MORE ON MEIOSIS

Introduction

Both plants and animals grow by _________________ cell division and form ________________ by meiosis. A ________________ (fertilized egg) forms from the fusion of male and female ________________. In humans, this union of ______ (#) chromosomes from the sperm cell and _________ (#) chromosomes from the egg cell produces the diploid # of _______ chromosomes in the zygote.

The specific type of meiosis that produces sperm cells is called _______________________ and occurs in the _____________________ tubules in the testes. The specific type of meiosis that produces egg cells is called _______________________ and occurs in the _______________.

Draw Fig. 3 on pg. 114













While spermatogenesis produces ______ (#) haploid sperm cells (each genetically ________________), oogenesis produces only _______ (#) haploid egg cell. The other egg cells are called ______________ bodies and die since most of their _________________ was contributed to the one surviving egg cell (called an _______________).


Sex Chromosomes

Humans possess ______ (#) chromosomes, or _______ (#) pairs. Forty-four of these (22 pairs) are called __________________. Two (1 pair) are called ____________ chromosomes (see Fig. 4 on pg. 115). Females possess 2 _______ chromosomes whereas males possess 1 _______ and 1 _________ chromosome in their somatic cells. Gametes, of course, have only 1 sex chromosome (egg cells have an X, sperm cells have an X or a Y). Union of an X-bearing egg and X-bearing sperm produce a ____________ whereas union of an X-bearing egg and Y-bearing sperm produce a ___________.


Karyotypes and Genetic Disorders

A special chart in which all of the chromosomes are photographed, cut out, and then paired up (in homologous pairs) is called a _____________________. Homologous chromosomes can be paired this way because they are similar in ________, ____________, and _______________ patterns. This chart allows some chromosomal genetic disorders to be easily visualized (see Fig. 2a and 2b on pg. 117).

A karyotype chart is especially useful in diagnosing ____________________ disorders. These occur when chromosomes do not _____________ properly during meiosis so that a sperm or egg cell has more or less than the normal number of chromosomes.


Chapter 3 Review (pp. 124-125)#1, 8, 9, 10, 11, 12, 13, 17, 19(a,b)