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What can proteins do?
latch on to substances that are not soluble to help transport them
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What can amino acids form and why?
Can form isomers but only two can get incorporated into proteins
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What is the backbone of amino acids?
Explain the groups.
anything but the R group
two are ionizable -- they have a proton that they aren't permanently attached to (the primary amino group and the primary -COOH group)
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Explain the groups in terms of pH.
In acidic solutions, COOH is constantly letting go of its proton. However, it is being reprotonated just as quickly. At a higher pH, (2-4), this reprotonation ceases; and, the amino acid exists as a zwitterion.
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If we are taking an ionizable group through titration, what is happening?
protons are being pulled away from these groups as --OH scavenges for H+ to form water
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Define pKa.
describes the strength of an acid
describes the susceptibility of a proton to removal by reaction with a base
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Why are there three letter abbreviations and one letter abbreviations?
Three letters: RNA reads it in three nucleotides (codons)
One letter: condenses protein structure
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In acid, how does an amino acid exist?
with both ionizable groups protonated
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In base, how does an amino acid exist?
with both ionizable groups deprotonated
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An increase in pH from acid causes?
the formation of a carboxylate
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What is the inflection point? What occurs at it?
A point on a chart that marks the beginning of a significant move, either up or down
the amino acid form changes from either protonated--> zwitterion or zwitterion--> deprotonated
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In acid base chemistry, what is the proton donor? proton acceptor?
- proton donor: acid
- proton acceptor: base
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Definition of pH
pH=log(1/[H+])= -log [H+]
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Definition of pKa (formula)
pKa=log(1/Ka)=-logKa
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At the halfway point, what is occurring?
the concentration of conjugate base equals that of the acid
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What are some functions of proteins?
- conversion of energy
- muscle contraction
- enzymes
- transport
- structural support
- immune response
- messengers
- growth and development
- motion
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__ is the most abundant protein.
__ and __ function in structural support.
collagen
collagen and keratin
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What is the difference between secondary and tertiary structure?
secondary: interaction is localized; between adjacent amino acids
tertiary: different regions will react together
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What is quaternary structure?
multiple subunits brought together
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How many atoms are involved in amino acids?
- five: -NH3+
- - COO-
- R
- alpha carbon
- Hydrogen
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How many different R groups are there?
20, but glycine has just a simple hydrogen, so technically nineteen
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