Chapter 7

Question 1

Fluid mosaic model

Answer 1

Consists of phospholipids arranged in a bilayer (fluid) and various proteins inserted in the lipid bilayer (mosaic of proteins)

Question 2

Fluidity of membranes

Answer 2

Membranes are held together mainly by weak hydrophobic interactions.

Question 3

Membrane structure

Answer 3

As temps cool, membranes become less fluid and more solid. Fluidity depends on the types of lipids.

Question 4

Cholesterol within the animal cell membrane

Answer 4

Cholesterol reduced membrane fluidity at moderate temperatures, but at low temperatures hinders solidification

Question 5

Membrane proteins and their functions

Answer 5

Membranes contains a variety of different proteins, embedded in the fluid matrix of the lipid bilayer. Proteins determine most of the membranes specific functions

Question 6

Peripheral proteins

Answer 6

Bound to the membrane surface

Question 7

Integral proteins

Answer 7

Penetrate the hydrophobic core

Question 8

Transmembrane proteins

Answer 8

Integral proteins that span the membrane

Question 9

The hydrophobic regions of an integral protein

Answer 9

Consist of one or more stretches of nonpolar amino acids, often cooled into alpha helices

Question 10

6 major functions of membrane proteins

Answer 10

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

Question 11

The role of membrane carbohydrates in cell-cell recognition

Answer 11

Carbs, on the extra cellular surface of the plasma membrane are used in cell recognition. (Glycolipids and glycoproteins). Membrane carbs vary among species, individuals, and even cell types in an individual.

Question 12

Glycolipids

Answer 12

Membrane carbohydrates covalently bonded to lipids

Question 13

Glycoproteins

Answer 13

Carbs bound to proteins

Question 14

Synthesis and sidedness of membranes

Answer 14

Membranes hace distinct inside and outside faces. The asymmetrical distribution of P, L, and associated carbs in the plasma membrane is determined when the membrane is built by the ER and Golgi apparatus

Question 15

Membrane structure results in selective permeability

Answer 15

Plasma membranes are selectively permeable, regulating the cells molecular traffic

Question 16

Hydrophobic (nonpolar) molecules

Answer 16

Can dissolve in the lipid bilayer and pass through the membrane rapidly

Question 17

Hydrophilic molecules

Answer 17

Including ions and polar molecules do not cross the membrane easily

Question 18

Diffusion

Answer 18

The tendency for molecules to spread out evenly into the available space

Question 19

Membrane structure results in selective permeability

Answer 19

Substances diffuse down their concentration gradient from high to low concentration. No work has to be done to move substances down the concentration gradient

Question 20

Passive transport

Answer 20

The diffusion if a substance across a biological membrane because no energy is expended by the cell to make it happen

Question 21

Osmosis

Answer 21

The diffusion of water across a selectively permeable membrane

Question 22

Effects of osmosis on water balance

Answer 22

Water diffuses across a membrane from the region of lower solute concentration to the region of higher solute concentration 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 solution

Answer 24

Equal solute concentration on both sides of plasma membrane. No net water movement

Question 25

Hypertonic solution

Answer 25

Solute concentration is greater than that inside the cell; cell loses water

Question 26

Hypotonic solution

Answer 26

Solute concentration is less than that inside the cell; cell gains water

Question 27

Osmotegulation

Answer 27

Adaptions to control solute concentrations and water balance, is a necessary adaption for life hypotonic or hypertonic areas

Question 28

Water balance of cells with walls

Answer 28

Cell walls help maintain water balance.

Question 29

Transport proteins

Answer 29

Move hydrophilic substances across the membrane

Question 30

Channel proteins

Answer 30

Have a polar interior allowing polar molecules to pass through

Question 31

Aquaporins

Answer 31

Channel proteins that allow diffusion of water across membranes

Question 32

Carrier proteins

Answer 32

Bind to molecules and change shape to shuttle them across the membrane. Is specific for the substance it moves

Question 33

Facilitated diffusion

Answer 33

A type of passive transport. Both channel and carrier proteins can be forms of this.

Question 34

Passive transport

Answer 34

Diffusion of a substance across a membrane with no energy investment. Molecules move down a concentration gradient

Question 35

Facilitated diffusion

Answer 35

Transport proteins speed the passive movement of molecules across the plasma membrane

Question 36

Channel proteins include

Answer 36

Aquaporins (for water), ion channels (that open or close in response to a stimulus/ gates channels).

Question 37

Carrier proteins

Answer 37

Can help transport both ions and other solutes, such as some sugars and amino acids. Requires a concentration difference across the membrane and must bind to the specific molecule they transport

Question 38

Carrier proteins undergo

Answer 38

A subtle change in shape that trans locates the solute-binding site across the membrane. This change in shape can be triggered by binding and realize of the transportes molecule

Question 39

Active transport

Answer 39

Requires energy (ATP). Nice substances from low to high concentration (against gradient). Requires the use of highly selective carrier proteins

Question 40

Sodium-potassium puño

Answer 40

Active transport mechanism. Pumps 3Na+ out of the cell and 2K+ into cell. Against their concentration gradient

Question 41

Coupled transport

Answer 41

Usura the energy released when a molecule moves by diffusion to supply energy to active transport of a different molecule

Question 42

Bulk transport

Answer 42

Accomplished by endocytosis and exocytosis

Question 43

Endocytosis

Answer 43

Movement of substances into the cell. Cell takes in macromolecules by forming vesicles from the plasma membrane.

Question 44

Exocytosis

Answer 44

Movement is substances out of cell

Question 45

Phagocytosis

Answer 45

The cell takes in particulate matter

Question 46

Pinocytosis

Answer 46

The cell takes in only fluid, including dissolved solutes

Question 47

Receptor-mediated endocytosis

Answer 47

Specific molecules are taken in after they bind to a receptor