Chap. 13

The genetic material of all living organisms is

• protein

• deoxyribonucleic acid

• ribonucleic acid

• glycoprotein

• polypeptide

If a stretch of human double stranded DNA contains 47% G + C, then

• it contains 47% A + T

• there are more pyrimidines than purines

• there are more purines than pyrimidines

• it contains 53% A + T

• there are no genes in this stretch of DNA

The DNA of an organism is studied and found to contain 30% adenine. Based on this you would predict that the DNA of this organism also contains 30% _?_.

• thymine

• cytosine

• each of cytosine and guanine

• each of thymine and guanine

• guanine

In DNA the purines are

• thymine and cytosine

• adenine and cytosine

• adenine and guanine

• thymine and adenine

• thymine and adenine

In DNA the pyrimidines are

• thymine and cytosine

• adenine and cytosine

• adenine and guanine

• thymine and adenine.

Which of the following nucleotide sequences represents the complementary sequence that would bind to the DNA strand 5'-GACGTT-3'?

• 5'-TCATGG-3'

• 3'-TCATGG-5'

• 3'-CTGCAA-5'

• 5'-TTGCAG-3'

A DNA double helix has two strands that are held to each other by _?_.

• hydrogen bonds

• ionic bonds

• hydrophobic interactions

• phosphodiester bonds

• covalent bonds

Which of the following assembles a short RNA chain as the first nucleotides in a new DNA strand?

• topoisomerase

• primase

• DNA polymerase

• helicase

• DNA ligase

The two strands of a DNA double helix are said to be antiparallel. This means that

• the 5' end of one strand is directly paired with the 5' end of the other strand.

• since the double helix twists, it is not perfectly parallel.

• one strand has a negative charge and the other strand has a positive charge.

• the 5' end of one strand is directly paired with the 3' end of the other strand.

• both strands have a negative charge.

DNA replication is said to be semiconservative because

• the number of nucleotides within genes remains constant

• half of the DNA in a cell comes from one parent and the other half from the other parent.

• the same process of DNA replication is used by all organisms.

• the total amount of DNA within an individual remains the same.

• each new DNA molecule is composed of one old strand and one new strand.