1.2.2

RNA

Test yourself on RNA

After reading these notes, test your knowledge with free interactive questions on Seneca — used by over 10 million students.

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.
Diagram
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 & miRNA

rRNA & miRNA

  • 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.
  • MicroRNAs (miRNAs) are the smallest RNA molecules and their role involves the regulation of gene expression by interfering with the expression of certain mRNA messages
Jump to other topics
1

Unity & Diversity - Molecules

1.1

Water

1.1.1Water & Hydrogen Bonding1.1.2IB Multiple Choice - Water & Hydrogen Bonding1.1.3Extended Response - Water
1.2

DNA Structure & Replication

1.2.1DNA1.2.2RNA1.2.3DNA Replication1.2.4DNA Replication - Summary1.2.5IB Multiple Choice - DNA Replication
1.3

Transcription & Gene Expression

1.3.1Introduction to Transcription & Protein Synthesis1.3.2Types of RNA1.3.3Transcription1.3.4RNA Processing in Eukaryotes1.3.5IB Multiple Choice - Transcription
1.4

Translation

1.4.1Translation1.4.2Retroviruses1.4.3Scientific Practices: Coronavirus1.4.4IB Multiple Choice - Translation
2

Unity & Diversity - Cells

2.1

The Origin of Cells

2.1.1Origins - Endosymbiosis
2.2

Introduction to Cells

2.2.1Introduction to Cells2.2.2Cell Size & Surface Area2.2.3Surface Area to Volume Ratio2.2.4Eukaryotic vs Prokaryotic Cells2.2.5Stem Cells2.2.6Stem Cells in Disease
2.3

Ultrastructure of Cells

2.3.1Golgi, Lysosomes & Ribosomes2.3.2Cell Walls & Vacuole2.3.3Prokaryotes2.3.4Binary Fission
2.4

Cell Division

2.4.1The Cell Cycle2.4.2Mitosis2.4.3Regulation of the Cell Cycle2.4.4End of Topic Quiz - The Cell Cycle2.4.5IB Multiple Choice - The Cell Cycle2.4.6Extended Response - Mitosis
2.5

Structure of DNA & RNA

2.5.1DNA & RNA
2.6

DNA Replication, Transcription & Translation

2.6.1Protein Synthesis2.6.2Transcription & Translation2.6.3End of Topic Test - DNA, Genes & Protein Synthesis2.6.4Exam-Style Question - Protein Synthesis2.6.5End of Topic Test - Coronavirus Translation2.6.6IB Multiple Choice - Transcription2.6.7IB Multiple Choice - Translation
2.7

Cell Respiration

2.7.1Overview of Respiration2.7.2Anaerobic Respiration2.7.3End of Topic Test - Anaerobic Respiration2.7.4Respiration Experiments2.7.5End of Topic Test - Respiration2.7.6IB Multiple Choice - Respiration
2.8

Photosynthesis

2.8.1Overview of Photosynthesis
2.9

Viruses

2.9.1Viruses
3

Unity & Diversity - Organisms

3.1

Diversity of Organisms

3.1.1Chromosomal Theory of Inheritance3.1.2Chromosomal Basis of Inherited Disorders3.1.3IB Multiple Choice - Chromosomal Inheritance
3.2

Evidence for Evolution

3.2.1Evidence for Evolution - Fossils & DNA3.2.2Evidence for Evolution - Anatomy & Geography3.2.3IB Multiple Choice - Evidence for Evolution3.2.4Extended Response - DNA & Evolution
3.3

Natural Selection

3.3.1Introduction3.3.2Evolutionary Fitness3.3.3Natural Selection & Variation3.3.4End of Topic Quiz - Natural Selection3.3.5IB Multiple Choice - Natural Selection3.3.6Speciation
4

Unity & Diversity - Ecosystems

4.1

Classification

4.1.1Introduction to Biodiversity4.1.2Keystone Species4.1.3Courtship & Ancestry4.1.4Classification
4.2

Cladistics

4.2.1Evolutionary Relationships4.2.2IB Multiple Choice - Species & Taxonomy
4.3

Evolution & Speciation

4.3.1Evidence for Evolution - Fossils & DNA4.3.2Evidence for Evolution - Anatomy & Geography4.3.3IB Multiple Choice - Evidence for Evolution4.3.4Extended Response - DNA & Evolution4.3.5Populations4.3.6Mutations, Genetic Drift, & Gene Flow4.3.7Speciation4.3.8Rate of Speciation4.3.9Allopatric & Sympatric Speciation
4.4

Conservation of Biodiversity

4.4.1Coming Soon!
5

Form & Function - Molecules

5.1

Carbohydrates & Lipids

5.1.1Monosaccharides5.1.2Disaccharides & Polysaccharides5.1.3Triglycerides & Phospholipids5.1.4Cellulose5.1.5Starch & Glycogen
5.2

Proteins

5.2.1Structure & Functions of Proteins
6

Form & Function - Cells

6.1

Membranes & Membrane Transport

6.1.1Passive Movement Across Membranes6.1.2Active Movement Across Membranes6.1.3Endocytosis & Exocystosis6.1.4Cell Membrane Structure & Permeability
6.2

Organelles & Compartmentalization

6.2.1Eukaryotic Cells & Organelles6.2.2Subcellular Components & Organelles
6.3

Cell Specialization

6.3.1Cell Specialization
7

Form & Function - Organisms

7.1

Gas Exchange

7.1.1Lung Structure & Alveoli7.1.2Ventilation7.1.3Lung Disease7.1.4Lung Disease Data
7.2

