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29 Cards in this Set
- Front
- Back
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3 reasons that water is important
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1 - Nearly all biological molecules assume their shape (and thus their function) in response to the physical and chemical properties of the surrounding water.
2 - The medium for the majority of biochemical reactions is water. 3 - Water itself participates in many critical reactions. Concentrations of H+ and OH- determine many reactions of functional groups. |
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Life is based on _____ _____ _____ interactions.
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...low affinity non-covalent...
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The structure of biological molecules and their interactions are determined by the contributions of...
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...many weak interactions.
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List the 6 types of bonds, from strongest to weakest.
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Covalent ----->
Ionic -----> Van der Waal forces -----> Hydrogen bonds -----> Dipole-diploe interactions -----> London dispersion forces |
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Polarity of water is due to (2 things)...
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electronegativity and geometry
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The most important hydrogen donors are _____ and _____.
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alcohols and amines
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The most important hydrogen acceptors are _____ and _____
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oxygen and nitrogen
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Define:
Hydrophobic Effect |
Causes nonpolar substances to aggregate in water.
Also, the tendency of water to minimize its contracts with hydrophobic molecules. |
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Define:
Micelles |
Globules of amphiphilic molecules arranged so that the hydrophilic portion is outside and can interact with solvent, while the hydrophobic portion is inside, away from solvent.
i.e. a ball with the hydrophobic heads on the outside, and the hydrophilic tails on the inside |
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Define:
Bilayers |
Hydrophilic portion faces the solvent, while hydrophobic portion faces inside.
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Define:
Osmosis |
The movement of water molecules across a selectively permeable membrane.
Goes from high concentration to low concentration. |
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Define:
Osmotic Pressure |
Pressure that must be applied to solution to prevent inward flow of water. It is proportional to the concentration of the solute.
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Define:
Colligative Properties Give some examples |
Physical properties that depend on the concentration of dissolved substances rather than on their chemical features.
EXAs: - lowering of vapor pressure - elevation of boiling point - depression of freezing point - osmotic pressure |
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An acids strength is based on it's ability to...
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...transfer a proton to water.
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A weak acid is able to perform as a buffer if it's within what range of it's pKa?
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+/- 1
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K, pKa, pH, [H+], etc.:
Decreasing K does what to pKa, pH, [H+]? |
Decreasing K leads to a weaker acid, thus:
Increases pKa. Increases pH Decreases [H+] |
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K, pKa, pH, [H+], etc.:
Increasing K does what to pKa, pH, [H+]? |
Increasing K leads to a stronger acid, thus:
Decreases pKa. Decreases pH Increases [H+] |
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K, pKa, pH, [H+], etc.:
Increasing pKa does what to K, pH, [H+]? |
Increasing pKa lowers the acidity of the solution thus:
Decreases K. Increases pH Decreases [H+] |
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K, pKa, pH, [H+], etc.:
Decreasing pKa does what to K, pH, [H+]? |
Decreasing pKa raises the acidity of the solution thus:
Increase K. Decrease pH Increase [H+] |
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K and pK are _____ related.
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...inversely...
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A strong acid...
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...dissociates completely in water.
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Weak acids have a K value of
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< 1
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Strong acids have a K value of
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>> 1
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Because strong acids dissociate completely in water, the concentration of (EXA) HCl in water will equal...
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...the concentration of [H+] ions in solution.
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Why does ice float?
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Because water expands when it is frozen; i.e. it becomes less dense.
There are 15% less hydrogen bonds in the crystalline structure of ice. |
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Water is a good solvent for...
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...polar or ionic substances (Hydrophilic substances.)
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Water is a poor solvent for...
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...non-polar/non-charged substances (hydrophobic)
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A buffer's capacity is at it's highest at...
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...it's pKa.
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*Practice Test #8c*
What are two strategies organisms use to minimize the osmotic influx of water into cells? |
pg. 29
1) Many animal cells are surrounded by a solution of similar osmotic pressure(so there is no net flow of water) 2) Most plants and bacteria enclose their cell with a rigid cell wall that can withstand the osmotic pressure generated within. |
