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56 terms

Meiosis/Genetics

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amniocentesis
14th-16th week of pregnancy. Physician inserts needle and removes 10ml of amniotic fluid
anaphase I
homologues move to opposite poles
aneuploidy
abnormal number of chromosomes
angleman syndrome
Maternal chromosome 15 missing.
autosome
any chromosome that is not a sex chromosome
centromere
the region of the chromosome that holds the two sister chromatids together during mitosis
chiasma
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.
chromatin
granular material visible within the nucleus; consists of DNA tightly coiled around proteins
chromosome
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
cytokinesis
Division of the cytoplasm of one cell into two new cells - only in animal cells
deletion
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.
duplication
an abnormality to a chromosome in which part of the chromosome is repeated
fertilization
The union of haploid gametes to produce a diploid zygote.
fetoscopy
involves inserting a thin fiber-optic scope into uterus
gametes
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
genome
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)
interkinesis
period of time between meiosis I and meiosis II during which no DNA replication takes place
interphase
A period between two mitotic or meiotic divisions during which the cell grows, copies its DNA, and synthesizes proteins but does not divide
inversion
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
karyotype
picture of an individual's chromosomes
klinefelter
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
leukemia
malignant disease of blood-forming organs
locus
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
monosomy
Condition in a diploid cell in which one chromosome of a pair is missing
nondisjunction
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
oogenesis
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
polyploidy
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
spermatogenesis
the production of sperm cells
synapsis
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
translocation
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
zygote
diploid cell formed when a sperm fertilizes an egg