Why do guanine and cytosine go together

So for example, if there's a G on one side of the strand, there will always be a C on the other. If there's a T on one side of the strand, there will always be an A on the other. And those nucleotides always pair. We also count DNA and the amount of DNA, or the length of DNA by using units of base pairs, so if we're discussing a gene and we want to describe how big is a gene, we might say that the gene is a thousand base pairs long.

If it's a really big gene, it may be 10, base pairs, or essentially 10 kilobases long. Each nucleotide has three parts: a sugar, a phosphate , and a base. The sugar and phosphate molecules are linked together in two long chains. The bases are linked to the sugar-phosphates. Bases of one strand are bound to those of the other strand by hydrogen bonds making what is called a base pair. The structure of DNA is a double helix which allows it to perform the functions of replication and information storage.

Base pairs look similar to rungs on a ladder. In fact, the DNA structure could be described as a long ladder twisted into a spiral. DNA has a double helix structure composed of nucleotides. Alex Falk. This diagram illustrates the factors that determine base pairs. Image source: By Alex Falk. Adenine is long and has two binding sites. Thymine is short and has two binding sites.

Guanine is long and has three binding sites. Cytosine is short and has three binding sites. Complementary Base Pairing If you look at the diagram, you will see that it is impossible for a base to bond with any base other than its counterpart. Which of these is a factor in determining how bases pair with one another? Show Solution Check. Related Lessons. What Are Carbohydrates? Complex Carbohydrates Are Polysaccharides.

View All Related Lessons. Deena Hauze. The Four Bases. DNA has four nucleobases: adenine, thymine, guanine, and cytosine.

Vocabulary Review: Monomer : Any molecule that can react with other molecules of the same or different makeup to form a chain, or polymer Polymer : A chain of monomers made of a specific type of compound Macromolecule : A polymer that has a large macro molecular mass. There are four main types in organisms: carbohydrates , proteins , lipids , and nucleic acids Nucleotides : The monomers of nucleic acids.

Made up of a nitrogen group, a phosphorus group, and a 5- carbon ring Nucleic Acid : Complex polymer that stores genetic information in a cell in the form of a code. Valeri Natole. Aaron Lauer. Complementary Pairing. You've reached the end.