The Cell Cycle
And MITOSIS!!
The Cell Cycle
• Part of every cells life, how DNA is passed on
– Occurs as asexual reproduction in bacteria and
somatic cells of your body
• Ex: Every few days for skin cells
• Two phases: Growth (Interphase), Division
(Mitotic phase)
Growth Phase
• Called Interphase
– G1: normal cellular funcitons
• Increase cytoplasm, make more organelles
– S: DNA replicates (Synthesized)
• Duplicate DNA
– G2: preparing to divide
M Phase
• Mitosis
– Nucleus and doubled chromosomes divide
evenly among two daughter nuclei
• Cytokinesis
– Process of divide cytoplasm
– Creating two new daughter cells
MITOSIS
• 4 continuous phases which divide duplicated
chromsomes (containing DNA) evenly among two cells
• Prohpase:
– Sister chromatids visible
– Centrioles move
– Nucleolus dissapears, nuclear envelope breaks down
• Metaphase:
– Sister chromatids line up on equitorial plane
• Anaphase
– Separation of sister chromatids
• Telophase
– Chromatids uncoil into chromatin
– Nuclear envelopes reform
Prophase
• Chromatin condenses into
chromatids
– Chromatids double to form sister
chromatids of one chromosome
• Where they join is called a
centromere
• Once separated at the end of mitosis each
chromatid will be a chromosome in a new cell.
• Nucleolus disapears
• Nuclear envelope breaks down
• Centrioles move to poles, develop
spindle fibres
Metaphase
• Spindle fibers attach to centromeres
• Align sister chromatids in centre of cell
Anaphase
• Spindle fibers are pulled in by centriole
• Pulls sister chromatids appart
– Now individual chromosomes
• Groups of chromosomes at either pole of
the cell
Cytokinesis
• Completes cell division
• Divides cytoplasm into two
cells, each w/its own new
nucleus
– Cleavage furrow appears in
animal cells, pinches in the
centre to create two new cells
– Cell plate is laid down in plant
cells
– Contains new membrane and
wall material
• Occurs during telophase
Telophase
• Chromosomes uncoil, reform into
chromatin
• Spindle fibers disappear
• Nuclear envelope reforms
• Nucleolus appears
Plant and Animal Cells