Bio Exam 1 Lecture 1 Genetics the scientific study of heredity and hereditary variation Development the events involved in an organisms changing from a simple to a more complex or specialized form Evolution the idea that living species are descendents of ancestral species that are different from the present day ones Ecology the study of how organisms interact with each other and their environment Biology the scientific study of life Levels of organization Biosphere ecosystem communities populations organisms organs organ system tissues cells organelles molecules o Biosphere all places where life exists on earth o Ecosystem all living things in a particular area along with the nonliving components of the environment with which life interacts i e soil water atmospheric gases and light o Communities the entire array of organisms inhabiting a particular ecosystem o Population all the individuals of a species living within the bounds of a specified area o Organisms individual living things o Organ organ system a body part that carries out a particular function in the body organs that cooperate towards a larger function are organ systems o Tissues a group of cells that work together performing a specialized function o Cells life s fundamental unit of structure and function o Organelles various functional components present in cells o Molecules chemical structure consisting of two or more small chemical units called atoms Eukaryotic cell subdivided by internal membranes into various membrane enclosed organelles Prokaryotic cell DNA is not separated from the rest of the cell by enclosure in a membrane bound nucleus Interactions between organisms and their environment usually results in the cycling of nutrients in the ecosystem The molecular structure of DNA accounts for its ability to store information DNA cells genetic material An unfertilized egg cell or sperm cell has only half the amount of DNA of a human cell but when the egg gets fertilized the embryo s cell now has DNA from both parents Negative feedback accumulation of an end product of a process slows that process blocks a step Positive feedback an end product speeds up its own production stimulates a step Scientists attempt to understand natural phenomena using a process of inquiry that includes making observations forming logical hypothesis and testing them Inquiry a search for information explanation Hypothesis a tentative answered to a well framed question Controlled experiment designed to demonstrate the effects of one variable by testing control groups and experimental groups that differ in only one variable Lecture 2 Histone a small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA and plays a key role in chromatin structure Chromatin the complex of DNA and proteins that makes up eukaryotic chromosomes When the cells is not dividing chromatin exists in its dispersed form as a mass of very long thin fibers that are not visible with a light microscope Nucleosome the basic bead like unit of DNA packing in eukaryotes consisting of a segment of DNA wound around a protein core composed of two copies of each four types of histone Sister chromatid two copies of a duplicated chromosome attached to each other by proteins at the centromere and sometimes along the arms While joined teo sister chromatids make up one chromosome Chromatids are eventually separated during mitosis or meiosis II Centromere in a duplicated chromosome the region on each sister chromatid where they are most closely attached to each other by proteins that bind to specific DNA sequences this close attachment causes a constriction in the condensed chromosome Genome the genetic material of an organism or virus the complete compliment of an organism of virus s genes along with its noncoding nucleic acid sequences Somatic cell any cell in a multi cellular organism other than a sperm or egg and their precursors Gamete a haploid reproductive cell such as an egg or a sperm Gametes unite during sexual reproduction to produce a diploid zygote Mitosis a process of nuclear division in eukaryotic cells conventionally divided into five stages mitosis conserves chromosome number by allocating replicated chromosomes equally to each of the daughter nuclei Meiosis the first division of a two stage process of cell division in sexually reproducing organisms that result in cells with half the number of chromosome sets as the original cell o In humans meiosis only occurs in the gonads The mitotic phase which include mitosis and cytokinesis is the shortest of the cell cycle S phase cell continues to grow as it copies its chromosomes G1 phase cell growth G2 phase cell grows more as it completes preparation for cell division Cytokinesis cleavage furrow forms and pinches the cell in two Chromatin packing in eukaryotic chromosomes o DNA has the structure of a double helix o Proteins called histones are responsible for the first level of DNA packing in chromatin o Histones are bunched together to form nucleosomes o Next packing level is between interacting histone tails and nucleosomes o Next the fiber packs forming loops o Looped domains coil into the known shape of chromosomes The continuity of life is based on cell division Identically genetic material gets passed off to offspring DNA is packaged into structures called chromosomes During cell division each chromatin fiber becomes densely coiled and folded The function of cell division is to distribute identical genetic material to two daughter cells Each duplicated chromosome has joined copies of the original chromosome called sister chromatids The two chromatids each with an identical DNA molecule are initially attached along their lengths by protein complexes called cohesins sister chromatid cohesins Each sister chromatid has a centromere which contains specific DNA sequences where the chromatid is attached most closely to its sister chromatid Sister chromatids are separated by a mitotic spindle Actual separation of the sister chromatids takes place during mitosis The cell cycle consists of both DNA replication and cell division interphase and mitotic phase Mitosis in an animal cell o G2 of interphase o Prophase A nuclear envelope encloses the nucleus The nucleus contains one or more nucleoli Two centrosomes have formed by duplication of a single centrosome a centrosome is the region in an animal cell that organizes the microtubules of a spindle Chromosomes duplicated during
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