Lecture 10

Question 1

how do Na+ ions get across the membrane?

Answer 1

Na+ ions move across a membrane by facilitated diffusion through an ion channel protein

Question 2

ATP

Answer 2

adenosine triphosphate;

used to change the conformation of the Na+/K+ pump

Question 3

what type of transport requires energy?

Answer 3

active transport

Question 4

voltage

Answer 4

electrical potentail energy or a separationof opposite charges

Question 5

plasma membrane voltage

Answer 5

polarized

Question 6

Na+ ions moving in cause a change in voltage

Answer 6

depolarization

Question 7

why dont Na+ ions cross all the time

Answer 7

ion channels are gated ( voltage gated channels)

Question 8

Polarized

Answer 8

positive stays out
negative stays in
gate closed

Question 9

depolarized

Answer 9

positive in
negative out
gate open

Question 10

how do neurons send signals

Answer 10

ions move across membranes

Question 11

What makes Na+ want to go from out to in

Answer 11

The Na+ concentration gradient (high to low)

Remember that the 2nd law of thermodynamics says that disorder should increase (entropy increases).

Question 12

How do Na+ ions get across the membrane

Answer 12

Na+ ions move across a membrane by facilitated diffusion through an ion channel protein.

Question 13

How can a neuron fire over & over without running out of Na+ or energy?

Answer 13

Without a [Na+] gradient, a neuron couldn’t fire.)

Question 14

neuron firing

Answer 14

Sodium ion concentration gradient

Ions move across membrane when nerve fires

Ions pumped back across membrane to recharge neuron

Question 15

when a neuron fires

Answer 15

Na+ ions move down their concentration gradient spontaneously

Question 16

A neuron recharges when

Answer 16

Na+ ions are actively pumped against their concentration gradient

Question 17

Fugu Poisoning

Answer 17

Tetrodotoxin is heat-stable and blocks sodium ion channels.

10-45 minutes after ingestion tingling of the tongue and inner surface of the mouth begins.

An ascending paralysis develops, and death can occur within 6-24 hours, after respiratory muscle paralysis.

Question 18

What does the puffer fish neurotoxin tetrodotoxin inhibit?

Answer 18

Channel proteins involved in diffusion

Question 19

Why would this lead to paralysis and death

Answer 19

Neurons can’t fire without a voltage change.

Question 20

How do signals move from one neuron to the next?

Answer 20

Exocytosis is used to move large molecules out of a cell

Question 21

Vesicles

Answer 21

Vesicles containing neurotransmitters move along the cytoskeleton and fuse with the plasma membrane during exocytosis

Question 22

Release of neurotransmitters (NTs) from vesicles

Answer 22

Travel from one neuron & bind to the plasma membrane of the next

Question 23

Acetylcholine

Answer 23

released at neuromuscular junctions

Question 24

Norepinephrine

Answer 24

released from neurons usually to other neuron

Question 25

Ligand-gated ion channel

Answer 25

opens/closes when a signaling chemical (its ligand) attaches, allowing or blocking flow of specific ions

Question 26

Stimulants

Answer 26

cocain, amphetamines, caffine

Question 27

depressants

Answer 27

barbituates, valium

Question 28

toxins

Answer 28

organophosphate pesticides) – inhibit the action of acetylcholinesterase, a neurotransmitter

Question 29

Heart medications (beta blockers)

Answer 29

inhibit ephinephrine mediated sympathetic reactions | Reduce the effect of excitement on heart rate

Question 30

Drugs funciton

Answer 30

Drugs often mimic neurotransmitters (analogs).Drugs bind to NT receptors to open or block them or alter the metabolism of NTs.

Question 31

How do channel proteins, pump proteins, and neurotransmitter receptor proteins get into a cell membrane?

Answer 31

.

