Wk 6 Lecture 2

Question 1

What are the 5 categories of cell signaling events?

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 is contact dependent signaling?

Answer 3

-Molecules bound to surface of cells serve as signals to cells coming in contact with them
-Receptors on adjacent cells bind to cell surface molecules

Question 4

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

Answer 4

Direct intercellular: Passed between cytoplasm to cytoplasm

Contact-dependent: Passed between adjacent cell membranes

Question 5

What is autocrine signaling?

Answer 5

-Cells secrete signaling molecules that bind to their own cell surface or similar neighboring cells
-Affects locally - self and nearby cells

Question 6

Real life example of autocrine signaling?

Answer 6

Screaming fire to a large crowd of people

Question 7

What is paracrine signaling?

Answer 7

-Signal does not affect originating cell, but still affects nearby cells

Question 8

What is endocrine signaling?

Answer 8

-Signals travel longer distances via blood stream and take longer to fade

Question 9

What is a hormone?

Answer 9

A signaling molecule in blood stream

Question 10

What are the four stages of cell signaling?

Answer 10

1. Signal Reception (receive signal)
2. Signal processing/transduction (transmit the signal)
3. Signal response (carry out the signal’s instructions)
4. Signal deactivation (stop signal)

Question 11

What are signal receptors? (step 1-signal reception)

Answer 11

Proteins that change their shape or activity after binding to a signaling molecule

Question 12

3 characteristics of signal receptors

Answer 12

1. Dynamic
2. May change in their sensitivity to particular hormones
3. Can be blocked

Question 13

What are signal receptors bound by? (step 1-signal reception)

Answer 13

1. Hormones
2. Other cell-cell signals

Question 14

What is a hormone?

Answer 14

A long distance messenger; an information carrying molecule that is secreted from a cell, circulates in the body, and acts on target cells far from the signaling cell

Question 15

Characteristics of a hormone (5 things)

Answer 15

1. Small
2. Present in extremely low concentrations
3. Have a large impact on the condition of the organism as a whole
4. Function/chemical structure of hormones vary widely
5. Two types: lipid soluble and lipid insoluble

Question 16

The presence of ____ dictates which cells will be able to respond to a particular hormone (step 1-signal reception)

Answer 16

An appropriate receptor protein

Question 17

Identical receptors in diverse cells and tissues can ____ (step1-signal reception)

Answer 17

Allow long-distance signals to coordinate the activities of cells throughout a multicellular organism

Question 18

What 3 things are protein function dependent on?

Answer 18

1. Binding
2. Shape
3. Location

Question 19

How does signal processing differ between lipid soluble and lipid insoluble horomones?

Answer 19

Different cell responses are produced

Lipid soluble hormones cross plasma membrane

Lipid insoluble hormones bind to membrane receptors

Question 20

Describe lipid soluble steroid hormones

Answer 20

-Hydrophobic
Diffuse across membrane and bind to receptors in cell
=> Hormone receptor complex binds to Hormone Response Elements (HRE; ex: estrogen, progesterone, glucocorticoids, ecdysone)

Question 21

Where does the hormone receptor complex get transported to? What does it do there? (step 2-signal processing-lipid soluble steroid hormones)

Answer 21

Transported to nucleus where it alters gene expression