ap bio unit 4 cell commnication and cell cycle study guide (may 5th)

What is the first step in cell communication?

Reception, where a ligand binds to a receptor.

What happens when a ligand binds to its receptor?

It causes a conformational shape change in the receptor.

What is a ligand?

A signaling molecule that can be a steroid hormone or a protein hormone.

How do steroid hormones like testosterone and estrogen bind to their receptors?

They are released by simple diffusion and bind to intracellular receptors.

How do protein hormones like insulin bind to their receptors?

They are released by exocytosis and bind to extracellular receptors.

What is the second step in cell communication?

Transduction, where signaling cascades relay signals from receptors to cell targets.

What is a phosphorylation cascade?

A series of events where protein kinases phosphorylate relay molecules to move through transduction.

What does phosphorylation mean?

The addition of a phosphate group.

What are secondary messengers?

Small molecules inside the cytosol that continue the signaling cascade, such as Ca²+ and cyclic AMP.

What is transduction in the context of cell communication?

The process of converting energy or a signal from one form to another.

What is the third step in cell communication?

Response, which includes cell growth, secretion of molecules, gene expression, altering cell function, or apoptosis.

What occurs during the response phase of cell communication?

Transcription factors initiate or inhibit the expression of specific genes.

What are the phases of interphase in the cell cycle?

G1 (growth), S (synthesis), and G2 (preparation for mitosis).

What occurs during the G1 phase of interphase?

Duplication of organelles and synthesis of proteins, RNA, and building blocks for new cells.

What happens during the S phase of interphase?

Replication of genetic material and centrosomes.

What is the role of the G2 phase in interphase?

Synthesis of proteins and RNA, making organelles, and reorganizing cellular contents.

What are the stages of mitosis?

Prophase, metaphase, anaphase, and telophase.

What is cytokinesis?

The final step in cell division where the cytoplasm is divided, resulting in two distinct daughter cells.

What is the purpose of checkpoints in the cell cycle?

To regulate the cell cycle and ensure proper division.

What does the G1 checkpoint assess?

Whether to complete the cell cycle, cell growth, adequate reserves, and checks for DNA damage.

What happens if a cell does not pass the G1 checkpoint?

The cell enters a non-dividing state called G0.

What does the G2 checkpoint check for?

Proper DNA replication and damage before proceeding to mitosis.

What is the M checkpoint?

It checks that sister chromatids are all attached to the spindle microtubules during metaphase.

What is the difference between negative feedback and positive feedback?

Negative feedback aims to restore homeostasis, while positive feedback amplifies a response until an event occurs.

prophase

preparation for division

metaphase

Sister chromatids line up in the middle of the cell, attached to spindle fibers.

anaphase

sister chromatids pulled apart to opposite poles of the cell

telophase

two new nuclei are formed

what are some things that occur because of a response besides inhibition or initiation of the gene (be specific)

cell growth ; secretion of molecules ; gene expression ( on and off of a gene ) ; alters cell function or phenotype ; apoptosis