chromosome structure,chromosome,cytogenetic

What is cytogenetics?

The branch of genetics that studies chromosomes and their behavior during cell division.

Difference between conventional and molecular cytogenetics?

Conventional: Analyzes number and structure of all 46 chromosomes (karyotype).
Molecular: Uses fluorescent probes to analyze specific chromosomes or loci.

What is a karyotype?

Organized visual profile of chromosomes arranged by number, size, and banding.

Total number of chromosomes in human diploid and haploid cells?

Diploid (somatic) = 46

Haploid (gametes) = 23.

What are autosomes and sex chromosomes?

Autosomes: Pairs 1–22 (identical in both sexes).
Sex chromosomes: XX in females, XY in males.

What are the key morphofunctional elements of chromosomes?

Sister chromatids
Centromere
Telomeres

What are sister chromatids?

Two identical nucleoprotein chains formed from DNA replication.

What is a gene locus and allele?

Locus: specific location or position of a gene

Alleles: A variant form of a gene at a given locus on a chromosome.

• Humans have two alleles for each gene (one from each parent) — if they are identical, the person is homozygous; if different, they are heterozygous.

• Alleles can be:

  • Dominant (expressed if present)

  • Recessive (expressed only if both alleles are recessive)

  • Or show codominance/incomplete dominance (e.g., ABO blood group)

What is the centromere and its function?

Region where chromatids attach, dividing arms into p (short) and q (long); site of kinetochore formation for spindle attachment.

What is the telomere and its function?

End structure of chromosome made of repetitive DNA that ensures stability, prevents fusion, and enables complete replication.