Unit 2 Test

Question 1

What are thylakoids?

Answer 1

A membranous system in the form of flattened and interconnected sacs

Question 2

What are the functions of the smooth ER?

Answer 2

1. Synthesize lipids
2. Metabolize hydrates
3. Detoxify drugs/poisons
4. Store calcium ions

Question 3

What organelles are in animal cells but not plant cells?

Answer 3

1. Lysosomes
2. Centrosomes/Centrioles
3. Flagella

Question 4

What organelles are in plant cells but not animal cells?

Answer 4

1. Chloroplasts
2. Central vacuole
3. Cell wall
4. Plasmodesmata

Question 5

What are cristae?

Answer 5

The foldings of the inner, convoluted membrane

Question 6

What are the main functions of intermediate filaments?

Answer 6

1. Maintenance of cell shape
2. Anchorage of nucleus
3. Formation of nuclear lamina

Question 7

What are dyneins?

Answer 7

A motor protein that are attached along each outer microtubule doublet

Question 8

What is an amphipathic molecule?

Answer 8

a molecule containing hydrophobic and hydrophilic regions

Question 9

What is the fluid mosaic model?

Answer 9

A model that states and shows that the plasma membrane is a mosaic of proteins bobbing in a fluid bilayer of phospholipids

Question 10

What happens to membranes when temperatures cool? What controls this reaction?

Answer 10

Membranes switch from a fluid to solid state. A membrane can remain fluid at a lower temperature if it is rich in phospholipids and hydrocarbon tails

Question 11

What are integral proteins?

Answer 11

Proteins that penetrate the hydrophobic interior of a lipid bilayer

Question 12

What are transmembrane proteins?

Answer 12

Integral proteins that span the the membrane

Question 13

What are peripheral proteins?

Answer 13

Proteins that are loosely bound to the surface of a membrane

Question 14

How is the plasma membrane built? What determines the distribution of proteins, lipids and carbs?

Answer 14

The membrane is built by the ER and golgi apparatus, the vesicle becomes the membrane. This is when the asymmetrical distribution of carbs, lipids and protein in the membrane is determined.

Question 15

What are transport proteins?

Answer 15

Proteins that allow hydrophilic substances to cross the membrane

Question 16

What are aquaporins?

Answer 16

Channel proteins that facilitate the passage of water across the membrane

Question 17

Which molecules cross the cellular membrane easily and which ones dont?

Answer 17

Hydrophobic/nonpolar molecules can dissolve in the lipid bilayer and cross it easily. Polar molecules such as sugars do not cross easily

Question 18

What is passive transport?

Answer 18

Diffusion of a substance across a membrane with no energy investment

Question 19

What is osmosis?

Answer 19

The diffusion of water across a selectively permeable membrane

Question 20

What is tonicity?

Answer 20

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

Question 21

What is an isotonic solution?

Answer 21

Solute concentration is the same as inside the cell, no net water movement

Question 22

What is a hypertonic solution?

Answer 22

Solute concentration is greater than inside the cell, the cell loses water

Question 23

What is a hypotonic solution?

Answer 23

Solution concentration is less than inside the cell, the cell gains water

Question 24

What is osmoregulation?

Answer 24

The control of solute concentrations and water balance

Question 25

How do plants use cell walls to maintain water balance?

Answer 25

A plant cell in a hypotonic solution swells until the wall opposes uptake, making the cell turgid(firm). The cell becomes flaccid(limp) in an isotonic solution. In a hypertonic environment, the membrane eventually pulls away from the wall, a usually lethal effect called plasmolysis

Question 26

What is facilitated diffusion?

Answer 26

Passive transport where transport proteins speed the passive movement of molecules across the plasma membrane

Question 27

What are ion channels?

Answer 27

Channel proteins that open or close like a gate in response to a stimulus

Question 28

What is active transport?

Answer 28

Diffusion that uses energy to move solutes against their gradients. It allows cells to maintain concentration gradients that differ from their surroundings

Question 29

What form of energy is used for active transport?

Answer 29

ATP

Question 30

How does the sodium potassium pump work?

Answer 30

1. Cytoplasmic Na+ binds to pump, affinity for Na+ is high 2. Na+ binding stimulates phosphorylation by ATP 3. Phosphorylation leads to a change in protein shape, reducing affinity for Na+ which is pinched off on the outside 4. The new shape has a high affinity for K+, which binds on to the extracellular side of the pump where he Na+ was released 5. Loss of phosphate to inside of the cell restores its original shape which has a low affinity for k+ and a high affinity for Na* again

Question 31

What is the electrochemical gradient?

Answer 31

The combined chemical(ion's concentration gradient) and electric force(effect of membrane potential on environment) that drives the diffusion of ions across a membrane

Question 32

What is the membrane potential?

Answer 32

The voltage across a membrane, created in the distribution of positive and negative ions

Question 33

What is an electrogenic pump?

Answer 33

A transport protein that generates voltage across a membrane. These pumps help store energy that can be used for cellular work(active transport)

Question 34

What is cotransport?

Answer 34

When active transport of a molecule indirectly drives transport of other solutes(active and passive transport)

Question 35

What is a proton pump?

Answer 35

The main electrogenic pump of plants, fungi and bacteria(active)

Question 36

What type of transport is a sodium-potassium pump?

Answer 36

electrogenic pump

Question 37

How does endocytosis occur?

Answer 37

The cell forms new vesicles on the plasma membrane to take in particles

Question 38

What are the 3 types of endocytosis?

Answer 38

Phagocytosis: eating Pinocytosis: drinking Receptor mediated endocytosis: taken in by protein receptors