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103 Cards in this Set
- Front
- Back
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The RNA template present in telomerase.
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guide RNA
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The substage of meiotic prophase I, immediately preceding metaphase I, in which the bivalents attain maximum shortening and condensation.
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diakinesis
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Chromatin that remains condensed and heavily stained during interphase; commonly present adjacent to the centromere and in the telomeres of chromosomes. Some chromosomes are composed primarily of heterochromatin.
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heterochromatin
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A protein-containing material in chromosomes, believed to be responsible in part for the compaction of chromatin.
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scaffold
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The set of chromosomes in a cell or organism.
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chromosome complement
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Any cell of a multicellular organism other than the gametes and the germ cells from which gametes develop.
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somatic cell
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A structure composed of fibrous proteins on which chromosomes align during metaphase and move during anaphase.
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spindle
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A tightly coiled, bead-like region of a chromosome most readily seen during pachytene of meiosis; the beads are in register in a polytene chromosome, resulting in the banded appearance of the chromosome.
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chromomere
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The growth cycle of a cell; in eukaryotes, it is subdivided into G1 (gap 1), S (DNA synthesis), G2 (gap 2), and M (mitosis).
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cell cycle
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The basic repeating subunit of chromatin, consisting of a core particle composed of two molecules each of four different histones around which a length of DNA containing about 145 nucleotide pairs is wound, joined to an adjacent core particle by about 55 nucleotide pairs of linker DNA associated with a fifth type of histone.
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nucleosome
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The substage of meiotic prophase I in which homologous chromosomes synapse.
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zygotene
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A chromosome in which two X chromosomes are joined to a common centromere; also called a compound-X chromosome.
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attached- x chromosome
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The meiotic division in which the centromeres split and the chromosome number is not reduced; also called the equational division.
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second meiotic division
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Said of the result of an experiment or study that has only a small probability of happening by chance on the assumption that some hypothesis is true. Conventionally, if results as bad or worse would be expected less than 5 percent of the time, the result is said to be stistically significant; if less that 1 percent of the time, the result is called statistically highly significant; both outcomes cast the hypothesis into serious doubt.
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statistically significant
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One of two X-linked forms of hemophilia; patients are deficient in blood-clotting factor VIII.
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hemophilia A
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A base or amino acid sequence that changes very slowly in the course of evolution.
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conserved sequence
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Chromatids produced by replication of a single chromosome.
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sister chromatids
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In mitosis, meiosis I, or meiosis II, the stage of nuclear division in which the centromeres of the condensed chromosomes are arranged in a plane between the two poles of the spindle.
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metaphase
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Said of the result of an experiment or study that has only a small probability of happening by chance on the assumption that some hypothesis is true. Conventionally, if results as bad or worse would be expected less than 5 percent of the time, the result is said to be statistically significant; if less that 1 percent of the time, the result is called statistically highly significant; both outcomes cast the hypothesis into serious doubt.
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significant
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The theory that chromosomes are the cellular objects that contain the genes.
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chromosomes theory of heredity
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The tip of a chromosome, containing a DNA sequence required for stability of the chromosome end.
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telomere
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Any of the small basic proteins bound to DNA in chromatin; the five major histones are designated H1, H2A, H2B, H3, and H4. Each nucleosome core particle contains two molecules each of H2A, H2V, H3, and H4. The H1 histone forms connecting links between nucleosome core particles.
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histone
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The sex chromosome present only in the heterogametic sex; in mammals, the male-determining sex chromosome.
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Y chromosome
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All chromosomes other than the sex chromosomes.
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autosomes
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In eukaryotes, a DNA molecule that contains genes in linear order to which numerous proteins are bound and that has a telomere at each end and a centromere; in prokaryotes, the DNA is associated with fewer proteins, lacks telomeres and a centromere, and is often circular; in viruses, the chromosome is DNA or RNA, single-stranded or double-stranded, linear or circular, and often free of bound proteins.
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chromosome
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The pre-DNA synthesis stage in the growth cycle of a cell; no DNA replication takes place.
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G1 period
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An integer that determines the significance level of a particular statistical test. In the goodness-of-fit type of chi-square test in which the expected numbers are not based on any quantities estimated from the data themselves, the number of degrees of freedom is one less than the number of classes of data.
