A Human Approach to Biology, Week 6 Notes
A Human Approach to Biology, Week 6 Notes EBIO 1030-002
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This 5 page Class Notes was uploaded by Jenna Notetaker on Wednesday October 5, 2016. The Class Notes belongs to EBIO 1030-002 at University of Colorado at Boulder taught by Caitlin Kelly in Fall 2016. Since its upload, it has received 6 views. For similar materials see Biology-Human Approach 1 in Biology at University of Colorado at Boulder.
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Date Created: 10/05/16
EBio Week 6 Cell Division: Mitosis and Meiosis Prokaryotes Bacteria and Archaea divide a sexually by a process called binary fusion Each daughter cell gets an exact copy of the parent’s DNA Prokaryotes Mitosis in semantic cells (everything except for gametes) One parent cell divides into two identical daughter cells, daughter cells have same genetic material as parent cells Meiosis forms gametes (egg and sperm cells) One parent cell divides into four genetically different cells, daughter cells have half as much material as parent cells Cell Cycle 4 phases G1 first growth phase; makes more organelles S DNA replication G2 second growth phase; DNA error checking M mitosis or meiosis Chromosome compactly wrapped up piece of DNA Prior to replication, each chromosome is compacted of two single DNA molecules (homologous pairs) After replication, each chromosome is composing of a pair of 2 identical DNA molecules called sister chromatids that are attached to one another at the centromere Chromatin long, loosely wrapped strand of double helix DNA are wrapped in spools of proteins called histones Each DNA histone pools are a nucleosome DNA in a human cell stretched out would be about 2 meters long and packed in less than 10 micrometers in diameter DNA replication making copies of DNA in a cell Break bonds between the 2 nucleotides strands Add complimentary bases to open strands Dehydration synthesis between new nucleotides to create new daughter strand DNA replication requires many enzymes DNA helicase breaks hydrogen bonds between DNA strands DNA polymerase joins free nucleotides into a new strand of DNA Semiconservative replication each new DNA molecule consists of one new strand and one old strand One strand duplicates continuously, the other strand duplicates discontinuously (in segments) Each species has their own specific chromosome number Humans have 46 chromosomes Human body cells have two of each type of chromosomes Their chromosome number is diploid (2n) Haploid= n (half the total number of chromosomes) All except one pair of chromosomes are autosomes Autosomes are nonsex chromosomes Pairs of sex chromosomes differ between males and females (human females have 2 X chromosomes, human males have one X and one Y chromosome) Karyotype how many chromosomes are in an individual cell and can reveal certain major abnormalities EBio Week 6 When proofreading and repair mechanisms fail, and error becomes a mutation Mutation a permanent change in the DNA sequence Ionizing radiation, UV light, and environmental pollutants can all cause DNA mutations Clones exact copies of a molecule, cell, or individual (asexual reproduction or embryo splitting) Reproductive cloning techniques produce an exact copy of an individual Somatic cell nuclear transfer (SCNT) nucleus of an adult is transferred to an enucleated egg Egg cytoplasm reprograms differentiated DNA to act like undifferentiated DNA The hybrid cell develops into an embryo that is genetically identical to the donor individual Therapeutic cloning uses SCNT to produce human cells or embryos for research purposes Research may lead ultimately to treatments for people who suffer from fatal disease After Sphase comes mitosis Mitosis a nuclear (nucleus of the cell) division mechanism that maintains the chromosome number Asexual reproduction a single individual can reproduce by mitosis and cytoplasmic division Microtubules push and pull chromosomes (fishing line) Spindle networks of microtubules that attach to chromosomes Centromere middle of chromosome Kinetochore protein protector on centromere where spindles attach 4 stages of mitosis Prophase = P Metaphase = M Anaphase = A Telophase = T Prophase spindle begins to form Nuclear envelope breaks down Microtubules attach to chromosomes Metaphase chromosomes line up midway between the spindle poles Anaphase microtubules pull sister chromatids apart Telophase chromosomes reach the spindle poles Nuclear envelopes reforms Two new nuclei are formed (each with the same number as the parent cell) Cytokinesis cytoplasmic division (cell splits itself) Animal cells cleavage furrow (contractile ring pinches the cytoplasm in two) Plant cells cell plate (forms midway between the spindle poles and portions the cytoplasm) Telomeres a region of repetitive nucleotide sequences at each end of a chromosome Chromosomes are shortened with each round of DNA replication Telomeres act as buffers at the ends of the chromosome ad when the telomeres are gone, the cell dies Rare occasions, controls over cell division are lost and a neoplasm is formed Neoplasm a group of cells that lost control over how they grow and divide Neoplasm forms a lump (tumor) Malignant neoplasms (cancers) disrupt body tissues, both physically and metabolically Cancer cells grow and divide abnormally EBio Week 6 Capillary blood supply to cells may increase abnormally Cytoplasm and plasma membrane are altered Altered recognition proteins and weakened adhesion they can break loose and invade other parts of the body (metastasis) Asexual reproduction fast and energetically efficient, less error prone Recombination can lead to new adaptions for a changing environment (sexual reproduction) Meiosis produces gametes (egg and sperm) with a single set of chromosomes Meiosis I each duplicated homologous chromosome is separated from its partner Meiosis II sister chromatids are separated
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