HW assignment 7 proteins PDF

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HW assignment 7 proteins Due: 6:00am on Thursday, You will receive no credit for items you complete after the assignment is due. Grading Policy

Visualizing the Concept: A protein's functional shape results from four levels of structure Watch this video and then answer the questions.

Part A Your body contains tens of thousands of different proteins, each with a specific structure and function. The unique threedimensional shape of each of these diverse proteins is based on several superimposed levels of structure. Which of the following statements is an accurate description of proteins? ANSWER: The 20 amino acids found in proteins differ in the composition of their R groups, which may be either polar or charged. The primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the DNA of a gene. Secondary structures, which include the alpha helix or beta pleated sheet, are held together by interactions between R groups. Tertiary structure is the overall shape of a polypeptide, which may be stabilized by hydrophobic interactions, hydrogen bonds, ionic bonds, and peptide bonds. Quaternary structure is only found in proteins that have four identical polypeptide subunits.

Correct The order of DNA nucleotides in a gene provides the code for the specific order of amino acids in the primary structure of a protein.

Part B

Identify the level(s) of protein structure present in this molecule.

Select all that apply. ANSWER: primary secondary tertiary quaternary

All attempts used; correct answer displayed This protein illustrates all four levels of protein structure. primary: the order of amino acids in the polypeptide chain secondary: localized regions of alpha helices and beta pleated sheets tertiary: the overall three-dimensional shape of a polypeptide, stabilized by interactions between R groups quaternary: the association of more than one polypeptide subunit into a functional protein.

Part C What could happen if a mutation in a gene caused a hydrophobic amino acid in a polypeptide to be replaced by a hydrophilic amino acid? ANSWER:

There would be no effect as long as the protein had quaternary structure, because primary structure does not affect that level. The hydrophilic amino acid could not form the proper peptide bond in its new location, so both the shape and function of the protein would be affected. The new amino acid would not form the same interactions with hydrophobic R groups, and the protein's shape would likely be affected. The shape of the protein would not be affected if only one amino acid in the primary structure is changed.

Correct In the formation of tertiary structure, a polypeptide folds so that amino acids with hydrophobic R groups often cluster in the center of the protein. Because the new amino acid has a hydrophilic R group, it would not be part of those interactions. Thus, this mutation would affect the overall shape of the protein.

Art Question - Chapter 3 - Question 33

Part A

Which bond in the figure is a peptide bond? ANSWER:

A B C D E

Correct

Multiple Choice - Chapter 3 - Question 55

Part A Which bonds maintain the primary structure of a protein? ANSWER:

peptide bonds disulfide bonds ionic bonds hydrogen bonds

Correct

Multiple Choice - Chapter 3 - Question 57

Part A Which type of interaction stabilizes the α helix and the β pleated sheet structures of proteins? ANSWER:

peptide bonds hydrogen bonds ionic bonds hydrophobic interactions

Correct

Multiple Choice - Chapter 3 - Question 58

Part A The α helix and β pleated sheet are examples of which level of protein structure? ANSWER:

primary secondary tertiary quaternary primary, secondary, tertiary, and quaternary

Correct

Multiple Choice - Chapter 3 - Question 61

Part A The tertiary structure of a polypeptide is the ANSWER:

localized region of a polypeptide chain that forms an α helix or β pleated sheet. overall three-dimensional shape of a fully folded polypeptide. overall three-dimensional shape of a protein composed of more than one polypeptide. linear sequence of amino acids in a polypeptide.

Correct

Multiple Choice - Chapter 3 - Question 62

Part A A disulfide bridge is an example of which type of bond? ANSWER:

covalent bond between R groups hydrogen bond between R groups ionic bond between R groups hydrophobic interaction between R groups

Correct

Multiple Choice - Chapter 3 - Question 63

Part A Interactions between the side chains (R groups) in a polypeptide are most important in stabilizing which of the following? ANSWER:

quaternary structure tertiary structure primary structure secondary structure

Correct

Score Summary: Your score on this assignment is 97.5%. You received 9.75 out of a possible total of 10 points....