AP Biology Topic 4: Cell Communication & Cycle

Direct Contact

a mechanism of cell communication where cells maintain physical contact, allowing for the exchange of molecules and signals between adjacent cells.

Endocrine Signalling

a form of cell communication where hormones are secreted into the bloodstream and travel to distant target cells, eliciting a response.

Paracrine Signalling

a form of cell communication where signaling molecules are released by cells and affect nearby target cells within the local environment.

Autocrine

A type of cell signaling where a cell targets itself by releasing signaling molecules that bind to its own receptors, influencing its own behavior or function.

Stimulus

Any change in the internal or external environment that causes a reaction/response from a cell or organism.

Reception

Detection of a signal molecule coming from outside the cell, leading to cellular responses through various pathways.

Transduction

Converts signal to a form that can bring about a cellular response, often involving a cascade of biochemical reactions.

Response

Specific cellular response to the signal molecule.

Target Cell

A cell that has receptors specifically designed to bind with certain ligands, resulting in a biological response.

Ligand

A molecule that irreversibly binds to a receptor, triggering a response in the target cell.

G-coupled Receptors

Cell surface proteins that act as messengers, transmitting signals from ligands to inside the cell.

How is regulation of protein synthesis an example of signal transduction?

Turning off/ on genes by signaling pathways that influence transcription and translation.

Kinases

Enzymes that phosphorylate to active/decative proteins.

Phosphatases

Enzymes that remove phosphate groups from proteins.

Inhibitors

Substances that can block or reduce the activity of enzymes, including kinases and phosphatases, thereby affecting signal transduction pathways.

How do mutations affect signal transduction pathways?

Can disrupt the normal functioning of proteins involved in signal transduction pathways, leading to altered cellular responses, uncontrolled cell division, or loss of communication, which can contribute to diseases such as cancer.

Inhibition of target cell?

The process by which signaling molecules prevent a target cell from responding to stimuli by halting or decreasing activity/function.

Negative Feedback

A response that reduces the imbalance to maintain regulation.

Positive Feedback

A response that enhances or amplifies an effect or response that leads to increased product or outcome production.

What is the purpose of the cell cycle?

The purpose to enable cellular growth and production of cells, replication of DNA, and division.

What happens in interphase?

G1 - cell growth and preparation for DNA synthesis.

S - DNA replication occurs.

G2 - cell prepares for mitosis by producing proteins and organelles needed for division.

Prophase

• Chromatin condenses into chromosomes

• Centrioles emit spindle fibers

• Nuclear membrane dissolves

• Chromosomes align at the equator

Metaphase

• Chromosomes are aligned at the equator

• Spindle fibers attach to the kinetochore of each chromatid

Anaphase

• Chromatids separate at the centromere and

• Spindle fibers pull the chromatids back to their respective poles

• Cell widens

Nondisjuction

The failure of homologous chromosomes or sister chromatids to separate properly during cell division, leading to gametes with an abnormal number of chromosomes.

Telophase

• Nucleus reforms

• Cleavage furrow forms

• Chromosomes reach opposite poles and decondense

• The cell prepares to divide into two daughter cells.

Direct Contact in plants

is the communication between adjacent plant cells through plasmodesmata, allowing for the exchange of substances and signaling molecules.

What molecule directs long distance communication?

Hormones

What molecule directs short distance communication?

Local signaling molecules

How do local regulators work in communication?

They influence nearby cells by binding to receptors and initiating responses, facilitating immediate cellular communication.

How do hormones work in cell communication?

Hormones travel through the bloodstream to target distant cells, where they bind to specific receptors, triggering a response.

Proto-oncogenes

They are normal genes that regulate cell growth and division but can become oncogenes when mutated.

Oncogenes

Are mutated proto-oncogenes that promote uncontrolled cell growth and division, leading to cancer.

Tumor Suppressor

genes are involved in controlling cell cycle progression and can prevent tumor formation when functioning properly. When mutated, they can lead to uncontrolled cell growth.

Cyclins

Signal proteins that signal cyclin-dependent kinases.