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.