Zoology 101: Animal Biology Last Lecture Outline Lecture 13 1. Translation continued• initiation• elongation• termination2. Posttransational localization and Cotransational localization3. Mutations• Point mutations4. Protein folding and Protein destruction in a cellCurrent Lecture 1. Cell division in Eukaryotes vs prokaryotes 2. Mitosis3. Cell Cycle 4. Prokaryote Intro Cell division in Eukaryotes vs prokaryotes • Eukaryotes◦ meiosis- leads to the production of gametes; only function ◦ mitosis- leads to a production of all other types of somatic cells • Prokaryotes◦ Binary fission- copy DNA, separate DNA into 2 daughter cells▪ same process how mitochondria and chloroplasts divide Mitosis• Division of nucleus • Cytokinesis: division of of cytoplasm • Daughter cells: identical to parent cell and each other; “clones”• Functions ◦ Growth; ex. Fertilized egg, many divisions ◦ Repair/replacement◦ Asexual reproduction (yeast cells)• Chromosome: structure carrying genetic material◦ genes and non-coding DNA ◦ 46 chromosomes, 23 pairs◦ All have a counterpart ◦ Cells/organisms with pair of chromosomes are DIPLOID (2n); one comes from mother, 1 comes from father (humans)◦ Cells/organisms with unpaired chromosomes are HAPLOID(n); gametes • Process:◦ Each chromosome is replicated prior to mitosis (sister chromatids: replicated chromosomes)◦ Chromosomes become compact (condensed)at the start of mitosis.▪ Center: centromere- region where sister chromatids attach (middle)▪ kinetochore: either side of centromere; protein structure where microtubules (Mts) attach during mitosis Cell Cycle• Life of the cell• Sits in the resting stage (G0), stays here until it gets a divide signal • Interphase: ◦ G1: cell growth, duplication of organelles, prepared for DNA replication◦ S(DNA synthesis): DNA replication (ONLY time it replicates)◦ G2: more growth prepares to divide; centrosomes appear in the Microtubule organizing center (MTOC)◦ Mitotic: prophase, metaphase, anaphase, telophase, cytokinesis• Prophase◦ Nuclear envelope disappears◦ ER and Golgi degrade ◦ Chromosomes condense◦ centrosomes migrate to opposite poles in the cell◦ mitotic spindle forms: MT's grow from centrosome (some attach to chromosomes)▪ Kinetochore MT's: attach to kinetochores ▪ Non-kinetochore MT's : do not attach to kinetochores• Metaphase◦ chromosomes align on “equator” (metaphase plate) of the cell◦ Sister chromatid on each side of the metaphase plate • Anaphase◦ Cohesis (proteins that hold sister chromosomes together) degrade◦ Kinetochore MT's get shorter → sister chromatids separate, pulled to opposite sides of the cell◦ Non-kinetochore MT's get longer (causing all to elongate) • Telophase/Cytokinesis◦ nuclear envelope reforms ◦ Golgi and ER reappear ◦ Chromosomes decondense (not duplicated, own chromosome) ◦ Centrosomes disappear◦ Mitotic spindle breaks down ◦ Actin helps pinch it into 2◦ Organelles▪ Endomembrane: fragments into vesicle structures, reforms in daughter cell▪ Mitochondria: split between 2 daughter cellsProkaryotes • Binary fission ◦ duplication of chromosomes ◦ Continued growth of cells ◦ division into 2 cells ◦ short
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