DNA Structure - Molecular Biology
DNA, RNA, and proteins absorb ultraviolet (UV) light at different wavelengths as indicated in the graph.
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Choose the DNA sequence of the strand that is complementary to 5' CAGCTAAATC 3'.
5' GATTTAGCTG 3'
Choose the DNA sequence of the strand that is complementary to 5' GTATCTGCCA 3'.
5' TGGCAGATAC 3'
The chromatogram shows fluorescent peak data from a dye-terminating nucleotide-sequencing reaction. The peaks are shown with shortest fragment on the left to longer fragments on the right.
5'-GATAAATCTGGTTC-3'
In 1953, the scientists James Watson and Francis Crick published their landmark findings on the structure of DNA. Watson and Crick deduced the structure of DNA by unifying evidence that they collected from several scientists who were also seeking to answer this important question.
A purine base forms hydrogen bonds to pair with a pyrimidine base located on the opposite DNA strand. Specifically, A pairs with T, and C pairs with G. The nitrogenous bases on each DNA helix are arranged perpendicularly to the central axis. The diameter of the DNA double helix is 2 nanometers, with each purine-pyrimidine base pair spanning an equivalent distance between the two chains. The sugar-phosphate backbones of each DNA helix run antiparallel to one another.
Identify the statements that describe the structure of DNA.
DNA double helix contains 2 sugar-phosphate backbones oriented in opposite directions 5-carbon sugar of DNA = deoxyribose adenine is paired with thymine, & guanine is paired with cytosine
DNA has unique properties that allow it to accurately retain genetic information, even after multiple rounds of replication. One aspect of DNA that allows it to accurately store genetic information is the base pairing from Chargaff's first rule of the four nucleotide bases. If the C content of a DNA molecule is 22%, what are the percentages of the remaining bases?
G = 22% T = 28% A = 28%
Classify each nucleotide or nucleoside by the type of base and sugar groups present in each image.
OH on right down = ribose singular structure = pyrimidine
Classify each feature as describing prokaryotic DNA structure or eukaryotic DNA structure.
Prokaryotic - DNA is circular - packaged without histone proteins - occurs as a single looped structure - does not have telomere region - condensed only by DNA supercoiling Eukaryotic - DNA is linear - packaged under histone proteins - occurs as multiple chromosomes - has repeating telomere region - condensed around histone proteins
Which of the statements describes purines and pyrimidines in DNA molecules?
Pyrimidines consist of a one-ring structure. Pyrimidines form hydrogen bonds with purines. Purines consist of a two-ring structure. Purines form hydrogen bonds with pyrimidines.
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.
The proportion of pyrimidines is roughly equal to the proportion of purines. The proportion of A is roughly equal to the proportion of T. The proportion of G is roughly equal to the proportion of C.
Identify the statements that describe the structure of DNA.
The two anti‑parallel sugar‑phosphate backbones twist to form a double helix. Adenine is paired with thymine, and guanine is paired with cytosine. The five‑carbon sugar of DNA is called deoxyribose. A DNA double helix contains two sugar‑phosphate backbones oriented in opposite directions.
How did Watson and Crick use the width of DNA to determine the nucleotide pairing in DNA?
The width is explained by a purine base pairing with a pyrimidine base.
The nucleotide base that complements thymine is
adenine
diagram depicts the general structure of DNA, with a single nucleotide circled. Label the diagram with the names of the 3 components of a nucleotide.
blue = phosphate group orange = nitrogenous base gray = deoxyribose
diagram depicts the molecular structure of DNA. Label the diagram with the names of the components of the nucleic acid.
clockwise: pyrimidine base purine base hydrogren bond sugar-phosphate backbone
The three-dimensional structure of DNA is shown in the interactive.
double helical
The nucleotide base that complements cytosine is
guanine
Label the indicated components of the DNA double helix.
major groove minor groove hydrogen bonds phosphodiester bonds
What is the monomer that makes up DNA?
nucleotide
Classify the molecule.
purine, deoxyribose
Classify the molecule.
pyrimidine, deoxyribose
Classify the molecule.
pyrimidine, ribose
