Basic Principles of Biological Communication

Question 1

How can a signalling cell send signals to a target cell?

Answer 1

Via signalling molecules/ ligands/ transmitters

Question 2

What are receptors?

Answer 2

Transmembrane proteins

Question 3

What are the 3 methods of local communication?

Answer 3

• Contact dependent
• Paracrine
• Autocrine (signalling molecule bound to target cell)

Question 4

What are the 2 methods of distant communication?

Answer 4

Endocrine
Synaptic

Question 5

What is the function of dendrites in the neurone?

Answer 5

Dendrites receive inputs and synapse with other cells.

Question 6

What is the alternative name for the cell body of a neurone?

Answer 6

The soma

Question 7

What ensures action potentials can only flow from soma to synapse?

Answer 7

The polarity of the neurone cell

Question 8

How does endocrine communication work?

Answer 8

• Hormones are released from specialised cell populations forming endocrine glands
• Hormones travel through the bloodstream and bind to receptors.

Question 9

What determines the duration of the hormone signal?

Answer 9

The half-life of the signalling molecule.

Question 10

Where are intracellular receptors located?

Answer 10

In the cytoplasm or in the nucleus.

Question 11

Ligands that bind to intracellular receptors must be hydrophobic. Why is this?

Answer 11

As they must pass through the phospholipid bilayer.

Question 12

What are the 3 regions of a membrane receptor?

Answer 12

• An extra-cellular domain
• Transmembrane domain
• Intracellular domain

Question 13

What is found in the extracellular domain?

Answer 13

• The hormone binding site
• The N-terminus

Question 14

What is found in the intracellular domain?

Answer 14

The C - terminus

Question 15

What are ligand-gated ion channels?

Answer 15

Protein channels which allow certain ions to pass through when ligands are bound (and change the structure).

Question 16

What are enzyme-linked receptors?

Answer 16

• Cell surface receptors with intracellular domains associated with an enzyme.

Question 17

What do receptor tyrosine kinases do?

Answer 17

They transfer phosphate groups to the amino acid tyrosine.

Question 18

What are the 3 subunits of G protein coupled receptors?

Answer 18

Alpha
Beta
Gamma

Question 19

What happens when a ligand binds to the G protein receptor site?

Answer 19

It activates the alpha sub-unit and causes dissociation of beta-gamma units.

Question 20

What do these sub-units then activate?

Answer 20

They stimulate/ inhibit enzymes in the cell membrane causing the opening or closing of ion channels.

Question 21

What sub-unit is used to define the G protein?

Answer 21

The alpha sub-unit.

Question 22

Which is faster, endocrine or neuronal communication?

Answer 22

Neuronal communication is faster.

Question 23

Which is more energetically efficient, endocrine or neuronal communication?

Answer 23

Endocrine communication is cheaper energetically.