Cell Membranes and Signaling CH5

Question 1

Fluid Mosaic Model

Answer 1

Phospholipid bilayer contains proteins which can move

Question 2

Membrane Protein Functions…

Answer 2

1. Move materials through the membrane

2. Receive chemical signals from the cell’s external environment

Question 3

Membrane Fluidity is affected by…

Answer 3

1. Lipid Composition - cholesterol/long chain fatty acids make membranes less fluid - decreases cell activity
2. Temperature

Question 4

Peripheral Membrane Proteins

Answer 4

Lack exposed hydrophobic groupos and are not embedded in the bilayer
Have polar/charged regions that interact w/ exposed parts of integral membane proteins or w/ polar heads of phospholipids

Question 5

Integral Membrane Proteins

Answer 5

At least partly embedded in the phos. bilayer

Have both hydrophilic and hydrophobic regions

Question 6

Anchored Membrane Proteins

Answer 6

Hydrophobic lipid components anchor them in phos. bilayer

Question 7

Transmembrane Protein

Answer 7

An integral membrane protein that extends all the way through the phos. bilayer and protrudes on both sides

Question 8

Glycolipid

Answer 8

Carbohydrate covalently bonded to a lipid

Extend outside the cell surface, serve as recognition signal for interactions between cells

Question 9

Glycoprotein

Answer 9

Carb covalently bonded to protein
Function as signaling sites (like glycolipids)
Can cause cells to adhere to eachother (cell-cell adhesion)

Question 10

Passive Transport

Answer 10

Does not require direct input of metabolic energy
Moves WITH concentration gradient
1. Simple Diffusion
2. Facilitated diffusion

Question 11

Active Transport

Answer 11

Requires input of metabolic (chemical) energy from an outside source
Moves AGAINST concentration gradient
1. Primary Active Transport
2. Secondary Active Transport

Question 12

Hypertonic

Answer 12

More solute outside of the cell, water moves out of the cell

Question 13

Hypotonic

Answer 13

More solute inside the cell, water moves into the cell

Question 14

Channel Proteins

Answer 14

1. An integral membrane protein that allows certain substances to pass (water/AA’s/ sugars/ions)
2. Speed up diffusion through phos. bilayer
3. Form of facilitated diffusion

Question 15

Gated Channels

Answer 15

Open when a stimulus causes a change in the 3D shape of a channel

Question 16

Ligand

Answer 16

Stimulus for the opening of gated channels –> Ligand Gated Channels

Question 17

Voltage Gated Channels

Answer 17

Opening of channel is stimulated by a change in the voltage across the membrane

Question 18

Aquaporins

Answer 18

Allow large amounts of water to move along its concentration gradient

Question 19

Primary Active Transport

Answer 19

Involves the direct hydrolysis of ATP which provides the energy required for transport

Question 20

Secondary Active Transport

Answer 20

Does not use ATP directly

Energy is supplied by an ion concentration gradient or an electrical gradient established by primary active transport

Question 21

Autocrine

Answer 21

signals bind to receptors on the same cell that secretes them

Question 22

Paracrine

Answer 22

signals bind to receptors on nearby cells

Question 23

Signal Transduction pathway

Answer 23

A sequence of molecular events and chemical reactions that lead to a cell’s response to a signal

Question 24

Hormones

Answer 24

Signals sent to distant cells that travel through the circulatory system

Question 25

Allosteric Regulation

Answer 25

Involves an alteration in the 3D shape of a protein as a result of the biding of another molecule at a site other than the proteins active site

Question 26

When ligand binds and causes a conformation change that initiates the cellular response, the ligand is behaving as an…

Answer 26

Allosteric regulator

Question 27

Cytoplasmic Receptors

Answer 27

Small/Nonpolar ligands that diffuse through the plasma membrane and bind to receptor w/in the cytoplasm

Question 28

Membrane Receptors

Answer 28

Large/Plar ligands that cannon cross the lipid bilayer

Question 29

Protein Kinase Receptors

Answer 29

Involve the phosphorylation of a target protein

Question 30

3 Units of G proteins

Answer 30

1. The Receptor
2. GDP/GTP
3. An effector protein

Question 31

Secondary Messengers

Answer 31

Can stimulate signal transduction, amplification

cAMP

Question 32

3 important responses

Answer 32

1. Opening of Ion Channels
2. Alterations in gene expression
3. Alteration of enzyme activities