Rapid Review Biochem, Chapter 3, Membrane Biochem And Signal Transduction

Front 1

What type of lipid is the major lipid component of most membranes?

Back 1

Phospholipids

Front 2

What two type of lipids are found predominantly on the outer leaflet of the ERYTHROCYTE plasma membrane lipid bilayer?

Back 2

1. Phosphatidylcholine
2. Sphingomyelin

Front 3

What two type of lipids are found predominantly on the inner leaflet of the ERYTHROCYTE plasma membrane lipid bilayer? (Phosphatidylcholine, Sphingomyelin, Phosphatidylserine, Phosphatidylethanolamine?)

Back 3

1. Phosphatidylserine
2. Phosphatidylethanolamine

Front 4

What type of lipid is present in BOTH inner and outer leaflets of a cell membrane lipid bilayer?

Back 4

Cholesterol

Front 5

Where/how do carbohydrates exist on cell membranes (extracellular or intracellular?)? What kinds of bonds do they make?

Back 5

Carbs are present only as extracellular moieties covalently linked to some membrane lipids (glycolipids) and proteins (glycoproteins)

Front 6

Does cholesterol increase or decrease cell membrane fluidity?

Back 6

Decreases it. It prevents the movement of fatty acyl chainsq

Front 7

What is another name for a transmembrane protein that spans the entire lipid bilayer?

Back 7

An Integral (intrinsic) Protein

Front 8

What types of proteins are loosely associated with the surface of either side of the cell membrane?

Back 8

Peripheral (extrinsic) proteins

Front 9

What types of proteins are tethered to the inner or outer membrane leaflet by a covalently attached lipid group?

Back 9

Lipid-anchored proteins

Front 10

What are two examples of Integral/Intrinsic/Transmembrane proteins?

Back 10

1. Glucose transporter
2. ATP Synthase

Front 11

Protein kinase C is a ___ protein that is loosely associated with the surface of the ____(outer or inner) membrane

Back 11

1. Peripheral (extrinsic)
2. Inner (cytosolic)

Front 12

Alkaline phosphate is a _____ protein that is anchored to the ____(outer or inner) leaflet of the membrane

Back 12

1. Lipid-anchored
2. Outer

Front 13

RAS and other G-proteins are _____ proteins that are anchored to the ____ (outer or inner?) leaflet of the membrane

Back 13

1. Lipid-anchored
2. Inner

Front 14

Long-chain SATURATED fatty acids ____(increase or decrease) membrane fluidity

Back 14

Decrease membrane fluidity because they interact strongly with each other (lots of hydrophobicity?)

Front 15

Cis UNSATURATED fatty acids ____ (increase or decrease) membrane fluidity

Back 15

Increase membrane fluidity because the cis form (the kinks) disrupt the interaction of the fatty acyl chains

Front 16

Higher temperatures _____ (increase or decrease) membrane fluidity

Back 16

Increase membrane fluidity because they favor a disordered state of fatty acids

Front 17

What restricts lateral movement in the membrane?

Back 17

Cell-cell junctions in the membrane or interactions between membrane proteins and the extracellular matrix

Front 18

What are three gases that can cross lipid bilayers by simple diffusion (without the aid of a membrane protein)?

Back 18

1. O2
2. CO2
3. Nitric Oxide

Front 19

What are 3 small, uncharged polar molecules that can cross lipid bilayers by simple diffusion (without the aid of a membrane protein)?

Back 19

1. Water
2. Ethanol
3. Short-chain neutral fatty acids

Front 20

True or false: Lipophilic molecules, such as steroid hormones, cross lipid bilayers by simple diffusion (without the aid of a membrane protein)?

Back 20

True

Front 21

The rate of diffusion of a molecule through simple diffusion across a cell membrane depends on what two factors?

Back 21

1. The size of the molecule (the smaller it is, the faster it diffuses)
2. The gradient steepness (the steeper, the faster the diffusion)

Front 22

Passive transport across cell membranes is characterized by what two types of diffusion mechanisms?

Back 22

1. Simple diffusion (down the concentration gradient, with no additional energy requirments, but WITHOUT the aid of a membrane protein)

2. Facilitated diffusion (down the concentration gradient, with no additional energy requirments, but WITH the aid of a membrane protein)

Front 23

What is the only difference between simple diffusion and facilitated diffusion?

Back 23

Simple diffusion does not use the aid of a membrane protein, while facilitated diffusion does (but both DO NOT require any additional energy requirements except for a concentration gradient)

Front 24

What are the 3 types of proteins in facilitated diffusion?

Back 24

1. Ion channels
2. Uniport carrier proteins
3. Cotransport proteins (also involved in secondary active transport)

Front 25

The Nicotinic acetylcholine (ACh) receptor in the plasma membrane of skeletal muscle (a Na+K+ channel) that opens on binding of an ACh is an example of what type of facilitated diffusion protein?

