Chapter 12 terms Flashcards
mitosis
the division of the nucleus of a cell
Occurs in somatic cells only
Is coupled with another process called cytokinesis
meiosis
a special type of division that can produce sperm and egg cells
genome
All the DNA in a cell
can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells)
chromatin
The DNA in cells that are not actively dividing
DNA and proteins loosely bound in nucleus
chromosomes
Chromatin molecules in a cell are packaged into this once cell division begins
gametes
(sex cells; sperm and ovum)
- Have one set of chromosomes (haploid)
- Human gametes have 23 chromosomes
somatic cells
(all non-sex cells)
- Have two sets of chromosomes (diploid)
- Human somatic cells have 46 chromosomes
ploidy
the number of chromosome sets in a cell
haploid
one set of chromosomes per cell (N)
diploid
two sets of chromosomes per cell
humans: haploid # = 23; diploid # = 46 or 23 homologous pairs
(2N)
cohesins
Attaches duplicated chromosomes’ two sister chromatids along their lengths
centromere
is the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached
replicated chromosome
In preparation for cell division, DNA is replicated and the chromosomes condense
sister chromatid
Each duplicated chromosome has two of these (joined copies of the original chromosome), attached along their lengths by cohesins
cytokinesis
the process by which the cytoplasm divides into two daughter cells (occurs during telophase of mitosis)
(the division of the cell)
–couples with mitosis
cleavage
process animals undergo that begins with the formation of a contractile ring that constricts the cell at the midline forming an indentation
-cytokinesis occurs by this
cleavage furrow
indentation formed by contractile ring that constricts cell at midline in cleavage process
cell plate
forms during cytokinesis
-precursor structure to the cell wall formed by plants beginning to recruit cell wall materials to the middle of the cell
cell cycle
the series of events that prepare a cell for division and also the division process itself G1 “first gap” S-phase “synthesis” G2 “second gap” M-phase “mitotic phase”
interphase
(cell growth and copying of chromosomes in preparation for cell division
consists of G1, S-phase, and G2
mitotic spindle
a collection microtubules that orchestrates the movement of chromosomes during mitosis
centrosome
the microtubule organizing center
-In animal cells, assembly of spindle microtubules begins in this
aster
a radial array of short microtubules
kinetochores
protein complexes that are connected to centromeres
metaphase plate
midline of the cell
The replicated chromosomes are being directed towards this in prometaphase
daughter cells
Most cell division results in daughter cells with identical genetic information, DNA
binary fission
Bacteria and other prokaryotes reproduce through this process
(division in half)
cell cycle control system
The sequential events of the cell cycle are directed by a distinct cell cycle control system
cell cycle checkpoints
where the cell cycle stops until a go-ahead signal is received
G1 checkpoint
G2 checkpoint
M phase checkpoint
cyclins
type of regulatory protein involved in cell cycle control
cyclin dependent kinases (CDK)
type of regulatory protein involved in cell cycle control
- The activity of a Cdk rises and falls with changes in concentration of its cyclin partner
maturation-promoting factor (MPF)
is a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phase
