14th-16th week of pregnancy. Physician inserts needle and removes 10ml of amniotic fluid

anaphase I

homologues move to opposite poles


abnormal number of chromosomes

angleman syndrome

Maternal chromosome 15 missing.


any chromosome that is not a sex chromosome


the region of the chromosome that holds the two sister chromatids together during mitosis


a point at which a chromatid of one chromosomes crosses with a chromatid of the homologues chromosomes during prophase I of meiosis; the site of exchange of chromosomal material between chromosomes

chorionic villus sampling (CVS)

sampling of placental tissues (chorionic villi) for prenatal diagnosis of fetal abnormalities.


granular material visible within the nucleus; consists of DNA tightly coiled around proteins


DNA coiled around and supported by proteins, found in the nucleus of the cell

cri du chat

a genetic disorder caused by a gene deletion of part chromosome 5 is lost -have very small head,mentally retarded,cry like a hurt cat

crossing over

the exchange of genetic material between homologous chromosomes during meiosis


Division of the cytoplasm of one cell into two new cells - only in animal cells


a mutation in which a of a part of DNA breaks off from a chromosome

diploid cell

A cell containing two sets of chromosomes (2n), one set inherited from each parent. (both sets in a homologous pair)

down syndrome

A human genetic disease resulting from having an extra chromosome 21, characterized by mental retardation and heart and respiratory defects.


an abnormality to a chromosome in which part of the chromosome is repeated


The union of haploid gametes to produce a diploid zygote.


involves inserting a thin fiber-optic scope into uterus


reproductive cells, have only half the number of chromosomes as body cells

genetic recombination

the regrouping of genes in an offspring that results in a genetic makeup that is different from that of the parents


the complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes

genomic imprinting

A phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent

germ line (germ cell)

the cell that undergoes meiosis (in humans, only found in the ovaries and testes)

haploid cell

a cell that has only one representative of each chromosome pair (ex - sex cells)


period of time between meiosis I and meiosis II during which no DNA replication takes place


A period between two mitotic or meiotic divisions during which the cell grows, copies its DNA, and synthesizes proteins but does not divide


chromosome piece breaks off and reattaches in reverse orientation

Jacob's syndrome

XYY - men with an extra Y chromosome usually taller than average, persistent acne, and tend to have speech and reading problems


picture of an individual's chromosomes


United States physician who first described the XXY-syndrome (born in 1912)

law of independent assortment

the law that states that genes separate independently of one another in meiosis

law of segregation

law stating that pairs of genes separate in meiosis and each gamete receives one gene of a pair


malignant disease of blood-forming organs


the specific site of a particular gene on its chromosome

meiosis I

offspring cells are haploid but each contains 2 copies of the chromosomes because the original is copied before meiosis I

metaphase I

the second stage of meiosis tetrads line up along middle, spindle fibers attach to centromere


Condition in a diploid cell in which one chromosome of a pair is missing


meiosis in which there is a failure of paired homologous chromosomes to separate (can occur in meiosis I or II)

nuchal translucency

a non invasive prenatal diagnostic test that measures the thickness of the skin in the back of the fetuses nest


the production of mature egg cells

ova (ovum)

female gametes (egg)

polar bodies

when an egg is produced, the other three (or two) cells are called polar bodies. They contain almost none of the cytoplasm and are destroyed


condition in which an organism has more than two complete chromosome sets (common in plants)

Prader Willi syndrome

Deletion on Chromosome 15 - Hypotonia, mental retardation, obesity

prophase I, II

DNA coils into chromosomes, nuclear envelope disappears, mitotic spindle forms, synopsis crossing over occurs. In II, cells are haploid because no copying of DNA before meiosis II

sex chromosome

one of two chromosomes of the 23rd pair of human chromosomes, which determine an individual's gender

sister chromatid

one of a pair of identical chromosomes created before a cell divides


the production of sperm cells


the pairing of homologous chromosomes during meiosis

telophase I, II

the final stage of meiosis, chromosomes reach the opposite ends of the cell and cytokinesis begins


chromosome fragment becomes attached to non homologous chromosome

trisomy 21

condition in which an individual has three number 21 chromosomes, resulting in Down syndrome

Turner's syndrome

a genetic disorder in which there is whole or partial deletion of one x chromosome - usually lethal

ultrasound imaging

technique for using high-pitched sound waves to form an image of the fetus in the womb - non-invasive


diploid cell formed when a sperm fertilizes an egg

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