Nucleotide/Nucleic Acids Sapling

DNA can undergo many types of modifications. One of these is methylation. In bacteria, which two bases undergo methylation more often? A. guanine B. adenine C. cytosine D. thymine

B and C

What do these descriptions pertain to: nucleosides, nucleotides, or both nucleosides and nucleotides? 1. are found in RNA and DNA 2. may contain either ribose or deoxyribose 3. contain a base and monosaccharide

Both

DNA renaturation experiments are useful strategies to estimate the: A. size of an organism's genome. B. proportion of GC content in an organism's genome. C. genetic relatedness between two species. D. number of single nucleotide differences between two species.

C

Identify two structural features of pyrimidines. A. contain four ring nitrogen atoms B. contain only three ring nitrogen atoms C. contain only two ring nitrogen atoms D. contain one heterocyclic ring E. contain two heterocyclic rings

C and D

Which molecules are pyrimidines?

Cytosine, Thymine, and Uracil

Calculate the weight in grams of a double-helical DNA molecule stretching from the Earth to the Moon (320000 km). Assume that the DNA double helix weighs 1×10−18 g per 1000 nucleotide pairs and that each base pair extends 3.4 Å

-This is a conversion factor problem. -1m = 1x10^10 angstroms -1km = 1000 meters -Distance to the moon (320,000 km or 3.2x10^5 km) -3.4 angstroms = 1 base pair (bp) (3.2x10^5 km)(1000m/km)(1x10^10 angstroms/m)(3.4 angstroms) = 9.412x10^17 bp -(9.412x10^17 bp)(1x10^-18 g/ 1000 bp) = 9.41x10^-4 g

As a result of rotation about six of its bonds, DNA can exist in a variety of forms. What are descriptions and images of A form?

1. About 26 Angstrom helix diameter 2. Favored form of dehydrated DNA

As a result of rotation about six of its bonds, DNA can exist in a variety of forms. What are descriptions and images of Z form?

1. Left handed 2. About 18 angstroms helix diameter 3. Syn form of purine **only in this form

As a result of rotation about six of its bonds, DNA can exist in a variety of forms. What are descriptions and images of B form?

1. Most stable form under physiological condition 2. Major groove is wide and deep 3. About 20 angstrom helix diameter

What are some descriptions that pertain to nucleosides?

1. are the product when a base bonds at Cl of ribose or deoxyribose 2. do not contain phosphate group 3. are found in RNA and DNA 4. may contain either ribose or deoxyribose 5. contain a base and monosaccharide

What are some descriptions that pertain to nucleotides?

1. contain a base, a monosaccharide and a phosphate group. 2. can be named adenosine 5'-monophosphate. 3. are the monomers of nucleic acid. 4. are found in RNA and DNA 5. may contain either ribose or deoxyribose 6. contain a base and monosaccharide

What is a g-tetraplex?

A four‑stranded, right‑handed helix formed by a DNA segment containing a high proportion of guanine residues

A single DNA strand with the sequence −ATATG⋅⋅⋅⋅⋅⋅⋅⋅⋅CATAT− can form a structure called what?

A hairpin structure

What is an example of an inverted repeat that occurs within a single DNA strand?

A hairpin structure

An analysis is performed to determine the proportions of each of the four nucleotide bases in the DNA of several tissue samples from various species. The results appear in the table. Human: 31% adenine, 20% guanine, 30% thymine, 19% cytosine. Chicken: 28% adenine, 21% guanine, 29% thymine, 22% cytosine. Yeast: 32% adenine, 18% guanine, 33% thymine, 17% cytosine. E. Coli: 26% adenine, 25% guanine, 24% thymine, 25% cytosine. Which conclusions can be drawn from this data? A. The proportion of A is roughly equal to the proportion of T. B. The proportion of G is roughly equal to the proportion of C. C. The proportion of pyrimidines is roughly equal to the proportion of purines. D. The proportion of A-T base pairs is roughly equal to the proportion of G-C base pairs.

