Chapter Eleven

Question 1

What does quorum cell signaling do?

Answer 1

• monitor local cell density
• coordinate behavior that requires a certain density (e.g., forming spores to lie dormant, forming biofilms, secreting toxins)

Question 2

What are biofilms?

Answer 2

aggregation of bacterical cells attached to a surface by secretions from the cells

Question 3

What kind of signaling is in yeasts? What does it do?

Answer 3

sex signaling; identify mates by chemical signaling

Question 4

What are the 3 steps of cell signaling?

Answer 4

• signal reception
• signal transduction
• cellular response

details of these steps are similar in simple and complex orgsnisms

Question 5

Early versions of cell signaling likely evolved before…

Answer 5

the first multicellular organisms

Question 6

What are the characteristics of local cell signaling?

Answer 6

• signaling molecules travel a short distance between cells
• direct connection
• surface signaling molecules andd receptors

Question 7

What are the characteristics of long-distance cell signaling?

Answer 7

• often small molecules that can diffuse through cell walls in plants
• mostly hormones that travel in the bloodstream in animals

Question 8

What 3 stages occur when a signal is recieved by a cell?

Answer 8

• reception
• transduction
• cellular response

Question 9

What happens in the reception stage of cell signaling?

Answer 9

• a cell detects a signaling molecule from outside of the cell
• a signal is detected when the chemical signal (ligand) binds to a receptor protein inthe surface of the cell of inside the cell

Question 10

What happens in the transduction stage of cell signaling?

Answer 10

• when the signaling molecule binds the receptor, it changes the receptor protein in some way
• this change initiates the process of transduction
• each relay molecuule in the signal transduction pathway changes the next molecule in the pathway

Question 11

What happens in the cellular response stage of cell signaling?

Answer 11

the signal triggers a specific cellular response

Question 12

What are the benefits of having multiple relay molecules in transduction?

Answer 12

• the signal caused by a small number of signaling molecules can be greatly amplified
• signal can be transferred to multiple molecules in the next step of the pathway
• more opportunities for coordination and control than simpler systems
  
  • allows for regulation of the response

Question 13

What is a first messenger and second messenger?

Answer 13

first messenger: signaling molecule
second messenger: smaller non-protein relay molecules

Question 14

How are responses regulated?

Answer 14

• controls in the relay
• threshold met
• presence of scaffolding proteins

Question 15

What is apoptosis?

Answer 15

a type of cell death where a series of molecular steps in a cell can lead to its death

Question 16

What happens during apoptosis?

Answer 16

• DNA, organelles, and cytoplasm chopped up and fragmented
• cell shrinks and becomes lobed
• cells parts packaged in vesicles and engulfed/digested by specialized scavenger cells
• protects surrounding cells from cell just breaking apart and leaking its contents out

Question 17

What happens when apoptosis isn’t regulated?

Answer 17

it can be involved in diseases like Parkinson’s and Alzheimers

killing cells that shouldn’t be marked for destruciton yet

Question 18

What happens when apoptosis doesn’t remove damaged cells?

Answer 18

diseases like cancer can occur

buildup of damaged cells