Transport

7.2.1The Circulatory System7.2.2The Heart7.2.3Blood Vessels7.2.4Cardiovascular Disease7.2.5Xylem Structure7.2.6Cohesion-Tension Theory7.2.7Investigating Transpiration Rate7.2.8Phloem Structure7.2.9Translocation
7.3

Muscle & Motility

7.3.1Skeletal Muscle7.3.2Sliding Filament Theory7.3.3Contraction
8

Form & Function - Ecosystems

8.1

Species, Communities & Ecosytems

8.1.1Population Dynamics8.1.2Communities & Measuring Diversity8.1.3Relationships Between Populations8.1.4Overview of Ecosystems8.1.5Nutrient Cycles8.1.6Fertilisers8.1.7Eutrophication8.1.8Chi-Squared Test
8.2

Energy Flow

8.2.1Energy8.2.2Energy Flow8.2.3Biomass & Food Chains8.2.4Heterotrophs & Autotrophs
8.3

Carbon Cycle

8.3.1Carbon Cycle
8.4

Climate Change

8.4.1Carbon Dioxide8.4.2The Greenhouse Effect8.4.3Global Warming8.4.4Maintaining Biodiversity
9

Interaction & Interdependence - Molecules

9.1

Enzymes

9.1.1Enzymes9.1.2Factors Affecting Enzyme Activity9.1.3Enzyme-Controlled Reactions9.1.4End of Topic Test - Enzymes
9.2

Metabolism

9.2.1Molecules to Metabolism
9.3

Cell Respiration

9.3.1Glycolysis9.3.2Aerobic Respiration
9.4

Photosynthesis

9.4.1Light-Dependent Reaction9.4.2Light-Independent Reaction9.4.3End of Topic Test - Photosynthesis Reactions9.4.4Limiting Factors9.4.5Photosynthesis Experiments9.4.6End of Topic Test - Photosynthesis9.4.7End of Topic Test - Photosynthesis
10

Interaction & Interdependence - Cells

10.1

Chemical Signalling

10.1.1Coming Soon!
10.2

Neural Signalling

10.2.1Medical Application10.2.2Speed of Transmission10.2.3Synapses10.2.4End of Topic Test - Nervous Comm&Coord10.2.5Neuron Structure10.2.6Types of Synapse10.2.7End of Topic Test - Neurones & Action Potentials10.2.8Transmission of an Impulse10.2.9End of Topic Test - Synapses
10.3

Adaptation to Environment

10.3.1Coming Soon!
10.4

Ecological Niches

10.4.1Coming Soon!
11

Interaction & Interdependence - Organisms

11.1

Integration of Body Systems

11.1.1Plant Tropisms
11.2

Defence Against Disease

11.2.1Immune System11.2.2The Immune Response11.2.3Antibodies11.2.4Primary & Secondary Response11.2.5Vaccines11.2.6HIV11.2.7End of Topic Test - Immune System
12

Interaction & Interdependence - Ecosystems

12.1

Populations & Communities

12.1.1Coming Soon!
12.2

Transfers of Energy & Matter

12.2.1Coming Soon!
13

Continuity & Change - Molecules

13.1

DNA Replication

13.1.1DNA Replication
13.2

Protein Synthesis

13.2.1Protein Synthesis13.2.2Transcription & Translation13.2.3End of Topic Test - DNA, Genes & Protein Synthesis
13.3

Mutation & Gene Editing

13.3.1Genes13.3.2Mutations13.3.3DNA Technology13.3.4PCR & Gel Electrophoresis13.3.5Genetic Modification13.3.6Cloning
14

Continuity & Change - Cells

14.1

Gene Expression

14.1.1Introduction to Transcription & Protein Synthesis14.1.2Types of RNA14.1.3Transcription14.1.4RNA Processing in Eukaryotes14.1.5IB Multiple Choice - Transcription
14.2

Water Potential

14.2.1Controlling Blood Water Potential
15

Continuity & Change - Organisms

15.1

Inheritance

15.1.1Non-Nuclear Inheritance15.1.2Linked Genes15.1.3IB Multiple Choice - Non-Mendelian Genetics15.1.4Extended Response - Inheritance15.1.5Introduction to Non-Mendelian Inheritance15.1.6Chi-Squared Test15.1.7End of Topic Quiz - Inheritance15.1.8Sex-Linked Genes15.1.9Grade 4-5 (Scientific Practices) - Inheritance
15.2

Homeostasis

15.2.1Overview of Homeostasis15.2.2Blood Glucose Concentration15.2.3Controlling Blood Glucose Concentration15.2.4End of Topic Test - Blood Glucose15.2.5Type I & Type II Diabetes15.2.6Human Reproductive Systems15.2.7Hormonal Control of the Menstrual Cycle15.2.8Kidneys & Osmoregulation
16

Continuity & Change - Ecosystems

16.1

Natural Selection

16.1.1Natural Selection
16.2

Stability & Change

16.2.1Coming Soon!
16.3

Climate Change

16.3.1Carbon Dioxide16.3.2The Greenhouse Effect16.3.3Global Warming16.3.4Maintaining Biodiversity

Practice questions on RNA

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

  1. 1
    Which of these statements correctly describes an RNA molecule?Multiple choice
Answer all questions on RNA

Unlock your full potential with Seneca Premium

  • Unlimited access to 10,000+ open-ended exam questions

  • Mini-mock exams based on your study history

  • Unlock 800+ premium courses & e-books

Get started with Seneca Premium

DNA

DNA Replication