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103 Cards in this Set

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The RNA template present in telomerase.
guide RNA
The substage of meiotic prophase I, immediately preceding metaphase I, in which the bivalents attain maximum shortening and condensation.
diakinesis
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.
heterochromatin
A protein-containing material in chromosomes, believed to be responsible in part for the compaction of chromatin.
scaffold
The set of chromosomes in a cell or organism.
chromosome complement
Any cell of a multicellular organism other than the gametes and the germ cells from which gametes develop.
somatic cell
A structure composed of fibrous proteins on which chromosomes align during metaphase and move during anaphase.
spindle
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.
chromomere
The growth cycle of a cell; in eukaryotes, it is subdivided into G1 (gap 1), S (DNA synthesis), G2 (gap 2), and M (mitosis).
cell cycle
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.
nucleosome
The substage of meiotic prophase I in which homologous chromosomes synapse.
zygotene
A chromosome in which two X chromosomes are joined to a common centromere; also called a compound-X chromosome.
attached- x chromosome
The meiotic division in which the centromeres split and the chromosome number is not reduced; also called the equational division.
second meiotic division
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.
statistically significant
One of two X-linked forms of hemophilia; patients are deficient in blood-clotting factor VIII.
hemophilia A
A base or amino acid sequence that changes very slowly in the course of evolution.
conserved sequence
Chromatids produced by replication of a single chromosome.
sister chromatids
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.
metaphase
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.
significant
The theory that chromosomes are the cellular objects that contain the genes.
chromosomes theory of heredity
The tip of a chromosome, containing a DNA sequence required for stability of the chromosome end.
telomere
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.
histone
The sex chromosome present only in the heterogametic sex; in mammals, the male-determining sex chromosome.
Y chromosome
All chromosomes other than the sex chromosomes.
autosomes
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.
chromosome
The pre-DNA synthesis stage in the growth cycle of a cell; no DNA replication takes place.
G1 period
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.
degrees of freedom
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.
diplotene
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.
meiosis
The extent to which observed numbers agree with the numbers expected on the basis of some specified genetic hypothesis.
goodness of fit
The aggregate of histones and DNA in a nucleosome, without the linking DNA.
core particle
The diploid, spore-forming generation in plants, which alternates with the haploid, gamete-producing generation (the gametophyte).
sporophyte
division of the cytoplasm
cytokinesis
The level of compaction of eukaryotic chromatin resulting from coiling of the extended, nucleosome-bound DNA fiber.
30-nm fiber
the stage in the cell cycle in which mitosis occurs
M period
A statistical quantity calculated to assess the goodness of fit between a set of observed numbers and the theoretically expected numbers.
chi squared (X2)
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.
tetrad
Of a number, the product of all integers from 1 through the number itself; 0! is defined as equal to 1.
factorial
Term applied to the second meiotic division because the haploid chromosome complement is retained throughout.
equational division
The aggregate of DNA and histone proteins that makes up a eukaryotic chromosome.
chromatin
Highly repetitive DNA sequences associated with mammalian centromeres.
alpha satellite
The cellular structure, formed in association with the centromere, to which the spindle fibers become attached in cell division.
kinetochore
A gene located in the X chromosome; X-linked inheritance is usually evident from the production of nonidentical classes of progeny from reciprocal crosses.
x- linked gene
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.
mitosis
The meiotic division that reduces the chromosome number; sometimes called the reduction division.
first meiotic division
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.
euchromatin
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.
prophase
The middle substage of meiotic prophase I in which the homologous chromosomes are closely synapsed.
pachytene
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.
x chromosome
A germ cell that undergoes meiosis to yield gametes in animals or spores in plants.
meiocyte
The pairing of homologous chromosomes or chromosome regions in zygotene of the first meiotic prophase.
synapsis
A pair of homologous chromosomes, each consisting of two chromatids, associated in meiosis I.
