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73 Cards in this Set
- Front
- Back
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cell division
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process by which a cell doubles its organelles & cytoplasm, replicates its DNA, & divides in 2
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mitosis
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division & distribution of cell's DNA to its 2 daughter cells such that each cell receives a complete copy of the original genome
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karyokinesis
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nuclear divison
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cytokinesis
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cell division
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interphase
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period of growth & replication of genetic material
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chromatin
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uncoiled DNA
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G1 phase
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initiates interphase; active growth phase & can vary in length; cell increases in size & synthesizes proteins; length of this phase determines length of entire cell cycle
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S phase
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period of DNA synthesis
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G2 phase
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cell prepares to divide; grows and synthesizes proteins
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M phase
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cell division occurs (mitosis), resulting in 2 identical daughter cells
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prophase
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chromosomes condense; centriole pairs separate & move toward opposite poles of cell; spindle apparatus forms b/t them & nuclear membrane dissolves, allowing spindle fibers to interact with the chromosome
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metaphase
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centriole pairs are at opposite poles of cell; fibers of spindle apparatus attach to each chromatid at centromere to align chromosomes at the center of the cell, forming the metaphase plate
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anaphase
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centromeres split so that each chromatid has its own distinct centromere, allowing sister chromatids to separate; sister chromatids are pulled toward opposite poles of the cell by shortening of spindle fibers
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telophase
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spindle apparatus disappears; nuclear membrane forms around each set of newly formed chromosomes; each nucleus contains same number of chromosomes (diploid number 2n) as original nucleus; chromosomes uncoil, resuming interphase form
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cytokinesis
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near the end of telophase, cytoplasm divides into 2 daughter cells, each with a complete nucleus and its own set of organelles; in animal cells, cleavage furrow forms & cell membrane indents along equator of the cell & pinches through the cell, separating the 2 nuclei
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cell plate
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expanding partition that grows outward from the interior of the plant cell until it reaches the cell membrane
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meoisis
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process by which sex cells are produced; cell duplicates its chromosomes before the process but produces haploid number of chromosomes; involves 2 divisions of primary sex cells resulting in 4 haploid cells called gametes
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interphase of meiosis
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parent cell's chromosomes are replicated resulting in 2N number of sister chromatids
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first meiotic division
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produces 2 intermediate daughter cells with N chromosomes with sister chromatids
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prophase I
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chromatin condenses into chromosomes, spindle apparatus forms, nucleoli & nuclear membrane disappear; synapsis; tetrad; crossing over
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homologous chromosomes
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chromosomes that code for the same traits
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synapsis
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homologous chromosomes come together & intertwine
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tetrad
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synaptic pair of homologous chromosomes containing 4 chromatids
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crossing over
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chromatids of homologous chromosomes break at corresponding points & exchange equivalent pieces of DNA; recombination results in increased genetic diversity
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metaphase I
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homologous pairs align at equatorial plane & each pair attaches to separate spindle fiber by its kinetochore
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anaphase I
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disjunction
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disjunction
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homologous pairs separate and are pulled to opposite poles of cell; accounts for Mendelian law; each chromosome of paternal origin separates from its homologue of maternal origin and either chromosome can end up in either daughter cell
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telophase I
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nuclear membrane forms around each new nucleus; each chromosome consists of sister chromatids joined at centromere
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second meiotic division
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very similar to mitosis; not preceded by chromosomal replication; chromosomes align at equator, separate & move to opposite poles & are surrounded by reformed nuclear membrane; new cells have haploid number of chromosomes
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fission
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asexual reproduction seen in prokaryotes; DNA replicates & a new plasma membrane & cell wall grow inward along midline of cell, dividing it into 2 equally sized cells with equal amounts of cytoplasm, each containing a duplicate of parent chromosome; occurs in unicellular organisms
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budding
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asexual reproduction; replication of nucleus followed by unequal cytokinesis; cell membrane pinches in to form a new cell that is smaller in size but genetically identical to parent cell; occurs in hydra and yeast
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regeneration
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regrowth of a lost or injured body part; replacement of cells occurs by mitosis; hydra and starfish
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parthenogenesis
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development of an unfertilized egg into an adult organism
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alternation of generations
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diploid generation is succeeded by a haploid generation; plants
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sporophyte
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diploid generation that produces haploid spores
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gametophyte
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haploid generation developed from sporophytes
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spores
