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How do cells divide??
- Cell Replication
- Controling the Eukaryotic cycyle
- Failure to control the Eukaryotic Cell cycle: cancer
Where do cells come from?
every cell from a cell
cell division = cell reproduction and asecual reproduction
- Offspring genetically identical to original cell or organism (except mutations)
- All genes inherited from one parent
Binary Fission is??
Bacterial Cell Division
Asexual Resproduction ='s
Binary Fission (prokaryotes)
Where does Asecual Reproduction occur?
occurs in prokaryotic cells
in Asexual Reproduction there are _____ identical cells arise from one cell (except mutations)
What is the process of Asexual Reproduction??
- 1. Single circular chromosome duplicates (copies identical except for mutations)
- 2. Copies begin to separate from each other
- 3. Cell elongates, and chromosomal copies separate further
- 4. Plasma membrane grows inward at midpoint to divide into two cells
Asexual Resproduction can also equal
Cell division produces new cells in order to ??
- Produce new unicellular cells
- Health wounds and replace damaged cells/tissues
- Grow and develop
What are the three key events in a cell cycle??
- Cell growth and chromosome replication
- Chromosomes segregate
- cell division
M phase ='s
Mitosis + Cytokinesis
What makes up Interphase??
What makes up everything inside M phase
Levels of DNA Packaging
- 2-nm double stranded DNA molecule
- 11 nm nucleosomes
- 30 nm chromatin fiber
- Organization around a central scaffold
Homologous pair of chromosomes ='s
Maternal chromosome and Paternal chromosome
S phase is what?
Chromosome duplication of sister chromatids ---> chromosome distribution to daughter cells
G2 is Prior to what??
Prior to Mitosis
The mitotic Spindle ='s
- Mitotic spindle begining to form
- Condensed chromsomes
- Cytoskeleton is dissembled: spindle begins to form
- Golgi and ER are dispersed
- Nuclear envelop breaks down
What happens in Prometaphase
Chromosomes attach to microtubles at the kinetochores
Each chromosome is oriented such that the kinetochores of sister chromatids are attached to microtubules
Chromosomes move to equator of the cell
What happens in metaphase
- Alignment of chromosomes along metaphase plate
- -not an actual structure
- -future axis of cell division
What happens in Anaphase
Proteins holding centromeres of sister chromatids are degraded, freeing individual chromosomes
Chromosomes are pulled to opposite poles (anaphase A)
Spindle poles move apart (anaphase B)
in anaphase chromosomes move towards centrosoms by the ...??
dissolving "glue" by proteolysis of one subunit of cohesin commplex
What happens in Telophase
Chromosomes are clustered at opposite poles and decondense
Nuclear envelopes re-form around chromosomes
Golgi complex and ER re-form
Cytokinesis happens in ...??
what are the basic problems in Cell cycle control??
DNA must be replicated once per cell cycle
Sister chromatids must segregate accurately
Cell division must be coupled to growth and conditions
Events must ve coordinated
What controls cell cycle progression?
Cyclins and Cyclin-Dependent Kinases
in G2/M checkpoint Progression what is the relationship??
there is a relationship between Cyclin B levels and CDK1 activity
cyclin B + CDK1 =MPF
For the cell cycle Cyclin B is _____ But ____ ______?
Cyclin B is necessary, but NOT sufficient
In the cell cycle inhibitory _________ msut be _______ before MFP is ______
Phosphate must be removed (phosphate) before MFP is active (active cdk1)
Different CDK/Cyclin Complexes are Important at _____???
at Different Points in the Cell Cycle
The Spindle Checkpoint is what complex??
Anaphase promoting complex (APC)
What do Internal Signals that Regulate Cell Cycle Progression do ??
DNA Damage (G2/M checkpoint)
Dincomplete replication (G2/M checkpoint)
Chromosomes are misaligned (Mitotic/spindle checkpoint)
What are the External signals that regulate cell cycle progression
Growth Factors (G1/G0 checkpoint)
in the Mitotic cell cycle G1.G2 ='s
Gap or Growth phases
in the Mitotic cell cycle S ='s
Synthesis-when DNA is replicated
in the Mitotic cell cycle interphase ='s
Cancer is .....
breaching the controls that maintain normal homeostasis
What does cancer do??
- Does not require growth factors
- No density-dependent inhibition
- Anchorage independent
- Ignore DNA damage (G2/M checkpoint)
- Enter M (pass G2/M checkpoint) w/ incompletely replicated DNA
- Bypass M/spingle checkpoint w/ misaligned chromosomes
Development of cancer is a .....???
a Multi-Step Process
a tumor grows froma single cancer cell
invade neighboring tissue
spread to other parts of the body
may survive and establish a new tumor in another part of the body
What consists of Proto-Oncogenes??
- Growth factor receptor
- Ras Protein
- Src Kinase
Growth factor receptor in proto-oncogenes is
more per cell in many breast cancers
what does the Ras protein do in proto-oncogenes
Activated by mutations in 20-30% of all cancer
What does Src kinase do in proto-oncogenes
activated by mutations in 2-5% of all cancers
Tumor-suppressor Genes consist of what??
Rb protein does what in the tumor suppressor genes?
mutated in 40% of all cancers
p53 does what in tumor-suppressor genes?
mutated in 50% of all cancers
Activated Proto-oncogenes Promote??
Proto-oncogenes normally promote??
cell growth in response to proper signals
Oncogenes are ??
overactive: always promote cell-growth (gasoline tank always full)
What role do oncogenes play?
Proto-oncogenes normally promote cell division under proper conditions
oncogenes promote cell division all the time (constituively)
What is an example of proto-oncogene??
what is an example of an oncogene??
Inactivated Tumor Suppressor Genes lead to ____?
What do Tumor Suppressor genes normally do??
nomally inhibit cell growth
What happens when mutation inactivate TS genes?
It prevents their ability to inhibit cell growth
What does Radiation do??
some cancer cells are more susceptible to death from DNA damage-lost the ability to properly repair
drugs toxic to dividing cells
side effects due to damage to normally dividing cells
Specific to the relevant mutation
- -Few exist
- -no on cure for all cancer
- -not enough yet know about cell biology/cancer cell biology
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