MBG 2040 Lecture Notes - Lecture 12: Protein Folding, Aldehyde, Electronegativity

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magentadog113

19 Nov 2016

School

University of Guelph

Department

Molecular Biology and Genetics

Course

MBG 2040

Professor

Baozhong Meng

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Document Summary

Protein structure involves complex macromolecules composed of 20 different amino acids. Protein are the most prevalent component of living organisms in terms of total mass. Proteins are composed of polypeptides and every polypeptide is encoded by a gene. Each polypeptide consists of a long sequence of amino acids linked together by covalent bonds. A peptide is a compound composed of two or more amino acids. The amino acids in polypeptides are covalently linked by linkages called peptide bonds. Each peptide bond is formed by a reaction between the amino group of one amino acid and the carboxyl group of a second amino acid with the release of a water molecule (condensation) Four different levels of organization - primary, secondary, tertiary and quaternary. The primary structure of a polypeptide is its amino acid sequence which is specified by the nucleotide sequence of a gene. The secondary structure refers to the spatial interrelationships of the amino acid in segments of polypeptide.

Related Questions

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.

maroonwallaby335

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

indigofrog836

1. Polypeptide strands is the active form of a digestive enzyme in the stomach that breaks polypeptide chains into smaller polypeptides.

2. Cleavage of proteins by pepsin in the stomach results in formation of pepsinogen which get broken down further in the small intestine.

3. An amino acid chain made up of three amino acids joined together is called a tripeptide.

4. Dipeptide describes an amino acid chain made up of two amino acids joined together.

5. The 20 different amino acids are the building blocks used for protein synthesis.

6. Amino acid pools are stockpiles found in the blood and other cells of the body that can be used to build new proteins.

7. The continual process of degrading and synthesizing protein is called protein turnover.

8. The stomach produces pepsin, which denatures protein.

9. Denaturation occurs when a protein is exposed to heat, acid, bases, or mechanical agitation resulting in unfolding of the protein, though the peptide bonds remain intact.

10. The part of an amino acid that contains nitrogen is called the amine group.

11. The acid group is also known as the carboxyl group.

12. Single amino acids that are absorbed in the small intestine travel to the liver via the portal vein.

Please correct these sentences AS SOON AS POSSIBLE.. Some of them are not correct and I didn't figure out what are they!

violetdog828

MBG 2040 Lecture Notes - Lecture 12: Protein Folding, Aldehyde, Electronegativity

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