Chapter 12 Flashcards
What is the purpose of mitosis in multicellular orgnaisms?
- Development from zygote
- Growth and repair
Genome
All the DNA in a cell
Why is DNA coiled into chromosomes?
To condense so that each cell receives that accurate amount of genetic information
What does 1 chromosome consist of?
1 long coiled strand of DNA and protein
Centromere
Narrow waist between replicated chromosome where chromatids are attached
In which phase does the centriole replicate?
G2
What is the centrosome?
Microtubule organizing center
What forms from centrosomes?
Spindle microtubules and aster
How do microtubules shorten during anaphase?
Depolymerizing at the kinetochore
What do the microtubules that don’t connect to kinetochores do?
Overlap each other and elongate cell
What is the process that seperates animal cells?
Cleavage
What forms during cleavage?
Cleavage furrow
How do plant cells perform cytokinesis?
Cell plate forms from vesicles from golgi apparatus
How does a cleavage furrow split cell?
Actin microfilaments interact with myosin proteins to form ring and contract
Explain the steps of binary fission
Chromosomes replicates beginning at origin of replication and the two chromatin move to each side. Origins push to elongate and form new cells
If DNA is the same in every somatic cell, how do some cells divide quicker?
Through checkpoints
What is the cell cycle driven by?
Specific chemical signals present in cytoplasm
What is the most important checkpoint?
G1 checkpoint
What happens if cell at G1 checkpoint does not receive signal to go ahead?
It will enter G0, nondividing phase
What are cyclin-dependent kinases?
Regulatory protein that needs to be activated by cyclin to work
What is a cyclin?
Regulatory protein that activates Cdk to form complex that triggers cells passage past certain checkpoint
What is MPF?
Cyclin-dependent kinase and cyclin complex that triggers cell’s passage past G2 checkpoint into M phase
What happens to the cyclin of MPF after the M phase is over?
It is destroyed
How does the cyclin and MPF concentration change during the cell cycle?
Cyclin gradually increases and increases at point between G2 and interphase; MPF only appears during that point
What happens if not all kinetochores are connected to a microtubule?
Kinetochores send out internal signal to delay anaphase
What are the three external signals?
- Growth factors
- Density-dependent inhibition
- Anchorage dependence
What are growth factors
Proteins released that stimulate other cells to divide
What is density-dependent inhibition?
If area is too crowded, surrounding cells use receptor proteins to signal cell to stop dividing
What is anchorage dependence?
Most animal cells need to be attached to a surface before division (another cell or in culture)
How do cancer cells disregard growth factors?
- Make own growth factor
- Convey signal without presence of the receptor
- Have abnormal cell cycle control system
What is transformation?
Process that converts normal cell to cancerous cell
What is a benign tumor?
When cancerous cells remain at original site
What is a malignant tumor?
When cancerous cells invade surrounding tissues
What is the process of metastasize?
When malignant tumors transport cancer cells to other parts of body and form secondary tumors
