Podcast
Questions and Answers
Which of the following are components of a nucleotide?
Which of the following are components of a nucleotide?
- Nitrogenous base
- Pentose sugar
- Phosphate group
- All of the above (correct)
What is the genetic material for the majority of organisms?
What is the genetic material for the majority of organisms?
DNA
What type of sugar is present in RNA?
What type of sugar is present in RNA?
- Deoxyribose
- Fructose
- Ribose (correct)
- Glucose
What are the two types of nitrogenous bases?
What are the two types of nitrogenous bases?
Thymine is present in RNA.
Thymine is present in RNA.
What linkage forms a nucleoside from a nitrogenous base and a pentose sugar?
What linkage forms a nucleoside from a nitrogenous base and a pentose sugar?
The haploid content of human DNA is approximately ______ base pairs.
The haploid content of human DNA is approximately ______ base pairs.
What is the linkage called that connects two nucleotides in a DNA molecule?
What is the linkage called that connects two nucleotides in a DNA molecule?
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Study Notes
Molecular Basis of Inheritance
- DNA is identified as the primary genetic material in most organisms, with RNA also serving a genetic role in some viruses.
- DNA's structure involves long polymers of deoxyribonucleotides, characterized by the number of nucleotide pairs, also known as base pairs.
- Specific examples of DNA length include:
- Bacteriophage φ ×174: 5386 nucleotides
- Bacteriophage lambda: 48,502 base pairs
- Escherichia coli: 4.6 million base pairs
- Human haploid DNA: 3.3 billion base pairs
Structure of DNA
-
Each nucleotide comprises three components:
- A nitrogenous base (purines: Adenine, Guanine; pyrimidines: Cytosine, Thymine in DNA, Uracil in RNA)
- A pentose sugar (deoxyribose in DNA, ribose in RNA)
- A phosphate group
-
Nitrogenous bases link to the 1' carbon of the pentose sugar via N-glycosidic bonds, forming nucleosides (e.g., adenosine, guanosine).
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When a phosphate group is attached to the 5' carbon of a nucleoside through a phosphoester bond, a nucleotide is formed.
Formation of Polynucleotide Chains
- Nucleotides are joined by 3'-5' phosphodiester linkages, creating dinucleotides and longer polynucleotide chains.
- Each polynucleotide chain has a defined orientation with:
- A free phosphate group at the 5' end
- A free hydroxyl group at the 3' end
Transcription and Translation
- Replication of DNA leads to transcription, where RNA is synthesized from DNA templates.
- The genetic code derived from DNA determines the sequence of amino acids in proteins through translation.
Human Genome Project
- Recent developments in genomics, including comprehensive sequencing of the human genome, have significant implications for genetics and biotechnology.
RNA Functions
- In addition to acting as the genetic material in some viruses, RNA serves multiple roles:
- Messenger RNA (mRNA): carries genetic information.
- Adapter and structural roles in protein synthesis.
- Some RNA molecules exhibit catalytic properties.
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