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96 Cards in this Set

  • Front
  • Back
genome
the complete complement of an organism's genes
centromere
The centralized region joining two sister chromatids.
chromatin
The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, it exists as a mass of very long, thin fibers that are not visible with a light microscope.
chromosome
A threadlike, gene-carrying structure found in the nucleus. Each one consists of one very long DNA molecule and associated proteins.
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.
cleavage furrow
The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate.
gametes
A haploid cell such as an egg or sperm. They unite during sexual reproduction to produce a diploid zygote.
cytokinesis
The division of the cytoplasm to form two separate daughter cells immediately after mitosis.
M phase
The mitotic phase of the cell cycle, which includes mitosis and cytokinesis.
meiosis
A two-stage type of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
meiosis I
The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
meiosis II
The second division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
metaphase
The third subphase of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate.
metaphase plate
An imaginary plane during metaphase in which the centromeres of all the duplicated chromosomes are located midway between the two poles.
Mitosis
A process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. It conserves chromosome number by equally allocating replicated chromosomes to each of the daughter nuclei.
heredity
The transmission of traits from one generation to the next.
genetics
The scientific study of heredity and hereditary variation.
gene
A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).
locus
plural, loci) A particular place along the length of a certain chromosome where a given gene is located.
asexual reproduction
A type of reproduction involving only one parent that produces genetically identical offspring by budding or by the division of a single cell or the entire organism into two or more parts.
sexual reproduction
A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents.
diploid cell
A cell containing two sets of chromosomes (2n), one set inherited from each parent.
haploid
A cell containing only one set of chromosomes (n).
M phase
The mitotic phase of the cell cycle, which includes mitosis and cytokinesis.
meiosis
A two-stage type of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
meiosis I
The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
meiosis II
The second division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
metaphase
The third subphase of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate.
metaphase plate
An imaginary plane during metaphase in which the centromeres of all the duplicated chromosomes are located midway between the two poles.
Mitosis
A process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. It conserves chromosome number by equally allocating replicated chromosomes to each of the daughter nuclei.
aneuploidy
A chromosomal aberration in which certain chromosomes are present in extra copies or are deficient in number.
barr body
A dense object lying along the inside of the nuclear envelope in female mammalian cells, representing an inactivated X chromosome.
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.
cytological maps
Charts of chromosomes that locate genes with respect to chromosomal features.
deletion
A deficiency in a chromosome resulting from the loss of a fragment through breakage. (2) A mutational loss of one or more nucleotide pairs from a gene
Down syndrome
A human genetic disease resulting from having an extra chromosome 21, characterized by mental retardation and heart and respiratory defects.
Duchenne muscular dystrophy
A human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and a loss of muscle tissue.
duplication
An aberration in chromosome structure resulting from an error in meiosis or mutagens; duplication of a portion of a chromosome resulting from fusion with a fragment from a homologous chromosome.
fragile X syndrome
A hereditary mental disorder, partially explained by genomic imprinting and the addition of nucleotides to a triplet repeat near the end of an X chromosome.
genetic map
An ordered list of genetic loci (genes or other genetic markers) along a chromosome.
genetic recombination
The general term for the production of offspring with new combinations of traits inherited from the two parents.
genomic imprinting
The parental effect on gene expression whereby identical alleles have different effects on offspring, depending on whether they arrive in the zygote via the ovum or via the sperm.
hemophilia
A human genetic disease caused by a sex-linked recessive allele, characterized by excessive bleeding following injury.
inversion
An aberration in chromosome structure resulting from an error in meiosis or from mutagens; specifically, reattachment of a chromosomal fragment to the chromosome from which the fragment originated, but in a reverse orientation.
linkage map
A genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes. The greater the frequency of recombination between two genetic markers, the farther apart they are assumed to be. See also genetic map.
linked genes
Genes that are located on the same chromosome.
map units
A measurement of the distance between genes; one map unit is equivalent to a 1 percent recombination frequency.
monosomic
A chromosomal condition in which a particular cell has only one copy of a chromosome, instead of the normal two; the cell is said to be monosomic for that chromosome.
mosaic
A pattern of development in which an organism consists of two sets of cells that differ according to which X chromosome is inactivated.
