Sexual Reproduction and Meiosis

Vocabulary

aneuploidy

a condition in which the organism has an abnormal number of copies of a chromosome

asexual reproduction

a form of reproduction that does not involve fusion of gametes, producing offspring genetically identical to the parent

centromere

the point on a chromosome that attaches to the spindle fibers during cell division and at which sister chromatids are attached

chromosome

a structure that contains DNA, the genetic material that is passed from one generation to the next

crossing-over

the exchange of DNA between homologous chromosomes during meiosis

cytokinesis

the pinching off of the cytoplasm to form two new cells

diploid

having a double set of chromosomes in homologous pairs; the diploid condition is designated by 2n

gamete

the sex cell of a sexually reproducing organism, with a haploid set of chromosomes

gene

a unit of heritable material that codes for a particular trait

genetic disorder

any one of several diseases that are the result of mutations of damaged genes; they are often inherited

haploid

having a single set of chromosomes, which is half the total of the parent; the haploid condition is designated by 1n or n

homologous chromosomes

identical pairs of chromosomes which pair together during synapsis of meiosis I in diploid organisms

independent assortment

the random distribution of the pairs of genes on different chromosomes to the gametes during meiosis

meiosis

a process in cell division during which the number of chromosomes decreases to half the original number by two divisions of the nucleus, resulting in the production of gametes

nondisjunction

the failure of chromosomes or chromatids to separate during anaphase I or II of meiosis that results in an uneven distribution of genetic material

oogenesis

the process of egg cell formation during meiosis

polar body

nonviable cell produced at the end of meiosis in females

polyploidy

a condition in which an organism has more than the normal full sets of chromosomes

sexual reproduction

a form of reproduction involving fusion of gametes, producing genetically unique offspring

spermatogenesis

the formation of sperm through the process of meiosis

spindle fiber

microtubule that attaches to chromosomes and pulls them to opposite poles of a cell during cell division

synapsis

the pairing of homologous chromosomes during prophase I of meiosis

tetrad

the two pairs of homologous chromosomes (which share the same genes) that are formed and align next to each other during prophase I of meiosis