Cell Life and Communication

Ligand

small, volatile/soluble molecules specified to receptor site

Paracrine signals

cells some close together and signal diffuses through extracellular matrix

Synaptic Signal

• ligand travels between synapse propagated by electrical impulse

• binds to postsynaptic receptor, reuptaken/degraded after

Neurotransmitters

ligands that bind to postsynaptic dendrite’s receptor site

Chemical Synapses

junction between neurons

Endocrine Cells

send out signals to thyroid, hypothalamus, pituitary gland with slower but more long-lasting effect

Hormones

ligands of endocrine cells that travel through bloodstream and are diluted

Autocrine Signals

when a cell produces a ligand to bind to itself

Apoptosis

when cell kills issue/virus by killing itself

Gap Junctions

water-filled spaces that allow signal molecules to difuse across, acting as intracellular mediators

Internal Receptors

• respond to hydrophobic ligand molecules

Cell-Surface Receptors

integral proteins that bind to external ligands, transforming them into intracellular signals

Extracellular Domain

where external ligands bind

Ion Channel-Linked Receptors

when ligand binds to open channel for specific ions to be allowed in

G-Protein-Linked Receptors

when ligand binds to activate a membranal G-protein to interact with the ion channel/membrane enzyme

Membrane Region

• where ligand-prompted signal is transferred through the membrane, activating the enzyme as a catalyst

Hydrophobic Ligands

• direct diffusion, internal receptors

• steroids, and bind to carrier proteins

Hydrophilic Ligands

• polarized and usually large

• bind to external domain of cell-surface receptors

• can also be peptides, small molecules, proteins

Signal Transduction

transmitting signal through membrane to the cytoplasm

Dimer

chemical compound formed by 2 identical molecules

Signaling Pathway

chain of events that occur after ligand-binding

Phosphorylation

addition of phosphate group to a molecule, often to activate enzymes

Kinase

substrate that is phosphorylated

Second Messengers

small molecules propagating a signal after ligand binding, altering protein behavior

cAMP

• cyclic adenosine monophosphate

• binds and activates cAMP kinase

cAMP-dependant kinase

• activates serine and theorine nucleotides

Inositol phospholipids

lipids that are convertible into 2nd messengers

DAG

• diaglycerol in plasma membrane that activates protein kinase C to phosphorlyate serine + theorine

IP3

• inositol triphosphate

• binds to ligand-gated Ca2+ channels in ER

Signal Integration

2+ different receptors merge to activate a similar response

Mating Factor

signaling molecule that binds to surface receptors to initiate budding

Autoinducers

signaling molecules for communication with similar bacteria

Quorum Sensing

number of cells present as determinant for signaling

Diploid

two complete sets (x thingy)

Haploid

one set (l thingy)

Locus

location along a chromosome

Nucleosome

beadlike, histone complex with coiled chromatin

Chromatin Complex

8 histone proteins surrounded by short stretches of double-helix DNA

Mitotic Spindle

fibers that orchestrate movements of chromosomes

Centrioles

organelles that attach to centrosomes via mitotic spindle

Condensin

protein that condenses genetic material for movement

Kinetochore

protein developed on each sister chromatid to bind to mitotic spindle

Tubulin Monomers

assemble cytoskeletal parts

Cleavage Furrow

fissure in cell tissue prompted by contractile ring of actin filaments

Cell Plate

construct of glucose to build up plant cell walls

G0 Phase

inactive (quiescent) phase where cell performs regular functions

Positive Regulation

promotes progress to next phase

Cyclin

regulates when tightly bound to Cyclin-dependent kinase, dependent on the complex of both

Cyclin-Dependent Kinase

phosphorylates others proteins, changing shape to move into next phase

Negative Regulation

halts the cell cycle

Rb

• Retinoblastoma Protein

• monitors cell cycle and binds to transcription factors to halt protein production

p53

halts and gets enzymes to repair DNA, triggering apoptosis if material unavailable

p21

binds to an inhibits cdk/cyclin complex activity when p53 activated

Cancer

uncontrolled cell growth due to regulatory mechanic errors

Proto-Oncogenes

positive cell cycle regulators

Tumor Suppressors

negative regulators

Binary Fission

rapid, less complicated cell division in prokaryotes

Origin

where biodirectional replication starts

FtsZ protein

triggers building new membrane and establishing cell wall

Fertilization

2 haploid cells coming together

Homologous Chromosomes

matched pairs with identical genes in identical locations

Spores

haploid cells that can produce haploid organisms/fuse to make a diploid cell

Meiosis

processes to create haploid cells

Synaptomenal Complex

lattice of proteins between homologous chromosomes to support exchange of genetic material

Synapsis

tight pairing of genes when chromatids aligned precisely

Recombination Nodules

around where DNA is cleaved, ends modified, or new connection is made

Crossover

genetic recombination between NON-sister chromatids

Tetrads

four sister chromatids bound at chaismata

Chiasmata

point where legs of chromosomes cross

Reduction Division

reduction in ploidy level during mitosis