SlideShare ist ein Scribd-Unternehmen logo
1 von 17
Downloaden Sie, um offline zu lesen
What is RNA splicing?
Genetic information is transferred from genes to the
proteins they encode via a “messenger” RNA intermediate
DNA GENE
messenger RNA
(mRNA)
protein
transcription
translation
Most genes have their protein-coding information interrupted
by non-coding sequences called “introns”. The coding sequences
are then called “exons”
DNA GE NE
intron
exon 1 exon 2
transcription
precursor-mRNA
(pre-mRNA)
intron
The intron is also present in the RNA copy of the gene and
must be removed by a process called “RNA splicing”
protein
translation
mRNA
RNA splicing
pre-mRNA
intron
Splicing a pre-mRNA involves two reactions
pre-mRNA
intron branchpoint
A
spliced mRNA
Step 2
intermediates
Step 1
A
Splicing occurs in a “spliceosome”
an RNA-protein complex
(simplified)
pre-mRNA spliced mRNA
spliceosome
(~100 proteins + 5 small RNAs)
Splicing works similarly in different organisms, for
example in yeast, flies, worms, plants and animals.
RNA is produced in the nucleus of the cell. The
mRNA has to be transported to the cytoplasm to
produce proteins
Ribosomes are RNA-protein machines that make
proteins, translating the coding information in the
mRNA
Pre-messenger RNA Processing
cytoplasm
nucleus
mRNA
RNA splicing
M7G AAAAAAA200
pre-mRNA
intron
exon exon
AAAAAAA200
M7G
transport
M7G AAAAAAA200
ribosomes
protein
cap poly(A) tail
Alternative splicing
In humans, many genes contain multiple introns
3 4 5
1 2
1 2 3 5
4
intron 2 intron 3 intron 4
intron 1
Usually all introns must be removed before the
mRNA can be translated to produce protein
However, multiple introns may be spliced differently in
different circumstances, for example in different
tissues.
1 2 3 5
Heart muscle mRNA
1 4
3 5
Uterine muscle mRNA
Thus one gene can encode more than one protein. The proteins are
similar but not identical and may have distinct properties. This is
important in complex organisms
3 5
4
2
1
pre-mRNA
Different signals in the pre-mRNA and different proteins
cause spliceosomes to form in particular positions to give
alternative splicing
7
6
5
7
5
6
5 7
Fas pre-mRNA
APOPTOSIS
Alternative splicing can generate mRNAs encoding proteins with
different, even opposite functions
(programmed
cell death)
Fas ligand
Soluble Fas
(membrane)
Fas
Fas ligand
(membrane-
associated)
(+)
(-)
Alternative splicing can generate tens of thousands of mRNAs
from a single primary transcript
12 48 33 2
Combinatorial selection of one exon at each of four variable regions generates more than
38,000 different mRNAs and proteins in the Drosophila cell adhesion molecule Dscam
The protein variants are important for wiring of the nervous system and for immune response
protein
mRNA
pre-mRNA
The Genetic Code
• Describes how nucleotide sequence is
converted to protein sequence
• Unit of three nucleotides = a codon
• A codon codes for a specific amino
acid (structural component of protein)
• The four bases can
form 64 different
codons
• 20 amino acids are
found from the
nature
• Regulatory codons
The Nature of the Genetic Code
• A group of three bases codes for one amino
acid
• The code is not overlapping
• The base sequence is read from a fixed
starting point, with no punctuation
• The code is degenerate (in most cases, each
amino acid can be designated by any of
several triplets
Features of the Genetic Code
• All the codons have meaning: 61 specify amino acids,
and the other 3 are "nonsense" or "stop" codons
• The code is unambiguous - only one amino acid is
indicated by each of the 61 codons
• The code is degenerate - except for Trp and Met, each
amino acid is coded by two or more codons
• Codons representing the same or similar amino acids
are similar in sequence

Weitere ähnliche Inhalte

Ähnlich wie 6-splicing-1-1.ppt

Ähnlich wie 6-splicing-1-1.ppt (20)

