Module 1: Principles of Cell Function

Question 1

Phospholipids have a _______ head

Answer 1

Hydrophilic phosphate

Question 2

Phospholipids have two _________ tails

Answer 2

Hydrophobic hydrocarbon

Question 3

Phospholipids are _________ molecules, meaning they have both hydrophilic regions and hydrophobic regions

Answer 3

Amphipathic

Question 4

__________ phospholipids cause increased fluidity of the membrane

Answer 4

Unsaturated

Question 5

__________ phospholipids have no double bonds, so their tails are straight and are not kinked

Answer 5

Saturated

Question 6

Unsaturated phospholipids have kinked tails which prevent tight packing, thereby increasing _________

Answer 6

Membrane fluidity

Question 7

____________ phospholipids have kinked tails due to double bonds between carbon atoms

Answer 7

Unsaturated

Question 8

In addition to proteins and lipids, membranes contain _________

Answer 8

Cholesterol

Question 9

Cholesterol is important for ____________

Answer 9

Buffering the fluidity of membranes

Question 10

Membrane fluidity increases as you _________ temperature

Answer 10

Increase

Question 11

Decreasing temperature causes membrane to become ______ fluid

Answer 11

Less

Question 12

All proteins are made up of _________

Answer 12

Amino acids

Question 13

Integral proteins

Answer 13

Proteins inside a membrane

Question 14

Peripheral proteins

Answer 14

Proteins inside and outside of the cell that participate in signalling functions or catalyse enzymatic reactions

Question 15

Glycoproteins

Answer 15

Protein with carbohydrate attached to it

Question 16

Six major functions of membrane proteins

Answer 16

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

Question 17

Signal transduction

Answer 17

Membrane receptor proteins receive a signalling molecule from the outside and transduce a signal response on the inside of the cell

Question 18

Cell-cell recognition

Answer 18

Two different proteins on two different cell membranes interact

Question 19

Intercellular joining (cell-cell adhesion)

Answer 19

When cell adhesion molecules on the surfaces of adjacent cell membranes bind to each other, forming a connection between the two cells

Question 20

Without effective ____________, cells would remain isolated, and complex multicellular structures (like tissues and organs) couldn’t form properly

Answer 20

Intercellular joining

Question 21

Lipid bilayers are not permeable to _______such as K+, Na+, Ca2+ & Cl-

Answer 21

Ions

Question 22

Lipid bilayers are not permeable to small hydrophilic molecules like ____________

Answer 22

Glucose and fructose

Question 23

Lipid bilayers are not permeable to macromolecules like __________

Answer 23

Proteins and RNA

Question 24

Passive transport

Answer 24

Diffusion of a substance across a membrane with no energy investment

Question 25

Diffusion

Answer 25

Passive movement of particles from an area of high concentration to an area of low concentration until equilibrium is reached

Question 26

What happens to concentration gradients during diffusion?

Answer 26

Diffusion eliminates concentration gradients (differences in concentration) by equalizing concentrations across a space. At equilibrium, there is no net movement of particles, though they continue to move randomly

Question 27

Osmosis

Answer 27

Diffusion of water through a selectively permeable membrane into another aqueous compartment containing non-permeant solute at a higher concentration

Question 28

During osmosis, if there is a solute in a solution that cannot cross the membrane because the membrane is not permeable to it (e.g. an ion), _________will move instead to balance out the concentration

Answer 28

The water

Question 29

Osmotica

Answer 29

Solutes that are osmotically active. They can’t freely cross a membrane and therefore cause water to move across it by osmosis

Question 30

Osmotically active

Answer 30

Osmotically active substances draw water across a semipermeable membrane because it cannot move freely itself. This creates osmotic pressure

Question 31

Examples of osmotica

Answer 31

Ions, sugars, proteins, nutrients (things that can't cross the cell membrane)

Question 32

Molecules that can pass through cell membrane

Answer 32

Hydrophobic molecules (benzene & halothane), very small neutral molecules (oxygen & carbon dioxide)

Question 33

Membrane can let small amount of _______ through, but not large amounts

Answer 33

Water

Question 34

Particles that can't cross cell membrane

Answer 34

Polar organic molecules, sugar, ions (H+, Na+, K+, Ca2+, Cl-), proteins, large molecules

Question 35

Tonicity

Answer 35

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

Question 36

Isotonic solution

Answer 36

Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane

Question 37

Hypertonic solution

Answer 37

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

Question 38

Hypotonic solution

Answer 38

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

Question 39

Facilitated diffusion

Answer 39

Passive transport aided by proteins

Question 40

In ____________, transport proteins speed up the passive movement of molecules across the plasma membrane

Answer 40

Facilitated diffusion

Question 41

Facilitated diffusion doesn't require ______ and is a passive process

Answer 41

Energy

Question 42

Transport proteins

Answer 42

Proteins that allow passage of hydrophilic substances across the membrane

Question 43

Aquaporins and ion channels________

Answer 43

Transport proteins that open or close in response to a stimulus

Question 44

Carriers or transporters ______

Answer 44

Bind to molecules and change shape to shuttle them across membrane

Question 45

Transmembrane proteins ____________

Answer 45

form "pores" through which ions and molecules can pass

Question 46

Active transport occurs ____________ a concentration gradient

Answer 46

Against

Question 47

Passive transport occurs __________ a concentration gradient

Answer 47

Down

Question 48

Active transport uses _______ to move solutes against their gradients

Answer 48

Energy

Question 49

Electrogenic pump

Answer 49

Transporter that generates voltage across a membrane

Question 50

The ____________ pump is the major electrogenic pump of animal cells

Answer 50

Sodium-potassium

Question 51

The main electrogenic pump of plants, fungi, and bacteria is a _________

Answer 51

Proton pump

Question 52

Cotransport

Answer 52

Occurs when active transport of a solute indirectly drives transport of another solute

Question 53

Phagocytosis

Answer 53

Large particles are engulfed

Question 54

Pinocytosis

Answer 54

Coated pits form on the membrane and invaginations bring solutes inside

Question 55

Two types of local signalling

Answer 55

Paracrine signalling and synaptic signalling

Question 56

Paracrine signalling

Answer 56

A signalling celll acts on nearby target cells by secreting molecules of a local regulator

Question 57

Synaptic signalling

Answer 57

A nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell, such as a muscle or another nerve cell

Question 58

Endocrine (hormonal) signalling

Answer 58

Specialised endocrine cells secrete hormones into body fluids, often blood. Hormones reach most body cells, but are bound by and affect only some cells

Question 59

3 stages of cell signalling

Answer 59

Reception, transduction & response

Question 60

G protein-coupled receptors

Answer 60

interact with heterotrimeric G proteins to control the activity of enzymes, ion channels, and intracellular signal transduction pathways

Question 61

Kinases

Answer 61

Enzymes that phosphorylate their substrates and can activate target proteins

Question 62

What happens when a signalling molecule binds to an RTK?

Answer 62

The binding causes two RTKs to join (dimerise) and activate their kinase regions, which add phosphate groups to each other (phosphorylation)

Question 63

What happens after RTKs are phosphorylated?

Answer 63

Relay proteins attach to the phosphorylated RTKs and start a chain of reactions that lead to cellular response

Question 64

When something is phosphorylated, a ________

Answer 64

Phosphate group is added