IB Biology Topic D2.2.10 Monozygotic Twin Studies Revision Notes (HL)

IB Biology Topic D2.2.10 Monozygotic Twin Studies Revision Notes (HL) | RevisionDojo

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Identical Twins Are a Natural Experiment for Separating Genes From Environment

Definition

Monozygotic twins

Monozygotic twins (identical twins) arise when a single fertilized egg splits into two embryos.

Monozygotic twins share essentially 100% of their DNA, so any differences between them cannot be caused by their genes.
This lets researchers isolate environmental effects from genetic ones, treating the twin pair as a built-in control.
When twins differ in a trait, the difference points to environmental or epigenetic influence on gene expression rather than to a different genome.

Analogy

Identical twins are like two copies of the same recipe cooked in different kitchens.
Because the recipe is fixed, any difference in the final dish must come from the kitchen, not the ingredients list.

Discordance Between Twins Grows as Their Environments Diverge

Studies compare concordance rates, the frequency with which both twins share a trait or condition.
High concordance suggests a strong genetic contribution to the trait.

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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 nisi ut aliquip ex ea commodo consequat.

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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Identical Twins Are a Natural Experiment for Separating Genes From Environment

Definition

Monozygotic twins

Monozygotic twins (identical twins) arise when a single fertilized egg splits into two embryos.

Monozygotic twins share essentially 100% of their DNA, so any differences between them cannot be caused by their genes.
This lets researchers isolate environmental effects from genetic ones, treating the twin pair as a built-in control.
When twins differ in a trait, the difference points to environmental or epigenetic influence on gene expression rather than to a different genome.

Analogy

Identical twins are like two copies of the same recipe cooked in different kitchens.
Because the recipe is fixed, any difference in the final dish must come from the kitchen, not the ingredients list.

Discordance Between Twins Grows as Their Environments Diverge

Studies compare concordance rates, the frequency with which both twins share a trait or condition.
High concordance suggests a strong genetic contribution to the trait.

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 D2.2.10: Monozygotic Twin Studies Notes

Identical Twins Are a Natural Experiment for Separating Genes From Environment

Discordance Between Twins Grows as Their Environments Diverge

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

Identical Twins Are a Natural Experiment for Separating Genes From Environment

Discordance Between Twins Grows as Their Environments Diverge

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

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics