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Mitosis Chromosome • Chromosome: single ___________________associated with proteins Each species has a characteristic _____________of chromosomes in each cell. Histone • Histone: protein that ____________itself around. • Help maintain____________ of chromosome • keeps DNA _________tightly Chromatid • _________of a chromosome form as DNA copies itself in preparation for cell division Centromere • Holds 2 chromatids_______________. Also holds chromosome on the_________ fibers Kinetochores(Ke net a kor) • ____________covering of centromere • Provides ______________for chromosomal microtubules Sex Chromosomes • • • • Determine ________ Carries other __________for other characteristics XX-__________ XY-__________ Autosomes • All other____________________ except for sex cells • Every cell of an organism has _______ copies of each autosome(receives one copy from each parent) Homologous Chromosomes • 2 copies of each _________________ • Are the _________shape • Same size • Carry genes for some __________ Karotype • Photomicrograph of chromosomes • • • • Humans have ________Chromosomes 22 autosomes 2 sex chromosomes = 46 Diploid and Haploid Diploid(___) • 2 sets of chromosomes • All cells are except for _______cells • Haploid(n) • _____________of chromosomes • Sex cells only Mitotic Spindle • A network of _______________ • • • • Prokaryotic Cell Division Eukaryotic Cell Division Called_____________ Creates ______ daughter cells exactly like the original cell Meiosis Creates sex cells(___________) Cell Cycle • Repeating set of events that make up life of the cell • Interphase-___________ between cell divisions • Consists of 3 stages-G1, S, G2 Cell division has 2 phases 1)mitosis(__________- nucleus divides) • 2)Cytokinesis- division of cytoplasm of cell • Lasts ___________hours Interphase • G1 phase: offspring grows to _________size, Prepares for cell • • • • division, duplicates organelles, ___________ replication S Phase- DNA replication and chromosome duplication and_________ produced G(2) Phase: _____________, centriole replication, enzyme production, prepares for cell division __________Hours G(0) phase- cells do not copy DNA and _________prepare for cell division, resume normal activities. Some cells after maturity stay in this phase- nerve cells Interphase Continued • • • • • • Period of growth Period of digestion, excretion, protein synthesis Chromosomes _____________ Chromosomes are chromatin Nucleolus is ___________ Nuclear envelope ____________ Early Prophase • Centrioles begin to move with their developing daughter centrioles • • • • toward ____________ends Nuclear envelope begins to _______________ Nucleus _________________ Chromosomes ___________and are now considered chromatids Cytoskeleton ___________apart More on Prophase • Microtubule_______________ • Microtublules create _________located next to centrioles • Other microtublules form strands from ___________to centriole Late Prophase • Nuclear Envelope is ______ • Nucleolus __________ Metaphase • Chromatids move toward the _________of cell • Ends when all chromatid pairs have reached ___________ • • • • Anaphase Chromatid pairs separate at __________________ Each chromatid is now a ______________________ Chromosomes are pulled apart opposite sides on spindle fibers Plasma membrane is ______________________ Telophase • • • • • Spindle ____________ Nuclear membrane ____________ Chromosomes ________become chromatids again Nucleolus reforms Cytoskeleton re-forms Cytokinesis • Cleavage _______forms and constricts original cell _______smaller cells • Each cell has a copy of __________information in its chromosome Control of Cell Division • 3 main checkpoints – G1- proteins control whether cell will divide depending on size of _____and_________ – G2- DNA ______________check the results of DNA replication – Mitosis- proteins signal whether or not to exit mitosis • When Control is Lost: Cancer – Cancer may result if cells do not respond to__________ mechanisms. – ____________growth of cells