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30 terms

Meiosis and Human Genetics

Miller & Levine
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Homologous
term used to refer to chromosomes that each have a corresponding chromosome from the opposite-sex parent
Diploid
term used to refer to a cell that contains both sets of homologous chromosomes
Haploid
of a cell or organism having a single set of chromosomes
Meiosis
the process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell (resulting in 4 haploid cells)
Tetrad
structure containing 4 chromatids that forms during meiosis
Crossing Over
the interchange of sections between pairing homologous chromosomes during the prophase of meiosis
Interphase 1
cells undergo a round of DNA replication, forming duplicate chromosomes
Prophase 1
Each chromosome pairs with its corresponding homologous chromosome to form a tetrad crossing over occurs
Metaphase 1
spindle fibers attach to the chromosomes, homologous chromosomes line up down the middle of the cell
Anaphase 1
The fibers pull the homologous chromosomes toward opposite ends of the cell
Telophase 1
nuclear membranes form
Cytokinesis 1
the cell separates into two cells (each containing a haploid number of chromosomes)
Prophase 2
Chromosomes condense, spindles form in each new cell, and spindle fibers attach to chromosomes.
Metaphase 2
chromosomes line up
Anaphase 2
sister chromatids separate and move toward opposite ends of the cell
Telophase 2
results in 4 haploid daughter cells
Sperm
male haploid gametes
Egg
female haploid gamete
Polar Bodies
3 of the 4 cells produced by meiosis in a female which are not involved in sexual reproduction
number of chromosomes in a human haploid cell
23
number of chromosomes in a human somatic cell
46
Nondisjunction
An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other.
Mitosis
Somatic Cell division of the nucleus. Final product is 2 cells that are exactly like the parent cell.
karyotype
Shows the complete diploid set of chromosomes grouped together in pairs, arranged in order of decreasing size (allows to identify chromosomal number abnormalities)
pedigree
A diagram that shows the occurrence of a genetic trait in several generations of a family.
Barr body
An inactivated X chromosome can be seen in a cell under a microscope as a dense object inside the nuclear envelope.
heterozygous
An organism that has two different alleles for a trait (Gg)
homozygous
An organism that has two identical alleles for a trait (GG or gg)
Sex chromosomes in males
X and Y (normal gametes will have either the X or Y in addition to 22 autosomes)
Sex chromosomes in females
Two X chromosomes (normal gametes will have one X and 22 autosomes)