DNA Structure and Function

Which is not a component of a nucleotide?

• codon

• sugar

• phosphate group

• nitrogen base

The end of a DNA or RNA strand where nucleotides can be added during replication

• nucleotide

• telomere

• 5’ end

• 3’ end

An Okazaki fragments are

• the parts of the leading strand where replication occurs

• the lagging strand of DNA replication that contains gaps within it

• the parts of the DNA strand where hydrogen bond is broken

• the parts of the lagging strand that help bond the nucleotides together after they come together

Which is a purine? (Check all that apply)

• adenine

• thymine

• guanine

• cytosine

_________________________ attaches the fragments to each other

• DNA ligase

• DNA primase

• DNA polymerase

• Helicase

Erwin Chargaff investigated the nucleotide composition of DNA. He analyzed DNA from various organisms and measured the relative amounts of adenine (A), guanine (G), cytosine (C), and thymine (T) present in the DNA of each organism. Table 1 contains a selected data set of his results. Which of the following statements best explains the data set?

• Since the %A and the %G add up to approximately 50 percent in each sample, adenine and guanine molecules must pair up in a double-stranded DNA molecule.

• Since the %A and the %T are approximately the same in each sample, adenine and thymine molecules must pair up in a double-stranded DNA molecule.

• Since the %(A+T) is greater than the %(G+C) in each sample, DNA molecules must have a poly-A tail at one end.

• Since the %C and the %T add up to approximately 50 percent in each sample, cytosine and thymine molecules must both contain a single ring.

Which answer is not a part of a DNA nucleotide?

• thymine

• deoxyribose

• ribose

• phosphate

Which is the correct representation of a nucleotide in DNA?

• deoxyribose sugar, phosphate group, uracil

• deoxyribose sugar, phosphate group, thymine

• ribose sugar, phosphate group, thymine

• ribose sugar, phosphate group, uracil

Which type of bond (between the bases) can be easily broken, allowing the two sides of DNA to move apart for use in the cell?

• hydrogen bonds

• covalent bonds

• peptide bonds

• nitrogen bonds

What is the first cloned mammal?

• goat

• cat

• sheep

• cow