A, B, and C

Select the phrases that accurately describe properties of the most common form of the DNA double helix. A. The phosphodiester bonds between nucleotide residues run in opposite directions in the two strands B. The nitrogenous bases are exposed to the solvent, whereas the sugar-phosphate backbone of each nucleotide strand is in the interior of the double helix C. DNA contains equal amounts of adenine and thymine and equal amounts of cytosine and guanine D. A helical turn consists of about 3.4 base pairs E. Base pairs have a spacing of 3.4 Å

A, C, and E

Use the information gathered in the Nucleotides Molecular Structure Tutorial to answer the question. Select the phrases that accurately describe properties of the most common form of the DNA double helix. A. The phosphodiester bonds between nucleotide residues run in opposite directions in the two strands. B. A helical turn consists of about 3.4 base pairs. C. DNA contains equal amounts of adenine and guanine (the purines), and equal amounts of cytosine and thymine (the pyrimidines). D. Base pairs have a spacing of 3.4 Å. E. The sugar-phosphate backbone is in contact with water, whereas the nitrogenous bases are in the interior of the double helix.

A, D, and E

Which molecules are purines?

Adenine and Guanine

As a result of rotation about six of its bonds, DNA can exist in a variety of forms. What are descriptions and images of all forms?

Antiparallel strands

Identify two structural features of purines. A. contain only three ring nitrogen atoms B. contain four ring nitrogen atoms C. contain one heterocyclic ring D. contain only two ring nitrogen atoms E. contain two heterocyclic rings

B and E

Hairpins often form at palindromic sequences in single strands of either RNA or DNA. However, several key features differentiate the helical structure of an RNA hairpin and a DNA hairpin. Select the statements that describe the helical structure of an RNA hairpin. A. The pentose in the hairpin adopts only the C‑2′ endo pucker conformation. B. The pentose in the hairpin adopts only the C‑3′ endo pucker conformation. C. The hairpin adopts a right‑handed helix with a diameter of 26 Å. D. The hairpin contains G:C, A:U, and sometimes G:U base pairs. E. The hairpin adopts a left‑handed helix with a diameter of 20 Å

B, C, and D B)The pentose in the hairpin adopts only the C3' endo pucker conformation. There are two types of sugar pucker most commonly found in nucleic acids - The C3' endo pucker and C2' endo pucker. The C3′-endo pucker is prevalent in RNA and A-form DNA, whereas the C2′-endo pucker is characteristic of B-form DNA. It is seen that the C3′-endo pucker produces a significantly shorter phosphate-phosphate distance in the backbone, resulting in a more compact helical conformation. C) The hairpin adopts a right-handed helix with a diameter of 26 Å. Most RNA, RNA-DNA duplex, and A form DNA are of this diameter. D)The hairpin contains G:C, A:U, and sometimes G:U base pairs.RNA structure contains the Watson-Crick (WC) base pairs A (Adenine) with U (Uracil), and G (Guanine) with C (Cytosine) and also the non-Watson-Crick (non-WC) base pair G with U.

Which of the following single-stranded DNA sequences is most likely to form a stem-loop structure? A. TAAGTACATTACCCCG B. ACTTCTTCTCCGCTGC C. GACCGTATGCACGGTC D. GGATCACGTTACCGCC

C. Stem-loop intramolecular base pairing is a pattern that can occur in single-stranded DNA. The structure is also known as a hairpin or hairpin loop.

DNA can undergo many types of modifications. One of these is methylation. Which bases are methylated more often in human DNA? A. guanine B. thymine C. adenine D. cytosine

D

Using X‑ray crystallography, Rosalind Franklin was able to produce X‑ray diffraction images of DNA that were clearer than any previously produced images. What did the images show regarding the structure of DNA? A. The DNA bases face outward from the central core B. The amount of adenine in DNA is equal to the amount of thymine C. DNA has a central core of sugar and phosphate D. The complementary strands of a DNA molecule form the shape of a double helix

D

What intermolecular force is responsible for holding the two strands of a DNA double helix together? A. covalent bond B. phosphodiester bond C. ionic bond D. hydrogen bond

D. Hydrogen Bonds. DNA forms a hydrogen-bonding interaction between the base pairs adenine, guanine, cytosine, and thymine. The two helices are held together by pairing of the nucleotides' bases through hydrogen bonding.

