Meiosis & Genetics Flashcards.txt

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Meiosis & Genetics Flashcards.txt
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Meiosis & Mendel
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Meiosis & Mendel
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  1. ABO blood group
    Genetically determined classes of human blood that are based on the presence or absence of carbohydrates A and B on the surface of red blood cells. The ABO blood group phenotypes, also called blood types, are A, B, AB, and O.
  2. alleles
    An alternative form of a gene.
  3. amniocentesis
    A technique for diagnosing genetic defects while a fetus is in the uterus. A sample of amitotic fluid, obtained via a needle inserted into the amnion, is analyzed for telltale chemicals and defective fetal cells.
  4. anaphase I
    Pair of homologous chromosomes split up
  5. anaphase II
    Same as mitosis, sister chromatids separate
  6. Aneuploidy (aneuploid)
    Condition of having an abnormal number of certain chromosomes
  7. Angelman
    A neuro-genetic disorder characterized by intellectual and developmental delay, sleep disturbance, seizures, jerky movements especially hand-flapping, frequent laughter or smiling, and usually a happy demeanor.
  8. autosomes
    A chromosome not directly involved in determining the sex of an organism; in mammals, for example, any chromosome other than X or Y.
  9. carriers
    An individual who is heterozygous for a recessively inherited disorder and who therefore does not show symptoms of that disorder.
  10. centromere
    The region of a chromosome where two sister chromatids are joined and where spindle microtubules attach during mitosis and meiosis. The centromere divides at the onset of anaphase during mitosis and anaphase II during meiosis.
  11. chiasma
    The microscopically visible site where crossing over has occurred between chromatids of homologous chromosomes during prophase I of meiosis.
  12. chorionic villus sampling (CVS)
    A technique for diagnosing genetic defects while the fetus is in the uterus. A small sample of the fetal portion of the placenta is removed and analyzed.
  13. chromatin
    The combination of DNA and proteins that constitutes chromosomes; often used to refer to the diffuse, very extended form taken by the chromosomes when a eukaryotic cell is not dividing.
  14. chromosome theory of inheritance
    A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.
  15. chromosomes
    A threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell. Chromosomes consist of chromatin.
  16. codominant
    Inheritance pattern in which a heterozygote expresses the distinct trait of both alleles.
  17. complete dominant
    A type of inheritance in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable.
  18. Cri du Chat
    Deletion on chromosome 5.
  19. cross
    A hybrid
  20. cross-fertilization
    The fusion of sperm and egg derived from two different individuals.
  21. crossing over
    The exchange of segments between chromatids of homologous chromosomes during synapsis in prophase I of meiosis; also, the exchange of segments between DNA molecules in prokaryotes.
  22. cytokinesis
    The division of the cytoplasm to form two separate daughter cells. Cytokinesis usually occurs during telophase of mitosis, and mitosis and cytokinesis make up the mitotic (M) phase of the cell cycle.
  23. deletion
    The loss of one or more nucleotides from a gene by mutation; the loss of a fragment of a chromosome.
  24. dihybrid cross
    An experimental mating of individuals differing at two genetic loci.
  25. diploid cell
    In an organism that reproduces sexually, a cell containing two homologous sets of chromosomes, one set inherited from each parent; a 2n cell.
  26. dominant allele
    In a heterozygote, the allele that determines the phenotype with respect to a particular gene.
  27. Down Syndrome
    A human genetic disorder resulting from the presence of an extra chromosome 21; characterized by heart and respiratory defects and varying degrees of mental retardation.
  28. duplication
    Repetition of part of a chromosome resulting from fusion with a fragment from a homologous chromosome; can result from an error in meiosis or from mutagenesis.
  29. F1 generation
    The offspring of two parental (P generation) individuals; F1 stands for first filial.
  30. F2 generation
    The offspring of the F1 generation; F2 stands for second filial.
  31. fertilization
    The union of the nucleus of a sperm cell with the nucleus of an egg cell, producing a zygote.
  32. fetoscopy
    Involves inserting a thin fiber-optic scope into the uterus, done at the 18th week.
  33. gametes
    A sex cell; a haploid egg or sperm. The union of two gametes of opposite sex (fertilization) produces a zygote.
  34. genetic recombination
    The production, by crossing over and/or independent assortment of chromosomes during meiosis, of offspring with allele combinations different from those in the parents. The term may also be used more specifically to mean the production by crossing over of eukaryotic or prokaryotic chromosomes with gene combinations different from those in the original chromosomes.
  35. genetics
    The scientific study of heredity and hereditary variations.
  36. genome
    A complete (haploid) set of an organism's genes; an organism's genetic material.
  37. genomic imprinting
    A genetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner.
  38. genotype
    The genetic makeup of an organism.
  39. germ line (germ cell)
    • Germline of a mature or developing individual is the line (sequence) of germ cells that have genetic material that may be passed to a child.
    • For example, sex cells such as the sperm or the egg, are part of the germline. So are the cells that produce sex cells, called gametocytes, the cells that produce those, called gametogonia, and all the way back to the zygote, the cell from which the individual developed.
  40. haploid cell
    In the life cycle of an organism that reproduces sexually, a cell containing a single set of chromosomes; an n cell.
  41. heterozygous
    Having two different alleles for a given gene.
  42. homozygous
    Having two identical alleles for a given gene.
