteins?

Answer 7

They are shaped in a way that a specific molecule can bind to it.

Question 8

What is an enzymatic protein?

Answer 8

It catalyzes a specific reaction, and the membrane protein adenylate cyclase is involved in ATP metabolism.

Question 9

Describe the permeability of the plasma membrane.

Answer 9

It is selectively permeable for molecules that are small in size, and have no polarity or charge.

Question 10

What is a concentration gradient?

Answer 10

Move of a substance on one side of the membrane. Can go down naturally from an area of higher to lower concentration or up unnaturally from an area of lower to higher concentration.

Question 11

What are aquaporins?

Answer 11

Special channels that allow water to cross the membrane and are present in the majority of cells.

Question 12

How do large molecules cross the membrane?

Answer 12

Channel proteins, carrier proteins, and vesicle formation.

Question 13

Explain diffusion

Answer 13

Energy is not required as it happens naturally, it moves down a concentration gradient, and requires a concentration gradient, and it occurs until equilibrium is reached.

Question 14

Explain facilitated transport

Answer 14

Energy is not required, it moves down a concentration gradient, and requires a channel and carrier protein as well as a concentration gradient.

Question 15

Explain active transport

Answer 15

Energy is required, it moves up a concentration gradient, and it requires a carrier as well as energy (usually ATP). The molecules or ions combine with carrier proteins often called pumps.

Question 16

Explain exocytosis

Answer 16

Energy is required, it moves towards the outside, and requires a vesicle to fuse with the plasma membrane

Question 17

Explain Endocytosis

Answer 17

Energy is requires, it moves towards the inside, and requires vesicle formation

Question 18

What factors influence the rate of diffusion

Answer 18

Temperature, electrical currents, molecule size.

Question 19

What is osmosis

Answer 19

The diffusion of water across a differentially permeable membrane, 3 kinds: Hypotonic, Hypertonic, and Isotonic

Question 20

Describe Hypotonic solutions

Answer 20

A solution that has a lower solute concentration than the inside of the cell, the cell gains water. (Turgor pressure)

Question 21

Describe Isotonic solutions

Answer 21

Solute concentration is equal inside and outside the cell, there is no movement

Question 22

Describe Hypertonic solutions

Answer 22

A solution has a higher concentration than the inside of the cell, and the cell loses water. (Lyse)

Question 23

What is a sodium-potassium pump?

Answer 23

For muscle and nerve cells to work, Na+ is pumped out and K+ is pumped in. Since there is already a greater K+ concentration in the cell, goes up/across gradient. ATP is needed.

Question 24

What is bulk transport?

Answer 24

Macromolecules are transported in/out of cells by vesicle formation

Question 25

What is endocytosis

Answer 25

Cells take in substances by vesicle formation, part of the plasma membrane folds to envelope the substance and the membrane pinches off to form an intracellular vesicle. 3 types: Phagocytosis, pinocytosis, and receptor-mediated endocytosis

Question 26

Describe Phagocytosis

Answer 26

Larger, particular matter such as viruses and whole cells

Question 27

Describe pinocytosis

Answer 27

Liquids and small particles dissolved in a liquid like certain blood cells or plant root cells

Question 28

Describe receptor mediated endocytosis

Answer 28

A type of pinocytosis that involves a coated pit like specific placental cells.

Question 29

What are the 2 types of cell surfaces animal cells have

Answer 29

Extracellular matrix on the outside of the cell, and junctions that occur in between the cells.

Question 30

Describe the extracellular matrix

Answer 30

A meshwork of proteins and polysaccharides closely associated with cells that produced them, like a gel that surrounds cells. Polysaccharides made of amino sugars in ECM attach to proteins called proteoglycans which reach into the ECM but can attach to cell membrane.

Question 31

Describe the junctions between cells

Answer 31

Cell surfaces in certain tissues of animals.

Question 32

What are the different types of junctions and describe them.

Answer 32

Adhesion junctions: intercellular filaments between cells, cytoskeleton filaments maintain a short distance between cells, prominent with skin cells.
Tight junctions: proteins usually connect through plasma membranes together. “zipper like”
Gap junctions: plasma membrane channels are joined between cells so the cells can then communicate.