BIO 101 1st Edition Lecture 18 Outline of Last Lecture I Genes II Purposes of studying Genetics III Human Blood Types IV Codominance Outline of Current Lecture II Cells III The cell cycle IV Mitotic phase V Asexual reproduction VI Telomeres VII Meiosis Current Lecture Is your body making any new cells right now What kind o Yes Skin cells hair cells Are certain types of cells replaced faster What might be examples o Blood cells skin cells stomach lining cells Are certain types of cells never replaced or slowly replaced What might be examples o Brain cells Cells have regular cycles of growth and division The cell cycle is an ordered sequence of events in the lifetime of a cell There are two broad phases o Interphase 90 of cells lifetime Normal Cell function o Mitotic phase Active cell division The cell cycle Healthy cells only enter the mitotic phase if duplication is needed These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Most of a cells lifetime is spent in interphase During this the cell o Performs its normal functions During mitotic phase the cell Undergoes active division mitosis Splits into two offspring cells cytokinesis The result of the mitotic phase is two genetically identical offspring Mitosis nucleus divides Asexual cell reproduction in prokaryotic cells Goes from one cell to having two chromosome divides Called binary fission o Requires DNA replication o Synthesis of more cytoplasm o Simpler than in eukaryotic cells Cell division in plant cells leads to growth or vegetative reproduction No cleavage furrow in rigid plant cell instead build new plasma membrane and cell wall down the middle of plant cell to separate from inside out Aspen stand of clones means asexual reproduction predominates Asexual reproduction only needs one parent One parent produces genetically identical offspring There is no sperm or egg involved Cell division in animal cells leas to growth of organism Cleavage furrow in cell surface Cell multiplication unrestrained cancer Stopping the uncontrolled cell division can stop cancer growth Telomeres Every time a cell divides the telomere gets shorter After a critical number of cell division functional DNA is lost which means almost certain death for the cell Many chemotherapy drugs are used to treat cancer by killing cells undergoing mitosis What side effects have you heard of related to chemotherapy treatment for cancer With your understanding of mitosis can you explain some of the side effects of chemotherapy Penicillin works by stopping the reproduction of a cell IN class writing Is sex necessary What is sex o The recombination or exchange of DNA Do bugs have sex o Yes Do trees have sex o Yes They advertise they are ready to reproduce by showing flowers Do bacteria have sex o Bacteria can exchange genes but not during reproduction o Bacteria can have sex but there reproduction is asexual Can organisms reproduce without sex o Yes Sex is not necessary for reproduction of some organisms Flatworm Starfish Meiosis Reducing the Genome by half Each chromosome in a homologous pair replicates to form a sister chromatid In the first division of meiosis the homologous pairs separate In the second division of meiosis the sister chromatids separate This results in four haploid cells of which two contain a single copy of one of the original chromosomes and the other two contain a single copy of the other chromosome Too many or two few sex chromosomes Turner Syndrome o Short height o Web of skin between neck and shoulders o Underdeveloped ovaries often sterile o Some learning difficulties Klinefelter syndrome o Underdeveloped testes o Lower testosterone levels usually infertile o Development of some female features o Long limbs and slightly taller than average Super Males o Taller than average o Moderate to severe acne o Intelligence may be slightly lower than average Metafemales o May be sterile o No obvious physical or mental problems Sexual reproduction takes two parents Two parents reproduce genetic offspring The definition of male vs female Females produce the larger gamete Males produce the smaller more motile gamete Reproduction and sex is influenced by the environment in many species not just by the genetics Sexual reproduction leads to variation Three major processes mean variation is the normal for sexual reproduction o Independent assortment o Random fertilization o Crossing over Each gamete is genetically unique The point of sexual reproduction is hoping that your children will be better adapted to survive than you are Meiosis is not the same as mitosis E is for sex I is all by yourself