Cell biology and genetics · BEGINNER LESSON
Chromosome
A chromosome is a DNA-containing structure in the cell nucleus that packages genetic material and helps organize genome function. In humans, chromosomes are also the units counted in a karyotype, which is the full chromosome set.
What a chromosome is
A chromosome is a physical DNA-based structure in the nucleus that carries genetic information. In humans, the usual chromosome set is 46, arranged as 22 pairs of autosomes plus one pair of sex chromosomes. Chromosomes are not only carriers of genes; they also help organize how the genome is arranged and used in cells.
[1] From Chromosomes to Precision Therapy: Clinical Cytogenetics and ... [3] Genetics, Chromosome Abnormalities - StatPearls - NCBI Bookshelf
What is measured
Chromosomes are measured as count, shape, and large-scale structure in a karyotype, which is the full set of chromosomes in an organism. Cytogenetics is the study of chromosomes. A karyotype can reveal aneuploidy, meaning too many or too few chromosomes, and major structural changes such as deletions, duplications, inversions, translocations, ring chromosomes, and isochromosomes.
[3] Genetics, Chromosome Abnormalities - StatPearls - NCBI Bookshelf
How chromosomes affect genome function
Chromosomes are built from DNA plus proteins, and in eukaryotic cells this material is called chromatin. Chromatin proteins help genome function by supporting DNA-protein and DNA-RNA interactions, ATP-dependent chromatin remodeling, DNA looping, and loop extrusion. These processes help regulate when and where genes are active and how DNA is organized in space.
[2] (Re)defining the human chromatome: an integrated meta-analysis of ... [1] From Chromosomes to Precision Therapy: Clinical Cytogenetics and ...
How chromosome abnormalities arise
Chromosome abnormalities can be numerical or structural. Numerical abnormalities often come from failed chromosome separation during cell division, especially meiosis, so a cell gains or loses whole chromosomes. Structural abnormalities usually come from chromosome breakage and misrepair or unequal exchange between chromosomes.
[3] Genetics, Chromosome Abnormalities - StatPearls - NCBI Bookshelf
Limits of chromosome studies
Chromosome-related material is dynamic and can differ by cell type, cell cycle stage, and conditions inside the cell. Because of that, protein-based studies of chromatin can miss low-abundance proteins or be affected by contamination. Also, standard karyotyping is best for whole-chromosome changes and large deletions or duplications, not tiny DNA changes.
[2] (Re)defining the human chromatome: an integrated meta-analysis of ... [3] Genetics, Chromosome Abnormalities - StatPearls - NCBI Bookshelf
SEE THE IDEA
From DNA to chromosome-level observation
Genetic material is packaged with proteins in the nucleus.
Packaging helps arrange the genome and support gene regulation.
Cells are examined for chromosome number and large structural changes.
DNA and proteins form chromosomes; chromosome structure influences genome organization; karyotyping lets us observe large chromosome changes.
A chromosome is both a physical package of DNA and a unit that can be visually studied for major genomic changes.
TRY IT YOURSELF
Test your understanding
Choose an answer, then check the explanation.
PUT IT TOGETHER
Match each concept to its meaning
Drag a label onto its description, or select a label and then select a description. This also works with a keyboard.
4 pairs to match
Sources and further reading
This general lesson was generated from public source material. It explains a concept; it does not interpret a private paper or provide medical advice.