cell communication and cell cycle

Cell Communication

The process by which cells communicate with each other through signaling molecules.

Local Signaling

Communication between cells that are in direct contact with each other (sensing whether they are coming in contact with each other, no chemical signals)

Paracrine Signaling

One cell tells another cell to go though cell division using secreted messenger molecules that only travel short distances

Synaptic Signaling

Communication that occurs in the animal nervous system when a neurotransmitter is released in response to an electric signal.

Long Distance Signaling

Communication between cells that are far apart, using hormones.

Receptor

A protein on the cell surface or inside the cell that binds to signaling molecules and initiates a response.

Intracellular Receptors

Receptors found inside the cytoplasm or nucleus of target cells. Small or hydrophobic chemical messengers can readily cross the membrane and activate receptors

Transduction

binding of a signaling molecule to a receptor that triggers the first step in a chain of molecular interactions

(like falling dominoes, the receptor activates another protein, which activates another, and so on until the protein/receptor is activated)

Signal Amplification

The increase in the magnitude of a signal during transduction (enzyme cascades ____ the cell’s response to the signal).

Response

The cellular activity or change that occurs as a result of a signal.

Phosphorylation Cascades

A series of phosphorylation reactions that amplify a signal.

G Protein-Coupled Receptors (GPCRs)

Cell surface transmembrane receptors that work with the help of a G protein.

Secondary Messenger

Small, non-protein, water-soluble molecules or ions that spread throughout a cell by diffusion

Cyclic AMP (cAMP)

One of the most widely used second messengers.

Receptor Tyrosine Kinases (RTKs)

Membrane receptors that attach phosphates to tyrosines and can trigger multiple signal transduction pathways.

Ligand-gated Ion Channel Receptor

A receptor that acts as a gate for specific ions when a signal molecule binds to it.

Cell Cycle

The normal life cycle of a cell, including growth, division, and death.

Apoptosis

Programmed cell death.

Genome

All of an organism's DNA.

Chromosome

One long DNA molecule associated with proteins.

Chromatin

The complex of DNA and proteins that make up chromosomes.

Chromatids

Joined copies of an original chromosome.

Centromere

The region of a chromosome where chromatids are most closely joined.

Miotic Spindle

A structure of microtubules and other proteins that move the chromosomes during cell division.

Centrosome

An organelle that makes the mitotic spindle and recycles materials from the cell's cytoskeleton.

Kinetochore

A disc-shaped set of proteins at the centromere of a chromosome where microtubules attach.

Interphase

The longest stage of the cell cycle, consisting of G1, S, and G2 phases.

G1 Phase

The growth and normal life of the cell.

S Phase

The phase where the cell replicates its DNA in preparation for cell division.

G2 Phase

The phase where the cell grows a little more and makes final preparations for cell division.

G0 Phase

A phase where a cell does not divide and remains in a resting state.

G1 Checkpoint

The point of no return in the cell cycle, where the cell decides whether to continue with cell division or undergo apoptosis.

G2 Checkpoint

A checkpoint that ensures the cell’s DNA is not damaged after going through synthesis.

Mitosis

The division of the nucleus during cell division.

Cytokinesis

The division of the cell membrane, resulting in two daughter cells.

Microtubules

Protein structures that attach to the kinetochores of chromosomes during cell division.

Mitotic Spindle

A structure made of microtubules that helps separate chromosomes during cell division.

Kinetochores

Protein structures on chromosomes where microtubules attach during cell division.

Chromosomes

Thread-like structures in cells that contain genetic information.

Metaphase plate

The middle region of the cell where chromosomes line up during metaphase.

Anaphase

The stage of mitosis where sister chromatids are separated and move towards opposite ends of the cell.

Cohesin proteins

Proteins that hold sister chromatids together before they are separated during cell division.

Sister chromatids

Two identical copies of a chromosome that are held together by cohesin proteins.

Telophase

The final stage of mitosis where chromosomes are repackaged into new nuclear envelopes and two daughter nuclei are formed.

Cytokinesis

The process of cell division that occurs after mitosis, resulting in the formation of two separate daughter cells.

Cell division

The process by which a cell divides into two or more daughter cells.

Contractile ring

A structure formed during cytokinesis in animal cells that helps pinch the cell membrane to divide the cell.

Cleavage furrow

A groove that forms during cytokinesis in animal cells, indicating the site of cell division.

Cell plate

A structure that forms during cytokinesis in plant cells, which will eventually become the new cell wall.

Meiosis characteristics

Creates 4 daughter cells, produces cells that are genetically different from parent cells and each other, produces daughter cells that are haploid

Meiosis

A special type of cell division that produces reproductive cells (gametes).

Gametes

Reproductive cells, such as sperm and egg cells.

Haploid

Having half the number of chromosomes compared to the parent cell.

Diploid

Having the full number of chromosomes, as in most body cells.

Gap Junctions

Animal and plant cells have cell junctions that directly connect the cytoplasm of adjacent cells

Kinases

An enzyme that transfers phosphate groups from ATP to a protein, phosphorylating the protein

By attaching to a cyclin

How do kinases activate?

Cyclin

A protein that gets its name from its cycling cyclically fluctuating concentration in the cell.

Cyclin-dependent kinases (CDKs)

Attached kinases and cyclins with a phosphate group

MPF

An important CDK that is the “M-promoting factor”

M Checkpoint

The kinetochores must all be attached to spindle fibers during metaphase, activating an enzyme (separase) that allows sister chromatids to separate and anaphase will proceed

Tumor Suppressor

Genes that inhibit cell division

Proto-oncogenes

Genes that stimulate cell growth

p53

A tumor suppressor gene that causes apoptosis when the cell is worn out or when defects are detected