Cell Division Flashcards
cell division
reproduction at cellular level
purposes of cell division
reproduction of single-celled organisms
growth of multicellular organisms
repair and replacement of damaged cells
development of embryo
chromatin
material of which chromosomes of eukaryotes are composed
behavior of chromatin before cell division
becomes highly compact and visible with microscope
cell cycle
ordered sequence of events that extends from time cell is first formed from dividing parent cell until its own division

stages of cell cycle
interphase
prophase
metaphase
anaphase
telophase

interphase
active phase in life of cell where cell does its job
longest stage of cell cycle

phases of interphase
growth 1 (G1)
synthesis (S)
growth 2 (G2)
(phases of interphase)
events during growth 1 (G1)
growth
metabolism
(phases of interphase)
events during synthesis (S)
DNA replication
(phases of interphase)
events during growth 2 (G2)
growth
metabolism
formation of microtubules
mitosis
process of dividing 1 diploid cell into 2 genetically identical diploid daughter cells
stages of mitosis
prophase
metaphase
anaphase
telophase

cells which undergo mitosis
diploid (somatic) eukaryotic cells
(stages of mitosis)
prophase
phase of mitosis in which chromosomes become visible as paired chromatids and nuclear envelope disappears
1st stage of mitosis

(stages of mitosis)
metaphase
phase of mitosis in which chromosomes line up in middle of cell and become attached to spindle fibers
2nd stage of mitosis
longest stage of mitosis

metaphase plate
plane or region that is approximately equidistant from 2 poles of dividing cell
site where chromosomes align during metaphase
(stages of mitosis)
anaphase
phase of mitosis in which chromosomes split to opposite poles of spindle
3rd stage of mitosis
shortest stage of mitosis

(stages of mitosis)
telophase
phase in mitosis in which chromosomes move to opposite ends of cell and two nuclei are formed
4th stage of mitosis

cytokinesis
cytoplasmic division of cell at end of mitosis or meiosis
brings about separation into two daughter cells

process of cytokinesis in animal cells
pinching in of cell membrane at cleavage furrows
process of cytokinesis in plant cells
formation of cell plate between nuclei
factors which control cell division
presence of essential nutrients
growth factors (proteins that stimulate division)
density-dependent inhibition
anchorage dependence
anchorage dependence
need for cells to be in contact with solid surface to divide
cell cycle control system
cycling set of molecules in cell that triggers and coordinates key events in cell cycle
functions of checkpoints in cell cycle
stoping events
signaling events to proceed
3 major checkpoints in cell cycle
G1
G2
M
functions of G1 checkpoint in cell cycle
allowing entry unto S phase
causing cell to leave cycle (and entering a nondividing G0 phase)
cyclin
group of proteins that ensure cell tasks are performed as correct time and cell only moves to next stage when appropriate
4 main cyclins
cyclin D
cyclin E
cyclin A
cyclin B
tumor
abnormally growing mass of body cells
benign tumor
tumor which remains at original site
malignant tumor
tumor which metastisizes
metastasis
spreading of tumor to other locations
sex chromosome
chromosome involved with determining the sex of an organism
autosome
chromosome that does not determine sex
number of pairs of autosomes in eukaryotic cells
22 pairs
homologous chromosomes
chromosomes which are matched in length, centromere position, and gene locations
locus
position of gene
diploid cell
somatic cell
cell with 2 homologous sets of chromosomes (1 chromosome of each pair from each parent)
haploid cell
gamete
cell with 1 set of chromosomes (from 1 parent)
fertilization
union of sperm and egg
production of zygote
zygote
diploid cell resulting from fusion of two haploid gametes
meiosis
process of dividing 1 diploid cell into 4 haploid daughter cells
meiosis I
first round of cell division in meiosis wherein homologous pairs are separated

meiosis II
second round of cell division in meiosis wherein sister chromatids are separated

timing of meiosis II
before DNA replication gets to occur
stages of meiosis
prophase I
metaphase I
anaphase I
telophase I
prophase II
metaphase II
anaphase II
telophase II

(stages of meiosis)
prophase I
phase of meiosis in which chromosomes become visible as paired chromatids and nuclear envelope disappears
involves synapsis
1st stage of meiosis

synapsis
fusion of chromosome pairs at start of meiosis

bivalent
tetrad
pair of homologous chromosomes
(stages of meiosis)
metaphase I
phase of meiosis in which chromosomes line up in middle of cell and become attached to spindle fibers
2nd stage of meiosis

(stages of meiosis)
anaphase I
phase of meiosis in which chromosomes split to opposite poles of spindle
3rd stage of meiosis

(stages of meiosis)
telophase I
phase in meiosis in which chromosomes move to opposite ends of cell and 2 new haploid cells are formed
4th stage of meiosis

(stages of meiosis)
prophase II
phase of meiosis in which chromosomes become visible as paired chromatids and nuclear envelopes disappear
5th stage of meiosis

(stages of meiosis)
metaphase II
phase of meiosis in which chromosomes line up in middle of cells and become attached to spindle fibers
6th stage of meiosis

(stages of meiosis)
anaphase II
phase of meiosis in which sister chromatids split to opposite poles of spindles
7th stage of meiosis

(stages of meiosis)
telophase II
phase in meiosis in which sister chromatids move to opposite ends of cells and 4 new haploid cells are formed
8th stage of meiosis

genetic recombination
production of new combinations of genes
caused by crossing over
crossing over
exchange of corresponding segments between separate (non-sister) chromatids on homologous chromosomes

chiasma
site of attachment and crossing over on chromatids

karyogram
karyotype
ordered display of magnified images of one’s chromosomes arranged in pairs
function of karyograms
observation of homologous chromosome pairs
observation of chromosome numbers
observation of chromosome structure

trisomy 21
Down syndrome
3 sets of chromosome 21

symptoms of trisomy 21
symptoms of Down syndrome
mental retardation
characteristic facial features
short stature
heart defects
susceptibility to respiratory infections, leukemia, and Alzheimer’s disease
shortened life span
nondisjunction
failure of chromosomes or chromatids to separate normally during meiosis
effect of nondisjunction
formation of zygotes with altered numbers of chromosomes
