The Shape Matters
This specific region of an enzyme must be compatible with the substrate's shape and charge.
Active Site
To maintain order and power cellular processes, energy ______ must exceed energy loss.
Input
This type of signaling involves direct contact or the use of local regulators over short distances.
Paracrine / Local
The three stages of cell signaling are Reception, ___________, and Response.
Transduction
This type of feedback works by working against the change in the homeostatic equilibrium.
Negative
Enzymes increase reaction rates by doing this to the activation energy.
Lowering it
______ Law of Thermodynamics, which states that entropy increases.
Second
A chemical messenger that binds specifically to a receptor protein is called...............
Ligand
Cyclic AMP is a famous one of these "loudspeakers" inside the cell.
Second messengers
This feedback loop says: "I like it! Give me MORE!
Positive
This "hater" binds to the allosteric site to ruin the enzyme's shape.
Non competitive Inhibitor
Photosynthesis is how plants "capture and ________" solar energy.
store
These specific eukaryotic receptors are like the "Gold Standard" of cell signaling.
GPCRs (G Protein-Coupled)
This is the cell's dramatic "exit plan" (programmed death) if the signal says so.
Apoptosis
Labor during childbirth or fruit ripening are examples of this loop.
Positive Feedback Loop
If a mutation changes an amino acid in the allosteric site, why might the enzyme’s reaction rate stay high even when an inhibitor is present?
noncompetitive inhibitor can no longer bind; the enzyme stays "locked" in its active shape.
Why must biological pathways be sequential (Step A B C) instead of releasing all energy in one single giant explosion?
controlled, efficient transfer of energy and to minimize heat loss.
A researcher adds a chemical that blocks GTP from binding to proteins. Which specific class of eukaryotic receptors will immediately stop working?
G Protein-Coupled Receptors (GPCRs), which require GTP to "switch on."
If a signal transduction pathway is "constitutively active" (always ON) due to a mutation, how would this affect the cell's phenotype
uncontrolled cell growth (cancer)
Explain how Negative Feedback at the molecular level (like end-product inhibition) prevents a cell from wasting chemical resources.
The final product of a pathway binds to the first enzyme, "shutting off" the assembly line once enough is made. Or something like that...
An enzyme produces 120 mg of product in 2 minutes. What is the rate of reaction in kg per minute?
0.06 Kg/min
If a cell stops taking in energy, its Entropy will do this, leading to cellular death
Increase
You expect a 1:1 ratio of "Signal On" vs "Signal Off" cells. If your Chi-Square value is lower than the critical value, do you reject or fail to reject the null hypothesis?
Fail to reject the null hypothesis
If 1 ligand activates 10 secondary messengers, and each messenger activates 10 enzymes, what is the amplification factor
100
The Fluorescent Pulse-Shrimp
"Scientists have discovered a deep-sea crustacean, the 'Pulse-Shrimp', living near volcanic vents. To survive sudden heat spikes, the shrimp hosts a layer of specialized symbiotic bacteria. When the shrimp’s body temperature rises above its set point, these bacteria begin to fluoresce, absorbing excess thermal energy and releasing it as bright blue light into the dark water. As the shrimp cools down and its temperature returns to normal, the fluorescence dims and eventually stops.
Analyze this discovery using your knowledge of biological systems:
Negative, thermal energy is transformed into light energy (probably by a special protein that is activated by increase of temperature, creating a gradient and using the ATP to power the fluorescence) decreasing temperature and helping shrimp survive in that environment