  43. hybrid
    The offspring of parents of two different species or of two different varieties of one species; the offspring of two parents that differ in one or more inherited traits; an individual that is heterozygous for one or more pairs of genes.
  44. incomplete dominance
    A type of inheritance in which the phenotype of a heterozygote (Aa) is intermediate between the phenotypes of the two types of homozygotes (AA and aa).
  45. interkinesis
    A period of rest that cells enter during meiosis. It is the abbreviated interphase that occurs between meiosis I and II. No DNA replication occurs during this stage of Meiosis. Many plants skip telophase I and interkinesis, going immediately into prophase II. Each chromosome still consists of two chromatids.
  46. interphase
    Chromosomes duplicate.
  47. inversion
    A change in a chromosome resulting from reattachment of a chromosome fragment to the original chromosome, but in a reverse direction. Mutagens and errors during meiosis can cause inversions.
  48. Jacob's Syndrome
    XYY. Males that are usually taller and aggressive but are still fertile and intelligent.
  49. karyotype
    A display of micrographs of the metaphase chromosomes of a cell, arranged by size and centromere position.
  50. Klinefelter
    XXY. Male sex organs with abnormally small testes. Sterile, feminine body contours, and breast enlargement, usually normal intelligence.
  51. law of independent assortment
    A general rule in in inheritance that when gametes form during meiosis, each pair of alleles for a particular characteristic segregate independently; also known as Mendel's second law of inheritance.
  52. law of segregation
    A general rule in inheritance that individuals have two alleles for each gene and that when gametes form by meiosis, the two alleles separate, and each resulting gamete ends up with only one allele of each gene; also known as Mendel's first law of inheritance.
  53. Leukemia (CML)
    A cancer of the blood or bone marrow characterized by an abnormal increase of blood cells, usually leukocytes (white blood cells).
  54. locus
    The particular site where a gene is found on a chromosome. Homologous chromosomes have corresponding gene loci.
  55. meiosis
    In a sexually reproducing organism, the division of a single diploid nucleus into four haploid daughter nuclei. meiosis and cytokinesis produce haploid gametes from diploid cells in the reproductive organs of the parents.
  56. metaphase I
    Tetrads line up.
  57. metaphase II
    Chromosomes line up.
  58. monohybrid cross
    An experimental mating of individuals differing at one genetic locus.
  59. monosmy
    Aneuploid cell missing a chromosome.
  60. multiple alleles
    Any of a set of three or more alleles, or alternative states of a gene, only two of which can be present in a diploid.
  61. nondisjunction
    An accident of meiosis or mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to separate at anaphase.
  62. nuchal translucency
    The scan is carried out at 11–13+6 weeks pregnancy and assesses the amount of fluid behind the neck of the fetus - also known as the nuchal fold or 'the nuchal translucency.
  63. oogenesis
    The formation of ova (egg cells).
  64. Ova (ovum)
    An unfertilized egg, or female gamete.
  65. P generation
    The parent individuals from which offspring are derived in studies of inheritance (P stands for parental).
  66. phenotype
    The expressed traits of an organism.
  67. Polar bodies
    A cell structure found inside an ovum. Both animal and plant ova possess it. It is also known as a polar cell.
  68. polyploidy
    An organism whose cells have more than two complete sets of chromosomes.
  69. Prader Willi
    Missing 7 genes chromosome 15 on the paternal chromosome, appetite low, muscle tone, emotional instability, immature physical features.
  70. prophase I
    Homologous chromosomes pair and exchange segments.
  71. prophase II
    The nuclear envelope breaks down and the spindle apparatus forms.
  72. Punnett Square
    A diagram used in the study of inheritance to show the results of random fertilization.
  73. recessive allele
    In a heterozygous individual, the allele that has no noticeable effect on the phenotype.
  74. Self fertilization
    THe fusion of sperm and egg produced by the same individual organism.
  75. sex chromosome
    A chromosome that determines whether an individual is male or female.
  76. sister chromatid
    One of the two identical parts of a duplicated chromosome in a eukaryotic cell.
  77. spermatogenesis
    The formation of sperm cells.
  78. synapsis
    The pairing of two homologous chromosomes that occurs during meiosis. It is a form of chromosomal crossover. Synapsis takes place during prophase I.
  79. telophase I
    2 haploid cells form; chromosomes are still double.
  80. telophase II
    Haploid daughter cells form.
  81. test cross
    The mating between an individual of unknown genotype for a particular characteristic and an individual that is homozygous recessive for that same characteristic.
  82. translocation
    A change in a chromosome resulting from a chromosomal fragment attaching to a nonhomologous chromosome; can occur as a result of an error in meiosis or from mutagenesis.
  83. trisomy 21
    Down syndrome.
  84. true breeding
    Referring to organisms for which sexual reproduction produces offspring with inherited traits identical to those of the parents; the organisms are homozygous for the characteristics under consideration.
  85. Turner's Syndrome
    One less chromosome, usually lethal. XO. Short stature, at puberty, secondary sexual characteristic fail to develop. Sterile.
  86. ultrasound imaging
    A technique for examining a fetus in the uterus. High-frequency sound waves echoing off the fetus are used to produce an image of the fetus.
  87. zygote
    The fertilized egg, which is diploid, that results from the union of a sperm cell nucleus and an egg cell nucleus.

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