chapter 12: the cell cycle Flashcards
the cell theory
all organisms are made of cells, and all cells arise from pre-existing cells
Rudolf Virchow
proposed that new cells are formed through cell division
cell division
the splitting of pre-existing cells to from new cells
embryos
newly developing organisms
meiosis
leads to the production of sperm and eggs; results in daughter cells that are genetically different from each other
gametes
male and female reproductive cells (sperm and eggs)
mitosis
leads to the production of somatic cells (non-reproductivee cells); results in daughter cells that are genetically identical to the parent cell
somatic cells
non-reproductive, “body-belonging” cells
the two ways that nuclei divide before cell division
meiosis and mitosis
cytokinesis
the division of the cytoplasm into two distinct cells
basic steps of cellular replication
(1) copying the DNA
(2) separating the copies
(3) dividing the cytoplasms to create two complete cells
Walther Flemming
in 1879, observed threadlike structures (chromosomes) in the dividing cells of salamander embryos; coined the term mitosis (from the Greek for “thread”)
Wilhelm Waldeyer
coined the term chromosome (“colored-body”) in 1888
chromosome
consists of a single long DNA double helix that is is wrapped around proteins (histones) in a highly organized manner
histones
the proteins around which the DNA is wrapped
gene
a region of DNA in a chromosome that codes for a particular protein or RNA
chromatid
each of the double-stranded DNA copies in a replicated chromosome
cohesions
proteins that join the two chromatids along their length
centromere
a specialized region of the chromosome where the connection between the two chromatids remains intact
sister chromatids
chromatid copies that remain attached at their centromere
M phase
occurs when cells are in the process of separating their chromosomes (“M” = mitotic or meiotic)
interphase
the phase during which cells spend most of their time; no dramatic changes in the nucleus are visible; chromosomes uncoil into extremely long, thin structures and no longer appear as individual threads; the cell is either growing and preparing to divide or fulfilling its specialized function in a mulitcellular organism
Alma Howard and Stephen Pelc
discovered (using what process? p. 255 review) that DNA replication occurs during a period in interphase; coined the term “cell cycle”
S (synthesis) phase
the part of interphase during which chromosomes are replicated
cell cycle
the orderly sequence of events that leads a eukaryotic cell through the duplication of its chromosomes to the time it divides
G1 phase
the gap between the end of M phase and the start of S phase; in multicellular organisms, cells perform their functional roles during this phase
G2 phase
the gap between the end of S phase and the start of M phase; cells uses this phase to prepare for M phase
chromatin
DNA wrapped around globular histone proteins (what’s the difference between this and a chromosome? — chromosomes consist of chromatin?)
the five subphases within M phase
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
prophase
chromosomes condense into compact structures
spindle apparatus
a structure consisting of microtubules that produces mechanical forces that (1) moved replicated chromosomes during early mitosis and (2) pull chromatids apart in late mitosis
MTOCs
“microtubule-organizing centers”; MTOCs define the two poles of the spindle apparatus and produce microtubules
polar microtubules
during prophase, microtubules, that extend from each spindle pole and overlap with one another
centrosome
a structure that contains a pair of centrioles
centrioles
two bundles of microtubules contained in the centrosome
cytoplasm
all the contents inside the cell membrane, excluding the nucleus
pulse-chase experiment
by (step 1) exposing experimental cells to a high concentration of a modified amino acid and then (step 2) washing it away and replacing it with the normal version of the amino acid, a pulse-chase experiment marks a population of molecules at a particular interval (the pulse) and then follows their fate over time (the chase)
microtubules
cytoskeletal components composed of alpha-tubulin polypeptides (at the minus end) and beta-tubulins (at the plus end)
prometaphase
“before middle-phase”; …
kinetochores
specialized structures at which the cytoplasmic microtubules attach to chromosomes; each sister chromatid has its own kinetochore, which is assembled at the centromere
kinetochore microtubules
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