6.1.7
RNA
Structure of RNA
Structure of RNA
RNA is usually single-stranded and is made of ribonucleotides that are linked by phosphodiester bonds.


RNA
RNA
- A ribonucleotide in the RNA chain contains ribose (the pentose sugar), one of the four nitrogenous bases (A, U, G, and C), and the phosphate group.
- Uracil (U) is a nucleotide only found in RNA. It replaces thymine and pairs with adenine.
- Uracil is a pyrimidine nucleotide.
- RNA base sequences are complementary to the DNA's coding sequence from which it has been copied.
- If the DNA strand has a sequence AATTGCGC, the sequence of the complementary RNA is UUAACGCG.




Uracil
Uracil
- Uracil is a pyrimidine nucleotide found only in RNA. It takes the place of the DNA nucleotide thymine.
- The RNA base sequence is complementary to the DNA's coding sequence from which it has been copied.
- If the DNA strand has a sequence AATTGCGC, the sequence of the complementary RNA is UUAACGCG.


Types of RNA
Types of RNA
- Ribonucleic acid, or RNA, is mainly involved in the process of protein synthesis under the direction of DNA.
- RNA is usually single-stranded and is made of ribonucleotides that are linked by phosphodiester bonds.
- There are four major types of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), and microRNA (miRNA).


mRNA
mRNA
- Messenger RNA (mRNA) carries messages from DNA, which controls all of the cellular activities in a cell.
- The sequence of nucleotides in mRNA encodes biological information.
- The RNA base sequence is complementary to the coding sequence of the DNA from which it has been copied.
- However, in RNA, the base T is absent and U is present instead.
- The mRNA is read in sets of three bases known as codons.
- Each codon codes for a single amino acid. In this way, the mRNA is read and the protein product is made.


tRNA
tRNA
- Transfer RNA (tRNA) is one of the smallest of the four types of RNA, usually 70–90 nucleotides long.
- It carries the correct amino acid to the site of protein synthesis.
- It is the base pairing between the tRNA and mRNA that allows for the correct amino acid to be inserted in the polypeptide chain.
- It has an anticodon, which is complementary to the mRNA codon.


rRNA
rRNA
- Ribosomal RNA (rRNA) is a major constituent of ribosomes on which the mRNA binds.
- The rRNA ensures the proper alignment of the mRNA and the ribosomes; the rRNA of the ribosome also has an enzymatic activity (peptidyl transferase) and catalyzes the formation of the peptide bonds between two aligned amino acids.
1Cell Structure
1.1Cell Structure
1.1.1Studying Cells - Microscopes
1.1.2Introduction to Eukaryotic & Prokaryotic Cells
1.1.3Ultrastructure of Eukaryotic Cells
1.1.4Ultrastructure of Eukaryotic Cells 2
1.1.5Ultrastructure of Eukaryotic Cells 3
1.1.6Prokaryotic Cells
1.1.7Viruses
1.1.8End of Topic Test - Cell Structure
1.1.9Exam-Style Question - Microscopes
1.1.10A-A* (AO2/3) - Cell Structure
2Biological Molecules
2.1Testing for Biological Modules
2.2Carbohydrates & Lipids
2.3Proteins
3Enzymes
4Cell Membranes & Transport
4.1Biological Membranes
5The Mitotic Cell Cycle
6Nucleic Acids & Protein Synthesis
6.1Nucleic Acids
7Transport in Plants
8Transport in Mammals
8.1Circulatory System
8.2Transport of Oxygen & Carbon Dioxide
9Gas Exchange
9.1Gas Exchange System
10Infectious Diseases
10.1Infectious Diseases
10.2Antibiotics
11Immunity
12Energy & Respiration (A2 Only)
13Photosynthesis (A2 Only)
14Homeostasis (A2 Only)
14.1Homeostasis
14.2The Kidney
14.3Cell Signalling
14.4Blood Glucose Concentration
14.5Homeostasis in Plants
15Control & Coordination (A2 Only)
15.1Control & Coordination in Mammals
15.1.1Neurones
15.1.2Receptors
15.1.3Taste
15.1.4Reflexes
15.1.5Action Potentials
15.1.6Saltatory Conduction
15.1.7Synapses
15.1.8Cholinergic Synnapses
15.1.9Neuromuscular Junction
15.1.10Skeletal Muscle
15.1.11Sliding Filament Theory Contraction
15.1.12Sliding Filament Theory Contraction 2
15.1.13Menstruation
15.1.14Contraceptive Pill
15.2Control & Co-Ordination in Plants
16Inherited Change (A2 Only)
16.1Passage of Information to Offspring
16.2Genes & Phenotype
17Selection & Evolution (A2 Only)
17.2Natural & Artificial Selection
18Classification & Conservation (A2 Only)
18.1Biodiversity
18.2Classification
19Genetic Technology (A2 Only)
19.1Manipulating Genomes
19.2Genetic Technology Applied to Medicine
19.3Genetically Modified Organisms in Agriculture
Jump to other topics
1Cell Structure
1.1Cell Structure
1.1.1Studying Cells - Microscopes
1.1.2Introduction to Eukaryotic & Prokaryotic Cells
1.1.3Ultrastructure of Eukaryotic Cells
1.1.4Ultrastructure of Eukaryotic Cells 2
1.1.5Ultrastructure of Eukaryotic Cells 3
1.1.6Prokaryotic Cells
1.1.7Viruses
1.1.8End of Topic Test - Cell Structure
1.1.9Exam-Style Question - Microscopes
1.1.10A-A* (AO2/3) - Cell Structure
2Biological Molecules
2.1Testing for Biological Modules
2.2Carbohydrates & Lipids
2.3Proteins
3Enzymes
4Cell Membranes & Transport
4.1Biological Membranes
5The Mitotic Cell Cycle
6Nucleic Acids & Protein Synthesis
6.1Nucleic Acids
7Transport in Plants
8Transport in Mammals
8.1Circulatory System
8.2Transport of Oxygen & Carbon Dioxide
9Gas Exchange
9.1Gas Exchange System
10Infectious Diseases
10.1Infectious Diseases
10.2Antibiotics
11Immunity
12Energy & Respiration (A2 Only)
13Photosynthesis (A2 Only)
14Homeostasis (A2 Only)
14.1Homeostasis
14.2The Kidney
14.3Cell Signalling
14.4Blood Glucose Concentration
14.5Homeostasis in Plants
15Control & Coordination (A2 Only)
15.1Control & Coordination in Mammals
15.1.1Neurones
15.1.2Receptors
15.1.3Taste
15.1.4Reflexes
15.1.5Action Potentials
15.1.6Saltatory Conduction
15.1.7Synapses
15.1.8Cholinergic Synnapses
15.1.9Neuromuscular Junction
15.1.10Skeletal Muscle
15.1.11Sliding Filament Theory Contraction
15.1.12Sliding Filament Theory Contraction 2
15.1.13Menstruation
15.1.14Contraceptive Pill
15.2Control & Co-Ordination in Plants
16Inherited Change (A2 Only)
16.1Passage of Information to Offspring
16.2Genes & Phenotype
17Selection & Evolution (A2 Only)
17.2Natural & Artificial Selection
18Classification & Conservation (A2 Only)
18.1Biodiversity
18.2Classification
19Genetic Technology (A2 Only)
19.1Manipulating Genomes
19.2Genetic Technology Applied to Medicine
19.3Genetically Modified Organisms in Agriculture
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