10 Questions
How does binding of a signaling molecule to its receptor affect its activity?
All of the above
How does phosphorylation of a protein affect its activity?
could increase or decrease the activity
Which of the following is INCORRECT regarding how enzymes lower the activation energy of a reaction?
Enzymes reduce the free energy of the products of the reaction.
The word "nucleoside" refers to_______.
the nitrogen base and sugar ring
Disulfide bonds stabilize protein shape outside the cell by__________
covalent bonds between cysteines.
Shown below is the ATP hydrolysis cycle of a motor protein. What sentence BEST describes the state of the motor protein in "C"?
The hydrolysis of ATP to ADP caused a conformational change in the protein.
Which method is most suitable for determining the location of a protein inside the cell?
confocal microscopy
The function of a feedback mechanism is to
turn on/off the synthesis of a gene or product.
Which of the following is true about a negative feedback loop?
The last enzyme in a chain of enzymatic reactions signals to a previous enzyme to stop the enzymatic reaction.
Which method is used for separating proteins based on specific interactions with other molecules?
affinity chromatography
Study Notes
Signaling Molecule Receptor Binding
- Binding of a signaling molecule to its receptor activates or inhibits the receptor's activity, leading to a response in the cell
- This binding causes a conformational change in the receptor, triggering a signal transduction pathway
Protein Phosphorylation
- Phosphorylation of a protein can either activate or inhibit its activity, depending on the protein and the site of phosphorylation
- This post-translational modification can alter the protein's function, localization, or interactions
Enzyme Activation Energy
- Enzymes lower the activation energy of a reaction by forming an enzyme-substrate complex, positioning the substrate for efficient catalysis
- The incorrect statement is that enzymes alter the free energy change (ΔG) of a reaction
Nucleoside Definition
- A nucleoside is a molecule composed of a sugar molecule (ribose or deoxyribose) and a nitrogenous base (A, C, G, T, or U)
Disulfide Bonds
- Disulfide bonds stabilize protein shape outside the cell by forming covalent bonds between cysteine residues
- This strengthens the protein's tertiary structure, making it more resistant to degradation
Motor Protein ATP Hydrolysis Cycle
- In state "C" of the ATP hydrolysis cycle, the motor protein is in a bound state to the microtubule, with ADP bound and no Pi released
Protein Localization
- The most suitable method for determining the location of a protein inside the cell is fluorescence microscopy
- This involves tagging the protein with a fluorescent marker, allowing visualization of the protein's distribution
Feedback Mechanisms
- The function of a feedback mechanism is to maintain homeostasis, regulating a process to achieve a stable outcome
- A negative feedback loop counters the original stimulus, reducing the response and promoting stability
Protein Separation
- The method used for separating proteins based on specific interactions with other molecules is affinity chromatography
- This involves binding the protein to a column with immobilized ligands, allowing separation based on specific interactions
Learn about signaling molecule receptor binding and protein phosphorylation, including how they affect cellular responses and protein activity.
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