Problem The DNA molecule is shaped like a twisted ladder. Related Content. Animation The DNA molecule is shaped like a twisted ladder. DNA Because it contains the directions for assembling the components of the cell, DNA is often thought of as the "instruction book" for assembling life.
ID: Source: G2C. Some DNA does not encode protein. Combinations of these atoms form the sugar-phosphate backbone of the DNA -- the sides of the ladder, in other words.
Other combinations of the atoms form the four bases: thymine T , adenine A , cytosine C , and guanine G. These bases are the rungs of the DNA ladder. It takes two bases to form a rung -- one for each side of the ladder. DNA Structure and Shape. By volunteering, or simply sending us feedback on the site. Scientists, teachers, writers, illustrators, and translators are all important to the program. If you are interested in helping with the website we have a Volunteers page to get the process started.
Digging Deeper. Digging Deeper: Depression and the Past. Digging Deeper: Germs and Disease. Digging Deeper: Milk and Immunity. How Do We See? How Do We Sense Smell? How Do We Sense Taste? How Do We Sense Touch? This backbone is formed when the 3' end dark gray of one nucleotide attaches to the 5' phosphate end light gray of an adjacent nucleotide by way of a phosphodiester bond. How is the DNA strand organized? Figure 4: Double-stranded DNA consists of two polynucleotide chains whose nitrogenous bases are connected by hydrogen bonds.
Within this arrangement, each strand mirrors the other as a result of the anti-parallel orientation of the sugar-phosphate backbones, as well as the complementary nature of the A-T and C-G base pairing. Figure Detail. Figure 6: The double helix looks like a twisted ladder.
How is DNA packaged inside cells? Figure 7: To better fit within the cell, long pieces of double-stranded DNA are tightly packed into structures called chromosomes. What does real chromatin look like? Compare the relative sizes of the double helix, histones, and chromosomes.
Figure 8: In eukaryotic chromatin, double-stranded DNA gray is wrapped around histone proteins red. Figure 9: Supercoiled eukaryotic DNA.
How do scientists visualize DNA? Figure This karyotype depicts all 23 pairs of chromosomes in a human cell, including the sex-determining X and Y chromosomes that together make up the twenty-third set lower right. Watch this video for a closer look at the relationship between chromosomes and the DNA double helix.
What are karyotypes used for? Who is James Watson? What do we know about Francis Crick? Topic rooms within Genetics Close. No topic rooms are there. Browse Visually. Other Topic Rooms Genetics. Student Voices. Creature Cast. Simply Science. Green Screen.
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