Cellular Respiration
What is the final electron acceptor in the electron transport chain?
Oxygen
What is the green pigment that absorbs light energy to power photosynthesis?
chlorophyll
What are the THREE major components of cell signaling?
1. Reception
2. Transduction
3. Response
What is an expansin? Where is this found?
An expansin breaks hydrogen bonds in the primary cell wall to allow for room to grow.
Rubisco
During the oxidation of pyruvate into acetyl-CoA, how many carbons are lost from one molecule of pyruvate, and in what form are they lost?
One CO2 is released
Where do the light reactions occur in the chloroplast? Calvin cycle?
light - thylakoid membrane/ kind of the lumen
calvin - stroma
A specific type of ligand will only bind to its receptor outside of the cell. What might this say about the ligand?
It is polar and cannot diffuse across the membrane.
What are the main functions of the primary and secondary cell walls?
Primary - growth, protective barrier, flexible
secondary - support, waterproofing (waxes), rigid
Compare competitive inhibition to allosteric inhibition.
Competitive inhibition: The inhibitor competes with the substrate for the enzyme’s active site. It can be overcome by adding more substrate.
Allosteric inhibition: The inhibitor binds to a different site (allosteric site), changing the enzyme’s shape so the active site doesn’t work properly. Cannot be overcome by just adding more substrate.
In which part of the mitochondria is the hydrogen gradient built up?
the intermembrane space
In the Calvin cycle, carbon dioxide is “fixed” into organic molecules using the energy from these two products of the light reactions.
ATP and NADPH
What are the two common types of receptors discussed in class? How do they work?
G-Protein Coupled Receptors: signal binds to receptor, G-protein interacts with receptor and GEF adds GTP to G-protein, activated G-protein activates another protein
Receptor Tyrosine Kinases: protein kinase adds phosphate, and protein phosphatases remove phosphates from proteins; when a ligand binds to the receptor, it causes a change in shape, which allows for modification by a kinase and signal can be relayed to a transducer (turned off by phosphatase)
What molecules make up the primary cell wall? Secondary cell wall?
Primary: made of polysaccharides →strong cable (cellulose) gelatinous substance (pectin)
Secondary: Waxes and lignin → waxes protect against water and gas loss, lignin provides support
Compare and contrast plasmodesmata and gap junctions?
Both connect the cytoplasm of adjacent cells to allow ions and small molecules to flow through.
Plasmodesmata are more of a bridge, NOT a protein channel, and it is found in plants, NOT animals
Why is NAD⁺ regeneration crucial for glycolysis, even under anaerobic conditions?
because glycolysis requires NAD⁺ as an electron carrier, and without regeneration, it would stop
Where does the hydrogen come from that helps produce ATP? Explain this process.
In Photosystem II, water molecules are split, releasing electrons, oxygen gas, and hydrogen ions. The electrons move through the electron transport chain, and their energy pumps additional protons from the stroma into the thylakoid lumen against the concentration gradient. This buildup of protons inside the lumen creates a proton gradient, which powers ATP synthase to produce ATP — similar to how the electron transport chain works in cellular respiration.
How can receptors be both transducers and effectors? What is a transducer? What is an effector? Can you give an example of a receptor being both?
A receptor would have to receive a signal, convert it, and execute the response.
Transduction is taking one signal and converting it into another signal.
An effector is the molecule/protein that does the effect.
Ligand-gated ion channel
What roles does the ECM play in multicellular organisms?
- The ECM provides structural support, helps cells stick together, regulates communication, and influences cell behavior.
When enzymes and substrates bind: the enzyme acts as a catalyst, the enzyme and the substrate are changed during binding, substrate is converted into a product
When ligands and receptors bind: the ligand is not changed by the binding, the receptor is either being activated or inactivated
If there is no oxygen, what is the first step that would not occur in cellular respiration?
The process would end at glycolysis. Pyruvate would not be oxidized because then the molecule would go into the mitochondria, and it is easier to keep things compartmentalized when stopping processes. Also, unnecessary energy is being spent creating electron carriers if the electron transport chain can not occur.
How many spins on the Calvin cycle does it take to produce a glucose molecule?
6
What are the two different types of signal transductions covered in class? Give an example of each.
kinase cascades: adding/removing phosphate to turn pathways on and off
Secondary messengers: cAMP, DAG, IP3
Name the three types of junctions and their functions? Bonus 50 points if you can give examples.
- Tight junctions seal cells together to prevent leakage of materials between them. (intestines)
- Desmosomes are anchoring junctions that connect cells using intermediate filaments, giving tissues mechanical strength. (skin)
- Gap junctions are protein channels that allow ions and small molecules to pass through (heart)
If Gibbs free energy is negative in a reaction, what is happening?
The reaction is spontaneous. Exergonic. Releasing energy. Potential energy is decreasing.