Cell Physiology - Topic 3 Slides

Question 1

What are the two types of Intracellular communication?

Answer 1

Direct and Indirect

Question 2

What is the Direct cell communication mechanism?

Answer 2

Gap Junctions

Question 3

What is the Indirect cell communication mechanism?

Answer 3

Chemical messengers

Question 4

What are the two types of chemical messengers?

Answer 4

Lipid soluble and lipid insoluble

Question 5

What is Signal transduction?

Answer 5

The sequence of events between binding of messenger to receptor and the production of a cellular response

Question 6

What are the Properties of Receptors?

Answer 6

• Specificity
• Saturation
• Affinity

Question 7

Where are the two places Receptors can be?

Answer 7

• In the plasma membrane (transmembrane)

* Intracellular (cytosolic, nuclear)

Question 8

What type of messengers do Intracellular membranes bind to?

Answer 8

Lipid soluble messengers like steroid hormones

Question 9

Where do Intracellular receptors bind to receptors?

Answer 9

In the Cytoplasm or Nucelus

Question 10

How do Intracellular receptors alter the transcription of mRNA?

Answer 10

By binding to the Response Element

Question 11

What is the Response Element?

Answer 11

A specific sequence of DNA near the beginning of a gene that alters the rate of protein synthesis

Question 12

What are Gap Junctions?

Answer 12

When transmembrane proteins form channels linking one cell to another

Question 13

What do gap junctions allow for?

Answer 13

Ions and small molecules to move from one cell to another

Question 14

What is Signal Transduction?

Answer 14

The sequence of events between the binding of messenger to its receptor and the production of the cellular response

Question 15

Why don’t chemical messengers affect all cells?

Answer 15

Because they can only affect cells that have receptors to the messenger

Question 16

How might the binding of a chemical receptor to two different messengers affect the response?

Answer 16

There will be two different cell responses depending on which receptor is bound to

Question 17

Where will a chemical messenger bind if it is hydrophilic or lipid insoluble?

Answer 17

Receptors in the plasma membrane

Question 18

What do water soluble chemical messengers bind to?

Answer 18

Receptors on the extracellular surface of the plasma membrane

Question 19

What are some examples of water soluble chemical messengers?

Answer 19

Hormones, neurotransmitters, paracrine/autocrine compounds

Question 20

What are membrane bone receptors usually linked to?

Answer 20

• A Channel
• An enzyme
• G-protein-linked receptors

Question 21

What is the First Messenger?

Answer 21

Extracellular chemical messenger that binds to a specific membrane receptor

Question 22

What is the Second Messenger?

Answer 22

Substance that enter or are generated in the cytoplasm of a cell in response to the binding of an extracellular messenger (first messenger) to receptor

Question 23

What is Protein Kinase?

Answer 23

An enzyme that phosphorylates another protein

Question 24

Where are G-proteins found?

Answer 24

The systolic surface of the plasma membrane

Question 25

What do G proteins bind to?

Answer 25

Guanosine nucleotides (GDP and GTP)

Question 26

What are the 3 subunits of G proteins?

Answer 26

α, β, γ

Question 27

What does the alpha subunit of G protein bind to?

Answer 27

Guanosine nucleotides

Question 28

What is the inactive form of G proteins?

Answer 28

G-GDP

Question 29

What is the active form of G proteins?

Answer 29

G-GTP

Question 30

What are the 3 types of G Proteins?

Answer 30

* Affect ion channels * Stimulatory G proteins * Inhibitory G proteins

Question 31

What do G proteins that affect ion channels do?

Answer 31

Open or close channles

Question 32

What do stimulatory G proteins do?

Answer 32

Activate enzymes

Question 33

What do Inhibitory G proteins do?

Answer 33

Inhibit enzymes

Question 34

What are Paracrine compounds?

Answer 34

Compounds released by one cell which act on neighboring cells near its secretion

Question 35

What are Autocrine compounds?

Answer 35

Compounds secreted into the extracellular fluid and act on the cell that created it

Question 36

What are the three types of receptors that water soluble chemical messengers bind to?

Answer 36

Channel, Enzyme or G-protein coupled receptors

Question 37

What do second messengers do?

Answer 37

Diffuse throughout the cell to surface chemical relays from the plasma membrane to the biochemical machinery inside the cell

Question 38

How do Protein Kinases phosphorylate other proteins?

Answer 38

By transferring a phosphate group to the protein from ATP

Question 39

How does Phosphorylation affect a protein?

Answer 39

The phosphate group is negatively charged so it causes the conformation of the protein

Question 40

What do G-protein coupled receptors activate?

Answer 40

Special membrane proteins called G proteins

Question 41

Where are G proteins found?

Answer 41

On the intracellular side of the plasma membrane (cytosolic surface)

Question 42

What do G-proteins function as a link between?

Answer 42

G protein coupled receptor and the effector protein

Question 43

What is the target of the G protein?

Answer 43

The effector protein

Question 44

What is the Effector protein?

Answer 44

The protein that the G protein will alter the activity of

Question 45

What are the two things that an Effector protein usually is?

Answer 45

An ion channel or an enzyme

Question 46

What do the Beta and Gamma subunit of G-proteins do?

Answer 46

Anchor the alpha subunit in the membrane

Question 47

What does the alpha subunit of the G protein bind to in it inactive state?

