bio ch4

120 thymine and 120 adenine molecules

A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be composed of

The charged phosphate groups and sugars of DNA are hydrophilic

DNA double helices are soluble in water but insoluble in alcohol. How do these physical properties reflect the chemical structure of the DNA molecule

The phosphodiester bonds between deoxyribose sugars would be broken.

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

These numbers tell us there are ten rungs, or steps, on the DNA "ladder" for every turn of the helix.

Franklin and Wilkins analyzed DNA by bombarding DNA crystals with X-rays. Their analysis yielded two numbers that sparked interest, 3.4 nm and 0.34 nm. What is the significance of these numbers?

40

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

Glucose

If cells are grown in a medium containing radioactive 32P-labeled phosphate, which of these molecules will be labeled?

The strands of the double helix are complementary.

In the context of chemical evolution, DNA's structure is interesting because it suggests a possible copying mechanism. What about DNA's structure facilitates copying?

nucleotides

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

Nucleic acids have a definite polarity, or directionality. Stated another way, one end of the molecule is different from the other end. How are these ends described?

One end has an unlinked 3 carbon; the other end has an unlinked 5 carbon.

function in the synthesis of proteins

One of the primary functions of RNA molecules is to

If 14C-labeled uracil is added to the growth medium of cells, what macromolecules will be labeled?

RNA

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

RNA can carry information and catalyze chemical reactions

Which of the following is a difference between RNA and DNA

RNA has ribose sugar and DNA has deoxyribose sugar

DNA double helices are soluble in water but insoluble in alcohol. How do these physical properties reflect the chemical structure of the DNA molecule

The charged phosphate groups and sugars of DNA are hydrophilic

contains one less oxygen atom

The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA _____.

An RNA world could produce molecules that could self-replicate

The work of Bartel's group on the ribozyme RNA replicase supports which conclusion?

their phosphate groups

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

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

What is the difference between a ribonucleotide and a deoxyribonucleotide

complementary pairing of the nitrogenous bases

What is the structural feature that allows DNA to replicate?

the sugar and the base

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

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

When nucleotides polymerize to form a nucleic acid

double antiparallel helical strands

Which of the following best describes DNA's secondary structure?

a nitrogenous base, a phosphate group, and a sugar

Which of the following descriptions best fits the class of molecules known as nucleotides

purines is always the same as pyrimidines

Which of the following did Watson and Crick already know when they were trying to determine the structure of DNA? The number of _____

cytosine, uracil, thymine

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

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

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

The width of the double helix would vary along the length of the strand

You have a polymer of DNA with 10 adenine bases followed by 10 cytosine bases. If that strand bonded to a strand of 20 thymine bases, how would the double helix shape vary from a typical DNA double helix?

are information-containing molecules

both DNA and RNA

Which of the following are pyrimidine nitrogenous bases

cytosine and uracil

Which of the following are purine nitrogenous bases

guanine and adenine

Phosphorus

ome viruses consist only of a protein coat surrounding a nucleic acid core. If you wanted to radioactively label the nucleic acids separately from the protein, you would use radioactive _____.