POST TRANSCRIPTIONAL MODOFICATION.pptx
POST TRANSCRIPTIONAL MODOFICATION.pptxPOST TRANSCRIPTIONAL MODOFICATION.pptx
POST TRANSCRIPTIONAL MODOFICATION.pptx
 
11 transcription
11 transcription11 transcription
11 transcription
 
protein synthesis
protein synthesisprotein synthesis
protein synthesis
 
Dna and protein synthesis
Dna and protein synthesisDna and protein synthesis
Dna and protein synthesis
 
Protein synthesis
Protein synthesis Protein synthesis
Protein synthesis
 
Mol genet-8. transkripsi2
Mol genet-8. transkripsi2Mol genet-8. transkripsi2
Mol genet-8. transkripsi2
 
Wtk apbi och17genetoprotein
Wtk apbi och17genetoproteinWtk apbi och17genetoprotein
Wtk apbi och17genetoprotein
 
Genetics
GeneticsGenetics
Genetics
 
4,transcription
4,transcription4,transcription
4,transcription
 
Biology notes-dna-and-protein-synthesis
Biology notes-dna-and-protein-synthesisBiology notes-dna-and-protein-synthesis
Biology notes-dna-and-protein-synthesis
 
IB Biology 2.7 Slides: Transcription & Translation
IB Biology 2.7 Slides: Transcription & TranslationIB Biology 2.7 Slides: Transcription & Translation
IB Biology 2.7 Slides: Transcription & Translation
 
Gene Expression_AA1.ppt
Gene Expression_AA1.pptGene Expression_AA1.ppt
Gene Expression_AA1.ppt
 
GENETIC EXPRESSION TRANSCRIPTION.pptx
GENETIC EXPRESSION TRANSCRIPTION.pptxGENETIC EXPRESSION TRANSCRIPTION.pptx
GENETIC EXPRESSION TRANSCRIPTION.pptx
 
Molecular Genetics Part II
Molecular Genetics Part IIMolecular Genetics Part II
Molecular Genetics Part II
 
BiologyExchange.co.uk Shared Resource
BiologyExchange.co.uk Shared ResourceBiologyExchange.co.uk Shared Resource
BiologyExchange.co.uk Shared Resource
 
Central Dogma of Life
Central Dogma of LifeCentral Dogma of Life
Central Dogma of Life
 
protein-synthesis.ppt
protein-synthesis.pptprotein-synthesis.ppt
protein-synthesis.ppt
 
Role of DNA and RNA in Protein Synthesis
Role of DNA and RNA in Protein SynthesisRole of DNA and RNA in Protein Synthesis
Role of DNA and RNA in Protein Synthesis
 
Unit 1 transcription
Unit 1 transcriptionUnit 1 transcription
Unit 1 transcription
 
Gene expression slide
Gene expression slideGene expression slide
Gene expression slide
 

Kürzlich hochgeladen

Role of Gibberellins, mode of action and external applications.pptx
Role of Gibberellins, mode of action and external applications.pptxRole of Gibberellins, mode of action and external applications.pptx
Role of Gibberellins, mode of action and external applications.pptxjana861314
 
Efficient Fourier Pricing of Multi-Asset Options: Quasi-Monte Carlo & Domain ...
Efficient Fourier Pricing of Multi-Asset Options: Quasi-Monte Carlo & Domain ...Efficient Fourier Pricing of Multi-Asset Options: Quasi-Monte Carlo & Domain ...
Efficient Fourier Pricing of Multi-Asset Options: Quasi-Monte Carlo & Domain ...Chiheb Ben Hammouda
 
Timeless Cosmology: Towards a Geometric Origin of Cosmological Correlations
Timeless Cosmology: Towards a Geometric Origin of Cosmological CorrelationsTimeless Cosmology: Towards a Geometric Origin of Cosmological Correlations
Timeless Cosmology: Towards a Geometric Origin of Cosmological CorrelationsDanielBaumann11
 
AICTE activity on Water Conservation spreading awareness
AICTE activity on Water Conservation spreading awarenessAICTE activity on Water Conservation spreading awareness
AICTE activity on Water Conservation spreading awareness1hk20is002
 
