Lesson 1: Foundations to Set the Stage – ✔
Focusing on Cellular Structure and Function – ✔
The Normal Cell Cycle – ✔-The cell cycle refers to the ordered series of processes of
DNA replication and mitosis, or cell division
-Cell nucleus regulates these processes by gathering and processing complexes
molecular information
Interphase and Mitotic Phase – ✔Cell division produces two identical cells through these
two major phases
During interphase: – ✔Cell grows and DNA is replicated through the following three
steps:
1: First growth phase (G1 or first gap)
2: Synthesis phase (S phase)
3:Mitotic Phse (M phase)
First Growth Phase (G1 or first gap) – ✔-cells increase in size
-reproduce RNA
-“quality assurance” test that the cell will be ready to synthesis DNA
-Length of time is variable, can be from hours to days
Synthesis Phase (S phase) – ✔-DNA replicates
-Results in the formation of identical pairs of DNA (chromatids)
-which are attached a t the centromere
-lasts 2-10 hours
Mitotic Phase (M phase) – ✔-Replicated chromosomes are aligned, separated, and
move into 2 new, identical daughter cells
-takes about 30-60 minutes
Major points of cell regulation are entry and exit from – ✔-G1 checkpoint
-S Phase
-G2 checkpoint
-M phase
Restriction Point – ✔-The transition from the resting phase into an actively dividing
phase (G0-G1) is a point where cellular transformation can occur
-During this time, cells pass through a transition phase known as a restriction point
-Extracellular growth factors trigger reentry into G1, and GF are required to send the
cells past the restriction point, or the point of no return
G0 Phase (resting phase) – ✔-After mitosis, cells may enter back into the G1 phase or
go into a resting phase, known as G0
-Most cells in the human body reside in G0
-Exceptions to this are those that are (Resting in G0 phase) – ✔-Exceptions to this are
those that are metabollically active, such as
-granulocytes
-and the epithelium of the GI tract
Cell Cycling Time – ✔Amount of time from mitosis to mitosis
Cell cycle video and image –
✔http://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation
__how_the_cell_cycle_works.html
Check points in the Cell Cycle: Keeping it All Under Control – ✔-The cell cycle is
carefully controlled through a series of checkpoints
-Variation in duplication or distribution of chromosomes during cell division can alter the
genetic information passed on to daughter cells, leading to cellular dysfunction and
disease, such as cancer
-These checkpoints monitor for DNA integrity and control progression through mitosis
Progression through the cell cycle is controlled through two proteins: – ✔1. cyclines (D,
E, A, B)
- Cyclin-dependent kinases (CDKs)
-Cyclin-CDK complex allows the cell to progress through each phase of the cell cycle
Locations of proteins Cyclins (D, E, A, B) and CDKs – ✔-(G0-G1) : Cyclin D and CDK
4/6
-Early S: Cyclin E and CDK 1/2
-Late S: Cyclin A and CDK 1/2
-G2: CDK 1/2 and cyclin A
-Before M: CDK 1 and Cyclin B
Inhibitory proteins – ✔-prevent progression of the cycle when DNA damage is detected
-An example of an inhibitory protein is p53 (AKA TP53)
DNA Damage Checkpoints – ✔-If DNA damage is present, cells are programmed to stop
dividing or undergo apoptosis (programmed cell death)
-The retinoblastoma protein (Rb), p53, and p21 are some of the most well-understood
inhibitory proteins (IP)
Inhibitory proteins p53 – ✔-Levels of this IP regulate several important target genes
-Will increase when DNA damage is present
-Protects against inappropriate signal proliferation
-sometimes called the “suicide gene”
M Phase Checkpoints – ✔When the cells prepare to divide, the chromosomes line up in
the mitotic spindle.
If the chromosomes are not properly aligned, division is not allowed to continue
Immunity – ✔
Cells of the Immune System – ✔