IB Biology Topic D2.1.16 Consequences of Mutations in Genes That Control the Cell Cycle Revision Notes (HL)

IB Biology Topic D2.1.16 Consequences of Mutations in Genes That Control the Cell Cycle Revision Notes (HL) | RevisionDojo

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Mutations in Cell-Cycle Genes Remove the Controls on Division and Can Cause Cancer

Think of the cell cycle as a car with an accelerator that drives division forward and brakes that stop it.
If the accelerator jams on or the brakes fail, the car speeds out of control and crashes.
A mutation in a gene that controls the cell cycle does the same thing to a cell.
It removes the normal control on division, so the cell divides again and again in uncontrolled cell division.
This runaway growth builds a tumour and can lead to cancer.

Note

The detailed job of cyclins and CDKs in driving the cycle is covered in D2.1.15.
Here the focus is on what happens when the genes behind that control are damaged.

Proto-oncogenes Are the Accelerator, and a Mutation Jams It On

Definition

Proto-oncogenes

Proto-oncogenes are normal genes that act as the cell’s accelerator, promoting cell division when needed.

From Proto-oncogene to Oncogene

A proto-oncogene is a normal gene whose protein tells the cell when it is safe to divide.
When it mutates it becomes an oncogene, an overactive version that keeps pushing the cell to divide even when it should not.
A mutation in just one of the two gene copies is enough, so the oncogene acts in a dominant way.

How the Mutation Overactivates the Gene

Point mutation: a single base change makes the protein hyperactive.
Gene amplification: extra copies of the gene make far too much of the protein.
Chromosomal rearrangement: the gene is moved next to a strong promoter that switches it on too much.

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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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Mutations in Cell-Cycle Genes Remove the Controls on Division and Can Cause Cancer

Think of the cell cycle as a car with an accelerator that drives division forward and brakes that stop it.
If the accelerator jams on or the brakes fail, the car speeds out of control and crashes.
A mutation in a gene that controls the cell cycle does the same thing to a cell.
It removes the normal control on division, so the cell divides again and again in uncontrolled cell division.
This runaway growth builds a tumour and can lead to cancer.

Note

The detailed job of cyclins and CDKs in driving the cycle is covered in D2.1.15.
Here the focus is on what happens when the genes behind that control are damaged.

Proto-oncogenes Are the Accelerator, and a Mutation Jams It On

Definition

Proto-oncogenes

Proto-oncogenes are normal genes that act as the cell’s accelerator, promoting cell division when needed.

From Proto-oncogene to Oncogene

A proto-oncogene is a normal gene whose protein tells the cell when it is safe to divide.
When it mutates it becomes an oncogene, an overactive version that keeps pushing the cell to divide even when it should not.
A mutation in just one of the two gene copies is enough, so the oncogene acts in a dominant way.

How the Mutation Overactivates the Gene

Point mutation: a single base change makes the protein hyperactive.
Gene amplification: extra copies of the gene make far too much of the protein.
Chromosomal rearrangement: the gene is moved next to a strong promoter that switches it on too much.

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 D2.1.16: Consequences of Mutations in Genes That Control the Cell Cycle Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Mutations in Cell-Cycle Genes Remove the Controls on Division and Can Cause Cancer

Proto-oncogenes Are the Accelerator, and a Mutation Jams It On

From Proto-oncogene to Oncogene

How the Mutation Overactivates the Gene

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

Mutations in Cell-Cycle Genes Remove the Controls on Division and Can Cause Cancer

Proto-oncogenes Are the Accelerator, and a Mutation Jams It On

From Proto-oncogene to Oncogene

How the Mutation Overactivates the Gene

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