The Cell Cycle

• The stages a cell goes through in order to divide and form two identical daughter cells.
• - Growth to take place and repair tissues

• Progeria is premature aging
• Cause: Defect in DNA ( genetic material ), happens in early stage in embroytic stage, not genetic, affects gene that regulates cell
• Consequences: cell does not divide normally, growth is affected(won't grow tall), Repair(bruise wont heal, be slow), lots of wrinkles b/c old cells reforming but new cells dont get replaced, skin not very eleastic, joint pain, blad(lose hair), hard time bending, NO CURE

Cell is preparing for cell division, long, preparatory phase that occurs " in btwn " cell divisions

the first gap phase where the cell increases in size due to the production of proteins and organelles.

is DNA " synthesis " phase, where the genetic materical replicates

• - genetic material
• - DNA wrapped around histones
• - uncoiled, very thin
• - not visible in light microscope

• After s-phase
• - identical, connected by nucleotides
• - copies of genetic material
• - each one is a CHROMATID, the duplicated one is chromatin

• -> mitosis
• - genetic material folds on to itself
• - coiled genetic material, thicker, shorter, more condensed
• - visible under light microscope
• - only appear when cell is about to divide (mitosis)

• - protein, both sides of chromatid
• - moving genetic material apart
• - acting as an anchor for spindle fibers

the 2nd gap where the cell grows even further

• The DNA has been replicated. Also, notice the increased cell size as the cytoplasm has been
• enlarged

the process of dividing the nucleus into two identical nuclei

• - nuclear envelope starts to break apart
• - genetic material starts to coil
• - shorter, thicker, more condensed ( duplicated chromosome )
• - centrosome + centrioles in opposite sides
• - spindle fibers ( bundles of microtubules )
• - attached to kinetochore
• - no nucleolus ( RNA, DNA, PROTEIN ) -> scatter, spread apart

• animal cell - look at image
• plant cell - has cell wall, no centrioles
• aster means star-> does not form in plant cells

• - chromosomes change position
• - changes in spindle fibre so chromosomes line up

• - chromosomes are split apart
• - spindle fibres are gonna pull in oppiste directions
• - centromere is gonna split in half and 2 chromatid going to be split apart
• -> going to be called chromosomes b/c they are split apart
• - stained genetic material seen by dye
• - chromatid pulled in oppisite directions

• end stage
• - opposite of prophase
• - chromosome uncoil
• - nucleolus reforms
• - reformation of membrane
• - microtubules go bk in cytoskeleton ( no more aster )
• - made 2 genetic material
• - nuclear envelope reforms and spindle fibers dissapear

process of dividing of the cytoplasm of a cell into 2 equal halves

• Animal cells: actin filaments -> connected to plasma proteins
• - starts to shorten length, makes a groove in plasma membrane

• Plant cells: cell wall (thick) and rigid has to be split in half using golgi complex
• - corners can pinch away to form vesicles which is accuminating cellulose to make cell wall
• - vesicles fuse together to form cell plate
• - more and more cellulose is building up
• - cell plate fuses with cell membrane
• - cytoplasm splits in half ( 2 identical cells )

process of " dividing " a prokaryote into 2 identical cells.

• - does not hae muclear envelope
• - having only 1 DNA molecule
• 1. genetic material is copied
• 2. separate DNA using plasma membrane
• - Dna attaches to plasma membrane; plasma membrane grows longer btwn DNA (lengthens)
• moves DNA strand at the end of cell
• ( no microtubules, no spindle fibers)
• - cell elongates a bit taking in more fluids
• - plasma membrane moves inwards and creates a new cell wall