Homework 1a

1. If a 40 base single stranded piece of DNA contains 22 T bases, how many G bases does the corresponding single-stranded DNA contain?

2. If a 35 base pair double stranded piece of DNA contains 11 C bases, how many T bases does it contain?

3. The two DNA strands of a chromosome are held together by: (What keeps the 2 single strands together to form a double strand?) choose all correct answers

a. DNA backbone

b. hydrogen bonds

c. the centromere

d. base complementarity

e. DNA polymerase

f. covalent bonds

4. Analysis of hte bases of a sample of nuclic acid yielded these percentages: A 20%, G 30%, C 20%, T 30%. The sample could be

5. Which of the following is not true about a linear molecule of double-stranded DNA?

a. Pentose sugars are linked via covalent phosphodiester bonds

b. At one end, two 5′ phosphate groups can be found

c. It is a double helix composed of antiparallel strands

d. Bases are paired via hydrogen bonds

6. In the Hersey-Chase experiment, T2 phage were radioactively labeled with either 35S or 32P, and allowed to infect E. coli. What results were proved that DNA was the genetic material?

a. The 35S was found in progeny phage, and the 32P was found in phage ghosts

b. The 32P was found in both progeny phage and in phage ghosts

c. The 35S was found in phage ghosts, and the 32P was found in progeny phage

d. The 35S was found in both progeny phage and in phage ghosts

7. Which of the following clusters of terms accurately describes DNA as it is generally viewed to exist in prokaryotes and eukaryotes

a. double-stranded, antiparallel, (A+T)/(C+G) = variable, (A+G)/(C+T) = variable

b. double-stranded, antiparallel, (A+T)/(C+G) = variable, (A+G)/(C+T) = 1.0

c. double-stranded, parallel, (A+T)/(C+G) = variable, (A+G)/(C+T) = 1.0

d. single-stranded, antiparallel, (A+T)/(C+G) = 1.0, (A+G)/(C+T) = 1.0

e. double-stranded, parallel, (A+T)/(C+G) = 1.0, (A+G)/(C+T) = 1.0

8. DNA molecules of different sizes are often separated with the use of a technique called electrophoresis. With this technique, DNA molecules are placed in a gel, and he DNA molecules migrate toward the + pole of the current. What aspect of its structure causes a DNA molecule to migrate toward the positive pole?

a. The hydrogen bonds

b. The double helix

c. The phosphate backbone

d. The nitrogenous bases

e. DNA is positively charged

9. Which of the following DNA molecules has the lowest melting temperature?

a. AAATTGCGCGCCCGA

b. AGGGTGGCTTAACGG

c. GAATTCCAATGTATA

d. GGGAGCTCGGTTGCC

e. GCATCGATCGATACG

10. A diploid human cells contains approximately 6.4 billion base pairs of DNA. How many histone proteins are complexed to this DNA?