bivalent
In genetic engineering, synthetic DNA fragments that contain restriction-enzyme cleavage sites that are used to join two DNA molecules. (See also Nucleosome.)
linker DNA
A chromosome, such as the human X or Y, that has a role in the determination of sex.
sex chromosome
Chromosomes that pair in meiosis and have the same genetic loci and structure; also called homologs.
homologous chromosomes
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.
nucleolus or nucleoli
Term applied to the first meiotic division because the chromosome number (counted as the number of centromeres) is reduced from diploid to haploid.
reductional division
A cell that gives rise to reproductive cells.
germ cell
An enzyme that adds specific nucleotides to the tips of the chromosomes to form the telomeres.
telomerase
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.
pascal's triangle
Imaginary plane, equidistant from the spindle poles in a metaphase cell, on which the centromeres of the chromosomes are aligned by the spindle fibers.
metaphase plate
The initial substage of meiotic prophase I during which the chromosomes become visible in the light microscope as unpaired thread-like structures.
leptotene
Gemes derived from a commmon ancestral gene, or proteins whose genes derive from a common ancestral gene. (See also Orthologous and paralogous.)
homologous
The final stage of mitotic or meiotic nuclear division.
telophase
Either of the longitudinal subunits produced by chromosome replication.
chromatid
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.
spore
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.
H4 histone
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.
satellite DNA
In plants, the haploid part of the life cycle that produces the gametes by mitosis.
gametophyte
A cell or organism of a species containing the set of chromosomes normally found in gametes.
haploid
A cell or organism with two complete sets of homologous chromosomes.
diploid
Failure of chromosomes to separate (disjoin) and move to opposite poles of the division spindle; the result is loss or gain of a chromosome.
nondisjunction
The post-DNA synthesis stage in the growth cycle of a cell; no DNA replication takes place.
G2 period
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.
anaphase
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.
interphase
The three-dimensional region occupied by a particular chromosome in the nucleus of an interphase or noncycling cell.
chromosome territory
In birds, the male has two copies of W sex chromosome and is called ___
Homogametic
A conventional measure of goodness of fit between a set of observed numbers and theoretical expectations is known as ___
chi square
Somatic cells of an organism normally have 40 chromosomes. What is the number of chromosomes present in the nucleus in telophase II of meiosis?
20
The pairing of homologous chromosomes during meiosis is known as____
synapsis
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?
0.75
The probability that all children in a four-children family will be girls is__
0.0625
What term describes the result of a statistical test in which the P value is less than 0.05?
statistically significant
A long meiotic stage lasting several days in most higher eukaryotes and is commonly divided into five substages is called___
prophase 1
The mechanism of restoring the ends of a DNA molecule in a chromosome relies on the enzyme called ___
telomerase
The ribosome incorporates an essential RNA molecule called___
rRNA
only one set of chromosomes means___
haploid
DNA molecules longer than ____form 1 band with gel electrophoresis
20 kb
stabile aggregate of DNA and protein molecules is___
chromatin
2 sets of chromosomes (one pair of each) means___
diploid
the bead-like unit in chromatin, composed of histones is the____
nucleosome
essential for chromosome stability, at the end of the chromosome
telomere
compact at interphase, fewer genes located here
heterochromatin
enzyme that restores the ends of the DNA molecule in a chromosome is ___
telomerase
the seimiconservative copying of a DNA molecule is___
DNA replication
information (by complimentary base paring) on template strand of DNA is copied to a single strand RNA
transcription
information on mRNA is decoded on a ribosome to synthesize a polypeptide in___
Translation
The process of making RNA from a DNA template is called____
transcription
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 ___
mitosis
the Stage of meiosis in which bivalents become aligned on the metaphase plate is_____
metaphase 1
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 ___
meiosis
Hemophilia is a classic example of ____ inheritance
x -linked
In some species, sex chromosomes can be reversed. A male butterfly is XX. true or false?
true