BMB 208 Lecture Notes - Lecture 4: Alpha And Beta Carbon, Zwitterion, Proline

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2 Jan 2018

School

University of Maine

Department

Micro and Molecular Biology

Course

BMB 208

Professor

Cashon

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Document Summary

Side chains: most proteins are built from a combination of 20 different amino acids, these amino acids are unique because they have differing side chains attached to the alpha carbon, the side chain is often denoted as r . Hydrophilic (polar) amino acids: acidic: aspartic acid and glutamic acid are both polar acidic because their side chains contain a carboxylic acid. Hydrophilic (polar) amino acids: basic: lysine, arginine, and histidine are all polar basic because their side chains contain an amine.

Related Questions

For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; each word or phrase should be used only once. Proteins are ______________ built from amino acids, which each have an amino group and a _____________ group attached to the central _______________. There are twenty possible _______________ that differ in structure and are generally referred to as âR.â In solutions of neutral pH, amino acids are _______________, carrying both a positive and negative charge. When a protein is made, amino acids are linked together through _______________, which are formed by condensation reactions between the carboxyl end of the last amino acid and the ___________________ end of the next amino acid to be added to the growing chain.

a: amino	b: ionized	c: polypeptides
d: alpha-carbon	e: length	f: protein
g: carbon	h: noncovalent	i: R group
j: carboxyl	k: peptide bonds	l: side chains

m: hydroxide

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1. Amino acid changes in the primary structure of the protein arenot capable of causing changes in the
overall shape of a protein.
a.) True
b.) False

2. An alpha helix:
a.) is destabilized by the amino acid alanine
b.) can only form by hydrogen bonding between different polypeptidechains
c.) can only form when cysteines form disulfide bridges within thisstructure
d.) all of the above
e.) none of the above

3. What will likely happen if two aspartates at pH 5 are next toeach other in a polypeptide chain?
a.) The side chains of these amino acids will be uncharged andthere will be no effect.
b.) The side chains of these amino acids will be charged and theywill attract each other.
c.) The side chains of these amino acids will be charged and theywill repel each other.
d.) Not enough information is given to determine the effect.

4. Consider the amino acid phenylalanine. Which of the followingbest describes where you predict this
amino acid would be found?
a.) This amino acid is hydrophobic and would be on the surface of aprotein that is in the middle
of a membrane.
b.) This amino acid is hydrophilic and would be on the surface of aprotein that is in the middle
of a membrane.
c.) This amino acid is hydrophobic and would be in the interior ofa protein that is in the middle
of a membrane.
d.) This amino acid is hydrophilic and would be in the interior ofa protein that is in the middle of
a membrane.
e.) Not enough information is given to determine.

5. The difference between fetal and adult hemoglobin with regard tooxygen binding occurs because fetal
hemoglobin has an amino acid substitution in one of its chains thatresults in a histidine being replaced by a
serine.
a.) True
b.) False

1. A sequence of amino acids in a certain protein is found to be â Ser â Gly â Pro â Gly â

The sequence is most probably part of a(n):

a. beta turn

b. antiparallel beta sheet

c. alpha-helix

d. parallel beta-sheet

e. alapha-sheet

2. Which statement about peptides bonds is NOT TRUE?

There is perfectly free rotation about the peptide bond.

The peptide bond has partial double-bond character.

The peptide bond is shorter than a normal carbon-nitrogen single bond.

The peptide bond usually has a trans configuration with respect to the alpha-carbons of the two amino acids involved in the peptide bond.

Peptide bonds are made via condensation of an amine and a carboxylic acid with loss of water.

3. Which of the following statements about proteins is FALSE?

	Active proteins are generally very loosely structured.
	In water-soluble proteins, hydrophobic amino acid residues are generally buried and not exposed to water.
	Primary structure determines tertiary structure.
	Secondary structure is regular, recurring arrangements in space of nearby amino acid residues in a polypeptide.
	Quaternary structure involves the interaction of subunits in a protein with more than one polypeptide chain.

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BMB 208 Lecture Notes - Lecture 4: Alpha And Beta Carbon, Zwitterion, Proline

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