Mastering Bio 160 Pt. 1/4

If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?

40

What would be the sequence of the strand of DNA that is made from the following template: 5′-GATCGATGT-3′ (Your answer must be written 5′ → 3′.)

5' ACATCGATC 3'

How would this sequence be different if RNA were made from this DNA template?

5' ACAUCGAUC 3'

What feature of single nucleotides provides the energy needed for polymerization when nucleic acids are formed?

their phosphate groups

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.

thymine ... cytosine

If one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence _____.

5' TGCAAT 3'

By convention, nucleotide sequences are always written from the _____.

5' end to the 3' end

How are nucleotides linked together to form a polynucleotide chain?

In DNA and RNA, a phosphodiester linkage connects the 3' carbon of one nucleotide and the 5' carbon of another.

RNA and proteins combine in cells to form structures called ribosomes. Ribosomes contain the active site for peptide bond formation. Based on their chemical structures, do you think protein or RNA molecules actually form the active site within the ribosome?

It could be either, because both molecules have catalytic properties.

DNA is the main hereditary material of all life. However, DNA lacks one important characteristic for the first forms of life. Why have researchers rejected the idea that DNA was found in the first life form?

It does not function as a catalyst.

Complementary base pairing is possible only if two DNA strands align in antiparallel—instead of parallel—fashion. Which statement best explains why?

Only antiparallel strands create the geometry that allows complementary base pairs to form via hydrogen bonding.

Why do researchers think the first self-replicating molecule was RNA?

RNA can carry information and catalyze chemical reactions.

Many RNA molecules exhibit tertiary structure, whereas most DNA molecules do not. Which statement best explains why?

RNA's secondary structure can leave bases free for interactions that produce tertiary structure; DNA's secondary structure generally does not.

Which statement accurately summarizes a difference between ribonucleotides and deoxyribonucleotides?

Ribonucleotides have a hydroxyl group bonded to their 2' carbon; deoxyribonucleotides have an H at the same location.

What is the difference between a ribonucleotide and a deoxyribonucleotide?

Ribonucleotides have a hydroxyl group on the 2 carbon of their sugar subunit.

DNAase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNAase?

The phosphodiester bonds between deoxyribose sugars would be broken.

Why is it that RNA can catalyze reactions but DNA cannot?

The sugar of RNA is much more reactive than the sugar of DNA.

What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA?

There is no difference.

When nucleotides polymerize to form a nucleic acid _____.

a covalent bond forms between the sugar of one nucleotide and the phosphate of a second

What are the components of a nucleotide?

a sugar, a phosphate group and a nitrogenous base

What is the structural feature that allows DNA to replicate?

complementary pairing of the nitrogenous base

Which of the following includes all of the pyrimidines found in RNA and DNA?

cytosine, uracil, and thymine

Identify three possible components of a DNA nucleotide.

deoxyribose, phosphate group, thymine

One of the primary functions of RNA molecules is to _____.

function in the synthesis of proteins

Nucleic acids are polymers made up of which of the following monomers?

nucleotides

An RNA molecule that can catalyze chemical reactions is called a_____.

ribozyme

What determines the primary structure of a DNA molecule?

the sequence of deoxyribonucleotides

What is/are the variable structure(s) of a nucleotide?

the sugar and the base