What does triplex DNA form?

Hoogsteen pairs with functional groups in the major groove of a homopurine-homopyrimidine duplex that contains a mirror repeat

Bacteria and other microbes can be used to "clean up" an oil spill by breaking down oil into carbon dioxide and water. Two samples isolated from the Deepwater Horizon leak in the Gulf of Mexico were labeled A and B. The DNA of each was isolated and the percent thymine measured in each sample. Sample A contains 23.1% thymine and sample B contains 28.7% thymine. Assume the organisms contain normal double‑stranded DNA and predict the composition of the other bases. What is the percentage of adenine, guanine, and cytosine in sample A? What is the adenine, guanine, and cytosine percentage in sample A? If both samples are then denatured to remove the secondary structure. Which will have the higher temperature to denature?

In sample A, 23.1% of adenine, 26.95% of guanine, 26.95% of cytosine. In sample B, 28.7% of adenine, 21.3% of guanine, and 21.3% of cytosine. Sample A will have a higher temperature to denature.

What is cruciform structure?

It causes interstrand hydrogen bonds break and intrastrand hydrogen bonds form

What is an inverted repeat?

It is a DNA repeat that does not have a complementary sequence in the same strand. It is also any sequence, such as a palindrome, that can be rotated 180° horizontally and 180° vertically such that it superimposes a sequence repeat on another sequence

What is the general structure of a purine?

It is a double ring with four nitrogens

What does guanine look like?

It is a double ring, purine with one amino group and one double bond O (can be OH)

What does cytosine look like?

It is a one ring, pyrimidine with one double bond O (can be OH) and an amino group

What does uracil look like?

It is a one ring, pyrimidine with two double bond O's (can be an OH)

What does thymine look like?

It is a one ring, pyrimidine with two double bond O's and a methyl group

What is the general structure of a pyrimidine?

It is a single ring with two nitrogens in the ring (looks like a benzene ring with two nitrogens)

What does adenine look like?

It is a two ring, purine with one amino group

What is the sequence −GTGAG⋅⋅⋅⋅⋅⋅CTCAC−−CACTC⋅⋅⋅⋅⋅⋅GAGTG− ? What does it have the potential to form?

It is an inverted sequence and it has the potential to form a cruciform structure

What is a mirror repeat?

It refers to self‑complementarity within a strand. This sequence may contribute to the formation of some secondary structures

What do these descriptions pertain to: nucleosides, nucleotides, or both nucleosides and nucleotides? 1. are the product when a base bonds at Cl of ribose or deoxyribose 2. do not contain phosphate group

Nucleosides

What do these descriptions pertain to: nucleosides, nucleotides, or both nucleosides and nucleotides? 1. contain a base, a monosaccharide and a phosphate group. 2. can be named adenosine 5'-monophosphate. 3. are the monomers of nucleic acid.

Nucleotides

Suppose that a hapless graduate student has forgotten to label four different sample tubes that contained thermophilic archaea, bacteria, single‑stranded DNA viruses, and double‑stranded RNA viruses. The table shows the nucleotide content of each sample, except for the nucleotide uracil, which is excluded. Identify each unknown sample with the appropriate sample name. Sample 1: 33% G, 33% C, 17% A, 17% T. Sample 2: 23% G, 23% C, 27% A, 27% T. Sample 3: 19% G, 31% C, 17% A, 33% T. Sample 4: 21% G, 21% C, 29% A, 0% T.

Sample 1: Thermophilic archaea Sample 2: Bacteria Sample 3: ss DNA virus Sample 4: ds RNA virus

How many phosphoester (phosphate ester) and phosphoanhydride bonds are in adenosine and adenosine diphosphate (ADP)?

There are no phosphoester and no phosphoanhydride bonds in adenosine. There is one phosphoester and one phosphoanhydride bond in ADP.