BSC2010 Ch

DNA Stability/Chapter 4 A solution of DNA contains two different DNA molecules. Molecule 1 is 500 base pairs and contains 100 A’s. Molecule 2 is 500 base pairs and contains 300 A’s. (1) How many AT base pairs and GC base pairs is in each DNA molecule? (2) How many, G’s, A’s, T’s and C’s are in each molecule? (3) Draw one figure that shows the relative melting temperature of the two DNA molecules.

STRUCTURE OF DNA Ueing the complementary base pairing rules in DNA, complete the following base pairs: Adenine - Cytosine -i Guanine -i Thymine - : Adenine : Cytosine :: Guanine :: Thymine 1

2) When DNA is placed in distilled water, which is pH 7.0, it denatures (i.e., the two strands separate). The pH inside a cell is generally 7.2-7.5, depending on the organism, but DNA is generally double-stranded under physiological conditions. Briefly explain, in your own words, why DNA denatures when placed in distilled water but not when it is inside a cell. [Reminder: the pKa for the phosphate groups in the sugar-phosphate backbone of a strand of DNA is 2.14]

One strand of DNA has the base sequence 5'-CATG-3' Draw this stretch of DNA, showing BOTH strands, using a simplified model of a nucleotide as shown: Label the sugar-phosphate backbone, the 5' and 3' ends of each strand, and the regions of hydrogen bonding.

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Consider normal B-form DNA. It forms a regular antiparallel double-helical structure with Watson-Crick base-pairing mediated through hydrogen bonding. The base pairs all stack upon one another, with 3.4 Å spacing between them. DNA strands having a complementary sequence will spontaneously form a double-helix in an aqueous solution. In terms of energy, what primarily drives helix formation? O Positive Entropy from base stacking van der Waals interactions O Hoogsteen interactions Positive Enthalpy from Hydrogen Bonding between GC and AT pairs Negative Enthalpy from Hydrogen Bonding between GC and AT pairs O Negative Entropy from base stacking

Describe the functions of the following proteins during DNA breaks and repair: (i) Ku70 (ii) Uracil DNA glycosylase

TRUE OR FALSE] 11. The structure of the DNA, being super coiled, promotes increased viscosity of the molecule.12. The stacking position of the nitrogenous bases is caused by intramolecular Van der Waals Interaction.13. The histone complex is a quaternary protein structure.14. The difference between ribose and deoxyribose is in the presence of oxygen in carbon number 3 of the sugar moiety.15. The sedimentation coefficient of the nucleic acid is higher compared to ribosomes.

N. NH 2. One of the key pieces of information that Watson and Crick used in determining the secondary structure of DNA came from experiments done by E. Chargaff, in which he studied the nucleotide composition of DNA from many different species. O=P-OCH, N. `NH, HN он O= P- OCH, NH, Chargaff noted that the molar quantity of A_was always approximately equal to the molar quantity of T. and the molar quantity of C was always approximately equal to the molar quantity of G. How were Chargaff's results explained by the structural model of DNA proposed by Watson and Crick? N OH N. O= P-OCH, OH OH

11b this was not graded and will not be graded

Using Fig. as a guide, draw the complete structure of a nucleoside triphosphate before and after it becomes incorporated into a polynucleotide chain. Draw the structure that would result if the newly formed phosphodiester bond were hydrolyzed.

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Give detailed Solution with explanation (don't give Handwritten answer

The Basic Structure of DNA 1. Nucleotides are the monomer subunits of DNA polymers. Review the structure of a nucleotide by labeling the three main parts: the sugar, the phosphate group and the nitrogenous base of the one shown below. NH2 N- || ОН 2. Which part (sugar, phosphate, or nitrogenous base) of the four types of nucleotides differ? 3. Based on the complementary base pairing rules we know that: A(denosine) pairs with and that G(uanine) pairs with 4. What two types of bonds are found in a DNA molecule and where are they found? а. bonds are found b. bonds are found O=a-o

Drawing of DNA Structure Next, draw the structure of your double-stranded DNA molecule with circles representing the beads you used. Label each circle with the color bead: W for white, R for red, Y for yellow, O for orange, B for blue, and G for green. Also include the hydrogen bond barbells. a. Draw your double-stranded DNA structure here:

Art-Labeling Activity: Structure of the nucleic acids DNA and RNA Reset Help Sugar-phosphate backbone (RNA) Double-helical Base uracil in Hydrogen bonds Single-stranded RNA Phosphate group Deoxyribose DNA place of thymine Complementary Sugar-phosphate backbone (DNA) base pairing G - H G N-H N CH N-H 0 O. 0-P0 A O-P-O H N- CH, AN-H CH, H. CH, H 0-P-0 (b) (a) O-P-O

nucleotides 1 What is the difference between the sugar component in DNA and RNA? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a The sugar in DNA is a D isomer and the sugar in RNA is an Risomer. The sugar in RNA is ribose and the sugar in DNA is dextrose. The sugar in DNA is a disaccharide. the sugar in DNA lacks an OH functional group.

Would you expect the double helix in a short segment of DNA to be more stable in a storage solution of sodium phosphate buffer at pH 7.0 or in pure water? Why? pure water; because any cations in the storage solution would prevent complementary bases from forming ionic interactions sodium phosphate buffer at pH 7.0; because a neutral pH is required to maintain the covalent bonds between complementary bases O pure water; because the high dielectric constant of water is sufficient to stabilize the covalent bonds between deoxyriboses in the DNA backbone sodium phosphate buffer at pH 7.0; because the presence of water and sodium neutralizes the charge of phosphate groups in the DNA backbone

Label the following -phosphodiester bond -AT base pair -hydrogen bond -deoxyribose sugar -GC base pair -purine base -pyrimidine base -5’ and 3’ ends of each strand

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stem-loop For each of the following, identify whether it is an example of primary, secondary, or tertiary structure that might be observed in a nucleic acid (such as DNA). Answers may be used more than once. nucleotide sequence B form supercoiling kinetochore of a yeast chromosome nucleosome secondary structure primary structure secondary structure tertiary structure tertiary structure secondary structure

5’ - A T G    G C C    C A A    C T G    A C C - 3’ a. How many nucleotides are listed here b. How many codons are listed here  c. What are the three structural components of one nucleotide D.Write the appropriate sequence for the complementary strand above or below the sequence shown.  Be sure to include which end of the complementary strand is 5’ and which end is 3 E.If the above sequence is the coding strand, write the RNA strand that will be transcribed