Answer 47

GTP

Question 48

What does the Alpha unit bind to in its active state?

Answer 48

GTP

Question 49

What alters the affinity of the Alpha sub unit for GDP?

Answer 49

The binding of an extracellular first messenger

Question 50

How does the alpha subunit on the G protein change in response to the binding of a first messenger to the membrane?

Answer 50

It responds through a conformational change that decreases its affinity for GDP and increases its affinity for GTP

Question 51

What occurs after the alpha subunit of the G protein binds to GTP?

Answer 51

The G protein is activated dissociates from the receptor and the GTP bound alpha subunit separates from the beta and gamma subunits

Question 52

What occurs after the Alpha subunit separates from the Beta and Gamma subunits?

Answer 52

It moves to its target protein in the membrane called, the effector protein

Question 53

What does Alpha subunit of G proteins move to after it has separated from the rest of the G protein?

Answer 53

The effector protein

Question 54

What does the Alpha unit do to the Effector protein?

Answer 54

Alter the activity of this target protein to produce some sort of response in the cell

Question 55

How does the Alpha subunit inactivate?

Answer 55

It hydrolyzes or breaks down GTP to GDP and inorganic phosphate

Question 56

What happens to the Alpha subunit once GTP is converted back to GDP?

Answer 56

The alpha subunit recombines with the other two unit and the G protein combines with the receptor

Question 57

Why does the Alpha Subunit not stay active for long?

Answer 57

Because it has intrinsic GTPase activity

Question 58

What is the meaning of the Alpha subunits intrinsic GTPase activity?

Answer 58

It means that it also functions as an enzyme that hydrolyzes ot breaks down GTP

Question 59

What are Stimulatory G proteins associated with?

Answer 59

Activation of an enzyme

Question 60

What are inhibitory G proteins associated with?

Answer 60

Inhibition of an enzyme

Question 61

Why is G protein activity slow?

Answer 61

Because it has many steps

Question 62

What do G protein catalyzed enzymes do?

Answer 62

Catalyze the production of second messengers in the cell

Question 63

What is the most common second messenger system found in the cells?

Answer 63

Cyclic AMP second messenger system

Question 64

What enzyme does the G protein activate in the Cyclic AMP system?

Answer 64

Adenylyl cyclase

Question 65

Where is the Catalytic site of Adenylyl Cyclase of the AMP messenger system located?

Answer 65

On the cytoplasmic surface of the plasma membrane

Question 66

What happens once the Alpha subunit binds to Adenylyl Cyclase in the Cyclic AMP messenger system?

Answer 66

Adenylyl cyclase catalyzes the conversion of cytosolic ATP into cyclic AMP

Question 67

What is the second messenger in the Cyclic AMP messenger system?

Answer 67

Cyclic AMP

Question 68

What does Cyclic AMP do once converted?

Answer 68

It diffuses through the cytoplasm and binds to Protein Kinase A

Question 69

What is another name for Protein Kinase A?

Answer 69

Cyclic AMP dependant protein kinase

Question 70

What is needed to activate Protein Kinase A?

Answer 70

The second messenger Cyclic AMP

Question 71

What does Protein Kinase A do?

Answer 71

Catalyzes the phosphorylation of proteins in the cell by transferring a phosphate group from ATP to cellular proteins

Question 72

What happens once Protein Kinase A phosphorylates cellular proteins?

Answer 72

Their activity is altered resulted in a cellular response

Question 73

How are the actions of Cyclic AMP terminated?

Answer 73

By the conversion of cyclic AMP to non cyclic AMP by the enzyme phosphodiesterase

Question 74

What is an example of a first messenger that exerts its effects through beta adrenergic receptors?

Answer 74

Epinephrine in the heart

Question 75

What receptors does Epinephrine act through?

Answer 75

Beta Adrenergic receptors

Question 76

What occurs in an Inhibitory Cyclic AMP system?

Answer 76

An inhibitory G protein which reduces the activity of adenylate cyclase producing less Cyclic AMP in the cell

Question 77

Where and how is calcium usually present?

Answer 77

In very low concentrations in the cytoplasm of cells (nanomolar range) and in higher concentrations in the extracellular fluid in the millimolar range

Question 78

Which organelles in the cell store calcium?

Answer 78

The Endoplasmic reticulum

Question 79

What is the normally low levels of calcium in the cytoplasm facilitated by?

Answer 79

Active transport systems found in the plasma membrane of the cell

Question 80

When Calcium enters the cell what does it cause the release of?

Answer 80

More calcium from the endoplasmic reticulum

Question 81

How does Calcium cause the release of more Calcium from the endoplasmic reticulum?

Answer 81

By binding to receptors on the endoplasmic reticulum causing ion channels to open

Question 82

What is Calcium Induced Calcium release?

Answer 82

When calcium allowed into the cell bind with the endoplasmic reticulum causing more calcium to be released into the cytoplasm of the cell

Question 83

What occurs once calcium levels are high enough in the cell?

Answer 83

Calcium acts as a second messenger and binds to Calmodulin, activating it

Question 84

What does the Calcium calmodulin complex do?

Answer 84

Activates a Calmodulin dependent protein kinase which phosphorylates proteins in the cell leading to a cellular response

Question 85

What is the Second messenger in the Calcium system?

Answer 85

Calcium