Chapter 11 - Cell Communication

Question 1

In cell communication, what are the two junctions (one in animal, one in plant) that allow direct cell contact?

Answer 1

The two junctions in direct contact:

1.Gap Junctions (anmial cells)

2. Plasmodesmata (plant cells)

Cell-to-cell recognition is achieved through membrane bound proteins.

Question 2

What are the two types of cell signaling?

Answer 2

1) Local Signaling: The messenger molecule travels a short distance.
e. g, paracine signaling, synaptic, quorum sensing
2) Long-distance Signaling: The messenger molecule travels a long distance.
e. g hormon release

Question 3

What are the three stages of cell signaling?

Answer 3

Stage 1: Reception

Ligand binds to receptor. Three types of receptors:

a) G protein-coupled receptors
b) Receptor Tyrosine Kinases
c) Ion Channel Receptor

Stage 2: Transduction

Multistep pathways that provide coordination and regulation of the cell

Stage 3: Response

The cell’s response to an extracellular signal is called “output resoinse” with two important benefits:

A) Signal Amplification

B) Specificity of response

Question 4

in Stage 1 of cell signaling (reception) what are the 3 main types of membrane receptors?

Answer 4

G-protein coupled receptors

Receptor Tyrosine Kinases

Ion Channel Receptor

Question 5

How is cell-to-cell recognition achieved?

Answer 5

by Membrane bound proteins

Question 6

Describe the first and second messengers.

Answer 6

1) “first messenger” - The extracellular signal molecule that binds to the receptor.
2) “Second messengers” - small, non0protein, water-soluable molecules or ions that spread throughout a cell by diffusion.

Question 7

What is Apoptosis, and Caspases?

Answer 7

Apoptosis - is the process of programmed cell death that may occur in multicellular organisms.

Caspases - are the main proteases (enzymes that cut up proetins) that carry out apoptosis.

Question 8

What does Apoptosis trigger? (3 parts)

Answer 8

Apoptosis can be triggered by:

• *1. An extracellular death-signaling ligand
  2. DNA damage in the nucleus**

3. Protein misfolding in the endoplasmic reticulum

Question 9

Apoptosis is vital early on for what?

Answer 9

Embroytic Development

such as seperation of fingers and toes and birth.

Question 10

What is Cyclic AMP (cAMP), and how does it work?

Answer 10

cAMP is one of the most widely used second messengers.

Many signal molecules trigger formation of cAMP.

cAMP usually activates protein kinase A, which phosphorylates various other proteins.

Further regulation of cell metabolism is provided by G-protein systems that inhibit adenylyl cyclase.