Production technology of Brinjal -Solanum melongena
Production technology of Brinjal -Solanum melongenaProduction technology of Brinjal -Solanum melongena
Production technology of Brinjal -Solanum melongenajana861314
 
Interpreting SDSS extragalactic data in the era of JWST
Interpreting SDSS extragalactic data in the era of JWSTInterpreting SDSS extragalactic data in the era of JWST
Interpreting SDSS extragalactic data in the era of JWSTAlexander F. Mayer
 
STELLAR SYSTEM IN PTERIDOPHYTE Seminar 2023- By Karishma
STELLAR SYSTEM IN PTERIDOPHYTE Seminar 2023- By KarishmaSTELLAR SYSTEM IN PTERIDOPHYTE Seminar 2023- By Karishma
STELLAR SYSTEM IN PTERIDOPHYTE Seminar 2023- By KarishmaAMiracle3
 
Rabies ,a deadly viral disease transmitted by the most beautiful beings. by ...
Rabies ,a deadly viral disease transmitted by the most beautiful beings.  by ...Rabies ,a deadly viral disease transmitted by the most beautiful beings.  by ...
Rabies ,a deadly viral disease transmitted by the most beautiful beings. by ...uzmashireenmbe01
 
FBI Profiling - Forensic Psychology.pptx
FBI Profiling - Forensic Psychology.pptxFBI Profiling - Forensic Psychology.pptx
FBI Profiling - Forensic Psychology.pptxPayal Shrivastava
 
DETECTION OF MUTATION BY CLB METHOD.pptx
DETECTION OF MUTATION BY CLB METHOD.pptxDETECTION OF MUTATION BY CLB METHOD.pptx
DETECTION OF MUTATION BY CLB METHOD.pptx201bo007
 
Total Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of CannabinoidsTotal Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of CannabinoidsMarkus Roggen
 
6.2 Pests of Sesame_Identification_Binomics_Dr.UPR
6.2 Pests of Sesame_Identification_Binomics_Dr.UPR6.2 Pests of Sesame_Identification_Binomics_Dr.UPR
6.2 Pests of Sesame_Identification_Binomics_Dr.UPRPirithiRaju
 
Science (Communication) and Wikipedia - Potentials and Pitfalls
Science (Communication) and Wikipedia - Potentials and PitfallsScience (Communication) and Wikipedia - Potentials and Pitfalls
Science (Communication) and Wikipedia - Potentials and PitfallsDobusch Leonhard
 
DNA isolation molecular biology practical.pptx
DNA isolation molecular biology practical.pptxDNA isolation molecular biology practical.pptx
DNA isolation molecular biology practical.pptxGiDMOh
 
Advances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of CancerAdvances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of CancerLuis Miguel Chong Chong
 
Think Science: What Are Eclipses, by Craig Bobchin
Think Science: What Are Eclipses, by Craig BobchinThink Science: What Are Eclipses, by Craig Bobchin
Think Science: What Are Eclipses, by Craig BobchinNathan Cone
 
