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Barbara McClintock (Her Life (Achievements (Genetics Society of America…

- - - - Life at University
        
        During her undergraduate years, she became happier and relaxed (Famous Scientists, 2015). She started socializing more through joining a jazz band and being elected president of the women’s freshman class (Famous Scientists, 2015) which reflected her described independent personality (UPI, n.d.).
      - Degrees
        
        Barbara had a very extensive education at Cornell University. She majored in biology in 1919 and received her Bachelor of Science in agriculture degree in 1923 (Famous Scientists, 2015).
        
        She achieved her Master’s of Science in Botany in 1925 specializing in cytology genetics and zoology (Famous Scientists, 2015).
        
        In 1927, she earned her Ph.D. in Botany (Famous Scientists, 2015) and she was a leader in maize (corn) cytogenetics (UPI, n.d.).
        
        In graduate school, she focused her work and soon to be future career on microscopic chromosome analysis of maize (The Editors of Encyclopedia Britannica, 2017). She was one of the firsts to study cytogenetics through the use of maize (Pray and Zhaurova, 2008).
    - - The teachers at Brooklyn’s Erasmus Hall High School was aware of intelligence and believed would most likely become a college professor (Famous Scientists, 2015). However, her mother objected the idea as that would turn Barbara into an “oddball” hence, did not go to college (Famous Scientists, 2015) until 1919, as she attended Cornell University in Ithaca, New York (Famous Scientists, 2015).
  - - - She developed a technique to help visualize maize chromosomes and explored many genetic concepts such as genetic recombination through microscopic analysis (UPI, n.d.).
      - She created the first genetic map for maize which helped explain the connections between the chromosomes and physical traits (UPI, n.d.).
    - - Harriet B. Chreighton
        
        Aside from her personal research work, she guided Harriet B. Creighton (a graduate student at the time) (Famous Scientists, 2015) and together, they published “A Correlation of Cytological and Genetical Crossing-over in Zea Mays (corn)” (The Editors of Encyclopedia Britannica, 2017) - which challenged the original idea of “beads on a string” (Ravindran, 2012).
        
        This publishment established that chromosomes are the basis of genetics (The Editors of Encyclopedia Britannica, 2017). They researched the behavior of chromosomes together through their improved staining technique but at the time, they did not know what DNA was in chromosomes (Famous Scientists, 2015). Through this technique, they were able to prove the existence of chromosomal crossover or genetic recombination in the late 1940s (Ravindran, 2012) and that during the process in which sex cells are created, DNA can shuffle and rearrange (Famous Scientists, 2015). #
  - - - Due to her publications in the 1930s, she was elected Vice President of the Genetics Society of America and President in 1944 (The Editors of Encyclopedia Britannica, 2017).
    - - She received the fellowship in 1933 to study in Germany, however, she later left due to Nazism (The Editors of Encyclopedia Britannica, 2017).
    - - She returned to Cornell discovering they would not hire a female professor so she continued her research as she was funded by the foundation from 1934 to 1936 (The Editors of Encyclopedia Britannica, 2017).
    - - She was then hired by the University from 1936 to 1941 (The Editors of Encyclopedia Britannica, 2017).
    - - Despite skepticism in her work throughout her career, her research was generally widely accepted, especially in the 1960's-1970's (UPI, n.d.). This led to her achievement of the National Medal of Science in 1970 and the Nobel Prize for Physiology or Medicine in 1983 (UPI, n.d.). She was the only woman that achieved that category (UPI, n.d.).
- - - - Meiosis is not to be confused with mitosis! Has 2 major categories; Meiosis I and Meiosis II (Medical Institution, 2015).
        
        Meiosis I:
        
        Before Meiosis I occurs, the sex cells undergo the life cycle of a cell, which includes the; G1, S, and G2 phases where their DNA is duplicated during the S phase and turns into sister chromatids (Medical Institution, 2015).
        
        The first stage of Meiosis I is Prophase I in which the DNA condenses into chromosomes and the sister chromatids are combined at the centromere (Medical Institution, 2015). #
        
        The chromosomes then undergoes synapsis where two homologous chromosomes (or two pairs of sister chromatids) are paired up (one paternal and one maternal) (Medical Institution, 2015).
        
        The nuclear membrane breaks down and centrosomes move to the opposite ends of the cell (Medical Institution, 2015). Microtubules then appear and attaches to the chromosomes (Medical Institution, 2015).
        
        DNA is then switched between the overlapping pairs of chromosomes which is the process of recombination or crossing over that Barbara along with Harriet discovered (Medical Institution, 2015). The chromosomes are now no longer copies and each is unique (Medical Institution, 2015).
        
        The next stage is Metaphase I where the chromosomes align randomly at the “equator” (Medical Institution, 2015). #
        
        The chromosomes then separate from their pairs and move to the two poles during Anaphase I (Medical Institution, 2015). Sister chromatids remain together as the two pairs of chromosomes separate resulting in one pair in each cell (Medical Institution, 2015). #
        
        Telophase I and Cytokinesis follows where the cell divides into 2 new daughter cells (Medical Institution, 2015). #
        
        Meiosis II:
        
        From the 2 new daughter cells, each one undergoes Meiosis II which is more similar to Mitosis than Meiosis I (Medical Institution, 2015). The first stage of Meiosis II is Prophase II. The chromosomes condense, the nuclear envelope breaks down, and spindle fibers form (Medical Institution, 2015). The difference from Prophase I is that the daughter cells only have one copy of the homologous chromosome therefore there are now 23 chromosomes in each daughter cell and no synapsis or crossing over can occur. #
        
        The next stage is Metaphase II where the chromosomes align at the equator (Medical Institution, 2015). #
        
        Anaphase Ii follows where the chromosomes are pulled apart as the microtubules shorten (Medical Institution, 2015). #
        
        8/9. In Telophase II, the nuclear membrane reforms and the cytoplasm is divided into two more daughter cells (Cytokinesis) (Medical Institution, 2015).
        
        From one cell, there are now 4 unique cells called haploid gametes with one copy of each chromosome (Medical Institution, 2015). As one female and male haploid gamete combines, creates a diploid embryo (Medical Institution, 2015).
  - - - For example in plants; if there are 10 genetically identical plants that cannot withstand frigid temperatures and it gets really cold one night and frost forms, all the plants will die (Ejdio, n.d.). However, if there are 10 genetically different plants due to variation, some might survive (Ejdio, n.d.).
        
        From this, entire plant species are not extinct as the ones that do survive can reproduce passing on the gene of survival in frigid temperatures (Ejdio, n.d.).
        
        This idea connects to the important concept of evolution within species. As diversity allows for the survival of different environmental conditions, some survive which can help keep species alive (Ejdio, n.d.).