reasons for cell division
maintain workable ratio; growth; repair and replacement
interphase
longest part of the cell cycle; period where DNA is duplicated
4 stages of mitosis
prophase, metaphase, anaphase, telophase
prophase
chromosomes visible, spindle fibers form
metaphase
chromosomes move to the middle of the cell
anaphase
doubled chromosomes separate, chromatids move to opposite ends of the cell
telophase
spindles breakdown nuclear envelope appears
cytokinesis
division of cytoplasm, 2 daughter cells
result of mitosis
two IDENTICAL cells that are diploid~ have a chromosome from mother and chromosome from father
cancer
uncontrolled cell divison
chromosomes
strands of DNA wrapped around proteins and coiled tightly; found in the nucleus of eukaryotic cells and free-floating in prokaryotic cells
double helix
twisted ladder of DNA is called .....
3 parts of a nucleotide
sugar, phosphate group, and a nitrogen base
possible nitrogen bases
adenine, thymine, guanine, cytosine
hydrogen bonds
two strands held together by ....... bonds
importance of DNA replication
need exact copy of the DNA to its daughter cells so they can function correctly
importance of enzymes
breaks, rebuilds, and proofreads
process of DNA replication
1. enzyme breaks the hydrogen bonds between the paired nitrogen bases~allows DNA to "unzip"
2. new unprepared nucleotides are paired
3. enzymes link nucleotides along the constructed side of the DNA ladder by bonding sugar to phosphate backbone
4. DNA is
result of DNA replication
two identical DNA molecules~ each 'daughter' DNA molecule is composed of one OLD strand and one NEW strand, semi-conservative; each daughter cell will receive one of the two copies of DNA
chromatid
each copy of DNA is packaged here ____, on a double chromosome