Podcast
Questions and Answers
Which of the following nitrogenous bases is found in both DNA and RNA?
Which of the following nitrogenous bases is found in both DNA and RNA?
What is the main difference between purines and pyrimidines?
What is the main difference between purines and pyrimidines?
Which carbon of the sugar molecule is involved in forming a phosphodiester bond between nucleotides?
Which carbon of the sugar molecule is involved in forming a phosphodiester bond between nucleotides?
In DNA, which nitrogenous base pairs with Guanine (G)?
In DNA, which nitrogenous base pairs with Guanine (G)?
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What is the function of nitrogenous bases in DNA?
What is the function of nitrogenous bases in DNA?
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Which of the following contains a single carbon-nitrogen ring?
Which of the following contains a single carbon-nitrogen ring?
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How many nitrogen atoms are present in purines?
How many nitrogen atoms are present in purines?
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Which of the following pairs correctly represents base pairing in DNA?
Which of the following pairs correctly represents base pairing in DNA?
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What do nucleotides consist of?
What do nucleotides consist of?
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Which of the following nitrogenous bases is found in both DNA and RNA?
Which of the following nitrogenous bases is found in both DNA and RNA?
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In DNA, which of the following nitrogenous bases pairs with Thymine (T)?
In DNA, which of the following nitrogenous bases pairs with Thymine (T)?
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Which type of nitrogenous base contains two carbon-nitrogen rings fused together?
Which type of nitrogenous base contains two carbon-nitrogen rings fused together?
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Which of the following represents the correct base pairing in DNA according to the Watson-Crick model?
Which of the following represents the correct base pairing in DNA according to the Watson-Crick model?
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How many nitrogen atoms are present in Pyrimidines?
How many nitrogen atoms are present in Pyrimidines?
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Which carbon of the sugar molecule is involved in forming a phosphodiester bond between nucleotides?
Which carbon of the sugar molecule is involved in forming a phosphodiester bond between nucleotides?
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What is the nitrogenous base that pairs with Cytosine (C) in DNA?
What is the nitrogenous base that pairs with Cytosine (C) in DNA?
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Which type of sugar is found in DNA nucleotides?
Which type of sugar is found in DNA nucleotides?
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Study Notes
DNA Structure
- DNA is a group of molecules responsible for carrying and transmitting genetic instructions from parents to offspring.
- DNA is used by eukaryotes and prokaryotes to synthesize proteins and enzymes essential for cell survival.
Basic Building Blocks of DNA
- Nucleotides are the basic building blocks of DNA, composed of a sugar group, a phosphate group, and a nitrogen base.
- Nucleotides are connected by a phosphodiester bond between the 3rd carbon of one sugar and the 5th carbon of the second sugar.
Nitrogenous Bases
- There are two types of nitrogenous bases: pyrimidines and purines.
- Pyrimidines have a single carbon-nitrogen ring and contain two nitrogen atoms in their structure.
- Purines have two carbon-nitrogen rings fused together and contain four nitrogen atoms in their structure.
- Nitrogenous bases in DNA: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T).
- Nitrogenous bases in RNA: Adenine (A), Guanine (G), Cytosine (C), and Uracil (U).
Base Pairing
- A pairs with T (DNA) or U (RNA) and G pairs with C.
- C pairs with G and T (DNA) or U (RNA) pairs with A.
Pentose Sugars
- Two types of pentose sugars are present in nucleic acids: ribose and deoxyribose.
- Ribose is present in RNA, and deoxyribose is present in DNA.
- Deoxyribose is missing one hydroxyl group at the carbon 2nd position compared to ribose.
Phosphate Group
- The phosphate group is bonded to the 5th atom of the sugar.
- The phosphate group has a negative charge, making DNA highly charged and polar.
The Watson-Crick Model
- The model has a single DNA molecule consisting of two individual nucleic acid chains that are coiled around a central axis.
- The two chains are antiparallel, with the backbone of the nucleic acid (sugar-phosphate) on the exterior and the nitrogenous base on the inside.
- Each complete turn of the helix is 10 bases per turn.
- The nitrogenous bases of opposite chains are electrostatically attracted to one another, forming hydrogen bonds.
Stability Factors for the DNA Helix
- Positive forces: hydrogen bonds, stacking interactions, and the negative charge of the phosphate group.
- Hydrogen bonds: A-T forms two hydrogen bonds, and G-C forms three hydrogen bonds.
- Stacking interactions: the arrangement of sugars and bases along the axis, with hydrophobic bases stacked on the inside and hydrophilic sugar phosphate backbone on the outside.
Chargaff's Rule
- The number of nitrogenous bases in DNA is present in equal quantities.
- The amount of A is equal to T, and the amount of C is equal to G.
The Structure of RNA
- RNA has ribose sugar instead of deoxyribose in DNA.
- RNA has uracil instead of thymine in DNA.
- Most RNA is a single-stranded polynucleotide chain, while DNA is a double helical structure.
- Some animal viruses have RNA as their genetic material, which is double-stranded helix.
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Description
Test your knowledge on the components of genetic material such as nitrogenous bases and pentose sugars. Learn how nitrogenous bases pair together in DNA and the differences between ribose and deoxyribose sugars in nucleic acids.
