AP European History (Sem 1), Unit 03, Lesson 04



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Nucleic Acids and Proteins

In this lesson you will learn how the structures of monomers determine the structures and functions of macromolecules. In particular, this lesson focuses on the structures of DNA, RNA, and proteins and how their molecular components interact with each other their environment. The concept of directionality will be introduced.

Lesson Objectives

• Define a monomer and state its importance to the structure and functions of a polymer.

• Recognize diagrams of DNA and RNA nucleotides, and relate the structure of the nucleotide monomers to the structure and function of both nucleic acids.

• Recognize the basic structure of an amino acid, tell how amino acids vary, and relate the structure of amino acid monomers to the structure and function of proteins.

• State how directionality of nucleic acids and proteins affects their function.

Questions

What is a monomers

What chemical reactions help to assemble polymers?

What are the 3 basic structures that make up DNA and RNA? Describe each.

What are the four basic structures of a protein?

What environmental variables can interfere with chemical bonds and cause proteins to denature?

Set the Stage

The function of all living things is indirectly governed by the genetic information encoded within DNA. The mystery of how DNA encoding works started to become clear in 1953 when James Watson and Francis Crick determined the structure of DNA with the aid of X-ray diffraction technology, mathematics, and ideas from other scientists. They were able to determine how the subunits called nitrogenous bases were paired together in unlimited combinations within the double-helical structure of DNA to provide the templates for life. Amino acids, the building blocks of proteins, can also be combined in thousands of varieties to provide the gene-regulated components for cells, tissues, organs, and organisms.

What might the consequences be for an organism if a nucleotide in DNA or an amino acid in a protein is substituted or excluded in the transcription or translation process?

Write your response below.

Reading Guide

Read the Nucleic Acids & Proteins: Reading Assignment and take notes. Review the Keywords, describe the Identifications, and answer the Essential Questions.

Keywords

|Keyword |Definition/Notes |

|amino acid |the organic molecules from which proteins are made |

|dehydration synthesis |an enzymatic reaction that connects two monomers while creating a water molecule |

|fatty acids |the organic molecules that serve as the units from which lipids are made |

|monomer |building block molecules for polymers |

|monosaccharides |the organic molecules that serve as the units from which carbohydrates are made |

|mRNA |messenger RNA: a linear RNA molecule that contains codons |

|nonpolar molecule |a molecule that lacks a dipole or permanent positive and negative areas |

|nucleotide |a subunit of a nucleic acid that consists of a phosphate group, a five-carbon sugar, and a nitrogenous base |

|peptide bond |a chemical bond connecting two amino acids together with the carboxyl group of one and the amino group of the |

| |other |

|polar molecule |a molecule in which there are positive and negative areas |

|polymer |large molecules of repeating groups of molecularly identical subunits |

|rRNA |ribosomal RNA: a type of RNA molecule that makes up the main part of the structure of a ribosome |

|tRNA |transfer RNA: a type of RNA molecule that carries amino acids to the site of protein synthesis in ribosomes |

Identifications

Describe the Identifications. Use names, events, dates, and research articles to help describe the identification.

|Identifications |Description/Notes |

|macromolecule | |

|chemical bonding | |

|DNA and RNA structure | |

|protein structure and folding | |

|protein structure and folding | |

Essential Questions

Answer the following questions from your reading:

1. What is a monomer, and what relation does it have to the structure and function of polymers?

2. How do nucleic acid monomers influence the function of DNA and RNA?

3. How does the sequence of an amino acid determine the three-dimensional structure of the protein?

4. What does directionality mean when referring to nucleic acids and proteins?

Free-Response

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Amino Acid Sequence of Protein – Primary Structure

In a microbiology lab, scientists discover that joining together amino acids B and I forms a catalyst that initiates enzymatic reactions within a muscle cell. They observe that these amino acids when in close proximity form an active site that is able to engage and bind specifically to a substrate molecule. (a) Given the primary structure of the protein in the figure, explain how it is possible for these two amino acids, that are distant in location, to work together to form an active site for enzymatic reactions. (b) Justify your answer with a discussion of the chemical interactions between monomers found in proteins.

Write your response below.

Extensions

1. Locate and read a few current event articles or watch a few videos about genetic engineering. How might advances in the field of genetic engineering affect you now and in the future?

2. Find out how genetic testing is conducted. What are some ethical pros and cons to using this technology?

3. Explore genetic diseases. What are some explanations for why there are so many different genetic diseases?

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|Remember: At the completion of this lesson, save your Student Guide in your unit folder. |

Information for Free Response

|Essential Knowledge |4.A.1 The subcomponents of biological molecules and their sequence determine the properties of that molecule.|

|Science Practice |6.1 The student can justify claims with evidence. |

| |6.4 The student can make claims and predictions about natural phenomena based on scientific theories and |

| |models. |

|Learning Objectives |4.3 The student is able to use models to predict and justify that changes in the subcomponents of a |

| |biological polymer affect the functionality of the molecule. |

Free-Response Scoring Guidelines

|4 points maximum. |

|(Part a) Up to 3 points for the following correct explanations. |

|Effects may include: |

|Proteins are unique macromolecules that are composed of several smaller monomers. These monomers, amino acids, are linked together through the process |

|of dehydration synthesis. Peptide bonds join amino acids in the primary structure (as seen in Figure 1, while additional chemical interactions may join |

|adjacent or distant amino acids as they form secondary, tertiary, and quaternary structures. |

|The chemical interactions of the R groups of the amino acids allow proteins to rearrange spontaneously to form tertiary and quaternary structures. The |

|order in which the amino acids are linked determines the structure and the function of that protein. |

|Although amino acids B and I are distant in its primary structure, chemical interactions between their functional groups allows them to partner as an |

|active site. |

|(Part b) 1 point for a correct justification of chemical interactions in proteins. |

|The structural design of monomers relies on the chemical interactions of their functional groups. Chemical bonds allow certain monomers to rearrange to |

|form various structures. Common functional groups found in amino acids are the amino group −NH2 and the carboxyl groups −COOH.The varying chemical |

|properties of these functional groups, according to how they are attached to the various carbon rings and chains, are the reason that different monomers|

|have unique characteristics that aid in protein function. |

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