Cell Biology & Cellular Transport (Quiz 1)

Question 1

What are the 3 main components of cells?

Answer 1

-cell membrane (plasma membrane or plasmalemma)
-cytoskeleton
-nucleus

Question 2

What molecule is in the phospholipid bilayer of the plasma membrane that provides rigidity and keeps it fluid?

Answer 2

cholesterol

Question 3

carbohydrates and proteins form…..

Answer 3

glycoproteins

Question 4

carbohydrates with lipids form….

Answer 4

glycolipids

Question 5

What are the 6 functions of the plasma membrane?

Answer 5

1) providing a selectively/semi-permeable barrier
2) transporting solutes
3) transporting macromolecules
4) responding to external signals (binding/recognizing)
5) intercellular interaction
6) energy transduction

Question 6

What are the 3 major transport mechanisms?

Answer 6

1) simple diffusion
2) channels
3) carrier/pump

Question 7

Diffusion transports __________, _____________ molecules directly through the lipid bilayer. Lipophilic (fat-soluble) molecules diffuse through membranes readily, water very slowly

Answer 7

Small, nonpolar

Question 8

____________ and small nonpolar/uncharged molecules can cross membranes by simple diffusion

Answer 8

Lipophilic

Question 9

Diffusion is the movement of _________ ions or molecules from the higher conc. to lower conc. of the same solute in the solution

Answer 9

Small

Question 10

Is the movement for diffusion up or down a concentration gradient?

Answer 10

Down a concentration gradient

Question 11

What factors affect the diffusion rate?

TEST Q

Answer 11

-distance
-gradient
-temp
-shape
-size (smaller is easier to get through membrane)
-charge (nonpolar = no charge is easier to get through membrane)

Question 12

Osmosis is the diffusion of water across a selectively permeable membrane from a ________ conc. to one with _________ water conc

Answer 12

Higher, lower

Question 13

What is high water?

Answer 13

Pure h2O

Minerals in water = low water

Question 14

__________ ___________ is the force required to prevent the movement of water across a selectively permeable membrane

Answer 14

Osmotic pressure

Question 15

The tonicity of fluid explains the extracellular or intracellular environment?

Answer 15

extracellular environment

Question 16

What are the 3 types of osmotic solutions?

Answer 16

hypotonic
hypertonic
isotonic

Question 17

Are channels always gated?

Answer 17

no, only sometimes

Question 18

Channels are multipass proteins forming transmembrane pores through which ions or small molecules pass selectively. Cells open and close specific channels for _____, ______, ______ and other ions in response to various physiological stimuli

Answer 18

Na+, K+, Ca+2

Question 19

Diffusions, channels, and carriers are all ___________ transport

TEST Q

Answer 19

PASSIVE

Question 20

Membrane pumps are enzymes engaged in active transport, utilizing energy from the hydrolysis of ATP to move ions and other solutes across membrane often referred to as….

Answer 20

ATPases

Question 21

Why would a cell use energy to move something?

Answer 21

-go against conc. gradient (go from low to high conc.)
-size, shape, and charge
-BULK transport (move lots quickly)
-establish a gradient

Question 22

How are larger molecules (macromolecules) transported in and out of cell?

Answer 22

through vesicles (active transport)

Question 23

When molecules bind to receptors and are pinched off and brought into a cell, this is termed as endocytosis. What are the 3 types of endocytosis?

Answer 23

phagocytosis, pinocytosis, and receptor mediated endocytosis

Question 24

Phagocytosis brings in what into the cell?

Answer 24

particles, solids, and/or prokaryotes

phagocytosis = “cell eating”

Question 25

Pinocytosis is bringing what into the cell?

Answer 25

fluids and dissolved contents

pinocytosis = “cell drinking”

Question 26

Receptor mediated endocytosis is where integral membrane proteins have high affinity receptors for _______ and ________ and will bind and pinch off the membrane

Answer 26

lipids, proteins

note: the formation and fate of vesicles in receptor mediated endocytosis depends on specific peripheral proteins on the cytoplasmic side of the membrane

each receptor here is like a lock and key with molecules (not all molecules fit into each receptor)

Question 27

Endocytosis-

Ligands bind with high affinity to specific surface receptors, which then associate with specific cytoplasmic proteins, including __________ and adaptor proteins and aggregate in membrane regions to form coated pits. ____________ facilitates invagination of the pits and ___________ forms constricting loops around the developing neck of the pit causing the invagination to pinch off as a coated vesicle.

Answer 27

clathrin, Clathrin, dynamin

Question 28

Movement of large molecules from inside to outside of the cell usually involves vesicular transport in the process of…..

Answer 28

exocytosis

Question 29

Exocytosis is triggered in many cells by a transient increase in cytosolic….

Answer 29

calcium (Ca+2)

Question 30

During exocytosis the membrane is returned to the cell surface. This process of membrane movement and recycling is called….

Answer 30

membrane trafficking

Question 31

Exocytosis of macromolecules made by cells occurs via either of two pathways. What are they?

Answer 31

constitutive secretion or regulated secretion

Question 32

What is constitutive secretion (exocytosis)?

Answer 32

products are released from cell continuously as soon as synthesis is complete

Question 33

What is regulated secretion (exocytosis)?

Answer 33

occurs in response to signals coming to the cells

Question 34

How many families of receptors are there to detect and respond to extracellular molecules and physical stimuli?

Answer 34

25

Question 35

Cells bearing receptors for a specific ligand are referred to as _______ cells for that molecule

Answer 35

target

Question 36

In endocrine signaling, the signal molecules (a _____________/chemical messenger) are carried in the blood from their sources to target cells throughout the body

Answer 36

hormone

Question 37

In paracrine signaling, the _________ ligand diffuses in extracellular fluid but is rapidly metabolized so that its effect is only local on target cells near its source (cannot diffuse very far)

Answer 37

chemical

Question 38

In synaptic signaling, neurotransmitters act on adjacent cells through specific contact areas called…..

Answer 38

synapses

Question 39

T/F: In autocrine signaling, signals bind receptors on the same cells that produced the messenger molecule

Answer 39

true

Question 40

In ____________ signaling, important in early embryonic tissue interactions, the signaling molecules are cell membrane bound proteins, which bind to surface receptors of the target cell when the 2 cells make direct physical contact.

Answer 40

juxtacrine

Note: also used in epithelial tissues