Biology Quiz 2 Vocab
crossing over
A condition where non-sister chromatid of homologous chromosomes exchange genes.
chromatid
A double-stranded chromosome following replication attached by a centromere.
spindle fibers
A number of threadlike filaments formed between poles of the cell during cell division to which the centromeres of chromosomes attach; used to pull chromosomes apart and segregate them during anaphase.
Y chromosome
A sex chromosome found in males; influencing the degree of maleness.
X chromosome
A sex chromosome; in human males only one is present and in females two are present.
centromere
A structure on the chromosome that holds a pair of chromatids together during replication.
autosome
Any pair of chromosomes other than the sex chromosome.
diploid
Both members of a pair of chromosomes are present.
tetrad
During metaphase I the two pairs of chromatids of the homologous pair of chromosomes comes together; crossing-over can occur at this time.
nondisjunction
Failure of chromosomes to segregate during the formation of gametes, resulting in extra or a shortage of chromosomes in the gamete.
sex-linked
Genes which are carried on the X chromosome.
haploid
One member of a pair of homologous chromosomes is present, such as in a gamete.
sex-chromosome
One of the chromosomes which determine the sex of the individual.
polar body
One of three small cells produced during oogenesis, each contain the haploid number of chromosomes.
oogenesis
Process of development of haploid female gametes.
chromosome theory
The behavior of chromosomes explains the inheritance of genes.
linkage
The presence of different genes on the same chromosome.
spermatogenesis
The production of haploid male gametes by the male parent.
Prophase I
The stage in the first meiotic division where the doubled chromosomes become visible and nuclear membrane disappears.
Metaphase I
The stage in the first meiotic division where the homologous chromosomes line up as a pair, forming a tetrad of chromatids, at the equator of the cell.
Anaphase II
The stage in the second meiotic division where sister chromatids of a chromosome split and migrate to opposite poles.
Metaphase II
The stage in the second meiotic division where the chromatid pair lines up at the equator of the cell..
Telophase I
The stage of the first meiotic division where the cell divides into two cells each containing one member of each pair of homologous chromosomes.
Telophase II
The stage of the second meiotic division when the cell divides into two cells with each being haploid; these cells become the gametes.
Anaphase I
The stage on the first meiotic division when the homologous chromosomes move to opposite poles but the sister chromatids remain together.
