Cell communication

• Direct contact


  communication through cell junctions
• Gap junctions

  animal cells communicate with these through direct contact
• Plasmodesmata


  Plant cells communicate through these
• Local Signaling

  Chemical messages are secreted by secreting cells
• Paracrine signaling


  local regulators are secreted via exocytosis
• Synaptic signaling


  neurons secret neurotransmitters across the synaptic cleft to the target cell
• Long Distance Signaling


  Hormones are used by animals and plants for long distance signaling
• Endocrine signaling


  animal cells secrete hormones into the bloodstream
• Vascular Tissue


  hormones travel in here to reach target tissues
• Reception

  Ligand binds to the receptor
• Transduction


  Signal is converted
• Response

  A cellular process is altered
• Plasma membrane receptors

  receptors on the plasma membrane; most ligands are polar
• Intracellular receptors


  receptors in the cytoplasm; ligands are hydrophobic-steroids
• Transduction


  conversion of extracellular signal to an intracellular signal
• Kinase


  starts the pathway
• Phosphatase


  stops the reaction
• Second messengers


  small non proteins that amplify messages
• Response

  A cellular process altered as a result
• Homeostasis


  State of balance
• The two types of feedback loops

  negative and positive
• Stimulus


  variable that causes a response
• Receptor


  sensory organ that detects a stimulus. Sends to the brain
• Effector


  Muscle or gland that responds
• Response

  Changes the effect of the stimulus
• Negative feedback

  reduces the effect of the stimuli
• cell cycle


  the life of a cell from it's formation to it's death
• histones


  proteins that DNA wraps around nucleosomes
• strings of nucleosomes form

  chromatin
• chromosomes

  chromatin condenses into chromatin
• centromere


  the region on each sister chromatid attach easily
• kinetochore


  proteins attached to the centromere that link each sister chromatid to the mitotic spindle
• genome


  all of a cell's genetic info
• prokaryotes


  have singular and circular dna
• eukaryotes

  one or more linear chromosomes
• somatic cells


  cells that divide by mitosis and contain diploids
• gametes


  reproductive cells that divide by meiosis, and contain haploids
• diploid


  two sets pf chromosomes; one from each parent
• haploid


  one set of chromosomes
• G1 checkpoint


  checks for cell size and growth. go signal allows cell to complete cell cycle, stop signal puts the cell into G0 phase.