DNA Structure and Replication Constructed Response

Name ______Period ______Date ______

Constructed Response Use and underline the following terms in your essay: Italicized words are optional (bonus). 5’ and 3’, Adenine, antiparallel, complementary, Cytosine, Deoxyribose, DNA ligase, DNA polymerase (I and III), DNA replication, double helix, Guanine, hydrogen bond, lagging strand, leading strand, monomer, nitrogenous base, nucleic acid, nucleotide, Okazaki fragments, origin of replication, phosphate, phosphodiester bond, polymer, purine, pyrimidine, replication bubble, replication fork, RNA primase, RNA primer, single-strand binding proteins, Thymine, Topoisomerase

A) Describe the structure of a DNA molecule. B) Describe the process of DNA replication in eukaryotes. ______Name ______Period ______Date ______

______Name ______Period ______Date ______

DNA Structure and Replication Constructed Response Answer Section

1. ANS: A DNA molecule has the shape of a double helix, or that of a twisted ladder. Each strand of the helix is a chain of nucleotides. The two strands are held together by hydrogen bonds between the nitrogenous bases of the nucleotides on opposite strands. The nitrogenous bases form hydrogen bonds with one another in pairs. Adenine forms hydrogen bonds with thymine, and guanine forms hydrogen bonds with cytosine.

PTS: 1 DIF: Below average/Average OBJ: 11.2.2 2. ANS: DNA replication begins with the two DNA strands separating and unwinding. Each strand serves as a template for the attachment of complementary bases, forming a new strand of DNA. As a result, two identical DNA molecules are formed, each with one original strand of DNA and one new strand of DNA. DNA replication begins at hundreds of points on the chromosomes (origins of replication) and proceeds in two directions away from these points.

PTS: 1 DIF: Average/Above average OBJ: 11.3.2