1.4 a) Coordination, Hydrophobic and Hydrophilic Signals

Question 1

Multicellular organisms signal between cells using ___ ___.

Answer 1

extracellular signalling

Question 2

What are the three types of extracellular signalling molecules?

Answer 2

peptide hormones, steroid hormones, neurotransmitters

Question 3

Some proteins in the plasma membrane act as ___, with a binding site for specific ___ molecules.

Answer 3

receptors, signal

Question 4

The act of ___ a signal molecule causes a ___ change of the receptor, which initiates a ___ within the cell.

Answer 4

binding, conformational, response

Question 5

Different cell types produce different ___ ___ which can only be detected by cells with the specific ___.
These cells then…

Answer 5

signal molecules, receptor.
respond to the signal

Question 6

Signalling molecules have ___ effects on different ___ types, due to differences in the ___ involved within the cell.

Answer 6

different, cell, pathways

Question 7

In multicellular organisms, different cell types can show a tissue-___ response to the ___ signal.

Answer 7

tissue-specific, same

Question 8

Hydrophobic signalling molecules can…
And so, can bind to ___ ___.

Answer 8

diffuse directly through the plasma membrane.
intracellular receptors

Question 9

The receptors for hydrophobic signalling molecules are ___ ___.

Answer 9

transcription factors

Question 10

What are transcription factors?

Answer 10

molecules that bind to HREs on DNA and either stimulate or inhibit the initiation of transcription (or: ‘they affect gene expression’)

Question 11

The steroid hormones ___ and ___ are examples of ___ signalling molecules.

Answer 11

oestrogen and testosterone, hydrophobic

Question 12

These steroid hormones bind to specific ___, in the ___ or ___.

Answer 12

receptors, cytosol, nucleus.

Question 13

The hormone-receptor complex then moves to the ___ where it binds to specific sites on ___, affecting ___ expression.

Answer 13

nucleus, DNA, expression

Question 14

What are the sites on DNA (that hormone-receptor complexes bind to) called?

Answer 14

Hormone Response Elements (HREs)

Question 15

What does binding at HREs affect?

Answer 15

The rate of transcription (aka gene expression)

Question 16

Each ___ hormone can affect the gene expression of many ___ genes.

Answer 16

steroid, different

Question 17

Hydrophilic signalling molecules bind to ___ ___, and do not ___ the cell.

Answer 17

membrane receptors (or transmembrane receptors), enter

Question 18

Examples of extracellular signalling molecules are ___ and ___ ___.

Answer 18

neurotransmitters, peptide hormones

Question 19

Sort the following three signalling molecules into either 1) or 2).

Neurotransmitters, steroid hormones, peptide hormones.

1. Hydrophobic signalling molecule
2. Hydrophilic signalling molecule

Answer 19

1. Steroid hormones (oestrogen and testosterone) are hydrophobic, and so diffuse through the membrane and bind to intracellular receptors (which may create a transcription factor which binds to HREs affecting the rate of transcription)
2. neurotransmitters and peptide hormones are hydrophilic, and so bind to transmembrane receptors

Question 20

Transmembrane receptors change ___ when a ___ binds to its extracellular face.

Answer 20

conformation, ligand

Question 21

Hydrophilic signalling molecules do not ___ the cell, but the signal is ___ across the ___.

Answer 21

enter, transduced, membrane

Question 22

Transmembrane receptors act as ___ ___, when a ligand/hydrophilic signalling molecule binds to it from ___ the cell.

Answer 22

signal transducers, outside

Question 23

Transmembrane receptors transduce ___ by converting the ___ binding event into intracellular ___, which activates a cellular ___.

Answer 23

signals, ligand, signals, response

Question 24

Transduced hydrophilic signals often involve _-__ or cascades of ___ by kinase enzymes.

Answer 24

G-proteins, phosphorylation

Question 25

G-proteins r___ signals from ___ receptors to ___ proteins.

Answer 25

relay, activated, effector

Question 26

What are activated receptors?

Answer 26

ones that have bound a signalling molecule/ligand

Question 27

Name two types of target proteins?

Answer 27

enzymes, ion channels

Question 28

What do phosphorylation cascades allow for?
*(given that they start with only one signal molecule binding to a receptor)

Answer 28

multiple intracellular signalling pathways to be activated, from a single binding event

Question 29

What do phosphorylation cascades involve?

Answer 29

a series of events whereby one protein kinase phosphorylates another, thereby activating it and allowing it to phosphorylate the next one… and so on

Question 30

What is a protein kinase and what does it do?

Answer 30

an enzyme which catalyses the phosphorylation reaction of another protein

Question 31

Phosphorylation cascades can result in the ___ of many different ___, as a result of the original ___ event.

Answer 31

phosphorylation, proteins, binding

Question 32

Select the correct word/phrase from each set of brackets.

When insulin, a (steroid/peptide) hormone, binds to its receptor it results in an (intra/extra) -cellular signalling pathway that triggers the ___ of ___-_ glucose transporter (proteins/vesicles) to the (nuclear/plasma) membrane of ___ and ___ cells.

Answer 32

(peptide), (receptor), (intra), recruitment, GLUT-4 (proteins), (plasma), fat and muscle

Question 33

In more detail:
The binding of insulin to its ___ causes a ___ ___ that triggers ___ of the receptor.
This starts a ___ ___ which eventually leads to ___-_ containing ____ being transported to the ___ ___, and then they travel to the plasma membrane of __ and __ cells.

Answer 33

receptor, conformational change, phosphorylation.
phosphorylation cascades, GLUT-4, vesicles, plasma membrane, fat and muscle.

Question 34

What is type 1 diabetes caused by?

Answer 34

a failure to produce insulin

Question 35

What is type 2 diabetes caused by?

Answer 35

a loss of insulin function

Question 36

What is type 2 diabetes associated with?

Answer 36

obesity

Question 37

How can you treat type 2 diabetes?
Why is this treatment effective?

Answer 37

exercise,
it triggers recruitment of GLUT-4, thereby increasing uptake of glucose to fat and muscle cells (essentially doing insulin’s job)