Quiz 2

Question 1

What is a Membrane’s function?

Answer 1

It works as a barrier to keep some things in and some things out; they are ubiquitous(found everywhere)

Question 2

What exists inside and outside of the cell?

Answer 2

The extracellular space(ECS) exists outside of the cell and the cytosol exists inside the cell

Question 3

What makes up the cell/plasma membrane(both parts that keep it together and parts that exist in it)?

Answer 3

• phospholipids(exist in a bilayer)
• cholesterol
• proteins

Question 4

What kinds of proteins exist in the membrane(short list)?

Answer 4

• enzymes
• transporters
• receptors

Question 5

What is the phospholipid bilayer made of?

Answer 5

• hydrophilic heads that exist on the outer and inner edges of the membrane
• hydrophobic chains that exist in the inner part of the phospholipid bilayer
• channels that serve as gates that open or close under different physiological conditions

Question 6

What is the lipid bilayer permeable and impermeable to?

Answer 6

permeable: fats and lipids
impermeable: polar molecules

Question 7

What drives ion movement across selectively permeable membranes?

Answer 7

• electrostatic attraction
• diffusion

Question 8

What is equilibrium potential and how is it maintained?

Answer 8

• the equilibrium of both the concentration of molecules across a membrane along with the charge across a membrane
• As the molecules diffuse across a membrane, the membrane potential will change, so this is then balanced by electrostatic attraction

Question 9

What are the differences between resting membrane potential and equilibrium potential?

Answer 9

There is none!

Question 10

What is the Resting Membrane Potential(value)?

Answer 10

It is approximately 65 mV

Question 11

What is a channel?

Answer 11

A transmembrane protein that allows passage for polar molecules

Question 12

How do you classify channels?

Answer 12

They are classified based on how you open them

Question 13

What are the four types of gates?

Answer 13

• Ligand-gated channel
• Phosphorylation-gated channel
• Voltage-gated channel
• Mechanically-gated

Question 14

What is the mechanism for a Ligand-gated channel?

Answer 14

The channel is closed when a ligand is not bound, but when a ligand is bound to its specific

Question 15

What is the mechanism for a Phosphorylation-gated channel?

Question 16

What is the mechanism for a Voltage-gated channel?

Question 17

What is the mechanism for a Mechanically-gated channel?

Question 18

What is an Agonist vs. an Antagonist?

Answer 18

Agonists facilitate NT effects and Antagonists inhibit NTs effect

Question 19

How can agonists facilitate NT effects?

Answer 19

• facilitate synthesis/release of NT(agonist)
• slow re-uptake - sustain NT in synaptic cleft to allow for more nT reuptake

Question 20

How can antagonists inhibit NT effects?

Answer 20

• eliminate/reduce NT in button(pre-synaptic space)
• destroy NT in cleft via enzyme(the enzyme literally eats up the NTs in the synaptic cleft)

Question 21

What are the differences between small and large signaling molecules?

Answer 21

• small signaling molecules: they are created in the buttons and are stored near the action zones; they are transported slowly, but are fast to be released; vesicles
• large signaling molecules: they are synthesized in the cell body and are stored/ moved throughout the nerve terminal; they are transported faster, but they replenish slower

Question 22

Where are NT/NDs created in the body?

Answer 22

• small molecules and are synthesized near the terminal of the pre-synaptic space as the enzymes for creating these molecules are created in the cell body and slowly transported to the terminal
• large molecules are created in the rough endoplasmic reticulum of the pre-synaptic cell body

Question 23

What is the speed of transfer for small signaling molecules versus large signaling molecules?

Question 24

What are the two types of synapses and their differences?

Answer 24

• chemical synapses: the transfer of other types of particles through exocytosis for further transport through the blood stream; is very large(synaptic cleft is huge)
• electrical synapses: charged particles that are transferred between two next-door cells through gap junctions; usually very fast-paced signaling to maintain a continuous flow of information

Question 25

What is the type of electrical synapse that is an important example for us?

Answer 25

Heart has sinoatrial(SA) node which is a cluster of cardiac pacemaker cells. These cells have a lot of gap junctions creating a kind of “leaky membrane” that was constantly depolarizing these node cells. These high density of gap junctions were called Purkinje fibers; coordinate beating of the heart

Question 26

Steps of cell signaling for chemical synapses

Answer 26

1:Presence of synaptic vesicles which contain signaling molecules (NTs/NMs)
2: Action potential
arrives by depolarizing the membrane, so the membrane potential now changes
3: Change leads to channels opening
4: CA+ ions flow in(this influx is CRUCIAL for chemical synaptic transmission)
5: Ca2+ increase in the cell causes vesicles to fuse with the
plasma membrane and release their contents into the cleft
6-8: The release of a substance
from one cell causes a
change in the adjacent cell
(exocytosis of the synaptic
vesicle)
7-9: A modification of postsynaptic
membrane proteins
(receptors)
10: Larger molecules and peptides are degraded by enzymes
11: smaller molecules and non-peptides are actively transported back to the presynaptic terminal

Question 27

What is a hormone(advanced)?

Answer 27

Chemical messenger signal produced
by glands with internal secretion, which serve to carry signals through the blood to target organs

Question 28

Steroid hormone is…

Question 29

Peptide hormone is…

Question 30

difference between peptide and steroid hormones are…