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Cells and genomes: how genes shape organisms

Key ideas • Key ideas

Key concepts

What you'll likely be quizzed about

  • A cell is the smallest unit that exhibits all characteristics of life.
  • Single-celled organisms perform all life functions within one cell, while multicellular organisms carry out specialized functions by organizing many cells into tissues and organs.
  • Cells are classified into two groups: prokaryotic cells, which are smaller and lack a nucleus, and eukaryotic cells, which are larger and contain a nucleus.
  • Organelles within eukaryotic cells perform distinct functions.
  • The nucleus contains chromosomes and DNA, mitochondria produce energy through respiration, and ribosomes synthesize proteins.
  • The structural differences between cell types lead to functional specialization, showing that cell structure dictates cell function and supports the organization into tissues and systems.

Flashcards

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How does DNA store information?

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DNA encodes information in the sequence of four bases (A, T, C, G) that form base pairs in a double helix.

Key notes

Important points to keep in mind

Cells are the smallest units displaying all life's processes; multicellular organization arises from specialized cells.

A genome is one complete set of DNA in a diploid body cell, organized into chromosomes.

Genes encode proteins through transcription and translation; proteins produce most observable traits.

Alleles are alternative forms of a gene; genotype plus environment determines phenotype.

Mutations alter DNA sequences; substitutions typically affect one amino acid, while insertions/deletions can cause broader changes.

Non-coding DNA constitutes a major part of the human genome and may influence gene regulation or other functions.

Environmental factors modify phenotype without changing the DNA sequence.

Natural selection acts on phenotypic variations with genetic bases, promoting adaptations over generations.

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