Cytogenetics Flashcards

Cytogenetics

  • Study of chromosomes.
  • Chromosome:
    • Thread-like structure made of protein and a single molecule of DNA in the nucleus.

Mitosis

  • Two daughter cells receive the same amount of genetic material as their mother producing cell.
  • Larger the chromosome number, the smaller the chromosome.

Diploid

  • When the cell of an organism carries 2 sets of chromosomes (most human cells - humans are 2n, where n = 23).
  • Autosomes: non-sex chromosomes; exception is gametes (sperm + egg cell).

Gametes

  • Sex cells contain 1 set of chromosomes.
  • Homologous chromosomes.

Homolog

  • Member of a pair of chromosomes in a diploid organism.

Homology

  • Similarity due to ancestry.
  • Pairs of chromosomes are derived from the same chromosome but are not usually identical because of genetic change.

Cell Cycle

  • Pre-cell division: A mother cell has 6 chromosomes (2 sets of each).
  • Chromosome replication: Produces 6 pairs of sister chromatids.
  • Replication is complete: The cell prepares to divide, and the nucleus breaks apart; replicated chromosomes condense in preparation for mitosis.
  • Sister chromatids separate during mitosis: 2 cells are formed during cytokinesis.
  • Sister chromatids: Two duplicated chromatids still joined together after DNA replication.

Cell Cycle Stages

  • G1 (1st gap): Cell becomes committed to divide; cell growth occurs.
  • Each chromosome is replicated to form sister chromatids; when completed, the cell will have twice as many chromatids.
  • G2: Cell synthesizes proteins for sorting + cell division; some cell growth may occur.

Mitosis (1st part)

  • Divides the cell nucleus into 2 nuclei, making sure each daughter cell receives the same amount of chromosomes (each cell gets 46).

Cytokinesis

  • Division of cytoplasm produces 2 daughter cells.

Meiosis

  • Haploid cells are produced from a cell that was originally diploid.
  • Fewer chromosomes in cells.
  • Meiosis makes cells smaller.