Back 25

Ion channel

Front 26

The Na+ independent glucose transporters (GLUTs) are examples of what type of facilitated diffusion protein?

Back 26

Uniport carrier protein

Front 27

The direction of transport by uniporters and cotransport carrier proteins depends on what?

Back 27

The direction of the concentration gradient for the transported molecule

Front 28

What are the two types of Cotransport carrier proteins?

Back 28

1. Symporters (move both transported substances in the same direction)

2. Antiporters (Move the transported substances in opposite directions)

Front 29

The CL-/HCO3- exchange protein in the erythrocyte membrane is an example of what type of facilitated diffusion protein?

Back 29

A cotransport carrier protein, specifically, an antiporter

Front 30

This type of transport moves ions AGAINST their concentration gradients and are supplied with energy by couple ATP hydrolysis. What type of transport is this?

Back 30

Primary active transport

Front 31

The Na+/K+ ATPase pump maintains ___ (high or low) intracellular Na+ and ___ (high or low) intracellular K+ concentrations through what type of transport of the ions?

Back 31

1. Low
2. High
3. Primary Active Transport

Front 32

True or false: Na+/K+ ATPase pumps are located on the plasma membranes of every cell

Back 32

True

Front 33

The Na+/K+ ATPase pump translocates ___ (1, 2, 3, or 4) Na+ ions ___ (out of or into) the cell, and ___ (1, 2, 3, or 4) K+ ions ___(out of or into) the cell

Back 33

1. 3
2. Out of
3. 2
4. Into

Front 34

Name two cardiotonic steroids.

What do they do to the Na+/K+ ATPase pump?

Back 34

1. Digitalis
2. Ouabain

3. They inhibit the Na+/K+ ATPase pump

Front 35

What drug enhances the Na+/K+ ATPase pump and drives K+ from the extracellular compartment into the cell?

Back 35

Albuterol (a bronchodilator that relaxes muscles in the airways and increases air flow to the lungs.
Albuterol is used to treat or prevent bronchospasm in people with reversible obstructive airway disease. Albuterol is also used to prevent exercise-induced bronchospasm.)

Front 36

What drug can cause hypokalemia because of its effects on the Na+/K+ ATPase pump?

Back 36

Albuterol (prevents bronchospasm)

Front 37

The Ca2+ ATPase pump maintains ___ (high or low) cytosolic Ca+ concentrations through what type of transport of the ions?

Back 37

1. Low
2. Primary active transport

Front 38

Why is it important to maintain low cytosolic Ca+ concentrations in cells (i.e., make sure that the Ca2+ ATPase functions properly)?

Back 38

Because cytosolic Ca2+ can activate various enzymes, like phospholipases and caspases (pro-apoptotic enzymes), that lead to irreversible cell damage

Front 39

In tissue hypoxia, the decrease in O2 reaching tissues causes a ____(decrease or increase) in ATP being made, which ___(activates or inhibits?) the Ca2+ ATPase pump and thus causes a/an ___ (increase or decrease) of cytosolic Ca2+

Back 39

1. Decrease
2. Inhibits
3. increase

The increase in cytosolic Ca2+ in the setting of tissue hypoxia activates destructive enzymes in the cell

Front 40

Where is the Ca2+ ATPase located in skeletal muscle?

In what direction does the pump move Ca2+?

Back 40

In the sarcoplasmic reticulum

From they cytosol (which caused muscle contraction) into the sarcoplasmic reticulum (which promotes relaxation).

Front 41

In this type of transport, a cotransport carrier protein moves one substance AGAINST its concentration gradient with energy supplied not by ATP, but by the coupled cotransport of a second substance (usually Na+ or H+) DOWN its concentration gradient. What is this type of transport called?

Back 41

Secondary active transport

Front 42

Since Na+ is more highly concentrated in the extracellular space (because of the Na+/K+ ATPase pump), secondary active transport will usually be pumping sodium ___ (into or out of) cells, down their concentration gradient, to provide energy

Back 42

Into

Front 43

what two ions are usually used to provide energy by going down their concentration gradients in secondary active transport?

Back 43

1. Na+
2. H+

Front 44

What Na+/glucose symporter is located on the apical membranes of kidney tubule epithelial cells and intestinal epithelial cells, which transports glucose and sodium out of the lumen and into the epithelial cells, eventually getting into the blood?

Back 44

SGLUT1

Front 45

What other molecule must be present for sodium to reabsorbed in the small bowel?

Back 45

Glucose

Front 46

What ion must be orally replenished in cholera?

Back 46

Na+

Front 47

What pump, located in the basement membrane of epithelial cells lining the small intestines and renal tubules, maintains an Na+ gradient necessary for the operation of Na+ linked symporters?

Back 47

Na+/K+ ATPase

Front 48

The SGLUT1 protein transports glucose into cells through what type of mechanism?

Back 48

Secondary active transport. It is a Na+/glucose symporter that pushes glucose against its concentration gradient and Na+ down its concentration gradient.