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degrees of freedom
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The substage of meiotic prophase I, immediately following pachytene and preceding diakinesis, in which pairs of sister chromatids that make up a bivalent (tetrad) begin to separate from each other and chiasmata become visible.
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diplotene
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The process of nuclear division in gametogenesis or sporogenesis in which one replication of the chromosomes is followed by two successive divisions of the nucleus to produce four haploid nuclei.
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meiosis
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The extent to which observed numbers agree with the numbers expected on the basis of some specified genetic hypothesis.
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goodness of fit
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The aggregate of histones and DNA in a nucleosome, without the linking DNA.
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core particle
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The diploid, spore-forming generation in plants, which alternates with the haploid, gamete-producing generation (the gametophyte).
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sporophyte
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division of the cytoplasm
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cytokinesis
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The level of compaction of eukaryotic chromatin resulting from coiling of the extended, nucleosome-bound DNA fiber.
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30-nm fiber
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the stage in the cell cycle in which mitosis occurs
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M period
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A statistical quantity calculated to assess the goodness of fit between a set of observed numbers and the theoretically expected numbers.
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chi squared (X2)
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The four chromatids that make up a pair of homologous chromosomes in meiotic prophase I and metaphase I; also, the four haploid products of a single meiosis.
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tetrad
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Of a number, the product of all integers from 1 through the number itself; 0! is defined as equal to 1.
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factorial
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Term applied to the second meiotic division because the haploid chromosome complement is retained throughout.
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equational division
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The aggregate of DNA and histone proteins that makes up a eukaryotic chromosome.
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chromatin
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Highly repetitive DNA sequences associated with mammalian centromeres.
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alpha satellite
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The cellular structure, formed in association with the centromere, to which the spindle fibers become attached in cell division.
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kinetochore
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A gene located in the X chromosome; X-linked inheritance is usually evident from the production of nonidentical classes of progeny from reciprocal crosses.
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x- linked gene
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The process of nuclear division in which the replicated chromosomes divide and the daughter nuclei have the same chromosome number and genetic composition as the parent nucleus.
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mitosis
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The meiotic division that reduces the chromosome number; sometimes called the reduction division.
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first meiotic division
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A region of a chromosome that has normal staining properties and undergoes the normal cycle of condensation; relatively uncoiled in the interphase nucleus (compared with condensed chromosomes), it apparently contains most of the genes.
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euchromatin
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The initial stage of mitosis or meiosis, beginning after interphase and terminating with the alignment of the chromosomes at metaphase; often absent or abbreviated between meiosis I and meiosis II.
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prophase
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The middle substage of meiotic prophase I in which the homologous chromosomes are closely synapsed.
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pachytene
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A chromosome that plays a role in sex determination and that is present in two copies in the homogametic sex and in one copy in the heterogametic sex.
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x chromosome
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A germ cell that undergoes meiosis to yield gametes in animals or spores in plants.
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meiocyte
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The pairing of homologous chromosomes or chromosome regions in zygotene of the first meiotic prophase.
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synapsis
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A pair of homologous chromosomes, each consisting of two chromatids, associated in meiosis I.
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bivalent
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In genetic engineering, synthetic DNA fragments that contain restriction-enzyme cleavage sites that are used to join two DNA molecules. (See also Nucleosome.)
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linker DNA
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A chromosome, such as the human X or Y, that has a role in the determination of sex.
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sex chromosome
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Chromosomes that pair in meiosis and have the same genetic loci and structure; also called homologs.
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homologous chromosomes
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Nuclear organelle in which ribosomal RNA is made and ribosomes are partially synthesized; usually associated with the nucleolar organizer region. A nucleus may contain several nucleoli.
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nucleolus or nucleoli
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Term applied to the first meiotic division because the chromosome number (counted as the number of centromeres) is reduced from diploid to haploid.
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reductional division
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A cell that gives rise to reproductive cells.
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germ cell
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An enzyme that adds specific nucleotides to the tips of the chromosomes to form the telomeres.
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telomerase
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Triangular configuration of integers in which the nth row gives the binomial coefficients in the expansion of (x + y)n - 1. The first and last numbers in each row equal 1, and the others equal the sum of the adjacent numbers in the row immediately above.
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pascal's triangle
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Imaginary plane, equidistant from the spindle poles in a metaphase cell, on which the centromeres of the chromosomes are aligned by the spindle fibers.
