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Bio Exam II

The Cell Cycle

TermDefinition
Cell theory all cellular life comes from one or more cells
genetic material organizational & functional units of all organisms
Organization of genetic material - some cells are terminally different (don't divide) - cell division=cell reproduction - unicellular organisms: just reproduction - multicellular organisms: 2 functions - growth & development - renewal & repair
Cell Division - all parts of a cell divide into new cells - main function: distribute genetic material into daughter cells
genome cell's total genetic material
prokaryotes 1 circular DNA mol.
eukaryotes usually linear DNA mol. = chromosomes
Genes - info unit of DNA; structure of all proteins in a cell - genes @ a specific location on chromosome-locus - arranged linearly on chromosomes - humans: 20,000 genes
Chromosomes - colored body - DNA wrapped around proteins - highly organized
Histones - proteins in eukaryotic cells; associate w/ chromosomes
Nucleosomes - 8 histones w/ 146 bp of DNA wrapped around adjacent nucleosomes linked by about 60 bp
Chromatin - DNA/ protein complex in dispersed state - thread or fiber like - DNA is usually in this state - condenses into chromosomes
Eukaryotic DNA packaging Chromosome structure - each w/ unique shape and size - centromere: constricted area, site of spindle attachment - telomeres: end regions
Chromosome # - Haploid (n): having one set of chromosomes (1 of each chromosome)
Gametes gametes are haploid
Diploid (2n) - 2 sets; 2 of the same chromosome: homologous chromosomes/ homologous pair - same length, centromere location, genes - somatic cells are diploid
Phases of the cell cycle - cells don't divide continuously; gen. time varies ex. 8-10 hrs in tissue
All domains divide - Prokaryotes: Binary Fission - starts as origin of replication; DNA replicates; organelles & cytoplasm are allocated; cell divides
Interphase- time b/w cell division - growth & synthesis; not resting (metabolically active) - 90% of cell cycle - DNA is chromatin, condensed chromosomes not visible
G1 (gap 1) - growth & normal development & functions; prep for s phase - cell spends most time in G1
S phase (synthesis) - cell doesn't change ploidy - chromosomes duplicated- DNA & chromosomal protein synthesis
After replication - 2 sister chromatids; exact copies - connected @ centromere - kinetochores - proteins attached to centromeres - attached to microtubules, more chromosomes during division
G2 (gap2) - usually shorter than G1 or S - DNA still as chromatin - high metabolic activities, prep. for mitosis - centromere duplicates
Events of M phase mitosis & cytokinesis
Mitosis - nuclear division of somatic cells - continous process in 4 stages
Prophase - chromosomes condense - mitotic spindle forms - nucleus breaks down
Mitotic Spindle - microtubules responsible for separation of chromosomes - microtubules: hollow rode of protein tubin - miotic spindle oriented from pole to pole of cell
Metaphase - chromosomes align @ metaphase plate - kinetochores attach to spindle
Anaphase - sister chromatids separate, more to opposite poles - pulled by kinetochores - seperase: enzyme that separate sister chromatids - after separation: each chromatid considered a chromosome
Chromsome movement - microtubles not contractile, subunits easily assembles & disassembled - hypothesis: microtubles shorten @ centromere end
Telophase- opposite of prophase - chromosomes de-condense, nuclear envelope reforms, new nuclei identical to parent
Cytokinesis - cytoplasm & organelles divide - part of M phase - cytoplasmic division= 2 cells, w/ nucleus - overlaps w/ telophase - nucleus reverts to interphase condition
Cytokinesis in animal cells: cleavage - cleavage furrow - contractile ring forms- actin filaments & contractile proteins - contracts until parent cell pinched in two
Cytokinesis in plant cells - vesicles form Golgi align where metaphase plate was - fuse= cell plate - cell plate fuses w/ plasma membrane, becomes new plasma membrane - cell wall from contents of vesicles
Created by: tennadeleta.