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Unformatted text preview: MT 430 Exam 1 How Do We Get to the DNA?- cellular environment is aqueous, membranes control movement of water and dissolved componenets through ion channels and active transport- bearing the membrane access to DNA o solution o surfactant Nucleus- nuclear membrane, keeps DNA separate from cytoplasm- regulate the movement of RNA and ribosomes- nucleolous Chromosomes- seen during metaphase- Centromere highly conserved center of DNA, point of attachment for microtubuli- Telomere, located at the end, highly conserved, function = stabilize linear DNA, eukaryotic, accounts for nuclei that are lost (keeps us alive) during DNA replication- Chromosome function = maintenance of DNA, helps make DNA replication a manageable process, regulates gene suppression, fits DNA into cell Number- Mammals, 22 pairs (44 chromosomes, 22 homologous pairs autosomes) - 2 sex chromosomes, (XX, XY) Ploidy (N)- number of homologous sets of chromosomes in a cell- haploid = 1N, sperm/egg- diploid = 2N- polyploidy = 3N, no seeds (banana) 4N (insects, amphibians) Mitosis Cell Cycle = mitosis & cytokinesis Mitosis = division of molecular material of DNA Cytokinesis = division of cytoplasm- starts after production of daughter cell is complete- interphase, growth longest phase o G1 = after mitosis, frowth and metabolic activity o G2 = cell is resting o G0 = non replicating cell o S = DNA synthesis- divide to give rise to 2 daughter cells, chromosomes are same as original cell, 4 stages 1) Prophase: replicate DNA dense, centrosomes appear 2) Metaphase: spindle fibers appear attach to centromere migration of chromosomes to center 3) Anaphase: chromosomes separate 4) Telophase: chromosomes reach end point, cytoplasm divides = results in 2 diploid cells *all cells undergo mitosis Meiosis- has 2 stages Stage 1 1) Prophase: crossing over first, genetic material shuffling 2) Metaphase 3) Anaphase: homologous, hairs separate 4) Telophase: Stage 2 1) Pro->Telo same = results in 4 haploid cells *not every cell undergoes meiosis Eukaryotic Prokaryotic- nucleus: linear DNA- proteins associated with DNA- billions of nucleus- organelles that contain DNA (genetic material) some have RNA- diff cell wall / structure - no organelles- or nucleus- DNA is circular- Exposed to intercellular enzymes- Size thousands, nucleic acid pairs- Has cell wall, outside diff sugars and proteins Mitochondria- has DNA- DNA is circular- genes of mitochondria encode enzymes that function in energy production- Some proteins originate from nucleus, accounts for hereditary status- In humans all mitochondria genes originate from ovacyte/egg, trace lineage 16,569 base pairs 37 genes Higher mutation rate 128 naturally occurring polymorphisms Maternal inheritance BIOCHEMISTRY OVERVIEW BUILDING BLOCKS OF DNA Nucleoside = base + sugar Nucleotide = base + sugar + phosphate Pentose Sugars...
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- Spring '08