22 Questions
What is the site of translation in a cell?
Ribosomes
What is the role of RNA polymerases?
To transcribe DNA into RNA
What is the function of a codon?
To determine the position of amino acids during protein synthesis
What is the process of translating the genetic information from mRNA into a specific sequence of amino acids?
Translation
What is the function of an anticodon?
To bind to a corresponding codon and designate a specific amino acid
What are the two main steps of gene expression?
Transcription and translation
What is the shape of a DNA molecule?
Anti-parallel double helix
Which of the following base pairs have a triple bond?
G=C
What is the function of RNA polymerase?
To transcribe DNA into RNA
Which type of RNA carries amino acids to the ribosomes for protein assembly?
tRNA
What is the function of messenger RNA (mRNA)?
To copy DNA's instructions and carry them to ribosomes for protein assembly
Which of the following is NOT a main class of RNA molecules?
snRNA
What is the function of ribosomal RNA (rRNA)?
To make up the large and small subunits of ribosomes
What is the process by which a section of DNA is copied into a piece of single-stranded nucleic acid?
Transcription
What is the primary function of nucleic acids in cells?
To store and express genomic information
What is the type of bond that links nucleotides together in DNA and RNA?
Phosphodiester bond
What is the difference between the sugar molecule in DNA and RNA?
DNA has deoxyribose sugar, while RNA has ribose sugar
What is the nitrogenous base that is found in RNA but not in DNA?
Uracil
What is the structure of DNA?
A double helix of two strands of nucleotides
What is the term for the repeating unit of DNA and RNA?
Nucleotide
What is the type of bonding that holds the two strands of DNA together?
Hydrogen bond
What is the class of nucleic acids that comes in different molecular forms and plays multiple cellular roles?
RNA
Study Notes
Nucleic Acids
- Nucleic acids are large biomolecules that play essential roles in all cells and viruses, storing and expressing genomic information that determines inherited characteristics.
- There are two main classes of nucleic acids: Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA).
Structure of Nucleotides
- Nucleotides are the building blocks of DNA and RNA, consisting of:
- Nitrogenous base (purines: adenine and guanine; pyrimidines: cytosine, thymine, and uracil)
- Pentose sugar (deoxyribose in DNA and ribose in RNA)
- Phosphate group
DNA Structure
- DNA is composed of a phosphate-deoxyribose sugar backbone and the nitrogenous bases adenine (A), guanine (G), cytosine (C), and thymine (T).
- DNA forms a double helix with two strands twisted around each other, held together by hydrogen bonding between complimentary base pairs (A-T and G-C).
RNA Structure
- RNA is a single-stranded nucleic acid polymer of the four nucleotides A, C, G, and U, with a backbone of alternating phosphate and ribose sugar residues.
- RNA is made by copying the base sequence of a section of double-stranded DNA, called a gene, into a piece of single-stranded nucleic acid through transcription.
Types of RNA Molecules
- There are three main classes of RNA molecules:
- Messenger RNA (mRNA): copies DNA's instructions and carries them to ribosomes for protein assembly.
- Transfer RNA (tRNA): carries amino acids in the cytoplasm to ribosomes for protein assembly.
- Ribosomal RNA (rRNA): makes up the large and small subunits of ribosomes.
- Other classes of RNA molecules include:
- Small nuclear RNA (snRNA)
- Micro RNA (miRNA)
- Small interfering RNA (siRNA)
- Heterogeneous nuclear RNA (hnRNA)
Gene Expression
- Gene expression is the process by which genetic information stored in a gene is used to synthesize a functional protein.
- Proteins synthesis occurs in two steps:
- Transcription: DNA → RNA
- Translation: RNA → protein
Transcription and Translation
- Transcription is the process of copying a gene's DNA sequence to make an RNA molecule, performed by enzymes called RNA polymerases.
- Translation is the process of translating the transcript (genetic information) from mRNA into a specific sequence of amino acids in the growing chain of a polypeptide.
- The three general steps of translation are:
- Initiation
- Elongation
- Termination
Learn about the structure and functions of nucleic acids, including DNA and RNA, and their building blocks, nucleotides. Explore the components of nucleotides and their roles in cells and viruses.
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