𝗧𝗖𝗢 (𝙩𝙧𝙖𝙣𝙨-𝗰𝘆𝗰𝗹𝗼𝗼𝗰𝘁𝗲𝗻𝗲) 𝗗𝗲𝗿𝗶𝘃𝗮𝘁𝗶𝘃𝗲𝘀: 𝗧𝗵𝗲 𝗙𝗮𝘀𝘁𝗲𝘀𝘁 𝗖𝗹𝗶𝗰𝗸 𝗥𝗲𝗮𝗰𝘁𝗶𝗼𝗻 𝗥𝗲𝗮𝗴𝗲𝗻𝘁𝘀
𝗧𝗖𝗢 (𝙩𝙧𝙖𝙣𝙨-𝗰𝘆𝗰𝗹𝗼𝗼𝗰𝘁𝗲𝗻𝗲) 𝗗𝗲𝗿𝗶𝘃𝗮𝘁𝗶𝘃𝗲𝘀: 𝗧𝗵𝗲 𝗙𝗮𝘀𝘁𝗲𝘀𝘁 𝗖𝗹𝗶𝗰𝗸 𝗥𝗲𝗮𝗰𝘁𝗶𝗼𝗻 𝗥𝗲𝗮𝗴𝗲𝗻𝘁𝘀𝗧𝗖𝗢 (𝙩𝙧𝙖𝙣𝙨-𝗰𝘆𝗰𝗹𝗼𝗼𝗰𝘁𝗲𝗻𝗲) 𝗗𝗲𝗿𝗶𝘃𝗮𝘁𝗶𝘃𝗲𝘀: 𝗧𝗵𝗲 𝗙𝗮𝘀𝘁𝗲𝘀𝘁 𝗖𝗹𝗶𝗰𝗸 𝗥𝗲𝗮𝗰𝘁𝗶𝗼𝗻 𝗥𝗲𝗮𝗴𝗲𝗻𝘁𝘀
𝗧𝗖𝗢 (𝙩𝙧𝙖𝙣𝙨-𝗰𝘆𝗰𝗹𝗼𝗼𝗰𝘁𝗲𝗻𝗲) 𝗗𝗲𝗿𝗶𝘃𝗮𝘁𝗶𝘃𝗲𝘀: 𝗧𝗵𝗲 𝗙𝗮𝘀𝘁𝗲𝘀𝘁 𝗖𝗹𝗶𝗰𝗸 𝗥𝗲𝗮𝗰𝘁𝗶𝗼𝗻 𝗥𝗲𝗮𝗴𝗲𝗻𝘁𝘀Tokyo Chemicals Industry (TCI)
 
Loudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxLoudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxpriyankatabhane
 

Kürzlich hochgeladen (20)

Role of Gibberellins, mode of action and external applications.pptx
Role of Gibberellins, mode of action and external applications.pptxRole of Gibberellins, mode of action and external applications.pptx
Role of Gibberellins, mode of action and external applications.pptx
 
Efficient Fourier Pricing of Multi-Asset Options: Quasi-Monte Carlo & Domain ...
Efficient Fourier Pricing of Multi-Asset Options: Quasi-Monte Carlo & Domain ...Efficient Fourier Pricing of Multi-Asset Options: Quasi-Monte Carlo & Domain ...
Efficient Fourier Pricing of Multi-Asset Options: Quasi-Monte Carlo & Domain ...
 
Timeless Cosmology: Towards a Geometric Origin of Cosmological Correlations
Timeless Cosmology: Towards a Geometric Origin of Cosmological CorrelationsTimeless Cosmology: Towards a Geometric Origin of Cosmological Correlations
Timeless Cosmology: Towards a Geometric Origin of Cosmological Correlations
 
AICTE activity on Water Conservation spreading awareness
AICTE activity on Water Conservation spreading awarenessAICTE activity on Water Conservation spreading awareness
AICTE activity on Water Conservation spreading awareness
 
Production technology of Brinjal -Solanum melongena
Production technology of Brinjal -Solanum melongenaProduction technology of Brinjal -Solanum melongena
Production technology of Brinjal -Solanum melongena
 
Interpreting SDSS extragalactic data in the era of JWST
Interpreting SDSS extragalactic data in the era of JWSTInterpreting SDSS extragalactic data in the era of JWST
Interpreting SDSS extragalactic data in the era of JWST
 
STELLAR SYSTEM IN PTERIDOPHYTE Seminar 2023- By Karishma
STELLAR SYSTEM IN PTERIDOPHYTE Seminar 2023- By KarishmaSTELLAR SYSTEM IN PTERIDOPHYTE Seminar 2023- By Karishma
STELLAR SYSTEM IN PTERIDOPHYTE Seminar 2023- By Karishma
 
Rabies ,a deadly viral disease transmitted by the most beautiful beings. by ...
Rabies ,a deadly viral disease transmitted by the most beautiful beings.  by ...Rabies ,a deadly viral disease transmitted by the most beautiful beings.  by ...
Rabies ,a deadly viral disease transmitted by the most beautiful beings. by ...
 
