Cell Communication and Cell Cycle

m phase (mitotic phase)

phase of the cell cycle where mitosis and cytokinesis occur, resulting in the division of a parent cell into two genetically identical daughter cells.

interphase

phase of the cell cycle between cell divisions, where the cell grows, performs normal functions, and prepares for division. It includes G1, S, and G2 phases.

g1 phase

first gap phase of interphase where the cell grows, synthesizes proteins, and prepares for DNA replication.

g0 phase

resting state where cells exit the cell cycle and do not divide. Some cells may re-enter the cycle, while others remain permanently in G0.

s phase

synthesis phase of interphase where DNA is replicated, ensuring that each daughter cell will have an identical set of chromosomes.

hormones

chemical messengers that move around the body to stimulate activity

g2 phase

second gap phase of interphase where the cell continues to grow and prepares for mitosis by synthesizing necessary proteins and organelles.

what is the cell cycle controled by

controlled by regulatory proteins and checkpoints that ensure proper progression and prevent errors, such as damaged DNA or incomplete replication.

cell cycle checkpoints

Specific control points in the cell cycle (G1, G2, and M checkpoints) that assess conditions like DNA damage, correct replication, and proper attachment of chromosomes to the spindle.

protein kinase

enzymes that active/deactivate other proteins by phosphorylation (adding a phosphate group to another molecule)

• always in the cell, usually inactive

• attached to a cyclin = activated

cyclin-dependent kinase (CDK)

family of enzymes that, when bound to cyclins, regulate the cell cycle's progression by phosphorylating target proteins.

g1 phase: restriction point

critical checkpoint in the G1 phase where the cell decides to proceed with division, enter G0, or undergo apoptosis, based on environmental and internal signals.

cyclins

Regulatory proteins (kinases) that bind to CDKs to activate them, controlling the timing and sequence of cell cycle events.

gap junction

paracrine signalling

communication of cells over relatively short distances

• important during development

endocrine signalling

long distance cell signaling

quorum sensing

bacteria monitor the density of the population based on chemical signals

autocrine signaling

a cell signals to itself, releasing a ligand that binds to receptors on its own surface

• helps cells take on and reinforce their correct identities (like cancer)

signal transduction

relay proteins + secondary messengers relay extracellular signals to activate cellular responses

ligands

signalling molecules that bind to receptors and trigger a response by changing the shape of the receptor protein

what are the four basic categories of chemical signalling in multicellular organisms?

paracrine signaling, autocrine signaling, endocrine signaling, and signaling by direct contact

synaptic signaling

a type of paracrine signaling; nerve cells transmitting signals

autoinducers

signaling molecules continually secreted by bacteria to announce their presence to their neighbours