Unit 4: Cell communication & Cell cycle

Direct contact

Communication through cell junctions.

Plasmodesata

Plant cells in direct contact with each other can diffuse substances through these structures to communicate

Hormones

Used in long distance signaling

In direct contact communication, animals cells communicate through ____junctions and plant cells communicate through

Gap and plasmodesmata

What do animals and plants use for long distance signaling? Differentiate between animals and plants when they use this to communicate?

They use hormones. Animals used endocrine signaling and plants release hormones.

Differentiate between paracrine signaling and synaptic signaling.

Paracrine signaling: secretory cells release local regulators via exocytosis to an adjacent cell. Synaptic signaling: occurs in animal nervous systems, neurons secrete neurotransmitters, diffuse across the synaptic cleft—space between the nerve cell and target cell.

True or false: Insulin signaling is an example of local signaling

False

Gap junctions

Type of communication used in animal cells

Reception

The detection and receiving of a ligand by a receptor in a target cell

Receptor

Macromolecule that binds to a signal molecule (ligand)

Transduction

The conversion of an extracellular signal to an intracellular signal that will bring about a cellular response

Second messengers

Small, non-protein molecules and ions help relay the message and amplify the response

Response

The final molecule in the signaling pathway converts the signal to a response that will alter a cellular process

Ligand

Chemical messenger

cAMP

A common second messenger

GPCR

Proteins on the surface of cells that receive messages from the outside and send signals inside the cell

Ligand-gated ion channel

Type of ion channel in a cell membrane that opens or closes in response to the binding of a specific molecule

Protein kinase

Family of enzymes that catalyzes the transfer of a phosphate group from ATP to a protein or peptide substrate

Summarize the 3 stages of cell signaling in one sentence each

Reception: ligand binds to recepter Transduction: signal is converted Response: a cell process is altered

If you were given a problem on the Ap Exam that described a water soluble (polar) receptor, where would it be located in the cell?

Plasma membrane receptors are described as a water soluble (polar) receptor, and it’s located in the plasma membrane

Receptors that bind to estrogen, a hormone would be found where in the cell?

Receptors that bind to estrogen would be located in the cytoplasm or nucleus

What do second messengers do, and why is this role so important in some cells

Second messengers relay signals received at a cells surface to the inside of the cell. It’s important because it allows for signal amplification and rapid distribution of information throughout the cell, enabling coordinated cellular functions in response to external stimuli like hormones or neurotransmitters

Differentiate between the role of protein kinase and protein phosphatase in cells

Protein kinase adds a phosphate group to a protein (phosphorylation), while a protein phosphatase removes a phosphate group from a protein (dephosphorylation)

What does the term signal refer to in a signal transduction cascade

In a signal transduction cascade, a signal refers to the initial information or stimulus that is detected by a cell, usually in the form of a chemical molecule like a hormone, growth factor, or neurotransmitters, which then triggers a series of molecular events inside the cell leading to a specific cellular response

Neurons can participate in both local and long distance signaling. How is this possible?

Neurons can participate in both local and long distance signaling due to their unique structure, which includes long, specialized projections called axons that allow for long distance transmission of electrical signals(action potentials), while also utilizing neurotransmitters related at synapses to communicate with nearby cells for local signaling

How are signals passed from outside of the cell to inside of the cell?

Signals are passed from outside of a cell to the inside through specialized protein receptors embedded in the cell membrane

Describe the response that a cell can have to a signal

When a cell receives a signal, it can respond in a variety of ways, including changes in gene expression, protein activity, cell shape, movement, cell division, or even programmed cell death(apoptosis). Signal can trigger a protein that can alter membrane permeability, trigger an enzyme that will change a metabolic process, or trigger a protein that turns genes on or off

How is it possible that a single signal molecule can elicit massive cellular responses

A single signal molecule can trigger a large cellular response through a process called signal transduction

True or False: the final molecule in a signal transduction pathway can act as a transcription factor, meaning that it can turn genes off or on.

TRUE

What does it mean if a gene is turned off vs on

When a gene is turned off it means that the cell is not currently actively transcribing the genetic information from that gene into a protein. When a gene is turned on it means that the genetic information encoded within that gene is actively being used to produce a protein.

What would happen to the signal transduction pathway if protein phosphatase was mutated?

If a protein phosphatase was mutated in a signal transduction pathway, the pathway would likely become hyperactive

What would happen to the signal transduction pathway if protein kinase was mutated?

If a protein kinase within a signal transduction pathway is mutated, the signal would likely be disrupted or significantly weakened

If a receptor protein is mutated, can it receive a ligand? Why or why not?

A mutated receptor protein may not be able to receive a ligand because the mutation could alter the proteins structure at the ligand binding site, preventing the ligand from properly fitting and binding to it

How can chemicals activate or inhibit a pathway?(i.e what does active means and what does inhibit mean in terms of a signaling cascade?)

Chemicals can activate or inhibit a pathway by binding to specific receptors on cell, which then triggers a series of molecular events within the cell, either initiating a cascade of reactions (activation) or blocking the pathways progression (inhibition). Activate means to initiate or start a process by causing a molecule, like an enzyme to become functional, usually by changing its shape or structure, allowing it to participate in a chemical reaction. Inhibit means to slow down or prevent a biological process.

Set points: values for various physiological conditions that the body tries to maintain