Chapter 13 Review Flashcards
Most signals occurs because of _________.
hormones
Insulin forces the glucose to be _______ by the body.
uptaken
What kind of protein receives hormones?
Transmembrane proteins
Transmembrane Proteins
- Signal is outside the cell
- Chemical process that occurs inside the cell
Target cells have ______ that receive the hormone signals.
receptors
Only the cells with the receptor of a ______ hormone will react with the __________.
specific ; hormones
Signal Transduction
is the conversion of an informational signal into a chemical process. Signaling molecules bind to a receptor protein.
Signal Transduction Process
1) a cell receives an external informational signal from the environment or another cell
2) These signals cause changes in the cell’s composition and function
3) Signal transduction may rely on secondary signals or relay molecules to produce a change. (The change may also occur in the cytoplasm, shown here, or affect gene expression in the nucleus)
Signal Transduction is highly specific due to __________ interactions.
receptor/signal
Receptors are ______ specific.
cell
Three factors that account for sensitivity of signal transduction:
1) High affinity
2) Cooperativity
3) Amplification
What is “high affinity”?
Kd is 10^-10 M or less. Signals are picked up at extremely low concentrations because they are super specific and super sensitive.
What is cooperativity?
- Large changes in receptor activation with small changes in [ligand]
- Binding one ligand increase affinity for a second ligand molecule in positive cooperativity.
What is Amplification?
- results when an enzyme associated with a signal receptor is activated.
- One signaling hits the receptor. The activated enzyme catalyzes the activation of many molecules of a second enzyme.
- Beginning of an enzyme cascade
The sensitivity of a receptor system is subject to modification called ____________.
desensitization
What is desensitization?
The sensitivity of a receptor is subject to modification. When the receptor is “flooded” with a signal, the receptor is turned off (can trigger the removal of a receptor from the surface.
What is integration?
the ability of a system to receive multiple signals and produce a unified response. Important for maintaining homeostasis
6 Major classes of Signaling Molecules
1) G-Protein Coupled Receptor
2) Receptor Tyrosine Kinase
3) Receptor Guanylyl Cyclase
4) Gated Ion Channel
5) Adhesion Receptor
6) Nuclear Receptor
G Protein-Coupled Receptor
External ligand binding to receptor activates an intracellular GTP-binding protein, which regulates an enzyme that generates an intracellular second messenger.
Receptor Tyrosine Kinase
Ligand-binding activates tyrosine kinase activity by autophosphorylation. The signal is received on the outside and phosphorylation occurs on the inside.
The simplest signal transducers are
Gated-Ion Channels
INSR (Insulin Receptor) is a which type of signaling molecule?
A tyrosine kinase
Two groups besides Tyr that can be phosphorylated
Serine and Threonine
Membrane receptors can be directly linked to _______.
Enzymes
MAP
Mitogen Activated Protein
The β-adrenergic receptors mediate changes in fuel metabolism in
muscle, liver and adipose
ERK
Extracellular Signal-Regulated Kinase
MEK
Mapkinase, ERK Kinase , Kinase
Signal transduction with a GPCR requires 3 components:
receptor with 7 transmembrane helilces, a guanosine nucleotide binding protein (or G Protein), and an effector enzyme or ion channel
