Download Cell Cycle Notes

Cell Cycle Notes
I. Chromosomes: thread-like structures of DNA and histones (protein)
forming a unit called a nucleosome
A. Chromatid: 2 sister chromatids make up a chromosome
B. Centromere: attaches 2 chromatids
C. Chromatin: unraveled DNA
D. Humans have 23 pairs of chromosomes = 46 total (diploid/2n)
II. The Cell Cycle:
A. somatic (body) cell grows, prepares for division, and divides to form
2 identical daughter cells
Consists of 2 phases: Interphase (G1
S G2) + Cell Division (M)
B. Interphase – phase between mitosis, 90% of the time that elapses
“Gap”1 – cell growth & assembly of carbs, lipids, and proteins
“Synthesis” – DNA replication
“G”2 – prep for mitosis
1. Proteins and organelles are made during all 3 stages
2. Nuclear envelope is well-defined
C. Cell Division (M) – division of nucleus (mitosis) & cytoplasm (cytokinesis)
mitosis
Prophase: longest phase of M; chromosomes coil and become
visible while the nuclear membrane breaks down
centrioles: separate and move to opposite poles organizing
the mitotic spindle
spindle fibers: microtubules attach to centromere and move
sister chromatids at a site called the kinetochore
Metaphase: chromatids line up on the cell equator and centrioles are
at opposite poles
Anaphase: chromosomes move to opposite poles as spindles pull on
centromere
Telophase: 2 new nuclei form and nuclear membrane reforms
Cytokinesis: division of the cytoplasm