nondisjunction
An accident of meiosis or mitosis, in which the members of a pair of homologous chromosomes or sister chromatids fail to move apart properly.
parental types
Offspring with a phenotype that matches one of the parental phenotypes.
recombinant
An offspring whose phenotype differs from that of the parents.
sex-linked gene
A gene located on a sex chromosome.
translocation
An aberration in chromosome structure resulting from an error in meiosis or from mutagens; specifically, attachment of a chromosomal fragment to a nonhomologous chromosome. (2) During protein synthesis, the third stage in the elongation cycle when the RNA carrying the growing polypeptide moves from the A site to the P site on the ribosome. (3) The transport via phloem of food in a plan
trisomic
A chromosomal condition in which a particular cell has an extra copy of one chromosome, instead of the normal two; the cell is said to be trisomic for that chromosome.
wild type
An individual with the normal phenotype.
alternation of generations
A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants.
autosome
A chromosome that is not directly involved in determining sex, as opposed to a sex chromosome.
chiasmata
The X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis.
crossing over
The reciprocal exchange of genetic material between nonsister chromatids during synapsis of meiosis I.
fertilization
The union of haploid gametes to produce a diploid zygote.
gamete
A haploid cell such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.
gametophyte
The multicellular haploid form in organisms undergoing alternation of generations that mitotically produces haploid gametes that unite and grow into the sporophyte generation.
homologous chromosomes
Chromosome pairs of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. One homologous chromosome is inherited from the organism's father, the other from the mother.
karyotype
A method of organizing the chromosomes of a cell in relation to number, size, and type.
life cycle
The generation-to-generation sequence of stages in the reproductive history of an organism.
meiosis
A two-stage type of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
meiosis I
The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
meiosis II
The second division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
recombinant chromosomes
Chromosomes created when crossing over combines the DNA from two parents into a single chromosome.
sex chromosomes
One of the pair of chromosomes responsible for determining the sex of an individual.
somatic cell
Any cell in a multicellular organism except a sperm or egg cell.
spore
In the life cycle of a plant or alga undergoing alternation of generations, a meiotically produced haploid cell that divides mitotically, generating a multicellular individual, the gametophyte, without fusing with another cell.
synapsis
The pairing of replicated homologous chromosomes during prophase I of meiosis.
sporophyte
The multicellular diploid form in organisms undergoing alternation of generations that results from a union of gametes and that meiotically produces haploid spores that grow into the gametophyte generation.
syngamy
The process of cellular union during fertilization.
tetrad
A paired set of homologous chromosomes, each composed of two sister chromatids. Tetrads form during prophase I of meiosis.
variation
Differences between members of the same species.
zygote
The diploid product of the union of haploid gametes in conception; a fertilized egg.
MPF (M-phase-promoting factor)
A protein complex required for a cell to progress from late interphase to mitosis; the active form consists of cyclin and cdc2, a protein kinase.
cyclin
A regulatory protein whose concentration fluctuates cyclically.
cyclin-dependent kinase (Cdk)
A protein kinase that is active only when attached to a particular cyclin.
G0phase
A nondividing state in which a cell has left the cell cycle.
G1 phase
The first growth phase of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.
G2 phase
The second growth phase of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.
density-dependent inhibition
The phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another.
anchorage dependence
The requirement that to divide, a cell must be attached to the substratum.
checkpoint
A critical control point in the cell cycle where stop and go-ahead signals can regulate the cycle.
codominance
A phenotypic situation in which the two alleles affect the phenotype in separate, distinguishable ways.
complete dominance
A type of inheritance in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable.
epistasis
A phenomenon in which one gene alters the expression of another gene that is independently inherited.
pleiotropy
The ability of a single gene to have multiple effects.
polygenic inheritance
An additive effect of two or more gene loci on a single phenotypic character.
incomplete dominance
A type of inheritance in which F1 hybrids have an appearance that is intermediate between the phenotypes of the parental varieties.
chorionic villus sampling (CVS)
A technique for diagnosing genetic and congenital defects in a fetus by removing and analyzing a small sample of the fetal portion of the placenta.
amniocentesis
A technique for determining genetic abnormalities in a fetus by the presence of certain chemicals or defective fetal cells in the amniotic fluid, obtained by aspiration from a needle inserted into the uterus.