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

Terms Definitions
nuclear division that does not create genetic diversity
sex cells whose purpose is to fuse with one another (syngamy)
the fusion of two gametes, which produces a zygote
one cell created by the fusion of two gametes
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
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
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
diploid cells
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
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
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
two daughter nuclei form, nuclear envelopes arise from fragments of parent cell, nucleoli reappear, chromosomes decondense
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
the division of the nucleus
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
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
a sub-cellular region containing material that functions throughout the cell cycle to organize the cell's microtubules
the radial array of short microtubules that extends from the centrosome
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
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
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
a protein that has a cyclically fluctuating concentration in the cell to be active
the activated form of cyclin that triggers prophase of mitosis and phosphorylates other enzymes that catalyze individual steps of prophase
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
factors that cause mutations
factors that cause cancer
anchorage dependence
the need for a cell to attach itself to something else when dividing; cancer cells lack this
one haploid cell, does not fuse during syngamy, divides by mitosis
the multicellular diploid stage of a plant; makes spores
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)
occurs when homologous chromosomes find one another to create a group of four strands of chromatin (known as a tetrad); occurs during prophase I
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
the creation of gametes
the creation of sperm
the creation of eggs
density-dependent inhibition
a phenomenon in which crowded cells stop dividing; cancer cells lack this
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
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
number of divisions in mitosis
number of divisions in meiosis
number of daughter cells in mitosis
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
the structures in which gametes are made; only present in gametophytes
the structures within gametangia that make eggs
the structures within gametangia that make sperm
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
fern leaves that grow from the base of the plant, originating in a curled state so that they unravel as they grow
an immature frond
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
the male structure on a flower that is composed of a stalk and a bulb
the stalk of a stamen
the bulb of a stamen that makes pollen
the female structure on a flower that is composed of the ovary, ovules, style, and stigma; sometimes called a pistil
the stalk that comes from the ovary
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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