Cell Communication and Cell Signals (U6) Flashcards
Plant intercellular junctions
plasmodesmata - channels that allow cytosol to pass between cells
Animal intercellular junctions
tight junctions - membranes of adjacent cells fused
desmosomes - anchoring junctions
gap junctions - allow cytoplasmic movement between adjacent cells
Signal transduction pathway
convert signals into cellular responses
Ligand
a signal molecule the binds with the cell receptor
Autocrine signal
affects the same cell
Paracrine signal
affects nearby cells
Endocrine (hormonal) signal
affects distant cells
Steps of cell signaling
reception, transduction, and response
Ion-gated channels
a signal molecule binds to a protein and the pore opens as ions go in
Protein Kinase receptors
a signal molecule attaches to the receptor and which causes an enzymatic reaction
G-protein receptors
GTP is attached to receptors, binding with protein receptor activates G-protein
Amplification
cascade multiplier that creates a fast response
Negative feedback
maintains homeostasis to raise or lower a specific body condition
Lipid-based horomones
hydrophobic, diffuse across cell membrane and turn on genes
Lipid-based hormones
hydrophobic, diffuse across cell membrane and turn on genes
Protein-based hormones
hydrophilic, can’t diffuse across cell membrane, trigger secondary messenger pathway
Pathogens
foreign antigens, ex. bacteria, virus, fungi, worms, toxins
Innate immunity
non-specfic immunity you are born with
Adaptive immunity
immunity acquired by contact with pathogens, relies on memory
First line of defense
non-specific barriers, skin and mucous membranes
Second line of defense
non-specific internal barriers, such as leukocytes
Inflammatory response
increase in body temp slows down invaders and increases WBC defense
Third line of defense
acquired defense that fights based on an invaders antigen
Antigen
cellular name tag protein
Antibody
protein tha binds to a specific antigen
Resting potential
when a neuron is unstimulated, -70mV
How does a neuron reset itself?
by using the sodium-potassium pump
How are signals received?
transported via vesicles and release through ion-gated channels in synapse
Why do cells divide?
for reproduction, growth, and repair
Phases of the cell cycle
interphase, prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis
Interphase
most of cell cycle life, where DNA synthesis takes place
Prophase
chromatin condenses, nucleus disappears, spindle and centrioles are formed
Prometaphase
spindle fibers attach to centromeres, chromosomes begin moving
Metaphase
chromosomes align along the middle of the cell
Anaphase
sister chromatids separate at the kinetochores and are pulled to opposite poles
Telophase
daughter nuclei form and chromosomes disperse
Cytokinesis in animals
actin filaments form a cleavage furrow and separates cell
Cytokinesis in plants
cell plate forms and new cell wall is laid down between membranes
Binary fission
single circular chromosomes and no membrane bound organelles believed to be beginning of mitosis
Cyclin and Cdk
protein signals that promote cell growth and division
Irreversible cell cycle checkpoints
replication of genetic material and separation of sister chromatids
