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30 Cards in this Set
- Front
- Back
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Cell Cycle |
90% interphase - G1 - Synthesis of DNA - G2 10% cell division |
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Cytokine |
secreted molecules that bind specific membrane receptors change cyclin concentration |
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cyclins |
interact with cyclin dependent kinase -> activate activity control cell cycle |
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high concentration of cyclin D |
cells enter S phase |
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G1 |
growth normal functions preparation for S phase / replication |
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S Phase / replication |
duplicates DNA |
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G2 |
preparation for cell division organelles replicate molecules for cell division are synthesized checked for mistakes |
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Mitosis |
in somatic cells division of nucleus new nucleus identical to parental 4 phases: prophase metaphase anaphase telophase |
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prophase |
chromosomes condense, attach to microtubules of spindle fibers spindle pore and kinetochores |
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metaphase |
condensed chromosomes are at equatorial line ,microtubules attached |
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anaphase |
separated sister chromatids one set of chromosomes moves to each pole along microtubules |
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telophase |
gathered into two clusters -> future nucleus area dashed nucleus |
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cytokinesis in plants |
need to build up cell wall as well in telophase vesicles coming from golgi filled with carbohydrates/cellulose assemble in midline --> Cellplate cell wall formed when vesicles fuse |
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cytokinesis in animals |
actin + myosin filaments |
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cellular (sexual) reproduction needs as well |
meiosis |
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diploid organisms posses |
homologous chromosomes |
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meiosis general |
occurs in germ cells produces gametes reductional division --> haploid two sequential divisions -> 4 cells genetically different cells produced source of genetic variability -> random alignment of homologous chromosomes + crossing over |
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first division of meiosis |
like mitosis homologous chromosomes separate |
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prophase 1 |
leptonema - chromosomes form strings zygonema - homologous chromosomes align pachynema - crossing over diplonema - disassembling diakinesis - condense in tetrads |
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gametogenesis |
reduction in chromosome number by meiosis gaining of structural and functional character oogenesis spermatogenesis |
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oogenesis |
-finite population of stem cells -one gamete produced per meiosis -meiosis begins in fetus then delayed in prophase I for month and years -differentiation of gamete occurs while diploid -all chromosomes exhibit transcription during prophase I |
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spermatogenesis |
-spermatid to spermatozoa -stem cells continuously dividing by mitosis -4 gametes per meiosis -meiosis begins in puberty -differentiation of gamete occurs while haploid -sex chromosomes excluded from transcription during prophase I |
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sertoli cells |
-associated with gametogenesis -with developing sperm -N-cadherins, gap junctions, cytoplasmic channels -nourish developing cells -translocate sperm towards lumen -secrete seminal fluid (5%) -inhibit production to decrease pituitary gonadotropin -establish blood testis barrier-drugs + hormones + immune barrier |
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leydig cells (interstitial cells) |
located between seminiferous tubules secrete testosterone |
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sperm development |
spermatogonium (diploid) mitosis primary spermatocyte meiosis I secondary spermatocyte meiosis II early spermatid late spermatid spermiogenesis immature sperm (haploid) |
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axonemes |
-bundles of microtubules associated with proteins -form core of cilia and flagella -9 (2 subfibrils) + 2 microtubule arrangements (tubulin) -connected with nexin + dyenin ->movement by this motor proteins result in cilia + flagella movement |
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spermatogenesis changes (5) |
1. nuclear changes: DNA 2. nuclear changes: Morphology 3. cellular changes: organelles -acrosome -middle section -axoneme formation -cell surface -cytoplasmic reduction 4. maturation 5. capacitation |
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hormone control in spermatogenesis |
1. hypothalamus releases gonadotropin-releasing hormone (GnRH) at onset of puberty 2. GnRH stimulates pituitary gland: luteinizing hormone (LH) + follicle stimulating hormone (FSH) 3. LH stimulates leydig cells: androgenes 4. androgenes: stimulate spermatogenesis + negative feedback to hypothalamus and pituitary 5. FSH stimulates sertoli celly |
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errors in meiosis |
nondisjunction -> gametes with abnormal chromosome numbers parthenocarpic reproduction -> ability of plants to produce seeds without fertilization |
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deletion of chromosome 5 arm |
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