FBI Profiling - Forensic Psychology.pptx
FBI Profiling - Forensic Psychology.pptxFBI Profiling - Forensic Psychology.pptx
FBI Profiling - Forensic Psychology.pptx
 
Battery Reasearch Reagents from TCI Chemicals
Battery Reasearch Reagents from TCI ChemicalsBattery Reasearch Reagents from TCI Chemicals
Battery Reasearch Reagents from TCI Chemicals
 
DETECTION OF MUTATION BY CLB METHOD.pptx
DETECTION OF MUTATION BY CLB METHOD.pptxDETECTION OF MUTATION BY CLB METHOD.pptx
DETECTION OF MUTATION BY CLB METHOD.pptx
 
Total Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of CannabinoidsTotal Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of Cannabinoids
 
6.2 Pests of Sesame_Identification_Binomics_Dr.UPR
6.2 Pests of Sesame_Identification_Binomics_Dr.UPR6.2 Pests of Sesame_Identification_Binomics_Dr.UPR
6.2 Pests of Sesame_Identification_Binomics_Dr.UPR
 
Science (Communication) and Wikipedia - Potentials and Pitfalls
Science (Communication) and Wikipedia - Potentials and PitfallsScience (Communication) and Wikipedia - Potentials and Pitfalls
Science (Communication) and Wikipedia - Potentials and Pitfalls
 
DNA isolation molecular biology practical.pptx
DNA isolation molecular biology practical.pptxDNA isolation molecular biology practical.pptx
DNA isolation molecular biology practical.pptx
 
Bioenergetics and the role of ATP to drive the beats of life.
Bioenergetics and the role of ATP to drive the beats of life.Bioenergetics and the role of ATP to drive the beats of life.
Bioenergetics and the role of ATP to drive the beats of life.
 
Advances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of CancerAdvances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of Cancer
 
Think Science: What Are Eclipses, by Craig Bobchin
Think Science: What Are Eclipses, by Craig BobchinThink Science: What Are Eclipses, by Craig Bobchin
Think Science: What Are Eclipses, by Craig Bobchin
 
𝗧𝗖𝗢 (𝙩𝙧𝙖𝙣𝙨-𝗰𝘆𝗰𝗹𝗼𝗼𝗰𝘁𝗲𝗻𝗲) 𝗗𝗲𝗿𝗶𝘃𝗮𝘁𝗶𝘃𝗲𝘀: 𝗧𝗵𝗲 𝗙𝗮𝘀𝘁𝗲𝘀𝘁 𝗖𝗹𝗶𝗰𝗸 𝗥𝗲𝗮𝗰𝘁𝗶𝗼𝗻 𝗥𝗲𝗮𝗴𝗲𝗻𝘁𝘀
𝗧𝗖𝗢 (𝙩𝙧𝙖𝙣𝙨-𝗰𝘆𝗰𝗹𝗼𝗼𝗰𝘁𝗲𝗻𝗲) 𝗗𝗲𝗿𝗶𝘃𝗮𝘁𝗶𝘃𝗲𝘀: 𝗧𝗵𝗲 𝗙𝗮𝘀𝘁𝗲𝘀𝘁 𝗖𝗹𝗶𝗰𝗸 𝗥𝗲𝗮𝗰𝘁𝗶𝗼𝗻 𝗥𝗲𝗮𝗴𝗲𝗻𝘁𝘀𝗧𝗖𝗢 (𝙩𝙧𝙖𝙣𝙨-𝗰𝘆𝗰𝗹𝗼𝗼𝗰𝘁𝗲𝗻𝗲) 𝗗𝗲𝗿𝗶𝘃𝗮𝘁𝗶𝘃𝗲𝘀: 𝗧𝗵𝗲 𝗙𝗮𝘀𝘁𝗲𝘀𝘁 𝗖𝗹𝗶𝗰𝗸 𝗥𝗲𝗮𝗰𝘁𝗶𝗼𝗻 𝗥𝗲𝗮𝗴𝗲𝗻𝘁𝘀
𝗧𝗖𝗢 (𝙩𝙧𝙖𝙣𝙨-𝗰𝘆𝗰𝗹𝗼𝗼𝗰𝘁𝗲𝗻𝗲) 𝗗𝗲𝗿𝗶𝘃𝗮𝘁𝗶𝘃𝗲𝘀: 𝗧𝗵𝗲 𝗙𝗮𝘀𝘁𝗲𝘀𝘁 𝗖𝗹𝗶𝗰𝗸 𝗥𝗲𝗮𝗰𝘁𝗶𝗼𝗻 𝗥𝗲𝗮𝗴𝗲𝗻𝘁𝘀
 
Loudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxLoudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptx
 

6-splicing-1-1.ppt

  • 1. What is RNA splicing?
  • 2. Genetic information is transferred from genes to the proteins they encode via a “messenger” RNA intermediate DNA GENE messenger RNA (mRNA) protein transcription translation
  • 3. Most genes have their protein-coding information interrupted by non-coding sequences called “introns”. The coding sequences are then called “exons” DNA GE NE intron exon 1 exon 2 transcription precursor-mRNA (pre-mRNA) intron
  • 4. The intron is also present in the RNA copy of the gene and must be removed by a process called “RNA splicing” protein translation mRNA RNA splicing pre-mRNA intron
  • 5. Splicing a pre-mRNA involves two reactions pre-mRNA intron branchpoint A spliced mRNA Step 2 intermediates Step 1 A
  • 6. Splicing occurs in a “spliceosome” an RNA-protein complex (simplified) pre-mRNA spliced mRNA spliceosome (~100 proteins + 5 small RNAs) Splicing works similarly in different organisms, for example in yeast, flies, worms, plants and animals.
  • 7. RNA is produced in the nucleus of the cell. The mRNA has to be transported to the cytoplasm to produce proteins Ribosomes are RNA-protein machines that make proteins, translating the coding information in the mRNA
  • 8. Pre-messenger RNA Processing cytoplasm nucleus mRNA RNA splicing M7G AAAAAAA200 pre-mRNA intron exon exon AAAAAAA200 M7G transport M7G AAAAAAA200 ribosomes protein cap poly(A) tail
  • 9. Alternative splicing In humans, many genes contain multiple introns 3 4 5 1 2 1 2 3 5 4 intron 2 intron 3 intron 4 intron 1 Usually all introns must be removed before the mRNA can be translated to produce protein
  • 10. However, multiple introns may be spliced differently in different circumstances, for example in different tissues. 1 2 3 5 Heart muscle mRNA 1 4 3 5 Uterine muscle mRNA Thus one gene can encode more than one protein. The proteins are similar but not identical and may have distinct properties. This is important in complex organisms 3 5 4 2 1 pre-mRNA
  • 11. Different signals in the pre-mRNA and different proteins cause spliceosomes to form in particular positions to give alternative splicing
  • 12. 7 6 5 7 5 6 5 7 Fas pre-mRNA APOPTOSIS Alternative splicing can generate mRNAs encoding proteins with different, even opposite functions (programmed cell death) Fas ligand Soluble Fas (membrane) Fas Fas ligand (membrane- associated) (+) (-)
  • 13. Alternative splicing can generate tens of thousands of mRNAs from a single primary transcript 12 48 33 2 Combinatorial selection of one exon at each of four variable regions generates more than 38,000 different mRNAs and proteins in the Drosophila cell adhesion molecule Dscam The protein variants are important for wiring of the nervous system and for immune response protein mRNA pre-mRNA
  • 14. The Genetic Code • Describes how nucleotide sequence is converted to protein sequence • Unit of three nucleotides = a codon • A codon codes for a specific amino acid (structural component of protein)
  • 15. • The four bases can form 64 different codons • 20 amino acids are found from the nature • Regulatory codons
  • 16. The Nature of the Genetic Code • A group of three bases codes for one amino acid • The code is not overlapping • The base sequence is read from a fixed starting point, with no punctuation • The code is degenerate (in most cases, each amino acid can be designated by any of several triplets
  • 17. Features of the Genetic Code • All the codons have meaning: 61 specify amino acids, and the other 3 are "nonsense" or "stop" codons • The code is unambiguous - only one amino acid is indicated by each of the 61 codons • The code is degenerate - except for Trp and Met, each amino acid is coded by two or more codons • Codons representing the same or similar amino acids are similar in sequence