Chapter 12: The Cell Cycle and Chapter 13: Meiosis Flashcards

Terms Definitions
mitosis
nuclear division that does not create genetic diversity
gametes
sex cells whose purpose is to fuse with one another (syngamy)
syngamy
the fusion of two gametes, which produces a zygote
zygote
one cell created by the fusion of two gametes
embryo
a multicellular zygote
binary fission
the way in which prokaryotes and bacteria divide when an exact copy of a cell is made, and then the copy and original split
somatic cells
non-sex cells
sister chromatids
copies of DNA before they become chromosomes; they are still bound at the centromere; they have the same alleles and the same genes
histones
protein groups that are present in DNA to help organize it
separate, repair, organize, make mRNA
roles of proteins in DNA
homologous chromosomes
pairs of chromosomes; each one in the pair has the same length, same shape, and same genes in same spot, but can have different alleles
alleles
different forms of the same gene
haploid cells
cells that have one type of chromosome (no homologous pairs)
diploid cells
cells that have two of each type of chromosome (homologous pairs); gives an insurance policy against mutations that can kill you
haploid cells
n
diploid cells
2n
prophase
chromatin fibers become tightly coiled, nucleoli disappear, each duplicated chromosome appears as two identical sister chromatids joined at their centromeres and along arms, mitotic spindle begins to form, centrosomes move away from each other
metaphase
centrosomes are at opposite poles of cell, chromosomes convene on the metaphase plate, for each chromosome kinetochores of sister chromatids are attached to kinetochore microtubules coming from opposite poles
anaphase
begins when cohesin proteins are cleaved, allowing two sister chromatids of each pair to part suddenly--each chromatid becomes a chromosome; daughter chromosomes move toward opposite ends of cell, cell elongates, two ends of cell are symmetric
telophase
two daughter nuclei form, nuclear envelopes arise from fragments of parent cell, nucleoli reappear, chromosomes decondense
cytokinesis
division of cytoplasm that finalizes the creation of daughter cells; animal cells have cleavage furrow, plant cells have cell plate
cell cycle
the life of a cell from the time it is formed from a dividing parent cell until its own division into two cells
mitosis
the division of the nucleus
meiosis
cell division which yields nonidentical daughter cells that have only one set of chromosomes; only occurs in gametes
mitotic phase
includes both mitosis and cytokinesis; shortest part of cell cycle
interphase
a long phase of the cell cycle that accounts for 90% of the cycle
G1 phase
"first gap" in which the cell grows; lasts 5-6 hours
S phase
"synthesis" in which the cell continues to grow and chromosomes are duplicated; lasts 10-12 hours
G2 phase
"second gap" in which the cell grows and prepares to divide; lasts 4-6 hours
M phase
the cell divides, the cycle repeats (lasts under an hour)
mitotic spindle
a structure that forms within a cell during prophase; consists of fibers made of microtubules and associated proteins; uses microtubules from the cytoskeleton, which partially disassembles before the mitotic spindle is formed; adding subunits of tubulin elongates spindle and taking them away shortens it
centrosome
a sub-cellular region containing material that functions throughout the cell cycle to organize the cell's microtubules
aster
the radial array of short microtubules that extends from the centrosome
kinetochore
a structure of proteins associated with specific sections of chromosomal DNA at the centromere; present in each of two sister chromatids of a replicated chromosome
metaphase plate
the imaginary plate that forms during metaphase at which the centromeres of duplicated chromosomes align
cleavage
the process by which cytokinesis occurs
cleavage furrow
the first sign of cytokinesis in animal cells, which is represented by a shallow groove in the cell surface near the old metaphase plate
cell plate
the sign of cytokinesis in plant cells in which vesicles derived from the Golgi move along microtubules to the center of the cell where they coalesce
origin of replication
a specific place on the bacterial chromosome at which cell division begins
checkpoint
a control point in the cell cycle where stop and go-ahead signals regulate the cycle; signals are transmitted via signal transduction
G0 phase
a nondividing, stalled state that ensues when no go-ahead signal is received by the cell at the G1 checkpoint
cyclin
