AP Biology : Understand types of signaling, receptors, and signaling molecules

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #1 : Understand Types Of Signaling, Receptors, And Signaling Molecules

Which is false regarding cell signaling?

Possible Answers:

Paracrine signals are used to communicate the nearby cells

Endocrine signals move via the bloodstream

Autocrine signals bind to receptors on the same cell that released the ligand

Paracrine signals are long-lasting

Correct answer:

Paracrine signals are long-lasting

Explanation:

Endocrine signals are signals from distance cells that move using the bloodstream, paracrine signals are signals used to communicate between cells in close proximity, and autocrine signals are signals that are received by the same cell in which the signal originated. Paracrine signals are signal are short-lasting, whereas endocrine signals are long-lasting.

Example Question #2 : Understand Types Of Signaling, Receptors, And Signaling Molecules

What type of signaling uses the bloodstream to transport ligands to targets?

Possible Answers:

Direct

Autocrine

Paracrine

Endocrine

Correct answer:

Endocrine

Explanation:

Endocrine signals are signals from distance cells that move using the bloodstream, paracrine signals are signals used to communicate between cells in close proximity, autocrine signals are signals that are received by the same cell in which the signal originated, and direct signaling occurs across gap junctions through the movement of small molecules (such as Calcium ions).

Example Question #3 : Understand Types Of Signaling, Receptors, And Signaling Molecules

Which type of cell-surface receptor, when bound by a ligand, begins a cycle where GDP is exchanged for GTP, causing the alpha subunit to separate from the beta and gamma subunits, and causing a cellular response?

Possible Answers:

Enzyme-linked receptor

GTP hydrolyzation receptor

 

G-protein linked receptor

Ion channel- linked receptor

Correct answer:

G-protein linked receptor

Explanation:

G-protein linked receptors are a type of cell-surface receptor that, when unbound by a ligand, consists of an alphaGDP subunit and a beta gamma subunit. When a ligand binds, GDP is exchanged for GTP, which causes the alphaGTP subunit to dissociate from the receptor and the beta gamma subunit. Then, the alphaGTP and beta gamma subunits can activate other molecules in the cell.

Example Question #4 : Understand Types Of Signaling, Receptors, And Signaling Molecules

A cell releases a ligand that binds to receptors on its own surface. Which type of signaling is this?

Possible Answers:

Paracrine

Autocrine

Direct

Endocrine

Correct answer:

Autocrine

Explanation:

Endocrine signals are signals from cells that move using the bloodstream and signal to distant cells, paracrine signals are signals used to communicate between cells in close proximity, autocrine signals are signals that are received by the same cell in which the signal originated, and direct signaling occurs across gap junctions through the movement of small molecules (such as Calcium ions).

Example Question #5 : Understand Types Of Signaling, Receptors, And Signaling Molecules

Beta cells in the pancreas secrete insulin, a hormone, that enters the bloodstream. This is an example of which type of signaling?

Possible Answers:

Endocrine

Autocrine

Paracrine

Direct

Correct answer:

Endocrine

Explanation:

Endocrine signals are signals from cells that move using the bloodstream to signal to distant cells, paracrine signals are signals used to communicate between cells in close proximity, autocrine signals are signals that are received by the same cell in which the signal originated, and direct signaling occurs across gap junctions through the movement of small molecules (such as Calcium ions). Beta cell in the pancreas produce insulin, a hormone, which is secreted into the bloodstream.

Example Question #7 : Understand Types Of Signaling, Receptors, And Signaling Molecules

Which type of ligand is water soluble, and thus unable to enter a cell?

Possible Answers:

Nitric oxide

Water-soluble ligands

Small, hydrophobic ligands

steroid hormones

Correct answer:

Water-soluble ligands

Explanation:

 The membrane of the cell is a phospholipid bilayer, which allows hydrophobic molecules to diffuse through it. Small, hydrophobic ligands are able to diffuse through the plasma membrane. Nitric oxide is lipophilic, readily dissolving in lipids, and can diffuse across the plasma membrane. Steroid hormones are hydrophobic, and can thus diffuse across the plasma membrane. Water-soluble ligands cannot diffuse across the plasma membrane to enter a cell.

 

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