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26 Cards in this Set

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Independent Assortment
(shuffling of chromosomes) random distribution of homologous chromsomes during meiosis
Crossing-over
(shuffling of genes) during prophase I, homologous chromosomes pair up forming tetrad and portions of chromosomes (genes) are exchanged
Random fertilization
(shuffling of gametes-sex cells) no telling which out of the millions/billions you produce will actually partake in fertilization
Meiosis
form of cell division in which the number of chromosomes is halved (haploid)
Alleles
different varieties of a particular gene (brown eye allele, blue eye allele)
Prophase I (diploid)
Chrosomes condense and become visible. The nuclear envelope dissolves. Homologous chromsomes pair up side by side and crossing-over occurs. Portions of chromatids or homologous pairs are swapped
Metaphase I
Chromosomes line up in center of cell. But homologous chromsomes remain side by side.
Anaphase I
Homologous chromosomes move to opposite poles of the cell.
Telophase I and Cytokinesis
Chromosomes gather at either end and cytoplasm divides. Form 2 haploid cells. *Each new cell contains 1 chromsome from each homologous pair.
Prophase II (2 haploid)
Nuclear envelope dissolves and new spindle forms. 2 new cells.
Metaphase II
Chromosomes line up along middle.
Anaphase II
Centromeres divide and sister chromatids (now called chromosome) split and move to opposite ends
Telophase and Cytokinesis
Cytoplasm divides. Nuclear envelope reform. *Results: 4 different haploid cells (aka sex cells)
Order of stages in meiosis
Meiosis I:
Prophase I
Metaphase I
Anaphase I
Telophase I and Cytokinesis

Meiosis II:
Prophase II
Metaphase II
Anaphase II
Telophase II and Cytokinesis
How to get the number of combinations of pairs of chromosomes
2^the number of pairs
sex chromosomes and autosomes
Sex chromosome- chromosomes involved in determining sex (1 pair- X & Y chromosomes)
Autosomes- chromosomes not involved in determining sex (22 pairs)
homolgous pair
similar in size, shape, and genetic information (one is from mom, one is from dad)
Diploid cell and haploid cell
Diploid cell- (2n=46 in humans) - cell with 2 sets of chromosomes (somatic cells)
Haploid- (n=23 in humans)- cell with one set of chromosomes (gametes)
Zygote
A fertilized egg
Fertilization and meiosis
fertilization- fusion of 2 haploid gametes to form a diplid zygote
meiosis- form of cell division in which the number of chromosomes is halved (haploid)
Mitosis and meiosis
Mitosis: results in 2 identical diploid cells
2n
| |
2n 2n
identical cloves

Meiosis: results in 2 haploid cells which contain a mixture of chromosomes from 2 parent gametes, so cannot be identical--> variation
2n
| |
n n
|| ||
nn nn
different
X and Y chromosomes
Female-XX Male-XY (humans)
Deletion
piece of chromosome breaks off
Duplication
chromosome fragment attaches to homologous chromosome which will then have 2 copies of a certain set of genes
Inversion
chromosome piece reattaches to original chromosome but in reverse orientation
translocation
chromosome piece attaches itself to a nonhomologous chromosome