a protein that has a cyclically fluctuating concentration in the cell to be active
MPF
the activated form of cyclin that triggers prophase of mitosis and phosphorylates other enzymes that catalyze individual steps of prophase
CDKs
enzymes in an inactive form that are present in consistent concentrations over the cell cycle; *most significant enzyme in regulating cell cycle
growth factors
molecules present in the cell cycle that act like hormones in that they cause a chemical change and send chemical signals; necessary for cell division
mutagens
factors that cause mutations
carcinogens
factors that cause cancer
anchorage dependence
the need for a cell to attach itself to something else when dividing; cancer cells lack this
spore
one haploid cell, does not fuse during syngamy, divides by mitosis
sporophyte
the multicellular diploid stage of a plant; makes spores
gametophyte
the multicellular haploid stage of a plant; makes gametes
alternation of generations
demonstrated by the plant life cycle because it alternates from sporophyte (diploid) to gametophyte (haploid)
synapsis
occurs when homologous chromosomes find one another to create a group of four strands of chromatin (known as a tetrad); occurs during prophase I
tetrad
a group of four strands of chromatin that is formed during synapsis in prophase I
crossing over
the exchange of exactly corresponding regions of two homologous chromosomes in a tetrad; causes genetic variation; occurs roughly 2-3 times per tetrad
gametogenesis
the creation of gametes
spermatogenesis
the creation of sperm
oogenesis
the creation of eggs
density-dependent inhibition
a phenomenon in which crowded cells stop dividing; cancer cells lack this
transformation
the sign of abnormal behavior in a normal cell that qualifies it as a cancer cell
benign tumor
a tumor that consists of cells that remain at the original site
malignant tumor
a tumor that consists of cells that become invasive enough to impair organ function
metastasis
occurs when tumor cells can enter blood vessels and travel to other parts of the body to grow
ectopic pregnancy
occurs when the embryo implants itself in the fallopian tube and begins to grow there; the baby will not survive, the mother can be endangered
1
number of divisions in mitosis
2
number of divisions in meiosis
2
number of daughter cells in mitosis
4
number of daughter cells in meiosis
nonvascular plants
plants known as bryophytes; classic example is moss
nonvascular plants
plants that typically form in large patches of green on the forest floor, dead logs, or bricks; do not contain xylem or phloem; usually are present only in sporophyte stage
gametangia
the structures in which gametes are made; only present in gametophytes
archegonia
the structures within gametangia that make eggs
artheridia
the structures within gametangia that make sperm
sporangia
the location on a plant at which spores are made; located in the capsule of the diploid sporophyte
vascular plants
plants the evolved second; contain xylem and phloem but lack seeds; classic example is a fern
fronds
fern leaves that grow from the base of the plant, originating in a curled state so that they unravel as they grow
fiddlehead
an immature frond
sori
black or brown structures on the underside of frond leaflets (known as sporangi) that are evidence for spore production
seed plants
plants that evolved third; called gymnosperms
seed plants
plants without fruits or flowers; produce naked seeds because they are not surrounded by fruit; examples include conifers, cycads, and Ginkgo trees
flowering plants
plants that have seeds, vascular tissues, flowers, and fruits; most successful group in kingdom plantae
flowering plants
plants known as angiosperms or anthophytes
stamen
the male structure on a flower that is composed of a stalk and a bulb
filament
the stalk of a stamen
anther
the bulb of a stamen that makes pollen
carpel
the female structure on a flower that is composed of the ovary, ovules, style, and stigma; sometimes called a pistil
style
the stalk that comes from the ovary
stigma
the top of the style on the carpel that receives the pollen
central cell
a cell that contains two haploid nuclei and is present within the ovule of a flowering plant
seven-cell female gametophyte
a structure contained inside each ovule that makes haploid eggs
double fertilization
one sperm fertilizes an egg and the other sperm fertilizes the central cell, which produces endosperm
tube cell
the cell from a male plant that grows down the style to the opening of the micropyle; grows a pollen tube
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