Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
55 Cards in this Set
- Front
- Back
How do cells in a multicellular organism communicate?
|
They communicate with each with signal molecules (ligands)
|
|
What does the signal molecule (ligands) bind to?
|
They bind to specific receptor proteins inside or on the plasma membrane of other cells and initiate signal transduction
|
|
What kind of ligands are used in multicellular organism communcation?
|
Proteins, amino acids, nucleotides, lipids and dissolved gases
|
|
Define signal transduction and what does it lead to?
|
The events that occur within the cell upon reception of a signal. Leads to a cellular response
|
|
Types of cell signaling
|
Direct contact, paracrine signaling, endocrine signaling, and synaptic signaling
|
|
Direct contact
|
Cells touching or signaling through gap junctions
|
|
Paracrine signaling
|
Signal molecules are released into the extracellular fluid by cells in immediate area
|
|
Endocrine signaling
|
Signal molecules (hormones) are sent to distant cells
|
|
Synpatic signaling
|
Signal molecules (neurotransmitters) released into the gap between neurons
|
|
Intracellular receptors
|
They bind to lipid-soluble signal molecules (steroids, vitamin D, NO) inside the cell
|
|
Cell surface receptors
|
They bind to water-soluble signal molecules (neurotransmitters, proteins)
|
|
Types of cell surface receptors
|
Ion channels, enzymic receptors, G protein-coupled receptors
|
|
Ion channels
|
Neurotransmitter opens or closes channels. Channels are chemically gated
|
|
Enzymic receptors
|
Signal molecule activates receptors which is an enzyme (protein kinase)
|
|
G Protein-coupled Receptors
|
Receptor uses assisting protein, GTP-binding protein (G protein), to transmit signal
|
|
Primary function of steroid hormone receptors
|
Act as regulators of gene expression
|
|
Three functional domains of each receptor
|
Hormone binding, DNA binding, and a domain that can interact with coactivators to affect the level of gene transcription
|
|
What does a cell's specific response depend on?
|
Depends on not only the receptor but also the presence of coactivators
|
|
Guanylyl cyclase
|
Receptor for NO which catalyzes the synthesis of cGMP that produces cell-specific response
|
|
What does cGMP stand for?
|
Cyclic guanosine monophosphate
|
|
What does nerve signal do to muscles?
|
Nerve signals to relax smooth muscles of blood cells
|
|
What is largest category of receptor types in animal?
|
Signal transduction through G protein-coupled receptors
|
|
Whats a major source of control for protein function?
|
Phosphorylation of protein from ATP by protein kinases; either serine/threonine kinases, or tyrosine kinases
|
|
What does RTK stand for?
|
Receptor tyrosine kinases
|
|
Function of RTK
|
Influence virtually all aspects of the cell
|
|
Three domains of RTK
|
Transmembrane, extracellular ligand-binding, and intracellular tyrosine kinase
|
|
What happens when a ligand binds to RTK
|
2 receptors dimerize and phosphorylate each other. Reponse proteins are phosphorylated by binding to phosphotyrosine domain on RTK
|
|
What does MAP stand for?
|
Mitogen-activated protein kinases
|
|
What are cytoplasmic kinases
|
Like MAP kinases, are activated by a phosphorylation cascade, or a kinase cascade
|
|
What is a function of kinase cascade?
|
To amplify the original signal
|
|
What does a cellular response to a kinase cascade usually involve?
|
Phosphorylating transcription factors that activate gene expression
|
|
What kind of signal transduction is RTK
|
Signal transduction through receptor kinases (cell surface receptors, which are enzymic)
|
|
What does a G protein link a receptor to?
|
G protein links receptor to effector on the membrane, usually an enzyme, which may produce a second messenger.
|
|
Adenylyl cyclase
|
Converts ATP to cAMP, a second messenger found in all animals
|
|
What does cAMP activate?
|
Activates protein kinase A (PKA) which phosphorylates a response protein
|
|
Phospholipase C
|
Cleaves phosphatidylinositol-4,5-biphosphate (PIP2) to yield diacylglycerol (DAG) and inositol-1,4,5-triphosphate (IP3), both are second messengers
|
|
Calcium ions as second messengers and relative concentration
|
One of the most versatile second messengers. Low conc. in cytoplasm, but high conc. outside of cell and inside ER
|
|
How is calcium ions released?
|
IP3 binds to receptor on ER (ion channel) releasing Ca2+, which binds to target protein or to calmodulin to activate other proteins
|
|
Can different receptors produce the same second messengers?
|
Yes.
|
|
What are glycolipids and their function
|
Unique cell surface molecules that allow a cell to know what tissue it belongs to
|
|
What functions as self markers
|
Major histocompatibility complex proteins
|
|
Characteristic of MHC protein
|
Usually are immunoglobulins, Everyone makes different MHC proteins, and immune system inspects cells and destroy cells with foreign ID markers
|
|
Cell junction
|
Physical connections between the cells of a tissue
|
|
Tight junctions
|
Connect adjacent cells in a sheet to prevent molecules from leaking between cells
|
|
How does tight junctions connect adjacent cells?
|
Has a fibrous protein belt around each cell which connects with the belt of its neighbors
|
|
Anchoring junctions
|
Attach cytoskeleton of cell to that of other cells or to extracellular matrix
|
|
Desmosomes
|
An anchoring junction. Connect adjacent cells
|
|
Hemidesmosomes
|
An anchoring junction. Connect cells to basement membrane
|
|
Intermediate filaments of cytoskeleton
|
Intermediate filaments of the cytoskeleton is linked with cadherin protein
|
|
Adherens junctions
|
Link actin filaments of cell with those of the neighbors or with matrix
|
|
Integrins
|
Protein links
|
|
Communicating junctions
|
Pass small molecules or ions from one cell to another
|
|
Gap junctions
|
Made from a channel of 6 proteins (connexon) which is gated passageway for sugars and amino acids
|
|
Plasmodesmata
|
Cytoplasmic connections between gaps in adjoining plant cell walls.
|
|
What is plasmodesmata lined with? What does it contain?
|
Lined with plasma membrane and contains tubule connecting the ER of the 2 cells
|