Lesson 6 Definitions Flashcards
chromatin
the cell’s collection of DNA, together with associated proteins
histone
any of a group of basic proteins found in chromatin
nucleosomes
basic structural unit of DNA packaging in eukaryotes. The structure of a nucleosome consists of a segment of DNA wound around eight histone proteins and resembles thread wrapped around a spool. The nucleosome is the fundamental subunit of chromatin.
kinetochore
a complex of proteins associated with the centromere of a chromosome during cell division, to which the microtubules of the spindle attach
centromere
the region of a chromosome to which the microtubules of the spindle attach, via the kinetochore, during cell division
mitosis
interphase → prophase → metaphase → anaphase → telophase → cytokinesis
meiosis
the process by which haploid cells form from diploid cells
binary fission
performed by all bacteria and some eukaryotes (protozoans)
budding
formation of a new organism by the protrusion of part of another organism
karyotype
preperation of chromosomes in mitosis
nondisjunction
crossing over: occurs during prophase I of meiosis, involves the swapping of genetic info on homologous chromosomes
crossing over
occurs during prophase I of meiosis, involves the swapping of genetic info on homologous chromosomes
gametogenesis
in female animals, results in one egg and three polar bodies, only the egg produces a viable offspring
trisomy
causes Down’s syndrome
karyotype
preparation of chromosomes in mitosis
spindle
cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells (composed of proteins)
sister chromatid
the identical copies (chromatids) formed by the DNA replication of a chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said to be ‘one-half’ of the duplicated chromosome. A pair of sister chromatids is called a dyad
daughter chromosome
a chromosome that results from the separation of sister chromatids during cell division. Daughter chromosomes originate from a single stranded chromosome that replicates during the synthesis phase (S phase) of the cell cycle
nondisjunction
failure of chromosome pairs to separate properly, usually during meiosis
polar body
each of the small cells which bud off from an oocyte at the two meiotic divisions and do not develop into ova.
homologous
in the same place
chromosomes
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes
monosomy
the state of having a single copy of a chromosome pair instead of the usual two copies found in diploid cells
trisomy
extra chromosome copy, causes Down’s syndrome
heredity
the passing on of physical or mental characteristics genetically from one generation to another
