Chapter 7

Question 1

Ampiphatic

Answer 1

A molecule containing both hydrophilic and hydrophobic areas

Question 2

What does the fluid mosaic model state?

Answer 2

That the membrane is a fluid structure with various proteins embedded into it

Question 3

Why can phospholipids move within bilayer?

Answer 3

Hydrophobic interactions are weak

Question 4

What are the two kinds of phospholipid movements?

Answer 4

Lateral (more often) and flip-flop

Question 5

Why do phospholipids in membrane move around?

Answer 5

Create heat to prevent solidification

Question 6

A membrane is fluid in ______ conditions

Answer 6

warmer

Question 7

Cells in colder climates have more ______ to prevent ________

Answer 7

unsaturated hydrocarbon tails

solidificiation

Question 8

How is cholesterol a buffer in both high and low temperatures?

Answer 8

High: cholesterol makes bilayer less fluid by restraining phospholipid movement
Low: cholesterol hinders close packing of proteins, lowering temperature required for solidification

Question 9

What determines the function of the membrane?

Answer 9

Proteins

Question 10

Integral proteins

Answer 10

Proteins that penetrate through whole bilayer

Question 11

Peripheral proteins

Answer 11

Proteins loosely binded to membrane surface

Question 12

Transmembrane proteins

Answer 12

Peripheral proteins that span membrane

Question 13

What does the hydrophobic region of integral proteins consist of?

Answer 13

1 or more stretches of non polar amino acids coiled into alpha helices

Question 14

Major functions of membrane proteins

Answer 14

Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton and extracellular matrix

Question 15

How do cells recognize eachother?

Answer 15

By binding to surface molecules (often carbs) on membrane

Question 16

Membrane carbs may be bonded to ______, creating _______, or more commonly bonded to _______, creating ____________

Answer 16

• bonded to lipids, forming glycolipid

- bonded to proteins, forming glycoprotein

Question 17

Exchange of material with surroundings is controlled by what?

Answer 17

Membrane

Question 18

______ molecules can pass through membrane easily

Answer 18

Hydrophobic

Question 19

List hydrophobic molecules that can pass through membrane

Answer 19

Carbon dioxide, oxygen, hydrocarbons

Question 20

_____ molecules can not cross membrane easily

Answer 20

Polar

Question 21

List some molecules that cannot pass membrane easily

Answer 21

Sugar, water

Question 22

What allows passage of hydrophilic substances

Answer 22

Transport proteins

Question 23

Transport proteins

Answer 23

Allows passage of hydrophilic substances

Question 24

Channel proteins

Answer 24

Transport protein with hydrophilic channel that certain molecules and ions can use as a tunnel

Question 25

Aquaporin

Answer 25

Channel protein that facilitates passage of water

Question 26

Carrier proteins

Answer 26

Transport proteins that bind to molecules and change shape to shuttle across membrane

Question 27

Transport protein is specific to _______

Answer 27

substance that it moves

Question 28

Diffusion

Answer 28

Tendency for molecules to spread out evenly into available space

Question 29

Rule of diffusion

Answer 29

Diffusion of population exhibits net movement in one direction

Question 30

Dynamic equilibrium

Answer 30

where as many molecules cross one way as the other way

Question 31

Concentration gradient

Answer 31

Difference in concentration of substance from one area to another

Question 32

Osmosis

Answer 32

Diffusion of water across selectively permeable membrane

Question 33

Tonicity

Answer 33

Ability of a solution to cause cell to gain/lose water

Question 34

What does tonicity depend on?

Answer 34

The concentration of solutes that cannot cross the membrane

Question 35

Osmoregulation

Answer 35

Control of water balance necessary for adaption to life in hypertonic/hypotonic conditions

Question 36

What's special about the Paramecium?

Answer 36

Pond is hypotonic to cell (water moves into cell), so it has contractile vacuole that acts as a pump

Question 37

Plant cell in hypotonic solution is calledf

Answer 37

Turgid

Question 38

Plant cell in hypertonic solution causes lethal effect called....

Answer 38

Plasmolysis

Question 39

Facilitated diffusion

Answer 39

Passive transport quickened by aid of transport proteins

Question 40

Facilitated diffusion, what do channel proteins do?

Answer 40

- Provide corridors for molecules/ions to move across | - Aquaporins and ion channels

Question 41

Active transport

Answer 41

Movement of substances against concentration gradient, requiring energy

Question 42

Active transport is performed by what?

Answer 42

Carrier proteins

Question 43

What does active transport allow for cell to do?

Answer 43

Maintain concentration gradient different from surroundings

Question 44

What does the sodium-potassium pump do?

Answer 44

Exchanges sodium for potassium across membrane to maintain steep concentration differences

Question 45

How do large molecules cross in bulk?

Answer 45

Packaging into vesicles, requiring energy

Question 46

Exocytosis

Answer 46

Transport vesicles migrate to membrane, fuse, and release contents

Question 47

In which cells is exocytosis useful?

Answer 47

Secretory cells (to export products)

Question 48

Endocytosis

Answer 48

Cells take in macromolecules by forming vesicles from plasma membrane

Question 49

Types of endocytosis

Answer 49

Phagocytosis, pinocytosis, receptor-mediated endocytosis

Question 50

Phagocytosis

Answer 50

Cell engulfs particle in a vacule

Question 51

How is the vacuole created in phagocytosis digested?

Answer 51

When fused with lysosomes

Question 52

Pinocytosis

Answer 52

Cell gulps droplets of extracellular fluid into tiny vesicles

Question 53

Receptor-mediated endocytosis allows...

Answer 53

Allows human cells to take cholesterol in for use in synthesis of membranes/steroids

Question 54

Ligands

Answer 54

Any molecule that binds specifically to receptor site of another molecule

Question 55

Receptor-mediated endocytosis

Answer 55

Binding of ligands to receptor, creating a vesicle

Question 56

Aquaporins speed up....

Answer 56

Rate at which water reaches water potential equilibrium