protein b – Chemistry

Flashcard maker : Karen Combs
When amino acids are classified by polarity, what is an example of a nonpolar amino acid?
Hydrocarbon alkanes or aromatic
What is an example of an acidic amino acid?
Has COOH
What is an example of a basic amino acid?
Amines
What is an example of a polar amino acid?
Has alcohol
What does the net charge on an amino acid depend on?
The pH of the solution in which it is dissolved
How does an amino acid exist in solution?
As a zwitterion
Are amino acids polyprotic acids?
Yes
When a low ph amino acid is added to a base over H3O, which H falls off?
The H on the carboxyl end
When a zwiterion form amino acid is added to a base over H3O, where does the H fall off?
It falls off the amino end
What is the pH at which an amino acid has a zero charge?
NO pH
What charge does a low pH have?
Positive
At high pH, what is the charge?
Negative overall charge
What is the isolectric point? pl
At intermediate pH the positive charge equals the negative charge-neutral
Is the isoelectric point different for each amino acid?
Yes
What pH and pl is representative of the Zwitterionic form?
pH=pl
How are polymers of amino acids connected to one another?
by peptide bonds
What is a dipeptide, tripeptide and polypeptide?
Dipeptide-2 amio acid residues joined by a peptide bond, etc
Describe a peptide bond?
Amide bond between the alpha carboxyl group of one amino acid and the alpha amino group of another- pop water off in the center
In the peptide bond, what does the NH3 join?
It joins the other side at the carboxyl end, popping off the o- and an H2 from the amino group
When are proteins least soluable in water?
At their isoelectric points- precipitate from solutions
Where is the c terminal amino acid?
at the end of the chain having the free coo- group
Where is the n terminal amino acid?
at the end of the chain having the free NH3+ group
What is another name for peptide linkage?
Amide linkage representing C=O and NH bond area between the two
How are polypeptides classified?
Based on the number of AA residues present- Residue is what is left when water is removed
What is an oligopeptide
12 to 20 residues
What is a polypeptide?
greater than 20 residues

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