Chapter 5 Nucleic Acids.ppt

Chapter 5/Nucleic Acids The Structure and Function of Large Biological Molecules PowerPoint® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., p...

Chapter 5/Nucleic Acids The Structure and Function of Large Biological Molecules PowerPoint® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 5.5: Nucleic acids store and transmit hereditary information • The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene • Genes are the fundamental units of hereditary and made of nucleotides, • Chromosomes are segments of the DNA that carry genes, • DNA (Deoxyribonucleic acid) is the genetic material in all cells and some viruses. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Q1 a Gene is part of a Chromosome. •A. True •B. False Q.2 DNA is a protein •A. True •B. False The Roles of Nucleic Acids • There are two types of nucleic acids: – Deoxyribonucleic acid (DNA) Double Strand – Ribonucleic acid (RNA) Single Strand • Three main RNAs: messenger, transfer, ribosomal RNAs • DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis • Protein synthesis occurs in ribosomes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings DNA and RNA • Q3. List the types of RNA that exist in our bodies. • Q4. DNA is a single strand while RNA is a double strand. • A. True • B. False • Replication: is the process by which the DNA molecule is duplicated before the cell divides. • Transcription: is the process that results in the synthesize of mRNA ( messenger RNA ) • Translation: Is the synthesis of proteins on the ribosomes using the mRNA and directed by DNA Fig. 5-26-3 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into cytoplasm via nuclear pore Ribosome 3 Synthesis of protein Polypeptide Amino acids • Q5. Define Replication of DNA? The Structure of Nucleic Acids • Nucleic acids are polymers called polynucleotides • Each polynucleotide is made of monomers called nucleotide • Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group • The portion of a nucleotide without the phosphate group is called a nucleoside Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-27 5 end Nitrogenous bases Pyrimidines 5C 3C Nucleoside Nitrogenous base Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA) Purines Phosphate group 5C Sugar (pentose) Adenine (A) Guanine (G) (b) Nucleotide 3C Sugars 3 end (a) Polynucleotide, or nucleic acid Deoxyribose (in DNA) Ribose (in RNA) (c) Nucleoside components: sugars • Q6: List the components of a Nucleotide? Nucleotide Monomers • Nucleoside = nitrogenous base + sugar • Nucleotide = nucleoside + phosphate group • There are two families of nitrogenous bases: – Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring – Purines (adenine and guanine) have a sixmembered ring fused to a five-membered ring • In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Q7. What is the difference between a Nucleoside and a Nucleotide? Nucleotide Polymers • Nucleotide polymers are linked together to build a polynucleotide • Adjacent nucleotides are joined by covalent bonds that form between the –OH group on the 3 carbon of one nucleotide and the phosphate on the 5 carbon on the next • These links create a backbone of sugarphosphate units with nitrogenous bases as appendages • The sequence of bases along a DNA or mRNA polymer is unique for each gene Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Formation of Polynucleotide • Q8. Explain the Condensation Reaction that makes a Polynucleotide? The DNA Double Helix • A DNA molecule has two polynucleotides spiraling around an imaginary axis, forming a double helix • In the DNA double helix, the two backbones run in opposite 5 → 3 directions from each other, an arrangement referred to as antiparallel • One DNA molecule includes many genes • The nitrogenous bases in DNA pair up and form hydrogen bonds: adenine (A) always with thymine (T), and guanine (G) always with cytosine (C) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings DNA Replication • DNA replication is the process in which DNA is copied. As a result, the two daughter molecules are both identical to the parent molecule. Fig. 5-28 5' end 3' end Sugar-phosphate backbones Base pair (joined by hydrogen bonding) Old strands Nucleotide about to be added to a new strand 3' end 5' end New strands 5' end 3' end 5' end 3' end • Q9. How many Polynucleotides a molecule of DNA has? • Q10. Why the way DNA is arranged called antiparallel? Fig. 5-UN9 Summary of Macromolecules