Chapter 5

Question 1

Membranes are composed of _____ and _____

Answer 1

phospholipids and proteins

Question 2

Many phospholipids are made from _______ fatty acids that have kinks in their tails

Answer 2

unsaturated

Question 3

Unsaturated fatty acids in phospholipid bilayer

Answer 3

Prevent them from packing tightly together, which keeps them liquid.

Question 5

Integrins

Answer 5

Give the membrane a stronger framework.

Integrins attach to the extracellular matrix on the outside of the cell as well as span the membrane to attach to the cytoskeleton.

Question 6

Glycoproteins in the membrane

Answer 6

Serve as identification tags that are specifically recognized by membrane proteins of other cells.

Question 7

Carbohydrates in the extracellular matrix

Answer 7

Significantly involved in cell-cell recognition

Question 8

Peripheral proteins

Answer 8

Proteins bound to the surface of the membrane

Question 9

Integral proteins

Answer 9

Proteins that penetrate the hydrophobic core

Question 10

Transmembrane proteins

Answer 10

Integral proteins that span the membrane

Question 11

Six major functions of membrane proteins

Answer 11

1. Transport
2. Enzymatic activity
3. Signal transduction
4. Cell-cell recognition
5. Intercellular joining
6. Attachment to the cytoskeleton and extracellular matrix (ECM)

Question 12

Membrane carbohydrates in cell-cell recognition

Answer 12

Cells recognize each other by binding to molecules, often containing carbohydrates, on the extracellular surface of the plasma membrane.

Membrane carbohydrates may be covalently bonded to lipids (forming glycolipids) or more commonly to proteins (forming glycoproteins).

Carbohydrates on the external side of the plasma membrane vary among species, individuals, and even cell types in an individual.

Question 13

The asymmetrical distribution of proteins, lipids, and associated carbohydrates in the plasma membrane are determined when ______________.

Answer 13

the membrane is built by the ER and Golgi apparatus

Question 14

Glycolipid

Answer 14

A sugar covalently bound to a lipid

Question 15

Glycoprotein

Answer 15

A sugar covalently bound to a protein

Question 16

Because membranes allow some substances of cross or be transported more easily than others, they exhibit ______________

Answer 16

selective permeability

Question 17

Nonpolar molecules (CO2 and oxygen) cross the cell membrane _____

Answer 17

easily

Question 18

Polar molecules (glucose and other sugars) cross the membrane ______

Answer 18

without ease

Question 19

Passive transport

Answer 19

Does not use energy to transport molecules across the membrane

Question 20

Diffusion

Answer 20

A process in which particles spread out evenly in an available space

Particles move from an area of more concentrated particles to an area where they are less concentrated

Eventually, the particles reach equilibrium where the concentration of the particles is the same throughout

Question 21

Concentration gradient

Answer 21

In diffusion, the difference in concentration of particles inside and outside the cell membrane

Question 22

Osmosis

Answer 22

The diffusion of water across a selectively permeable membrane.

Water moves across membranes in response to solute concentration (lower to higher) until the solute concentration is equal on both sides.

Question 23

Tonicity

Answer 23

The ability of a surrounding solution to cause a cell to gain or lose water.

Question 24

Isotonic

Answer 24

Indicates the concentration of a solute is the same on both sides.

Question 25

Hypertonic

Answer 25

Indicates that the concentration of a solute is higher outside the cell.

Question 26

Hypotonic

Answer 26

Indicates a higher concentration of a solute inside the cell.

Question 27

Osmoregulation

Answer 27

The control of solute concentrations and water balance; a necessary adaptation for life in hypertonic or hypotonic environments

Question 28

Contractile vacuole

Answer 28

Acts as a pump for osmoregulation

Question 29

Aquaporins

Answer 29

Special transport proteins that assist in facilitated diffusion, a type of passive transport.

Question 30

Active transport

Answer 30

Requires the expenditure of energy in the form of ATP Moves a solute against its concentration gradient The mechanism alters the shape of the membrane protein through phosphorylation using ATP Ex. the sodium-potassium pump

Question 31

Exocytosis

Answer 31

Used to export bulky molecules, such as proteins or polysaccharides.

Question 32

Endocytosis

Answer 32

Used to import substances useful to the livelihood of the cell.

Question 33

Phagocytosis

Answer 33

A type of endocytosis The engulfment of a particle by wrapping the cell membrane around it, forming a vacuole.

Question 34

Pinocytosis

Answer 34

A type of endocytosis The same as phagocytosis, in which a particle is engulfed by wrapping a cell membrane around it, forming a vacuole, except that it is fluids being taken into small vesicles.

Question 35

Receptor-mediated endocytosis

Answer 35

A type of endocytosis where receptors in a receptor-coated pit interact with a specific protein, initiating formation of a vesicle.

Question 36

Cholesterol in the phospholipid bilayer

Answer 36

Along with phospholipids being composed of unsaturated fatty acids with kinks in their tails, aid in helping phospholipids in the bilayer not be tightly packed together. Also help to keep it liquid at lower temperatures.