Biology Chapter: Nucleic Acids Overview

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Questions and Answers

What is the primary function of nucleotides in biological systems?

Serving as building blocks of proteins

Constituents of lipids

Regulating temperature in cells

Acting as a high energy source (correct)

Which bond connects the nucleotides in a polynucleotide chain?

Phosphodiester bond (correct)

Hydrogen bond

Peptide bond

Ionic bond

What are the components of a nucleotide?

Nitrogen base, pentose sugar, phosphate group (correct)

Pentose sugar, amino acid, phosphate group

Fatty acid, nitrogen base, carbohydrate

Nitrogen base, amino acid, sugar

What is the role of phosphodiester bonds in nucleic acids?

They link the monomers of nucleotides Signup and view all the answers

Which of the following is a pyrimidine nucleotide?

Cytidine Signup and view all the answers

Which of these statements is true regarding the polarity of polynucleotides?

They have a free -OH at the 3' end and a free phosphate group at the 5' end Signup and view all the answers

What are synthetic nucleotide analogues used for?

As chemotherapeutic drugs Signup and view all the answers

Which component of nucleotides can be classified as a purine base?

Adenine Signup and view all the answers

What are the two main types of nucleic acids?

Ribonucleic acid (RNA) and Deoxyribonucleic acid (DNA) Signup and view all the answers

Which of the following correctly describes the composition of a nucleotide?

Nitrogenous base + Pentose sugar + Phosphate group Signup and view all the answers

Which of the following nitrogenous bases is classified as a purine?

Adenine Signup and view all the answers

What is the role of a phosphate group in a nucleotide?

Attaches to ribose or deoxyribose via an ester bond Signup and view all the answers

Which sugar is found in ribonucleic acid (RNA)?

Ribose Signup and view all the answers

Which nitrogenous base is not a constituent of DNA?

Uracil Signup and view all the answers

What bond connects the nitrogenous base to the pentose sugar in nucleotides?

N-glycosidic bond Signup and view all the answers

Which of the following statements about nucleosides is true?

They consist of a nitrogenous base linked to a pentose sugar. Signup and view all the answers

Study Notes

Nucleic Acids

Nucleic acids are polymers composed of nucleotides linked by phosphodiester bonds.
They are responsible for storing and expressing genetic information.
Two types of nucleic acids exist: ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).

Nucleotides & Nucleosides

Nucleotides are composed of a nitrogenous base, a pentose sugar, and a phosphate group.
Nucleosides are composed of a nitrogenous base and a pentose sugar.
A nucleotide is essentially a nucleoside with a phosphate group added.

Nitrogenous Bases

Two families of nitrogenous bases exist: purine and pyrimidine.
Purines include adenine (A) and guanine (G).
Pyrimidines include cytosine (C), thymine (T), and uracil (U).

Pentose Sugar

Two types of pentose sugars exist: ribose and deoxyribose.
Ribose is present in ribonucleic acid (RNA).
Deoxyribose is present in deoxyribonucleic acid (DNA) and differs from ribose by lacking an oxygen atom at carbon 2.

Phosphate

Phosphate is derived from phosphoric acid (H3PO4) and attaches to carbon 5 of the ribose sugar by an ester bond.

Nucleotides and Nucleosides: Nomenclature and Structure

In nucleotides and nucleosides, the nitrogenous base is linked to carbon 1 of the sugar by an N-glycosidic bond.
Nucleotide Structure: Nitrogenous Base + Pentose Sugar + Phosphate Group
Nucleoside Structure: Nitrogenous Base + Pentose Sugar
Nucleotides are often named after their nucleoside with the addition of “monophosphate” (e.g., Adenosine monophosphate (AMP)).
Deoxy-nucleotides are denoted with a "d" prefix (e.g., dAMP for deoxyadenosine monophosphate).

Importance of Nucleotides and Nucleosides

Building blocks of Nucleic Acids: Form the basic structure of DNA and RNA.
High Energy Source: ATP (adenosine triphosphate) is a primary energy carrier in cells.
Coenzyme Components: Nucleotides are part of coenzymes like FAD (flavin adenine dinucleotide) and NAD (nicotinamide adenine dinucleotide).
Regulatory Function: Cyclic nucleotides like cAMP (cyclic adenosine monophosphate) and cGMP (cyclic guanosine monophosphate) act as signaling molecules.
Chemotherapeutic Drugs: Synthetic nucleotide analogues are used to target specific metabolic pathways in cancer treatment.
Metabolic Precursors: Pyrimidines are precursors for important metabolic intermediates like UDP-glucose and CDP-choline.

Polymerization of Nucleotides

Nucleotides within a nucleic acid are linked by 3' → 5' phosphodiester bonds.
This linkage involves the phosphate group of one nucleotide attaching to the 3' hydroxyl group of the sugar in the next nucleotide.
Nucleases are enzymes that hydrolyze phosphodiester bonds.
Each polynucleotide has a 3' end (with a free hydroxyl group) and a 5' end (with a free phosphate group).

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Description

Explore the essential components of nucleic acids, including their structure, types, and functions in genetic information storage. This quiz covers nucleotides, nitrogenous bases, and the significance of pentose sugars in RNA and DNA.