Cell Signaling
What are the three main steps of cell signaling?
Reception, Transduction, Response
This is the type of signaling where the secreted signal is from a neighboring cell.
Paracine signaling
What’s the difference between the rough ER and smooth ER?
Rough ER has ribosomes and synthesizes proteins; smooth ER synthesizes lipids and detoxifies.
Is photosynthesis endergonic or exergonic?
Endergonic
DNA and RNA are examples of which type of macromolecule?
Nucleic acids
What is an action potential?
Briefly describe the steps of reception in cell signaling.
The signal binds to the protein receptor, which causes a conformation change, allowing the signal to cross the membrane.
Name two organelles that contain their own DNA.
Mitochondria and chloroplasts
After light excites electrons and they leave PSII to travel down the first ETC, how are they replaced to PSII?
Water is split and the electrons are given to the chlorophyll molecules of PS II.
In which step of cellular respiration is oxygen the final electron acceptor?
ETC (Electron transport chain)
What is apoptosis?
Programmed cell death via proteases that break down proteins
What is the second step of signal transduction called? BONUS 200pts: Name a common second messenger in signal transduction.
Transduction – the signal is relayed inside the cell, often through a cascade.
Bonus: cAMP (cyclic AMP)
Describe the role of the lysosome.
It digests old cell parts and materials via hydrolytic enzymes. (breaking down using water)
Why do hydrogen ions flow from the thylakoid space to the stroma through ATP synthase?
They flow passively from high to low concentration via facilitated diffusion. As they flow through ATP synthase, the enzyme spins and produces ATP.
Why are ion channels necessary to transport ions in/out of the cell?
They are charged particles and therefore can’t diffuse through the hydrophobic core of the membrane.
What’s the role of phosphatases in signal transduction?
They remove phosphate groups, turning off the signal.
What is a phosphorylation cascade?
Amplifies the original signal by an enzyme that phosphorylates another, which leads to a chain reaction
Explain the full pathway a protein takes from synthesis to secretion.
Ribosome → Rough ER → Golgi apparatus → Transport vesicle → Plasma membrane
Which products of the light-dependent reactions are used in the Calvin cycle to help form reduced organic compounds?
ATP & NADPH
What would happen to cellular respiration if the mitochondrial membrane became permeable to protons?
ATP production would drop because the proton-motive force would disappear, so electron transport wouldn't be connected to ATP synthesis.
What is a tyrosine kinase receptors?
They are transmembrane proteins that act as receptors for various ligands like growth factors and hormones (Ligand binding results in a conformational change)
What is allosteric regulation?
How we can turn proteins on/off by the binding of a small molecule
What is glycosylation and where does it occur?
Adding sugar groups to proteins; in the Golgi apparatus and ER.
Compare the roles of PS I and PS II in terms of electron flow and product formation.
PS II: Captures a photon, splits water to generate electrons, establishes proton gradient that drives ATP synthase
PS I: Accepts electrons from PSII via ETC, another photon reduces NADP+ to NADPH
How would the fluidity of the phospholipid bilayer change if saturated fatty acids are replaced with unsaturated ones?
Unsaturated fatty acids increase membrane fluidity due to kinks in the hydrocarbon chains that prevent tight packing.