Nucleic acids & atp

1. Mr. Peters (c) 1999; Revised 2009 Nucleic acids & atp

2. A. Nucleic Acids • Deoxyribonucleic Acid, or DNA, belongs to a group of compounds called Nucleic Acids. • Nucleic acids are nitrogen-containing compounds and are composed of functional units called nucleotides. • Euch nucleotide is composed of a five-carbon sugar unit, a phosphate molecule, and a nitrogen base. • DNA nucleotides contain the five-carbon sugar deoxyribose, while RNA nucleotides are made of the five-carbon sugar ribose. • A nucleotide consists of a phosphate, sugar, and a nitrogen base. • There are four nitrogen bases in DNA: Cytosine, Guanine, Adenine, and Thymine. RNA replaces thymine with uracil. Mr. Peters (c) 1999; Revised 2009

3. A. Nucleic Acids • Nucleic acids are either double-stranded (DNA) or single-stranded (RNA) molecules. • The information in DNA guides the cell (along with RNA) in making new proteins that determine all of our biological traits which get passed (copied) from one generation to the next. • DNA exists within the nucleus of the cell. • RNA is constructed within the nucleus of the cell, and then moves out of the nucleus into the cytoplasm of the cell where it directs protein synthesis. Mr. Peters (c) 1999; Revised 2009

4. B. ATP • All cells constantly need energy to satisfy the demands of the hundres of reactions that are happening in them. • As a result, energy storage and conversion processes are critical for sustaining life. • Energy enters the body as food. After food is digested, tiny molecules of glucose transport energy to the body cells by way of the blood. • For use in cell reactions, energy must be supplied in a controlled way and in small amounts. • The cells have a special molecule to store energy and release it in small packets. • This molecule is known as adenosine triphospate, or ATP. • The mechanism by which this process occurs is called cellular respiration. Mr. Peters (c) 1999; Revised 2009

5. B. ATP Cellular Respiration ATP Mr. Peters (c) 1999; Revised 2009

6. B. ATP • ATP is the usable form of energy. Before cells can use chemical energy, carbohydrates and other organic compounds must be converted into ATP. • ATP provides the energy required for the synthesis of needed chemicals within cells, the active transport of materials across cell membranes, and the contraction of muscle fibres. • Once cells have “drawn” energy from the ATP “bank,” energy must be added to refill ATP supplies. • Exergonic chemical reactions supply needed energy for the synthesis of ATP. Mr. Peters (c) 1999; Revised 2009

7. B. ATP • A tremendous amount of potential energy is stored in chemical bonds. • The conversion of high-energy molecules into lower-energy molecules releases energy, which can be used to attach high-energy phosphate bonds to ADP, thereby making ATP. • The addition of a phosphate molecule is called phosphorylation. Mr. Peters (c) 1999; Revised 2009

8. C. Homework • Read pp. 70, 84-86 • Draw the structural formula for a nucleotide. • State the differences between DNA and RNA. • State the purpose of ATP. • Describe the ATP/ADP/AMP “Gold Coin/Silver Coin” Analogy. • Describe several ways in which cells use energy from ATP. • Do #15, 16 p. 90 Mr. Peters (c) 1999; Revised 2009 Mr. Peters (c) 1999; Revised 2009