Exam 3: Cell-cell interactions (Class 2)

Question 1

What are the five categories of signaling?

Answer 1

1. direct intercellular signaling
2. contact-dependent signaling
3. autocrine signaling
4. paracrine signaling
5. endocrine signaling

Question 2

What is direct intercellular signaling?

Answer 2

Cell junctions allow signaling molecules to pass from one cell to another at rate of diffusion (via gap junction)

Question 3

What type of junctions are used in direct intercellular signaling?

Answer 3

Gap junctions

Question 4

How does contact dependent signaling work?

Answer 4

Receptors on adjacent cells bind to other cell surface molecules

Question 5

What do the cell surface molecules in contact dependent signaling function as?

Answer 5

Signals

Question 6

What is the difference between direct intercellular signaling and contact dependent signaling?

Answer 6

Direct intercellular: passed from cytoplasm to cytoplasm
Contact dependent: adjacent cell membranes

Question 7

What is autocrine signaling?

Answer 7

Cells secrete signaling molecules that bind to its own surface or other neighboring cells

Question 8

What is paracrine signaling?

Answer 8

Same as autocrine, but no receptors so a cell cannot receive its own signal

Question 9

Endocrine signaling

Answer 9

Signals travel long distance through blood stream, take a long time to fade

Question 10

What are the 4 stages of cell signaling?

Answer 10

1. Signal reception
2. Signal processing/transduction
3. Signal response
4. Signal deactivation

Question 11

What occurs in signal reception (step 1)?

Answer 11

Signal receptors are bound

Question 12

What are the two type of signals

Answer 12

1. Hormones
2. Other cell-cell signals

Question 13

The presence of what dictates which cells will be able to respond to a particular hormone

Answer 13

appropriate receptor proteins

Question 14

What does protein function depend on? (3 factors)

Answer 14

1. Binding
2. Shape
3. Location

Question 15

When the signal binds to the receptor, what happens to the receptor

Answer 15

It undergoes a conformational change

Question 16

Signal receptors that bind to lipid-soluble hormones are located where

Answer 16

Inside the cell

Question 17

Signal receptors that bind to non lipid-soluble hormones are located where

Answer 17

in the plasma membrane

Question 18

Lipid-soluble steroid hormones are ___ soluble in water

Answer 18

less

Question 19

Estrogen, progesterone, glucocorticoids, and ecdysone are examples of what

Answer 19

hormone response elements

Question 20

The hormone receptor complex binds to…

Answer 20

the hormone response elements (HRE)

Question 21

Where is the hormone-receptor complex transported to and for what

Answer 21

the nucleus, for altering gene expression

Question 22

Are lipid-soluble hormones hydrophilic or hydrophobic

Answer 22

hydrophobic

Question 23

Are lipid-insoluble hormones hydrophilic or hydrophobic

Answer 23

hydrophilic

Question 24

When a signal binds at the cell surface, it triggers a complex series of events called a …

Answer 24

signal transduction pathway

Question 25

After the receptor undergoes a conformational change once a lipid-insoluble hormone binds to it, what happens

Answer 25

A secondary messenger is released

Question 26

What happens once the second messenger is released

Answer 26

It can be amplified

Question 27

Signal transduction moves information from where to where

Answer 27

From the cell surface to the nucleus/other targets

Question 28

What are the three kinds of cell surface receptors?

Answer 28

1. G-protein coupled receptors (GPCR) 2. Enzyme-linked receptors 3. Ligand-gated ion channels

Question 29

All of the three kinds of cell surface receptors are what type of membrane protein

Answer 29

Integral

Question 30

How many transmembrane segments do GPCRs have?

Answer 30

7

Question 31

When G-proteins are bound to GTP, the G-protein is ___

Answer 31

on

Question 32

When G-proteins are not bound to GTP, the G-protein is ___

Answer 32

off

Question 33

What is the first step for GPCRs

Answer 33

Signal received

Question 34

What is the second step for GPCRs

Answer 34

G protein binds GTP and splits

Question 35

What is the third step for GPCRs

Answer 35

The activated G protein binds to an enzyme, which catalyzes the production of a secondary messenger

Question 36

GPCRs are found in all _____ and are common in _____

Answer 36

eukaryotes, animals

Question 37

What are the two parts of an enzyme-linked receptor?

Answer 37

Extracellular domain and intracellular domain

Question 38

Which domain of enzyme-linked receptors binds the signal?

Answer 38

Extracellular

Question 39

Which domain of enzyme-linked receptors becomes a functional catalyst?

Answer 39

Intracellular

Question 40

Most enzyme-linked receptors are ___

Answer 40

kinases

Question 41

What are the two types of receptor kinases?

Answer 41

1. Receptor tyrosine kinase (RTK) 2. Receptor serine/threonine kinase (RSTK)

Question 42

What is the first step of RTK catalyzing a reaction?

Answer 42

Hormone binds to an RTK, signal received

Question 43

What is the second step of RTK catalyzing a reaction?

Answer 43

RTK forms a dimer and is phosphorylated by ATP

Question 44

What is the third step of RTK catalyzing a reaction?

Answer 44

Ras protein exchanges its GDP for GTP, while it is bridged to RTK

Question 45

What is the fourth step of RTK catalyzing a reaction?

Answer 45

Ras protein triggers the phosphorylation and activation of another protein

Question 46

What is the fifth step of RTK catalyzing a reaction?

Answer 46

Phosphorylation cascade amplifies the signal many times

Question 47

What is phosphorylation cascade?

Answer 47

Sequence pathway where one enzyme phosphorylates another and so on

Question 48

Which type of cell surface receptor is found both in plant and animal cells?

Answer 48

Ligand-gated ion channels

Question 49

What is another name for a signal

Answer 49

ligand

Question 50

What happens when a ligand binds to a ligand-gated ion channel

Answer 50

The ion channel opens and ions flow in through the membrane

Question 51

In animals, synaptic signals are between ___ and _____ or between two _____

Answer 51

Neurons and muscles or between two neurons

Question 52

What are three examples of signal response (stage 3)?

Answer 52

1. change enzyme activity 2. change function of structural proteins 3. change gene expression or regulation

Question 53

What are two factors that can alter signal deactivation

Answer 53

1. concentration of hormones 2. number and activity of signal receptors