IB Environmental systems and societies Topic 3.1D Genetic Diversity and Reproductive Isolation Revision Notes (HL)

IB Environmental systems and societies Topic 3.1D Genetic Diversity and Reproductive Isolation Revision Notes (HL) | RevisionDojo

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Genetic Diversity: The Variety Within a Species

Definition

Genetic diversity

Genetic diversity is the variety of genes within a species, allowing for adaptation to environmental changes.

Genetic diversity is the variety of genetic material (genes and alleles) within a population or species.
It is the foundation of evolution and adaptation, letting populations survive in changing environments.

Mutation: The Original Source of Variation

Definition

Mutation

A mutation is a random change in DNA that introduces new genetic variants (alleles).

A mutation is a random, spontaneous change in the DNA sequence.
It alters the sequence of nucleotide bases (A, T, C, G) and can create a new version of a gene, an allele.
Different alleles may be beneficial, neutral, or harmful.

Example

A mutation in the CCR5 gene gives resistance to HIV, an advantageous allele that has spread in some human populations.

Types of Mutation

Point mutation: a single base is substituted for another.
Insertion or deletion: bases are added or removed, causing a frameshift.
Chromosomal mutation: duplication, inversion, or translocation of larger segments.

Sources of Mutation

DNA replication errors: random mistakes when the genome is copied.
Radiation: UV or ionising radiation changes bases.
Chemical mutagens: for example tobacco smoke or pesticides.
Viruses: insert foreign DNA into the host genome.

Note

Mutations are random, but natural selection determines which ones persist.
Most mutations are neutral or harmful; only occasionally does one give a survival advantage.

Sexual Reproduction and Genetic Recombination

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IB Environmental systems and societies 3.1D Genetic Diversity and Reproductive Isolation Notes

Genetic Diversity: The Variety Within a Species

Mutation: The Original Source of Variation

Types of Mutation

Sources of Mutation

Sexual Reproduction and Genetic Recombination

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

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Genetic Diversity: The Variety Within a Species

Mutation: The Original Source of Variation

Types of Mutation

Sources of Mutation

Sexual Reproduction and Genetic Recombination

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Duis aute irure dolor in reprehenderit

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Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 3.1D Genetic Diversity and Reproductive Isolation Notes

Genetic Diversity: The Variety Within a Species

Mutation: The Original Source of Variation

Types of Mutation

Sources of Mutation

Sexual Reproduction and Genetic Recombination

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

Genetic Diversity: The Variety Within a Species

Mutation: The Original Source of Variation

Types of Mutation

Sources of Mutation

Sexual Reproduction and Genetic Recombination

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

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics