Biology 1 Notes 3/28
Biology 1 Notes 3/28 BIOL 11900
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This 3 page Class Notes was uploaded by jsmith22 on Sunday April 3, 2016. The Class Notes belongs to BIOL 11900 at Ithaca College taught by Professor Rebecca Brady in Spring 2016. Since its upload, it has received 18 views. For similar materials see Fundamentals of Biology I: Cells and Bodies in Biology at Ithaca College.
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Date Created: 04/03/16
● DNA and RNA Replication ○ DNA is made of two complementary strands ■ A pairs to T ■ C pairs to G ■ Held together with lots of hydrogen bonds ○ Each strand of DNA has a 5’ end and a 3’ end ■ 5’ the strand ends in a phosphate, beginning ■ 3’ strand ends in sugar ○ DNA strands are antiparallel ■ 5’ end matches with 3’ end ○ Each strand must have correct letters and be antiparallel in order to be complementary ○ New nucleotides are only added to the 3’ end ■ Loss of extra phosphate groups provide energy for the new bond ○ DNA polymerase is a large protein complex that synthesizes new DNA ■ DNA strand threads thru while new phosphates are added ■ Requires a primer to begin DNA synthesis ● Primase makes primers ■ Makes DNA from 5’ to 3’ ■ DNA synthesis occurs at the forks in a replication bubble ● Edges of the bubble called the fork ● Cell Cycle and Mitosis ○ Life cycle of a cell can be divided into multiple stages ○ Cells exit the cell cycle and go into G0 ■ This is where the cells do their bodily function ■ Most of the cells in your body are in the G0 phase ○ Chromosomes are single long pieces of DNA that contains thousands of genes ■ Most vertebrates are diploid two versions of each chromosome ■ At the beginning of mitosis chromosomes condense into chromatids ■ Identical copies of chromosomes made during S phase are sister chromatids ● They are glued together basically ○ Cell Cycle (Mitosis) ■ Prophase ● Chromosomes condense ● Begin to form long microtubules, becomes the spindle ■ Prometaphase ● Fully condensed chromosomes ● Spindle fibers attach at the centromeres of chromosomes ■ Metaphase ● Chromosomes are attached to spindles from both sides, pulled in both directions ● Chromosomes are lined up in the middle of the cell on the metaphase plate ● Critical to complete before next phase ■ Anaphase ● Sister chromatids are pulled apart by the spindle, become daughter chromosomes ■ Telophase ● Chromosomes in each side ● Nuclear envelope reforms ■ Cytokinesis ● The process of dividing the rest of the organelles in the cells ■ Cell cycle control system provide quality control for cell division ● G1 checkpoint is controlled by external signals and conditions ○ Growth factors proteins outside the cell that signal a cell to divide ○ Usually required to exit G0 ○ Density dependent inhibition crowded cells stop dividing ○ Anchorage dependent cells must be attached to divide ● G2 checkpoint internal ○ DNA ok? ○ Cell big enough?? ● M checkpoint metaphase of mitosis ○ The point of no return ○ Chromosomes sound alarm until all are attached to microtubules ● Meiosis ○ The formation of gametes ○ Homologous chromosomes Each person has two versions of each chromosome