Chapter 1

Which has the greater entropy, liquid water at 0C or ice at 0C

Liquid water

According to molecular sequence data, to which prokaryotic group are eukaryotes more closely related?

The data indicate that eukaryotes are more similar to the archaea than to the eubacteria.

How does the entropy of ice st -5C differ, if at all, from its entropy at -50C

The entropy at -50C is lower than the entropy at -5C

Identify the circled functional groups

A: Thiol (sulfhydryl) B: Carbonyl C: Amide D: Phosphoanhydride (pyrophosphoryl) linkage E: Phosphoryl (Pi) F: Hydroxyl

Which reactions tend to be characterized by an increase in entropy: condensation or hydrolysis?

Hydrolysis reactions tend to occur with an increase in entropy, because the highly ordered polymer is broken down into separate units.

Free Energy Change

The balance between enthalpy, entropy and temperature for a process

A spheroidal bacterium with a diameter of 1 μm contains two molecules of a particular protein. What is the molar concentration of the protein?

Concentration = (number of moles)/(volume)

Does the entropy increase or decrease?

Decrease

Label the following statements true or false: A reaction is said to be spontaneous when it can proceed in either the forward or reverse direction. A spontaneous process always happens very quickly A nonspontaneous reaction will proceed spontaneously in the reverse direction A spontaneous process can occur with a large decrease in entropy

False. A spontaneous reaction occurs in only one direction. False. Thermodynamics does not specify the rate of a reaction. True. True. A reaction is spontaneous as long as ΔS > ΔH/T

For the conversion of reactant A to product B, the change in enthalpy is 7 kJ⋅mol and the change is entropy is 20 J⋅K−1⋅mol. Above what temperature does the reaction become spontaneous?

In order for deltaG to have a negative value (a spontaneous reaction), TdeltaS must be greater than deltaH.

Does the entropy increase or decrease?

Increase

Does the entropy increase or decrease?

Increases

Most of the volume of T. namibiensis cells (see Problem 4) is occupied by a large central vacuole. Why were scientists surprised to discover a bacterial cell containing a vacuole?

Membrane-enclosed cellular compartments are typical of eukaryotic but not prokaryotic cells.

Does the entropy increase or decrease?

No change

Can a process occur if the entropy of the system decreases and the enthalpy increases?

No. When the change in enthalpy is positive and the change in entropy is negative, the free energy change for the process is greater than zero, which makes the process unfavorable.

Which of the following functional groups give a molecule a positive charge? Which give a negative charge?

Positive Charge: amino or imino groups Negative Charge: carboxylate or phosphoryl group.

Why is the cell membrane not an absolute barrier between the cytoplasm and the external environment?

The cell membrane must be semipermeable so that the cell can retain essential compounds while allowing nutrients to enter and wastes to exit.

The bacterium Thiomargarita namibiensis-at about 0.1 to 0.3 mm in diameter-is visible to the human eye. How does it compare to the size of the typical prokaryotic cells? How does it compare to the size of typical eukaryotic cells?

Typical prokaryotic cells are 1-10 μm in diameter, so T. namibiensis is about 10-300 times larger (or has 1000 to 27 million times the volume). Typical eukaryotic cells are 10-100 μm in diameter, so T. namibiensis is about the same size or up to 30 times larger (or has the same to 27,000 times the volume).