C2.1 Chemical Signaling

Question 1

Summary of signaling in cells

Answer 1

• Release of ligand from signaling cell.
• Ligand transports to target cell.
• Binds to receptor on target cell.
• Binding to receptor causes a series of reactions within the cell.
• The cell produces a response.
• Ligand is degraded to terminate signal.

Question 2

Methods used by cells to communicate

Answer 2

Cell-cell communication

Cell signaling using chemical messengers.

Local signaling over short distances: cell-cell recognition, local regulators (paracrine and synaptic).

Long distance signaling: hormones.

Question 3

Explain signal transduction pathway

Answer 3

Series of steps by which a signal on a cell’s surface is converted into a specific cellular response.

Question 4

Structure and function of receptor molecules

Question 5

Relationship between receptor and a specific gland

Answer 5

Ligands are a specifically shaped molecule that bind to specifically shaped larger molecules via receptors on the larger molecules.

Question 6

Describe the process of quorum sensing in a population of bacteria

including the role of signalling molecules, receptors and a threshold for gene expression.

Question 7

Process of bioluminescence in Vibrio Fischeri as an example of quorum sensing in bacteria

Answer 7

Vibrio Fischeri bacteria release small signalling molecules called autoinducers.

In reponse to a rise in population density, V. Fischeri releases N-acyl homoserine lactone (an autoinducer)

Autoinducer induces the lux operon, which produces more autoinducers.

When autoinducers reach certain concentration, enzyme luciferase is expressed.

Luciferase catalyzes a reaction which oxidizes luciferin to oxyluciferin (which releases light).

As release of light energy intensifies, process ensures light is only released when numbers of bacteria are high

Question 8

Define ligand

Answer 8

A specifically shaped molecule that will bind to a specifically shaped larger molecule.

Question 9

Compare structure and function of different categories of animal chemical signalling molecules

including hormones, neurotransmitters, cytokines and calcium ions.

Question 10

Properties shared by all signalling chemicals

Question 11

Chemical categories of hormones

Question 12

Chemical categories of neurotranmitters