Cell communication & receptor families

Question 1

What are the different types of signaling?

Answer 1

Local and long-distance

Question 2

What are the two different types of local signaling?

Answer 2

Paracrine and synaptic signaling

Question 3

What is paracrine signaling?

Answer 3

A signaling cell acts in nearby target cells by secreting molecules of a local regulator (growth factor)

Question 4

What is synaptic signaling?

Answer 4

Where nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cells - Muscle/another nerve cell

Question 5

What is long-distance signaling?

Answer 5

Endocrine (hormonal signaling), specialised endocrine cells secrete hormones into body fluids, often blood. Hormones reach body cells bound by and affect some cells
1) endocrine cells -> hormone levels in bloodstream -> blood vessel –> target cells specialised binds hormone

Question 6

Steps in cell to cell communication

Answer 6

1) reception
2) transduction
3) response

Question 7

What occurs in reception?

Answer 7

The signalling molecule binds to the receptor

Question 8

What occurs transduction?

Answer 8

three relay molecules in a signal transduction pathway

Question 9

What occurs in response?

Answer 9

Activation of cellular response such as activation of glycogen phosphorylase

Question 10

What are ion channels?

Answer 10

Ion-channel linked receptors = ionotropic receptors (Na+ channels opens by ligand e.g. nicotinic receptors glutamate receptors) –> VERY FAST –> NEUROTRANSMISSION
Ion channels are protein molecules that span across the cell membrane allowing the passage of ions from one side of the membrane to the other. Ion channels are selective meaning that they only allow certain ions to pass through them, and they play critical roles in controlling neuronal excitability

Question 11

What are G-coupled protein receptors?

Answer 11

7 TM spanning regions (hormone action)

Question 12

Receptor Tyrosine kinases

Answer 12

Insulin receptors - metabolism, cell growth, cell reproduction (hormone action)

Question 13

Intracellular?

Answer 13

Steroid receptors (hormone action)

Question 14

What are ligand-gated ion channels?

Answer 14

Ligand-gated ion channels are ion channels that can open in response to the binding of a ligand. To form a channel, this type of cell-surface receptor has a membrane-spanning region with a hydrophilic (water-loving) channel through the middle of it.

Question 15

What are G protein-coupled receptors?

Answer 15

G protein-coupled receptors (GPCRs) are a large family of cell surface receptors that share a common structure and method of signaling. The members of the GPCR family all have seven different protein segments that cross the membrane, and they transmit signals inside the cell through a type of protein called a G protein
When its ligand is not present, a G protein-coupled receptor waits at the plasma membrane in an inactive state.

Question 16

What are receptor tyrosine kinases?

Answer 16

Signaling molecules first bind to the extracellular domains of two nearby receptor tyrosine kinases. The two neighboring receptors then come together or dimerize. The receptors then attach phosphates to tyrosines in each others’ intracellular domains. The phosphorylated tyrosine can transmit the signal to other molecules in the cell.

Question 17

How are G-coupled proteins activated>

Answer 17

They are activated by a variety of stimuli –> light ions, Calcium, odourants, gustative molecules, neurotransmitters, hormones, peptides and proteins

Question 18

What do G coupled proteins control?

Answer 18

They control the activity of enzymes, ion channels, and intracellular signal transduction pathways