24 Questions
What is the primary function of nucleic acids in living organisms?
To store and transmit genetic information
What is the role of mRNA during translation?
To decode the amino acid sequence of proteins
What is the purpose of DNA replication during cell division?
To generate a duplicate set of genetic instructions for the new cell
What is the characteristic of viral genomes?
They consist of either double- or single-stranded nucleic acids and contain either DNA or RNA
What is the role of certain RNAs in riboprotein complexes?
To provide structural scaffolds
What is the relationship between the sequence of mRNA and the characteristics of the organism?
The sequence of mRNA specifies the amino acid sequence of proteins that contribute to the phenotypic characteristics
What is the difference between the nucleic acid bases found in DNA and RNA?
DNA contains thymine and RNA contains uracil
What type of bonds link nucleotides together in a nucleic acid?
Covalent phosphodiester bonds
What is the direction of a polynucleotide sequence when written?
5' to 3'
What is the characteristic of the 5' end of a nucleic acid?
It has a free phosphate group
What is the structure of the predominant form of DNA?
Double-stranded and double helical
What type of bonds form between the bases in a double-stranded DNA?
Hydrogen bonds
What is the number of hydrogen bonds involved in A–T pairing?
Two
What is the orientation of the sugar–phosphate backbones of the two strands in DNA?
Antiparallel
What type of bond links the 5′ and 3′ ends of the genomes of single‐stranded DNA viruses?
Phosphodiester bond
What is the typical structure of most cellular RNA?
Single-stranded
What type of base pairs are typically found in double-stranded regions of RNA?
G–C, A–U, and atypical base pairs
What is the result of the association of RNA domains through tertiary interactions?
Compact structures
What is a crucial requirement for viruses to replicate their nucleic acids and multiply?
Exploiting the biochemical machinery of a host cell
What is the role of reverse transcriptase in some RNA viruses?
To catalyze the reverse transcription of a DNA copy of the viral RNA genome
What are the four components of a nucleotide?
Purine or pyrimidine base, sugar, and phosphate group
What is the difference between the sugar molecules in RNA and DNA?
RNA contains ribose, while DNA contains deoxyribose
Why is RNA generally less stable than DNA?
Due to the reactive 2′‐hydroxyl groups in RNA
How many types of nitrogenous bases are found in nucleic acids?
Four, two purines and two pyrimidines
Study Notes
Nucleic Acids and Viruses
- Viruses must exploit the host cell's biochemical machinery to replicate their nucleic acids and multiply.
- RNA viruses can translate their RNA directly into protein or use it as a template to synthesize complementary RNAs.
- Some RNA viruses encode reverse transcriptase, which uses RNA as a template for DNA synthesis.
Composition of Nucleic Acids
- DNA and RNA are polymers composed of four types of nucleotides, each consisting of a purine or pyrimidine base, a pentose sugar, and a phosphate group.
- DNA contains adenine, guanine, cytosine, and thymine, while RNA contains adenine, guanine, cytosine, and uracil.
- RNA is less stable than DNA due to reactive 2′-hydroxyl groups.
Nucleic Acid Structure
- Nucleic acids are composed of nucleotides linked by phosphodiester bonds.
- The sugar-phosphate backbone has two distinct ends with different biochemical characteristics.
- The 5′ end has a free phosphate group, and the 3′ end is typically hydroxylated.
- Polynucleotide sequences are written 5′ to 3′.
Double-Stranded DNA
- The predominant form of DNA is a double-stranded, double helical structure formed from two separate polynucleotide chains.
- Hydrogen bonds form between purine bases on one chain and pyrimidine bases on the other chain.
- A-T pairing involves two hydrogen bonds, while G-C pairing involves three hydrogen bonds.
Nucleic Acids and Genetics
- Nucleic acids store and transmit genetic information.
- DNA serves as a template for RNA synthesis during transcription.
- RNA provides structural scaffolds, regulates gene expression, and is decoded by ribosomes during translation.
- The information in translated mRNA sequences specifies the amino acid sequence of proteins.
Viral Genomes
- Viral genomes consist of either double- or single-stranded nucleic acids and contain either DNA or RNA.
- Viral genomes are generally small and encode only a few proteins required for viral propagation.
RNA Structure
- Most cellular RNA is single-stranded, but often folds locally to form domains with stems and loops.
- These domains associate with each other through specific tertiary interactions, allowing RNAs to assume compact structures.
This quiz covers the basics of nucleic acids, including DNA and RNA, and their role in storing and transmitting genetic information. Learn about the structure and function of these molecules and how they are used in the process of transcription. Test your knowledge of cell biology and genetics!
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
