CHAPTER 5 DNA AND CHROMOSOMES 2009 Garland Science Publishing The Structure and Function of DNA 5 1 Using terms from the list below fill in the blanks in the following brief description of the experiment with Streptococcus pneumoniae that identified which biological molecule carries heritable genetic information Some terms may be used more than once Cell free extracts from S strain cells of S pneumoniae were fractionated to DNA RNA protein and other cell components Each fraction was then mixed with cells of S pneumoniae Its ability to change these into cells with properties resembling the cells was tested by injecting the mixture into mice Only the fraction containing was able to the cells to or cells that could kill mice carbohydrate DNA identify label lipid nonpathogenic pathogenic purify R strain RNA S strain transform 5 2 Many of the breakthroughs in modern biology came after Watson and Crick published their model of DNA in 1953 In what decade did scientists first identify chromosomes a 1880s b 1920s c 1940s d 1780s 5 3 Mitotic chromosomes were first visualized in the 1880s with the use of very simple tools a basic light microscope and some dyes Which of the following characteristics of mitotic chromosomes reflects how they were named a motion b color c shape d location 5 4 In a DNA double helix a the two DNA strands are identical b c d purines pair with purines thymine pairs with cytosine the two DNA strands run antiparallel 5 5 Indicate whether the following statements are true or false If a statement is false explain why it is false A DNA molecules like proteins consist of a single long polymeric chain that is assembled from small monomeric subunits B The polarity of a DNA strand results from the polarity of the nucleotide subunits C There are five different nucleotides that become incorporated into a DNA strand D Hydrogen bonds between each nucleotide hold individual DNA strands together 5 6 Several experiments were required to demonstrate how traits are inherited Which scientist or team of scientists first demonstrated that cells contain some component that can be transferred to a new population of cells and permanently cause changes in the new cells a Griffith b Watson and Crick c Avery MacLeod and McCarty d Hershey and Chase 5 7 Several experiments were required to demonstrate how traits are inherited Which scientist or team of scientists obtained definitive results demonstrating that DNA is the genetic molecule a Griffith b Watson c Crick d Hershey and Chase 5 8 Which of the following chemical groups is not used to construct a DNA molecule a five carbon sugar b phosphate c nitrogen containing base d six carbon sugar 5 9 Which of the following sequences can fully base pair with itself a 5 AAGCCGAA 3 b 5 AAGCCGTT 3 c 5 AAGCGCAA 3 d 5 AAGCGCTT 3 5 10 The DNA from two different species can often be distinguished by a difference in the a ratio of A T to G C b ratio of A G to C T c ratio of sugar to phosphate d 5 11 presence of bases other than A G C and T For a better understanding of DNA structure it helps to be able to compare physical characteristics evident from a side view of double stranded DNA with those of individual base pairs A Use brackets to designate the major and minor grooves on Figure Q5 11A and shade in the surface that will be exposed in the major grove in Figure Q5 11B B If base pairs were aligned and stacked directly on top of each other the major and minor grooves would be linear depressions all along the DNA Explain why this is not the actual conformation of a DNA molecule Figure Q5 11 5 12 Which DNA base pair is represented in Figure Q5 12 a A T b T A c G C d C G Figure Q5 12 5 13 Use the terms listed to fill in the blanks in Figure Q5 13 A A T base pair B G C base pair C deoxyribose D phosphodiester bonds E purine base F pyrimidine base Figure Q5 13 5 14 The structures of the four bases in DNA are given in Figure Q5 14 Figure Q5 14 A B Which are purines and which are pyrimidines Which bases pair with each other in double stranded DNA 5 15 Using the structures in Figure Q5 15 as a guide sketch the hydrogen bonds between the base pairs in DNA Hint The bases in the figure are all drawn with the NH that attaches to the sugar at the bottom of the structure 5 16 Because hydrogen bonds hold the two strands of a DNA molecule together the strands can be separated without breaking any covalent bonds Every unique DNA molecule melts at a different temperature In this context Tm melting temperature is the point at which two strands separate or become denatured Order the DNA sequences listed below according to relative melting temperatures from lowest Tm to highest Tm Assume that they all begin as stable doublestranded DNA molecules Explain your answer A GGCGCACC B TATTGTCT C GACTCCTG D CTAACTGG 5 17 Indicate whether the following statements are true or false If a statement is false explain why it is false A Each strand of DNA contains all the information needed to create a new doublestranded DNA molecule with the same sequence information B All functional DNA sequences inside a cell code for protein products C Gene expression is the process of duplicating genes during DNA replication D Gene sequences correspond exactly to the respective protein sequences produced from them 5 18 The complete set of information found in a given organism s DNA is called its a genetic code b coding sequence c gene d genome 5 19 The manner in which a gene sequence is related to its respective protein sequence is referred to as the code a protein b genetic c translational d expression 5 20 Given the sequence of one strand of a DNA helix as 5 GCATTCGTGGGTAG 3 give the sequence of the complementary strand and label the 5 and 3 ends 5 21 When double stranded DNA is heated the two strands separate into single strands in a process called melting or denaturation The temperature at which half of the duplex DNA molecules are intact and half have melted is defined as the Tm A Do you think Tm is a constant or can it depend on other small molecules in the solution Do you think high salt concentrations increase decrease or have no effect on Tm B Under standard conditions the expected melting temperature in degrees Celsius can be calculated from the equation Tm 59 9 0 41 G C 675 length of duplex Does the Tm increase or decrease if there are more G C and thus fewer A T base pairs Does the Tm increase or decrease as the length of DNA increases Why C Calculate the predicted Tm for a stretch of