IB Biology Topic D1.2.14 Non-coding Sequences in DNA Do Not Code for Polypeptides Revision Notes (HL)

IB Biology Topic D1.2.14 Non-coding Sequences in DNA Do Not Code for Polypeptides Revision Notes (HL) | RevisionDojo

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Most of Your DNA Does Not Code for Polypeptides, Yet It Is Far From Junk

Most of the genome is non-coding DNA, meaning it is not translated into polypeptides.
These sequences still carry out essential functions in gene expression, chromosome stability, and protein synthesis.
1. Calling them "junk DNA" is misleading, because losing them would disrupt how cells build and control proteins.

Note

Non-coding DNA is any region of the genome that is not translated into a polypeptide.
It includes regulators of gene expression, introns, telomeres, and the genes for rRNA and tRNA.

Regulatory Sequences Control When and How Strongly Genes Are Expressed

Regulatory sequences are non-coding DNA that switch genes on or off and tune their output.
Promoters
1. These are the sites where RNA polymerase binds to begin transcription.
Enhancers
1. These distant sequences increase transcription of a gene.
Silencers
1. These sequences decrease or shut down transcription of a gene.

Note

How promoters and enhancers drive transcription initiation is covered in detail in D1.2.13.
Regulatory sequences are often highly conserved across species, which signals their importance.

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Most of Your DNA Does Not Code for Polypeptides, Yet It Is Far From Junk

Most of the genome is non-coding DNA, meaning it is not translated into polypeptides.
These sequences still carry out essential functions in gene expression, chromosome stability, and protein synthesis.
1. Calling them "junk DNA" is misleading, because losing them would disrupt how cells build and control proteins.

Note

Non-coding DNA is any region of the genome that is not translated into a polypeptide.
It includes regulators of gene expression, introns, telomeres, and the genes for rRNA and tRNA.

Regulatory Sequences Control When and How Strongly Genes Are Expressed

Regulatory sequences are non-coding DNA that switch genes on or off and tune their output.
Promoters
1. These are the sites where RNA polymerase binds to begin transcription.
Enhancers
1. These distant sequences increase transcription of a gene.
Silencers
1. These sequences decrease or shut down transcription of a gene.

Note

How promoters and enhancers drive transcription initiation is covered in detail in D1.2.13.
Regulatory sequences are often highly conserved across species, which signals their importance.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic D1.2.14: Non-coding Sequences in DNA Do Not Code for Polypeptides Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Most of Your DNA Does Not Code for Polypeptides, Yet It Is Far From Junk

Regulatory Sequences Control When and How Strongly Genes Are Expressed

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Most of Your DNA Does Not Code for Polypeptides, Yet It Is Far From Junk

Regulatory Sequences Control When and How Strongly Genes Are Expressed

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account