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Genetics
Ch. 1-25
29
Biology
Undergraduate 2
09/12/2009

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Term
diploid number
Definition
(2n) characteristic number of chromosomes
Term
homologous chromosomes
Definition
chromosomes in diploid cells exist in these pairs. identical in size and location of the centromere
Term
haploid number
Definition
number in cell when they have only one chromosome from each chromosome pair
Term
chromosome theory of inheritance
Definition
inherited traits are controlled by genes residing on chromosomes faithfully transmitted through gametes, maintaining genetic continuity from generation to generation
Term
mutation
Definition
any heritable change
Term
allele
Definition
alternative form of a gene
Term
genome
Definition
complete haploid content of DNA specific to that organism
Term
biotechnology
Definition
use of modified organisms or their products
Term
chromosomes
Definition
vehicles for transmitting genetic information
Term
chromatin
Definition
genetic material unfolded and uncoiled
Term
prometaphase
Definition
period of chromosome movement
Term
metaphase
Definition
period of chromosome configuration following migration
Term
anaphase
Definition
chromatids of each chromosome disjoin from each other
Term
telophase
Definition
cytokinesis occurs
Term
prophase
Definition
chromosomes coil up and condense; centrioles divide and move apart
Term
synapse
Definition
early in meiosis homologous chromosomes form pairs in a process called...
Term
bivalent
Definition
two chromatids
Term
tetrad
Definition
four chromatids
Term
reductional division
Definition
first division in meiosis I, where the number of centromeres, each representing one chromosome, is reduced by one half
Term
dyad
Definition
sister chromatids joined at a common centromere (after meiosis I)
Term
equational division
Definition
second division during meiosis II (the number of centromeres remains equal)
Term
phases of prophase I
Definition
divided into leptonema, zygonema, pachnema, diplonema, diakinesis
Term
leptonema
Definition
interphase chromatin material begins to condense and chromosomes become visable. homology search begins
Term
zygonema
Definition
chromosomes shorten and thicken, rough pairing occurs, synaptonemal complex begins to form, paired homologs referred to as homologs (n # of homologs)
Term
pachynema
Definition
chromosomes coil and shorten, synapsis occurs, each homolog (or bivalant) is now evident as a double structure termed a tetrad, crossing over occurs
Term
diplonema
Definition
within each tetrad, each pair of sister chromatids begins to separate--chiasmata remain in contact
Term
chiasma
Definition
a point where nonsister chromatids have undergone genetic exchange through crossing over
Term
diakinesis
Definition
chromosomes pull further apart, nonsister chromatids remain loosely associated at chiasmata until terminalization. nucleolus and nuclear envelope break down, spindle fibers attach to centromeres. At end, lined up at metaphase plate of cell
Term
terminalization
Definition
as chromosome separation proceeds, chiasmata move toward the ends of the tetrad
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