BIOCHEM 524 Study Guide - Quiz Guide: Non-Covalent Interactions, Relative Permittivity, Hydrogen Bond

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peachcattle169

11 Apr 2014

School

UMASS-Amherst

Department

Biochemistry & Molecular Bio.

Course

BIOCHEM 524

Professor

David Gross

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Here are some very brief guidelines as to what i would like you to know for quiz 1. And also archaea: organisms that inhabit exteme environments, but are found most everywhere: eukaryotes: usually larger than prokaryotic cells and contain a nucleus and membrane-bound cellular compartments. H bonds: second strongest noncovalent bond, forms between h attached to o, s, or n and forms between open o, s, or n. Chapter 3: experimental basis for model of dna double helix (in a very general sense) Chargaff"s rules: a & t and g & c are present in the same concentrations in dna. In dna bases stack 3. 4a apart: properties of dna double helix single turn is 34a (10 bp, the entire helix is 20a wide, there is a major and minor groove. Waals contact the side chains extend out from the helix.

Related Questions

Photosynthesis is the process by which plants effectively capture energy from the sun and store it for later use by organisms. It's the fundamental process that enables the entire food chain. Actual photosynthesis is a highly complex process involving many steps and many different chemicals, but we can get an idea of what's happening to thermodynamic quantities (enthalpy, Gibbs free energy, and entropy) using simpler reactions.

Let's consider a toy model in which an input of energy (for example from the sun) is be used to combine water and carbon dioxide to create an organic molecule (formaldehyde) and oxygen, effectively "storing" that energy for use later. The simplest possible such process is given by:

CO₂ + H₂O â O₂ + CH₂O

The table lists the enthalpy of formation, ÎH_f and the entropy S for 1 mol of each of the substances involved in this reaction at 298 K and 10⁵ Pa.

	ÎH_f (kJ)	S (kJ/K)
CH₂O	-115.9	0.2189
H₂O	-241.82	0.1888
CO₂	-393.51	0.2138
O₂	0	0.2051

Answer the following questions assuming that 1 mol of formaldehyde molecules are formed.

1. What is the change in enthalpy of this reaction?
ÎH = ____ kJ

Does this change in enthalpy represent energy that must be added to the system, or energy that is released from the system?
-Energy must be added or Energy is released?

2. What is the change in entropy for this reaction?
ÎS = ____ kJ/K

Does the entropy increase or decrease?
-Entropy increases or Entropy decreases?

At 298 K, what is the heat transfer that corresponds to this change in entropy?
Q = ____ kJ
Does this heat transfer represent energy that is added to the system, or energy that is released from the system?
--Energy is added Energy is released ?

3. What is the change in Gibbs free energy for this reaction?
ÎG = _____ kJ

The Gibbs free energies of formation, ÎG_f, are: -228.57 kJ for water; -394.36 kJ for CO₂; and 0 kJ for O₂. What is the Gibbs free energy of formation for formaldehyde?
ÎG_f (formaldehyde) = _______ kJ

4. Using the formation of formaldehyde as a model, comment on photosynthesis and the formation of sugars using what we know about entropy and free energy.

Is each statement true or false? If false, correct it.

(a) All spontaneous reactions occur quickly.

(b) The reverse of spontaneous reaction is nonspontaneous.

(d) The boiling point of water at 100 °C and 1 atm is spontaneous.

(e) If a process increases the freedom of motion of the particles of a system, the entropy of the system decreases.

(f) The energy of the universe is constant; the entropy of the universe decreases toward a minimum.

(g) All systems disperse their energy spontaneously.

(h) Both ΔS_sys and ΔS_surr equal zero at equilibrium.

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BIOCHEM 524 Study Guide - Quiz Guide: Non-Covalent Interactions, Relative Permittivity, Hydrogen Bond

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