Chapter 9 - Cellular Reproduction PDF

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Cellular Reproduction...

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Chapter 9 – Cellular Reproduction 

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Cells reproduce by cell division -parent cell gives rise to 2 daughter cells o Each daughter cell has a complete set of hereditary info and half the cytoplasm from the parent Chromosome – 2 long strands of nucleotides wound around each other – double helix Units of inheritance – gene – segments of DNA The specific sequence of nucleotides in genes spells out instructions for making the proteins of a cell The cell division of eukaryotic cells – mitotic cell division After cell division the daughter cells may differentiate, becoming specialized for specific functions Stem cells – found in embryonic tissue – don’t have former function – programmable to specific needs Potency of an organism – multiple differentiated cell types Sexual reproduction – offspring is produced by fusion of gametes (sperm and egg) from two adults o Gametes have half the genetic info from each parent cell Asexual reproduction – offspring are formed from a single parent o Cloning – offspring is identical to parent and to each other Bacteria reproduces asexually – can grow and reproduce very quickly DNA in prokaryotic cell is contained in a chromosome – 1-2mm in circumference o No nucleus Prokaryotic fission – splitting in 2 o Anchor point to cell wall and reproduces a copy of itself o When copy is made- binary fission o Separate into 2 daughter cells o Faster that eukaryotic cell division Eukaryotic chromosomes are longer and have more DNA than prokaryotic (human chromosomes 10-50x more DNA) o Human chromosome about 50-250million nucleotides long DNA is coiled down into histones Telomere - The two ends of chromosomes – stability Centromere – holds DNA helices together after replication o Attachment site for microtubules that move the chromosomes during cell division Eukaryotic cell cycle o Interphase – acquisition of nutrients, growth, and chromosome duplication  G1 – acquisition of nutrients and growth to a proper size  S – DNA synthesis when every chromosome is replicated  G2 -completion of cell growth and preparation for division into daughter cells

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o Late interphase – centriole pairs separate o Mitotic cell division – mitosis (division of nucleus)  Early prophase – spindle microtubules begin to form between separating centriole pairs  Prophase – nucleus disappears, microtubules attach to kinetochore located at centromere  Metaphase – microtubules line up at center  Anaphase – sister chromatids separate  Telophase – start to separate, nuclear envelopes start to form  Cytokinesis – plasma membrane pinched off from microfilament cytoplasm is divided between 2 daughter cells Duplicated chromosome consists of 2 identical DNA double helices (sister chromatids) attached to each other at the centromere In plant cells – carbohydrate filled vesicles move to the equator of cell fusing to form cell plate growth factor – hormone like molecules Cyclin-dependent kinases (CDKs) o Kinases are enzymes that phosphorylate other proteins, stimulating the proteins activity o CDKs can only bind to cyclins o Can be found throughout interphase o Help drive cell cycle – checkpoint  Successfully completed DNA synthesis 3 checkpoints o G1  S – suitable for replication o G2  mitosis – DNA has been accurately and completely replicated o Metaphase  anaphase – all chromosomes are attached to spindle and aligned at equator of cell...