Question 32

Nucleus

Answer 32

stores DNA

Question 33

Endoplasmic reticulum

Answer 33

Rough ER makes membranes & secreted (secretory) proteinsSmooth ERlipid synthesis

Question 34

Ribosomes

Answer 34

in the cytoplasm read the RNA instructions & synthesize proteins (manufacturing plants)

Question 35

Golgi Apparatus

Answer 35

protein modification and sorting

Question 36

The secretory pathway

Answer 36

1. Protein is put into RER as ribosome makes it 2. Vesicle buds off RER with protein cargo and delivers it to Golgi where the proteins are modified 3. Vesicle buds off Golgi with protein cargo 4. Vesicle fuses to plasma membrane Secreted proteins are released by exocytosis Membrane bound proteins become part of the cell membrane

Question 37

The cytoskeleton

Answer 37

``` interior framework of the cell A dense network of protein fibers that 1. Supports the shape of the cell 2. Anchors organelles 3. Used in vesicle transport ```

Question 38

Which of the following choices best describes the route of a Na+ channel protein from its production to its final destination in the membrane?

Answer 38

. Rough ER, transport vesicles, Golgi, transport vesicles, cell membrane

Question 39

How does a transport vesicle move from the cell body to the nerve terminal?

Answer 39

Along the cytoskeleton

Question 40

Acetylcholine

Answer 40

Acetylcholine is important in the brain, and at synapses between motor neurons and muscle cells. Acetylcholine excites skeletal muscles. Acetylcholine slows down the heart.

Question 41

Toxins released by black widow spider venom cause an explosive release of acetylcholine from neurons. These toxins cause paralysis by…

Answer 41

Triggering increased exocytosis of the transport vesicles containing acetylcholine.

Question 42

In contrast, toxins produced by Clostridium botulinum (botulism toxin) block the release of acetylcholine from neurons. These toxins work by…

Answer 42

Inhibiting exocytosis of the transport vesicles containing acetylcholine.

Question 43

What is an enzyme?

Answer 43

A protein that catalyzes reactions

Question 44

activation E

Answer 44

energy required to contort molecules so bonds will break

Question 45

Exergonic reactions

Answer 45

release energy;delta G is negative

Question 46

Endergonic reactions

Answer 46

require energy;delta G is positive 

Question 47

what lowers activation energy

Answer 47

Enzymes

Question 48

what kind of energy is ATP

Answer 48

Potential

Question 49

Activation energy vs. coupled reactions

Answer 49

Coupled reactions harness energy from an exothermic reaction to drive an endothermic reaction. Activation energy is the energy required to get any reaction, exothermic or endothermic, to proceed.

Question 50

Inhibitors

Answer 50

Enzymes are not always on.Inhibitors lower the activity (turning off).

Question 51

Amino acid side chains in the center of a cytoplasmic protein will typically be

Answer 51

non-polar

Question 52

The fatty acid tails on a phospholipid are

Answer 52

non-polar

Question 53

What types of amino acids would you expect to find on the outside of a membrane protein?

Answer 53

non-polar

Question 54

Na+ is a charged ion. What types of amino acids would you expect to find lining the channel it passes through?

Answer 54

polar uncharged and polar charged

Question 55

Channel proteins

Answer 55

selective pores in the membrane; amino acids lining ht echannel only allow one type of ion through

Question 56

Although animal cells are always hyperosmotic to fresh water, the [Na+] in an animal cell is about the same as the [Na+] in fresh water. The scud could avoid too much osmosis of water into its cells by

Answer 56

Pumping out Na+ ions by active transport

Question 57

The plant can adapt to a hypotonic solution because its cell walls

Answer 57

Prevent the cell membrane from swelling until it bursts

Question 58

Tay-Sachs Disease

Answer 58

Genetic disorder in which children become mentally retarded and suffer damage to their central nervous system. Caused by a mutation in the lysosomal enzyme hexosaminidase which breaks down lipids called gangliosides in neurons.

Question 59

Lysosomes

Answer 59

are organelles that break down molecules = recycling center

Question 60

The enzyme hexosaminidase normally breaks down lipids called gangliosides found in the membranes of neurons.

Answer 60

smooth ER

Question 61

The enzyme hexosaminidase normally breaks down lipids called gangliosides found in the membranes of neurons. What would happen to the levels of gangliosides in the neurons of children with Tay Sachs disease?

Answer 61

Gangliosides would increase