DNA and RNA DNA Deoxyribonucleic acid DNA contains

DNA and RNA

DNA § Deoxyribonucleic acid (DNA)- contains information on how to make proteins. Proteins are the building blocks of life. § DNA is made up of nucleotides, which consist of: a sugar (deoxyribose), a phosphate group and four nitrogen bases. § The 4 nitrogen bases are: § Guanine (G), Cytosine (C), Thymine (T) and Adenine (A).

§ In DNA, Adenine and Thymine make up a base pair, while Guanine and Cytosine make up the other base pair. § Together a phosphate group, a sugar and one nitrogen base make up a NUCLEOTIDE.

Structure § DNA is a double stranded structure referred to as a double helix or twisted ladder. § DNA always turns to the right. § Nitrogen base pairs are held together by Hydrogen bonds*A=T, G=C*

Where is DNA found? § DNA is found in the nucleus of cells, and can be referred to as chromatin.

RNA § Like DNA, Ribonucleic acid is also made up a sugar, phosphate group and nitrogen bases. But there are some major differences-§ The sugar in RNA, is Ribose. § the nitrogen bases consist of Uracil (U), Adenine (A), Guanine (G) and Cytosine (C). § Uracil and Adenine = Base Pair § Guanine and Cytosine = Base Pair

§ A nucleotide consist of a sugar, phosphate group and one nitrogen base. § Like DNA, the backbone of RNA is composed of phosphates and sugars. § RNA is single stranded.

Time for practice! Practice Questions

Question from Fall 2005 TAKS Test 28. “Thymine-guanine-thymine-cytosine” describes: F. Nucleotides within an RNA strand G. A sequence of bases within the DNA section H. Points of DNA separation during protein synthesis J. t. RNA codons for specific amino acids

Answer!!! § The answer is G!!!! § Thymine, adenine, Guanine and Cytosine are all nitrogen bases that can be found in a DNA sequence.

Question from July 2004 33. All of the following are found in a DNA molecule except. A. carbon dioxide B. deoxyribose C. nitrogen D. phosphate

Answer!!! § The answer is A!!! § A DNA molecule is made up of 3 main parts. The Phosphate group, a nitrogen base and a sugar (deoxyribose). Together these 3 parts are called a nucleotide.

Question from 2003 TAKS test 24. If the template of a strand of DNA is AGATGCATC, the complementary strand will be. F. TCTACGTAG G. CTACGTAGA H. AGATGCATC J. AGACGTCTA

Answer!!! § § § The answer is F!!! Adenine and Thymine pair up together Guanine and Cytosine pair up together

Question from April 2006 40. In all plant and animal cells, the nucleus contains long molecules of DNA. Which of the following best describes the function of DNA? F. DNA provides the shape and structure of the nucleus. G. DNA packages materials for transport through the nucleus. H. DNA carries materials into and out of the nucleus. J. DNA contains the blueprint for producing the whole organism.

Answer!!! § The answer is J!!! § DNA can be thought of as a blueprint, or a set of instructions for building an organism.

Question from April 2006 45. Erwin Chargaff studied the DNA of organisms within a single species. Chargaff discovered that the amount of adenine is about equal to the amount of thymine. Which of these explains why the ratio of adenine to thymine is nearly 1: 1? A. Adenine and Thymine pair with each other. B. Adenine binds with phosphates, while thymine binds with nitrates. C. Adenine and thymine are identical in their chemical composition. D. Adenine bases contain a form of thymine.

Answer!!!! § You guessed it! The answer is A!!!!! § Remember, Adenine binds with thymine and guanine binds with cytosine. § Each base is its own chemical, they are not like each other.