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specialized cells with hard coverings that prevent loss of water
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natural vegetative propagation
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1. bulbs: split to form several bulbs
2. tubers: underground stems with buds that can develop into adult plants 3. runners: stems running above & along the ground, extending from main stem; can produce new roots & upright stems 4. rhizomes(stolons): woody, underground stems; can develop new upright stems |
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artificial vegetative propagation
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1. cut: piece of stem can develop new roots in water or moist ground
2. layering: stems of certain plants will take root when bent to the ground and covered with soil 3.stock: stem of one plant (scion), can be attached to rooted stem of another closely related plant called stock; cambium tissues must be in contact |
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gonads
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specialized organs that produce gametes
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testes
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male gonads that produce sperm in seminiferous tubules
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ovaries
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female gonads produce oocytes (eggs)
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spermatogenesis
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sperm production; diploid cells called spermatogonia undergo meiosis to produce 4 haploid sperm of equal size; spermatocytes (2n), spermatids (1n), spermatozoa
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oogenesis
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production of female gametes; 1 diploid primary female sex cell undergoes meiosis in ovaries to produce single mature egg; each meiotic division produces a polar body
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fertilization
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union of egg & sperm nuclei to form zygote with diploid number of chromosomes
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sperm pathway
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testes, vas deferens, ejaculatory duct, urethra, penis
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testosterone
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regulates secondary male sex characteristics including facial & pubic hair & voice changes
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acrosome
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caplike structure derived from golgi apparatus that develops over anterior half of sperm head; contains enzymes needed to penetrate tough outer covering of ovum
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follicle
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multilayered sac of cells that contains, nourishes, & protects an immature ovum; produce estrogen
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uterus
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site of fetal development
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oogenesis
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after menarche, 1 primary oocyte per month completes meiosis I, yielding 2 daughter cells of unequal size: a secondary oocyte & a polar body; meiosis II occurs during fertilization and yields 2 haploid cells: mature ovum & polar body
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zona pellucida & corona radiata
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layers of cells surrounding oocyte cell membrane
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estrogen
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steroid hormones necessary for normal female maturation; stimulate development of female reproductive tract & contribute to development of secondary sexual characteristics & sex drive; thickening of endometrium; secreted by ovarian follicles & corpus luteum
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progesterone
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steroid hormone secreted by corpus luteum during luteal phase of menstrual cycle; stimulates development & maintenance of endometrial walls in preparation for implantation
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menstrual cycle
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1. follicular phase
2. ovulation 3. luteal phase 4. menstruation |
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follicular phase
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begins with cessation of menstrual flow from previous cycles; FSH from anterior pituitary promotes development of follicle, which grows & begins secreting estrogen
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ovulation
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mature ovarian follicle bursts and releases an ovum; caused by a surge in LH that is preceded by a peak in estrogen levels
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luteal phase
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LH induces ruptured follicle to develop into corpus luteum which secretes estrogen & progesterone
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mestruation
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if ovum isn't fertilized, corpus luteum atrophies & estrogen & progesterone levels drop & cause endometrium to slough off
if fertilization occurs, developing placenta produces hCG (human Chorionic Gonadotrophin) maintaining corpus luteum & supply of estrogen & progesterone maintain uterus until placenta takes over production of hormones |
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acrosomal process
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once in contact with membrane of ovum, sperm forms tubelike structure which extends to the cell membrane & penetrates it, fusing the sperm cell membrane with that of the ovum; ovum completes meiosis II
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cortical reaction
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acrosomal reaction triggers calcium ions to be released into cytoplasm which result in formation of fertilization membrane; first mitotic division
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sexual reproduction in plants
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2n sporophyte --> meiosis --> 1n spore --> mitosis --> 1n gametophyte --> fertilization --> sporophyte
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gametophyte generation
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haploid; reproduces sexually; mosses
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sporophyte generation
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diploid; reproduces asexually; ferns & angiosperms
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stamen
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male organ of flower with filament & anther
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epicotyl
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precursor of upper stems & leaves
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cotyledons
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seed leaves; dicots have 2, monocots have 1
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hypocotyl
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lower stem & root
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endosperm
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grows & feeds embryo
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seed coat
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develops from outer covering of ovule; together with embryo, comprise seed
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meristem
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embryonic, undifferentiated cells
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apical meristem
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found in tips of roots & stems; growth in length
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lateral meristem/ cambium
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located between xylem & phloem; tissue permits growth in diameter & can differentiate into new xylem & phloem cells
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