Chapter 11

Question 1

What suggests signal molecules evolved in prokaryotes?

Answer 1

Signal transduction pathway similarities

Question 2

What are the 2 forms of communication in local signaling?

Answer 2

• Direct contact and transfer between cell junctions

- Cell-to-cell recognition

Question 3

Local regulator

Answer 3

Messenger molecule that travels short distances

Question 4

What type of messenger is a growth factor?

Answer 4

Local regulator

Question 5

What is the initial transduction of a signal?

Answer 5

Shape change of receptor

Question 6

What are the three types of membrane receptors?

Answer 6

• G protein-coupled receptors
• Receptor tyrosine kinases
• Ion channel receptors

Question 7

What is attached to the tyrosines in receptor tyrosine kinase pathways?

Answer 7

Phosphate group

Question 8

What forms of messengers can cross membrane? As in, what are the physical characteristics of them?

Answer 8

Small or hydrophobic

Question 9

A steroid is what kind of messenger?

Answer 9

Hydrophobic

Question 10

An activated hormone-receptor complex acts as ______

Answer 10

transcription factor

Question 11

What is the benefit of a multistep pathway?

Answer 11

Amplification of signal, coordination and regulation

Question 12

Protein kinase

Answer 12

Proteins that phosphorylate proteins (transfer phosphate from ATP to protein)

Question 13

Protein phosphatases

Answer 13

Proteins that dephosphorylate proteins (remove phosphates from proteins)

Question 14

Second messenger

Answer 14

Small, nonprotein, water-soluble molecules that spread through cell by diffusion

Question 15

In certain pathways, ______ _______ creates cAMP. How so?

Answer 15

• Adenylyl cyclase

- Converting ATP to cAMP

Question 16

How is a G protein activated?

Answer 16

When its GDP is switched with a GTP

Question 17

What does cAMP typically do after it is created?

Answer 17

Phosphorylates protein kinase A

Question 18

In certain pathways, second messengers ______ and ______ lead to release of calcium into cell.

Answer 18

• IP3

- DAG

Question 19

Why is there such a large concentration of calcium ions in the ER?

Answer 19

Calcium ions are actively imported from cytoplasm

Question 20

Many pathways regulate synthesis of enzymes and various proteins, usually by…
Other pathways do what?

Answer 20

• turning genes on or off in the nucleus

- regulate activity of enzymes and proteins

Question 21

At each step in a cascade, what is greater than in the previous step?

Answer 21

Number of activated products

Question 22

Scaffolding proteins

Answer 22

Large relay proteins in which other relay proteins are attached

Question 23

How can scaffolding proteins increase signal transduction efficiency?

Answer 23

Grouping different proteins in same pathway

Question 24

What is the actual signal that is being transduced in the various pathways?

Answer 24

Interactions that involve shape changes

Question 25

GTPase

Answer 25

Hydrolyzes GTP binding to G protein