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metaphase plate
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The initial substage of meiotic prophase I during which the chromosomes become visible in the light microscope as unpaired thread-like structures.
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leptotene
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Gemes derived from a commmon ancestral gene, or proteins whose genes derive from a common ancestral gene. (See also Orthologous and paralogous.)
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homologous
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The final stage of mitotic or meiotic nuclear division.
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telophase
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Either of the longitudinal subunits produced by chromosome replication.
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chromatid
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A unicellular reproductive entity that becomes detached from the parent and can develop into a new organism upon germination; in plants, these are the haploid products of meiosis.
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spore
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One of the five major histone bound to DNA in chromatin. Each nucleosome core particle contains two molecules of H4 histone, along with two each of H2A, H2V, and H3.
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H4 histone
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Eukaryotic DNA that forms a minor band at a different density from that of most of the cellular DNA in equilibrium density gradient centrifugation; consists of short sequences repeated many times in the genome (highly repetitive DNA) or of mitochondrial or chloroplast DNA.
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satellite DNA
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In plants, the haploid part of the life cycle that produces the gametes by mitosis.
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gametophyte
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A cell or organism of a species containing the set of chromosomes normally found in gametes.
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haploid
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A cell or organism with two complete sets of homologous chromosomes.
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diploid
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Failure of chromosomes to separate (disjoin) and move to opposite poles of the division spindle; the result is loss or gain of a chromosome.
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nondisjunction
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The post-DNA synthesis stage in the growth cycle of a cell; no DNA replication takes place.
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G2 period
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The stage of mitosis or meiosis in which chromosomes move to opposite ends of the spindle. In anaphase I of meiosis, homologous centromeres separate; in anaphase II, sister centromeres separate.
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anaphase
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The interval between nuclear divisions in the cell cycle, extending from the end of telophase of one division to the beginning of prophase of the next division.
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interphase
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The three-dimensional region occupied by a particular chromosome in the nucleus of an interphase or noncycling cell.
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chromosome territory
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In birds, the male has two copies of W sex chromosome and is called ___
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Homogametic
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A conventional measure of goodness of fit between a set of observed numbers and theoretical expectations is known as ___
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chi square
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Somatic cells of an organism normally have 40 chromosomes. What is the number of chromosomes present in the nucleus in telophase II of meiosis?
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20
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The pairing of homologous chromosomes during meiosis is known as____
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synapsis
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Hemophilia is an X-linked trait. A woman whose father suffers from hemophilia married a normal man and they have one son. What is the probability that he is affected?
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0.75
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The probability that all children in a four-children family will be girls is__
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0.0625
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What term describes the result of a statistical test in which the P value is less than 0.05?
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statistically significant
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A long meiotic stage lasting several days in most higher eukaryotes and is commonly divided into five substages is called___
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prophase 1
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The mechanism of restoring the ends of a DNA molecule in a chromosome relies on the enzyme called ___
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telomerase
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The ribosome incorporates an essential RNA molecule called___
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rRNA
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only one set of chromosomes means___
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haploid
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DNA molecules longer than ____form 1 band with gel electrophoresis
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20 kb
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stabile aggregate of DNA and protein molecules is___
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chromatin
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2 sets of chromosomes (one pair of each) means___
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diploid
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the bead-like unit in chromatin, composed of histones is the____
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nucleosome
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essential for chromosome stability, at the end of the chromosome
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telomere
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compact at interphase, fewer genes located here
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heterochromatin
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enzyme that restores the ends of the DNA molecule in a chromosome is ___
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telomerase
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the seimiconservative copying of a DNA molecule is___
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DNA replication
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information (by complimentary base paring) on template strand of DNA is copied to a single strand RNA
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transcription
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information on mRNA is decoded on a ribosome to synthesize a polypeptide in___
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Translation
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The process of making RNA from a DNA template is called____
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transcription
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The process of cell division that ensures that each of the two daughter cells receives a chromosome complement identical with the complement of the parent cell is known as ___
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mitosis
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the Stage of meiosis in which bivalents become aligned on the metaphase plate is_____
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metaphase 1
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The mode of cell division which results in four daughter cells that are genetically different, with each cell containing one haploid set of chromosomes, is known as ___
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meiosis
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Hemophilia is a classic example of ____ inheritance
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x -linked
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In some species, sex chromosomes can be reversed. A male butterfly is XX. true or false?
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true
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