Chapter 5

Question 1

Phospholipid

Answer 1

Phospholipids belong to the lipid family of biological polymers. A phospholipid is composed of two fatty acids, a glycerol unit, a phosphate group and a polar molecule.

Question 2

Amphipathic

Answer 2

An amphipathic molecule is polar at one end and nonpolar at the other. They interact in specific ways when placed in an aqueous environment

Question 3

Hydrophobic

Answer 3

nonpolar substances that are excluded by water and other polar molecules

Question 4

Hydrophilic

Answer 4

Polar molecules that associate readily with water

Question 5

Bilayer

Answer 5

A double layer of phospholipids in which the tails face inwards and are hydrophobic and the phosphate groups face outwards and are hydrophilic. This allows for the membrane to be selectively permeable.

Question 6

Micelle

Answer 6

A sphere composed of a single layer of lipid molecules

Question 7

Fatty acid

Answer 7

One of two components of a neutral lipid, containing a single hydrocarbon chain with a carboxyl group linked at one end.

Question 8

Unsaturated hydrocarbon

Answer 8

hydrocarbons with one or more doubles bonds linking the carbons. This makes the melting point go down.

Question 9

Saturated hydrocarbon

Answer 9

Hydrocarbons with only single bonds linking the carbon atoms. This makes the melting temperature higher.

Question 10

Desaturase

Answer 10

Bacteria, Plants and Animals use desaturase enzymes to alter their membrane fatty acids in response to their environment. A fatty acid desaturase is an enzyme that removes two hydrogen atoms from a fatty acid, creating a carbon/carbon double bond.

Question 11

Sterol

Answer 11

Steroid with a single polar –OH group linked t one end of the ring framework and a complex, nonpolar hydrocarbon chain at the other end.

Question 12

Cholesterol

Answer 12

Cholesterol is also found in the membranes of most animal cells. The presence of cholesterol in plasma membranes has the same affect as double bonds. It disrupts the hydrophobic interactions in the fatty acid tails

Question 13

Integral membrane protein

Answer 13

Integral or Trans-membrane proteins travel all the way across the membrane. They may cross once, twice or many times – depending on the protein being examined

Question 14

Diffusion

Answer 14

The net movement of ions or molecules from a region of higher concentration to a region of lower concentration

Question 15

Transmembrane protein

Answer 15

Transmembrane proteins have a number of important functions in the plasma membrane
They can aid transport of ions and polar molecules or they can help communicate signals from one side to the other

Question 16

Peripheral membrane protein

Answer 16

Extrinsic or Peripheral membrane proteins are more loosely attached
1 & 2 Partly embedded in the membrane
3 protein is anchored by a lipid

Question 17

Cytoskeleton

Answer 17

The interconnected system of protein fibres and tubes that extends throughout the cytoplasm of a eukaryotic cell

Question 18

Selectively permeable

Answer 18

Membranes that selectively allow, impede, or block the passage of atoms and molecules

Question 19

Passive transport

Answer 19

The transport of substances across the cell membranes without expenditure of energy, as in diffusion.

Question 20

Concentration gradient

Answer 20

The concentration difference that dives diffusion

Question 21

Simple diffusion

Answer 21

Mechanism by which certain small substances diffuse through the lipid part of a biological membrane

Question 22

Channel protein

Answer 22

Transport protein that binds a specific single solute and transports it across the lipid bilayer

Question 23

Gated channel

Answer 23

Ion transporter in a membrane that switches between open, closed, or intermediate states.

Question 24

Carrier proteins

Answer 24

Transport protein that binds a specific single solute and transports it across the lipid bilayer

Question 25

Uniport

Answer 25

A uniporter is an integral membrane protein that is involved in facilitated diffusion. They can be either ion channels or carrier proteins. Uniporter carrier proteins work by binding to one molecule of substrate at a time and transporting it with its concentration gradient.

Question 26

Osmosis

Answer 26

The passive transport of water through a selectively permeable membrane in response to solute concentration gradients, a pressure gradient, or both.

Question 27

Aquaporin

Answer 27

A specialized protein channel that facilitates diffusion of water through cell membranes

Question 28

Hypotonic

Answer 28

Solution containing dissolved substances at a lower concentration than the cells it surrounds

Question 29

Hypertonic

Answer 29

Solution containing dissolved substances at higher concentrations than the cells it surrounds

Question 30

Isotonic

Answer 30

Equal concentration of water inside and outside cells

Question 31

Active transport

Answer 31

The mechanism by which ions and molecules move against the concentration gradient across a membrane, from the side with the lower concentration to the side with the higher concentration.

Question 32

Active transport pump

Answer 32

A pump which allows for active transport across the cell membrane

Question 33

Primary active transport

Answer 33

Transport in which the same protein that transports a substance also hydrolyzes ATP to power the transport directly

Question 34

Secondary active transport

Answer 34

Transport indirectly driven by ATP hydrolysis

Question 35

Proton/H+ pump

Answer 35

Pump that moves hydrogen ions across membranes and pushes hydrogen ions across the plasma membrane from the cytoplasm to the cell exterior.

Question 36

Calcium pump

Answer 36

Pump that pushes calcium from the cytoplasm to the cell exterior and from the cytosol into the vesicles

Question 37

Sodium-potassium pump

Answer 37

a pump which pushes 3 Na+ out of the cell and 2 K+ into the cell in the same pumping cycle.

Question 38

Membrane potential

Answer 38

An electrical voltage that measures the potential inside a cell membrane relative to the fluid just outside; it is negative under resting conditions and becomes positive during an action potential

Question 39

Electrochemical gradient

Answer 39

A difference in chemical concentration and electric potential across a membrane

Question 40

Symport

Answer 40

The transport of two molecules in the same direction across a membrane. Also referred to as cotransport.

Question 41

Cotransport

Answer 41

The transport of two molecules in the same direction across a membrane. Also referred to as Symport

Question 42

Exchange diffusion

Answer 42

A secondary active transport mechanism in which a molecule moves through a membrane channel into a cell and powers the transport of a second molecule out of a cell. Also referred to as antiport.

Question 43

Vesicle traffic

Answer 43

can move molecules between locations inside the cell, e.g., proteins from the rough endoplasmic reticulum to the Golgi apparatus. Membrane-bound and secreted proteins are made on ribosomes found in the rough endoplasmic reticulum.

Question 44

Endocytosis

Answer 44

In eukaryotes, the process in which molecules are brought into the cell from the exterior involving a bulging in of the plasma membrane that pinches off to form a endocytic vesicle.

Question 45

Bulk-phase endocytosis

Answer 45

Mechanism by which extracellular water is taken into a cell together with any molecules that happen to be in solution in the water. Also referred to as pinocytosis.

Question 46

Pinocytosis

Answer 46

Mechanism by which extracellular water is taken into a cell together with any molecules that happen to be in solution in the water. Also referred to a bulk-phase endocytosis.

Question 47

Receptor-medoated endocytosis

Answer 47

The selective uptake of macromolecules that bind to cell surface receptors concentrated in clathrin-coated pits.

Question 48

Coated pit

Answer 48

A depression in the plasma membrane that contains receptors for macromolecules to be taken up by endocytosis

Question 49

Clathrin

Answer 49

The network of proteins that coat and reinforce the cytoplasmic surface of cell membranes

Question 50

Phagocytosis

Answer 50

Process in which some types if cells engulf bacteria or other cellular debris to break them down

Question 51

Exocytosis

Answer 51

In eukaryotes, the process by which a secretory vesicle fuses with the plasma membrane and releases the vesicle contents to the exterior.