AP Biology

Advanced Placement Biology course covering cellular processes, genetics, evolution, and ecology.

Cellular ProcessesGenetics and HeredityPrinciples of Evolution
Biochemistry of LifeGene Expression and RegulationInteractions in Ecosystems
Genetic Technologies in MedicineConservation and BiodiversityBiology in Agriculture
Mastering Multiple Choice QuestionsEffective Free Response Answers
Cellular ProcessesGenetics and Heredit...Principles of Evolut...Biochemistry of LifeGene Expression and ...Interactions in Ecos...Genetic Technologies...Conservation and Bio...Biology in Agricultu...Mastering Multiple C...Effective Free Respo...
Advanced Topics

Gene Expression and Regulation

Turning Genes On and Off

Not all genes are active at all times. Cells control which genes are expressed to respond to their needs and environment.

How It Works

  • Transcription and Translation: DNA is transcribed into RNA, which is then translated into proteins.
  • Regulatory Elements: Promoters, enhancers, and repressors help control when genes are turned on or off.
  • Epigenetics: Chemical changes to DNA or histones can alter gene activity without changing the sequence.

Real-World Connections

  • Cancer can arise when genes regulating cell growth are misregulated.
  • Stem cells can become any cell type because they can turn on/off different genes.

Why It Matters

Gene regulation enables specialization of cells and adaptation to changing conditions.

Examples

  • Bacteria activate genes for lactose digestion only when lactose is present.

  • Identical twins can have different traits due to epigenetic changes.

In a Nutshell

Gene regulation lets cells respond to their environment by controlling which proteins are made.

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Interactions in Ecosystems