Bio 161 Exam 4 content

What is the final effect of glucose release from liver cells?

Glucose diffuses into the bloodstream and enters muscle cells to produce ATP.

What is endocytosis?

Endocytosis is the process where the cell membrane surrounds a part of the exterior environment and buds off as an internal vesicle.

What is exocytosis?

Exocytosis is the process where a vesicle fuses with the cell membrane, releasing its contents outside the cell.

How do large molecules enter the cell?

Large molecules enter the cell through endocytosis, where the plasma membrane invaginates and pinches off to form a vesicle.

How do large molecules exit the cell?

Large molecules exit the cell via exocytosis, where materials packaged in vesicles are secreted from inside to outside the cell.

What is the role of ribosomes in vesicle trafficking?

Ribosomes on the rough ER synthesize secreted proteins and transmembrane proteins, which are then packaged into vesicles.

What are the three types of filaments in the eukaryotic cytoskeleton?

The three types of filaments are Actin Filaments, Intermediate Filaments, and Microtubules.

What are actin filaments made of?

Actin filaments are made up of strands of the protein actin and are often involved in cell movement and structure.

What is the structure of intermediate filaments?

Intermediate filaments are made up of fibrous proteins organized into tough, ropelike assemblages that stabilize a cell's structure.

What are microtubules composed of?

Microtubules are long, hollow cylinders made of tubulin proteins, specifically α-tubulin and β-tubulin dimers.

What is the function of actin filaments during endocytosis?

During endocytosis, actin polymers assemble under the membrane to help form a vesicle and bring in molecules from the external environment.

What role do microtubules play in cellular transport?

Microtubules act as 'highways' for the transport of vesicles via motor proteins like dynein and kinesin.

What is the function of dynein and kinesin?

Dynein moves cargo towards the microtubule minus end (inwards), while kinesin moves cargo towards the microtubule plus end (outwards).

What is phagocytosis?

Phagocytosis is a type of endocytosis known as 'cell eating,' where the cell engulfs large particles.

What is the dynamic nature of the cytoskeleton?

The cytoskeleton is dynamic, meaning microtubules can grow and shrink, allowing for cellular movement and shape changes.

What is a receptor in cell signaling?

A receptor is a specific binding site for a ligand, usually a protein located on the plasma membrane or within the cell.

What determines the affinity of a receptor for its ligand?

The affinity is determined by the shape of the molecules and the strength of the bonds or interactions they form with each other.

How does ligand binding affect receptor shape?

Upon binding to a ligand, the receptor changes shape, which can initiate the signaling process inside the cell.

What is the significance of specificity in cell signaling?

Only target cells with the appropriate receptors respond to a signal, ensuring that signals are received and processed correctly.

What is signal transduction?

Signal transduction is the process by which a cell relays and processes information from a signal to create a response.

What happens when a receptor binds to a ligand?

The binding of a ligand changes the overall 3D shape of the receptor, affecting its function and the signaling pathway.

What types of signals can cells receive?

Cells can receive chemical signals from near or far, which can be polar or non-polar depending on their nature.

What is the role of the centrosome in microtubule organization?

The centrosome organizes microtubules, with all minus ends together at the centrosome and plus ends growing outward.

What is the role of ATP in cellular work involving motor proteins?

Motor proteins like dynein and kinesin require ATP hydrolysis to move cargo along microtubules, making this process non-spontaneous.

What is the difference between the plus and minus ends of microtubules?

The plus end is the rapidly growing end where new tubulin dimers are added, while the minus end is more stable and often anchored.

What happens to receptor affinity when ligand concentration increases?

Affinity does not change; it remains constant.

How does an increase in ligand concentration affect receptor binding?

It increases the likelihood that a receptor molecule will be bound to a ligand molecule.

What is the effect of a decrease in ligand concentration on receptor binding?

It decreases the likelihood that a receptor molecule will be bound to a ligand molecule.

What determines the specificity of the ligand-receptor interaction?

The ability to form non-covalent bonds.

What is an agonist?

A compound that binds to a receptor and produces a similar cellular effect as the natural ligand.

What is an antagonist?

A compound that binds to a receptor and blocks the normal cellular effect.

Can a receptor bind multiple ligands?

Yes, if the ligands have chemically similar structures.

Can a ligand bind to multiple receptors?

Yes, if the receptors have chemically similar binding sites.

What is the role of acetylcholine in receptor binding?

Acetylcholine can bind to two different types of receptors, leading to different cellular responses.

What must happen to all signals in cell signaling?

They must be turned off.

What is one method of signal termination in cell signaling?

Slow ligand removal, where the signal diffuses away, reducing ligand concentration.

What is another method of signal termination?

Enzymatic degradation of the signal, such as acetylcholinesterase breaking down acetylcholine.

What are ligand-gated ion channels?

Receptors that open when bound to a ligand, allowing ions to flow across the membrane.

What are G-protein coupled receptors (GPCRs)?

Transmembrane proteins that bind an extracellular ligand and activate G-proteins to produce a cellular response.

What occurs when a ligand binds to a GPCR?

The receptor undergoes a conformational change that allows it to interact with an adjacent G-protein.

What is the role of G-proteins in cell signaling?

They act as intermediaries between the receptor and effector proteins.

What happens during the activation of a G-protein?

The G-protein exchanges GDP for GTP upon activation by the GPCR.

What is adenylyl cyclase?

An effector protein that catalyzes the formation of cAMP from ATP.

What is cAMP?

A second messenger that amplifies the signal within the cell

How does cAMP activate protein kinase A (PKA)?

cAMP binds to regulatory subunits of PKA, releasing catalytic subunits that are active kinases.

What is the function of protein kinases?

They catalyze the covalent addition of a phosphate group onto a protein.

What is the role of protein phosphatases?

They remove phosphate groups from proteins, reversing the action of kinases.

What is the significance of phosphorylation in cell signaling?

Phosphorylation is a fast way to change protein function or activity, leading to activation or inactivation.

What is the outcome of ligand binding to a receptor?

It causes a conformational change in the receptor, initiating the signaling cascade.

What is signal amplification in cell signaling?

One molecule may create many active products that carry out the next step in the signaling pathway.

How does epinephrine signaling affect liver cells?

Epinephrine binds to GPCRs on liver cells, leading to the breakdown of glycogen into glucose.