The four nucleotides are given one letter abbreviations as shorthand for the four bases. Purines are the larger of the two types of bases found in DNA. The 9 atoms that make up the fused rings 5 carbon, 4 nitrogen are numbered All ring atoms lie in the same plane.
Cytosine and thymine are pyrimidines. The 6 atoms 4 carbon, 2 nitrogen are numbered They are both linear polymers, consisting of sugars, phosphates and bases, but there are some key differences which separate the two 1. These distinctions enable the two molecules to work together and fulfil their essential roles. Before we delve into the differences, we take a look at these two nucleic acids side-by-side. I Understand. Published: December 18, Last Updated: November 11, DNA encodes all genetic information, and is the blueprint from which all biological life is created.
In the long-term, DNA is a storage device, a biological flash drive that allows the blueprint of life to be passed between generations 2. RNA functions as the reader that decodes this flash drive. This reading process is multi-step and there are specialized RNAs for each of these steps. Below, we look in more detail at the three most important types of RNA.
Cytosine, thymine, and uracil are classified as pyrimidines. These are structurally distinguished by a single carbon-nitrogen ring. You will be expected to recognize that each of these ring structures is decorated by functional groups that may be involved in a variety of chemistries and interactions.
Take a moment to review the nitrogenous bases in Figure 1. Identify functional groups as described in class. For each functional group identified, describe what type of chemistry you expect it to be involved in.
Try to identify whether the functional group can act as either a hydrogen bond donor, acceptor, or both? The pentose sugar contains five carbon atoms. The two main functional groups that are attached to the sugar are often named in reference to the carbon to whch they are bound. We will often use the carbon number to refer to functional groups on nucleotides so be very familiar with the structure of the pentose sugar.
The difference between the sugars is the presence of the hydroxyl group on the 2' carbon of the ribose and its absence on the 2' carbon of the deoxyribose. You can, therefore, determine if you are looking at a DNA or RNA nucleotide by the presence or absence of the hydroxyl group on the 2' carbon atom—you will likely be asked to do so on numerous occasions, including exams. There can be anywhere between one and three phosphate groups bound to the 5' carbon of the sugar.
The phosphoanhydride bonds between that link the phosphate groups to each other have specific chemical properties that make them good for various biological functions. The hydrolysis of the bonds between the phosphate groups is thermodynamically exergonic in biological conditions; nature has evolved numerous mechanisms to couple this negative change in free energy to help drive many reactions in the cell. Figure 2 shows the structure of the nucleotide triphosphate Adenosine Triphosphate, ATP, that we will discuss in greater detail in other chapters.
The term "high-energy bond" is used A LOT in biology. This term is, however, a verbal shortcuts that can cause some confusion. The term refers to the amount of negative free energy associated with the hydrolysis of the bond in question.
The water or other equivalent reaction partner is an important contributor to the energy calculus. In ATP, for instance, simply "breaking" a phosphoanhydride bond - say with imaginary molecular tweezers - by pulling off a phosphate would not be energetically favorable. We must, therefore, be careful not to say that breaking bonds in ATP is energetically favorable or that it "releases energy".
Rather, we should be more specific, noting that they hydrolysis of the bond is energetically favorable. Some of this common misconception is tied to, in our opinion, the use of the term "high energy bonds". While in Bis2a we have tried to minimize the use of the vernacular "high energy" when referring to bonds, trying instead to describe biochemical reactions by using more specific terms, as students of biology you will no doubt encounter the potentially misleading - though admittedly useful - short cut "high energy bond" as you continue in your studies.
So, keep the above in mind when you are reading or listening to various discussions in biology. Related Concepts 9. You have authorized LearnCasting of your reading list in Scitable. Do you want to LearnCast this session?
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