Ácido nucleico, nucleotidos y bases nitrogenadas / Biología: Ácidos nucleicos

Introduction to Nucleic Acids

In this section, an extensive introduction to nucleic acids is provided. The composition of nucleic acids, specifically nucleotides, is discussed along with the types of bonds formed and the structures involved.

Nucleic Acids and Genetic Information

• Nucleic acids are complex molecules that store genetic information in cells.

• DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are the main types of nucleic acids responsible for storing and transcribing genetic information.

• Nucleotides are the building blocks of nucleic acids.

Composition of Nucleotides

• Nucleotides consist of a nitrogenous base, a pentose sugar, and a phosphate group.

• Nitrogenous bases can be purines (adenine and guanine) or pyrimidines (cytosine, thymine, and uracil).

• Purines have two rings in their structure while pyrimidines have one ring.

Formation of Nucleosides and Nucleotides

• A nucleoside is formed by combining a nitrogenous base with a pentose sugar.

• When an acid phosphate group is added to a nucleoside, it becomes a nucleotide.

• The type of sugar used determines whether it forms DNA or RNA.

Nitrogenous Bases

This section focuses on nitrogenous bases found in nucleotides. The different types of bases are explained along with their structures.

Types of Nitrogenous Bases

• There are two types of nitrogenous bases: purines and pyrimidines.

• Purines consist of two rings and include adenine (A) and guanine (G).

• Pyrimidines consist of one ring and include cytosine (C), thymine (T) in DNA, and uracil (U) in RNA.

Structure of Purines and Pyrimidines

• Purines have a pentagon with five points and a hexagon with six points.

• Pyrimidines have a hexagon structure.

• The arrangement of atoms within the rings may vary, but the overall structure remains consistent.

Formation of Nucleotides

This section explains how nucleotides are formed by combining nitrogenous bases, pentose sugars, and phosphate groups.

Components of Nucleotides

• Nucleotides are composed of a nitrogenous base, a pentose sugar (ribose or deoxyribose), and a phosphate group.

• The type of sugar used determines whether it forms DNA or RNA.

Pentose Sugars

• There are two types of pentose sugars: ribose and deoxyribose.

• Ribose is used in RNA while deoxyribose is used in DNA.

• Deoxyribose lacks an oxygen atom at carbon number 2 compared to ribose.

Phosphate Group

• The phosphate group consists of a phosphorus atom surrounded by oxygen atoms.

• It plays an important role in the structure and function of nucleotides.

Formation of Nucleotide Bonds

This section describes the process of forming bonds between nitrogenous bases, pentose sugars, and phosphate groups to create nucleotides.

Bonding Process

• To form a nucleotide, a nitrogenous base is bonded to a pentose sugar using an n-glycosidic bond.

• The bond occurs between the nitrogen atom on the base and the carbon atom at position 1 on the sugar.

Types of Pentose Sugars

• The type of pentose sugar used determines whether it forms DNA or RNA.

• Ribose is used for RNA, while deoxyribose is used for DNA.

Phosphate Group

• A phosphate group is added to the nucleoside to form a nucleotide.

• The phosphate group consists of a phosphorus atom surrounded by oxygen atoms.

Conclusion

This section concludes the discussion on nucleic acids and their components.

Recap

• Nucleic acids are complex molecules that store genetic information in cells.

• Nucleotides are the building blocks of nucleic acids, consisting of a nitrogenous base, pentose sugar, and phosphate group.

• Nitrogenous bases can be purines (adenine and guanine) or pyrimidines (cytosine, thymine/uracil).

• Nucleotides are formed by bonding nitrogenous bases with pentose sugars using n-glycosidic bonds.

• The type of sugar used determines whether it forms DNA or RNA.

New Section

This section explains the process of joining the nitrogenous base and the pentose sugar to form a nucleotide.

Formation of Nucleotide

• The nitrogenous base is always joined to the pentose sugar through a glycosidic bond.

• The nitrogenous base is connected to the carbon 1 position of the pentose sugar.

• When a hydrogen from the hydroxyl group (OH) of the pentose sugar combines with a hydrogen from a hydroxyl group (OH) on another molecule, a water molecule is lost.

• The resulting structure consists of the nitrogenous base, pentose sugar, and a phosphate group.

• Two water molecules are lost in total during nucleotide formation: one in the glycosidic bond between the base and sugar, and another in the ester bond between the sugar and phosphate group.

New Section

This section discusses how to connect the nucleoside with phosphoric acid to form a nucleotide.

Connecting Nucleoside with Phosphoric Acid

• The nucleoside, consisting of a nitrogenous base and pentose sugar, needs to be connected with phosphoric acid to form a nucleotide.

• A hydrogen from one of the hydroxyl groups (OH) on phosphoric acid combines with a hydrogen from the last carbon of the pentose sugar.

• Another water molecule is lost during this process due to ester bond formation between phosphoric acid and pentose sugar.

New Section

This section highlights important aspects regarding water loss during nucleotide formation.

Water Loss during Nucleotide Formation

• Two water molecules are lost in total during nucleotide formation: one in glycosidic bond formation between base and sugar, and another in ester bond formation between sugar and phosphate group.

• In contrast, if only a nucleoside is formed without the phosphate group, only one water molecule is lost.

• The name of the final molecule changes depending on the presence or absence of oxygen in the pentose sugar. For example, if it is a ribose sugar with an OH group, it is called a ribonucleotide.

New Section

This section explains how the name of the final molecule depends on its components.

Naming of Final Molecule

• The name of the final molecule depends on its components.

• If the base nitrogenous is adenine, it will be called a ribonucleotide of adenine.

• If there is no oxygen present in the pentose sugar, it would be called a deoxyribonucleotide instead.

New Section

This section mentions that besides appearing in DNA, nitrogenous bases can also be found in other molecules such as ATP.

Nitrogenous Bases in Other Molecules

• Nitrogenous bases are not only found in DNA but also appear in other molecules like ATP (adenosine triphosphate) and ADP (adenosine diphosphate).

• These molecules store energy primarily within their phosphoric acid groups.

• By adding or removing phosphoric acid groups, cells can control energy storage and release.

Timestamps are provided for each section to help locate specific information within the transcript.