1. Lesson 1: Foundations to
Set the Stage
2. What is the cell cycle The cell cycle is the ordered series of processes of DNA replication
and mitosis or cell division
3. What are the two phases of interphase and mitotic phase
the cell cycle
4. During interphase: A typical cell spends most of its life in interphase, it is the metabolic
phase where the cell obtains nutrients and metabolizes them,
grows and replicates its DNA in preparation of mitosis. It has the
following three steps:
1: First growth phase (G1 or first gap)
2: Synthesis phase (S phase)
3:Second growth phase ( G2 or second gap)
5. First Growth Phase (G1 or -cells increase in size
first gap)
-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
6. Synthesis Phase (S phase) -DNA replicates
-Results in the formation of identical pairs of DNA (chromatids)
attached to a centromere
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-lasts 10-20 hours
7. Second Growth Phase ( G2 -RNA and protein Synthesis
or second gap)
- last 2-10 hours
8. Mitotic Phase (M phase) -Replicated chromosomes are aligned, separated, and move into
2 new, identical daughter cells
-takes about 30-60 minutes
9. How many steps in the Mi- 4 steps in the mitotic phase
totic Phase
- Prophase
- Anaphase
- Metaphase
-Telophase
10. Cytokenesis ( C phase) division of cytoplasm and organelles
11. Major points of cell regula- -G1 checkpoint
tion are entry and exit from
-S Phase
-G2 checkpoint
-M phase
12. 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
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-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
13. 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
14. -Exceptions to this are -Exceptions to this are those that are metabollically active, such as
those that are (Resting in
G0 phase) -granulocytes
-and the epithelium of the GI tract
15. Cell Cycling Time Amount of time from mitosis to mitosis
16. Check points in the Cell Cy- -The cell cycle is carefully controlled through a series of check-
cle: Keeping it All Under points
Control
-Variation in duplication or distribution of chromosomes dur-
ing 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 progres-
sion through mitosis
17. Progression through the 1. cyclines (D, E, A, B)
cell cycle is controlled
through two proteins: 2. Cyclin-dependent kinases (CDKs)
-Cyclin-CDK complex allows the cell to progress through each
phase of the cell cycle
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18. Locations of proteins Cy- -(G0-G1) : Cyclin D and CDK 4/6
clins (D, E, A, B) and CDKs
-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
19. Inhibitory proteins -prevent progression of the cycle when DNA damage is detected
-An example of an inhibitory protein is p53 (AKA TP53), P21,
Retinoblastoma protein (Rb)
20. 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)
21. 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"
22. 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 al-
lowed to continue