Front 49

In what two types of epithelial cells does the SGLUT1 symporter exist?

Back 49

On the apical membranes (lining the lumen) of intestinal epithelium and kidney tubular epithelium

Front 50

What are the two types of cotransporter carrier proteins we talked about that are used in secondary active transport? (hint: involve glucose, amino acids, and calcium)

Back 50

1. Na+ linked symporters (for glucose and amino acids)
2. Na+ linked Ca+ antiporter

Front 51

In cardiac muscle, what cotransport carrier protein is responsible for maintaining a low cytosolic Ca2+ concentration?

Back 51

Na+ linked Ca2+ antiporter

Front 52

What drug INDIRECTLY inhibits the Na+ linked Ca2+ antiporter? (hint: it directly inhibits the Na+/K+ ATPase pump)

Back 52

Digitalis

Front 53

What two ion transporters in the membrane are inhibited by digitalis (one directly, and one indirectly)?

Back 53

1. Na+/K+ ATPase pump (in ALL cells)
2. Na+ linked Ca2+ antiporter (in cardiac muscle cells) (INDIRECTLY)

Front 54

What is the difference between the Na+ linked Ca2+ antiporter and the Ca2+ ATPase pump, in terms of where they're located?

Back 54

The Na+ linked Ca2+ antiporter is located in cardiac muscle cells (to keep cytosolic Ca2+ concentration down)

The Ca2+ ATPase pump is located in most cells, but in skeletal muscle, it is located in the sarcoplasmic reticulum to induce muscle relaxation by reducing cytosolic Ca2+.

Front 55

In the Na+ linked Ca2+ antiporter of cardiac muscle, how many Na+ must be moved IN to the cell, and how many Ca2+ ions must be moved OUT of the cell?

Back 55

1. Na+ IN = 3
2. Ca2+ OUT = 1

Front 56

Hereditary defects in transport proteins cause what three diseases?

Back 56

1. Cystic Fibrosis
2. Cystinuria
3. Hartnup's disease

Front 57

Increased blood glucose stimulates what type of pancreatic cells to releae insulin?

Back 57

Beta cells

Front 58

What are the most common types of extracellular signals (4 of them. Start with H, G, N, C)?

Back 58

1. Hormones
2. Growth Factors
3. Neurotransmitters
4. Cytokines

Front 59

How can the same hormone have different actions in two different cells, even though the receptors in both types of cells are the same?

Back 59

Because, intracellularly, there are different downstream proteins (the messengers are different, they have different "voices")

Front 60

True or false: Digitalis affects both cardiac and skeletal muscle

Back 60

False, digitalis only affects caridac muscle because in skeletal muscle, Na+ independent Ca2+ pumps are used to increase and decrease cytosolic Ca2+ levels for contracion and relaxation.

Front 61

This hereditary defect of a transport protein is autosomal recessive, and affects the Cl- ATPase pump in lungs, pancreas, intestines, and skin.

Back 61

Cystic Fibrosis

Front 62

This hereditary defect of a transport protein leads to high Na+ and Cl- in sweat and production of highly viscous mucus, which obstructs the airways and the pancreatic and bile ducts.

Back 62

Cystic Fibrosis

Front 63

This hereditary defect of a transport protein causes a dysfunction in exocrine glands, and common symptoms include failure to thrive, malabsorption, and recurrent respiratory infections by Pseudomonas aeruginosa

Back 63

Cystic Fibrosis

Front 64

This hereditary defect of a transport protein is due to an autosomal recessive mutation in a carrier protein that mediates the reabsorption of DIBASIC amino acids from renal tubules.

Back 64

Cystinuria

Front 65

This hereditary defect of a transport protein causes the formation of cystine kidney stones and excessive urinary excretion of dibasic amino acids.

Back 65

Cystinuria

Front 66

This hereditary defect of a transport protein is caused by an autosomal recessive mutation in a carrier protein that mediates intestinal and renal tubular absorption of NEUTRAL amino acids.

Back 66

Hartnup's disease

Front 67

This hereditary defect of a transport protein is clinically marked by pellagra-like symptoms (diarrhea, dermatitis, and dementia) due to impaired absorption of tryptophan, which reduces the synthesis of niacin.

Back 67

Hartnup's disease

Front 68

This hereditary defect of a transport protein is AUTOSOMAL DOMINANT (!) characterized by a lack of functional receptors for low-density lipoprotein.

Back 68

Familial hypercholesterolemia

Front 69

This hereditary defect of a transport protein results in high blood levels of cholesterol, which contributes to premature atherosclerosis and susceptibility to acute myocardial infarctions and stroke at an early age.

Back 69

Familial hypercholesterolemia

Front 70

True or false: Thyroxine and retinoic acid are lipophilic and diffuse through the plasma membrane to receptors in the cytosol

Back 70

False. They bind to receptors in the NUCLEUS. Steroid hormones bind to receptors in the cytosol.