Biology Essentials For Dummies by Rene Fester Kratz & Donna Rae Siegfried & Medhane Cumbay & Traci Cumbay

Author:Rene Fester Kratz & Donna Rae Siegfried & Medhane Cumbay & Traci Cumbay
Language: eng
Format: epub
ISBN: 9781119589549
Publisher: Wiley
Published: 2019-05-14T00:00:00+00:00

FIGURE 5-3: Cytokinesis.

After cytokinesis is complete, the new cells move immediately into the G1 stage of interphase. No one stops to applaud the great accomplishment of successfully completing the mitosis process, which is really too bad because it’s the root of renewal and regeneration.

Meiosis: It’s all about sex, baby

Meiosis is unique because the resulting cells have only half their parent cells’ chromosomes, or singular pieces of DNA. Human body cells have 46 chromosomes, 2 each of 23 different kinds. The 23 pairs of chromosomes can be sorted by their physical similarities and lined up to form a chromosome map called a karyotype (see Figure 5-4). The two matched chromosomes in each pair are called homologous chromosomes. (Homo- means “same,” so these are chromosomes that have the same kind of genetic information.) In each pair of your homologous chromosomes, one chromosome came from Mom, and one came from Dad. For every gene that your mom gave you, your dad also gave you a copy, so you have two copies of every gene (with the exception of genes on the X and Y chromosomes if you’re male).

FIGURE 5-4: A human karyotype.

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