Chapter 12: The Cell Cycle Flashcards
What is the purpose of cell division?
- Reproduction
- Growth and Development
- Tissue Renewal
What is the genome?
All of the cell’s DNA content
What is a chromosome?
One strand of DNA that holds genetic material
What is a chromatin?
A complex (group) of DNA and protein
What is a gene?
Region of DNA that encodes a trait
What is the difference between the centromere and the cohesin protein?
Centromere - area where chromatids are joined
Cohesin protein - the protein holding them together
What are the 6 stages of cell division?
- Interphase
- G1
- S phase
- G2
- Mitosis
- Cytokinesis
What is interphase?
When the cell is just living life
What is G1 phase?
(Part of interphase)
- when the cell grows a bit larger
(Preparation for cell division)
What is S phase?
When the cell copies its DNA content
- One chromosome inside the nucleus will duplicate and produce sister chromatids (still one chromosome)
- These two chromatids are connected by centromere
What is G2 phase?
- Cell grows even more
- Checking that there are no mistakes in the copying of DNA
What is Mitosis and what are the 4 steps?
Cell division
PpMAT
Prophase (prometaphase)
Metaphase
Anaphase
Telophase
What is Prophase?
- The duplicated chromatin condense
- Mitotic Spindle forms
What is Prometaphase?
- Centrosomes at ends of spindles go towards the spindle poles
- Spindles contain microtubules and start attaching to the chromosomes
Prometaphase:
What is the centromere called?
What is the mitotic spindle called?
Centromere is called Kinetichore
Spindle is called Kinetochore Microtubule
What is Metaphase?
- Chromosomes align at the metaphase plate
What is Anaphase?
Cohesins are cleaved and the Kinetochore Microtubules pull the daughter chromosomes towards the poles
What is Telophase and Cytokinesis?
Telophase - Two nuclei form around the two sets of chromosomes
Cytokinesis - the cleavage furrow punches the cell into two
In Anaphase, how do the Kinetochore microtubules pull the daughter chromosomes to the poles?
The Kinetochores have motor proteins in them and the Kinetochore Microtubules walk towards the poles and pull the cargo (chromosomes) in that direction
Which is positive and negative? The spindle poles or the metaphase plate?
The spindle poles are negative
The metaphase plate is positive
Does the motor protein walk towards the positive or negative end of the Kinetochore microtubule?
Negative
In plant cells, Cytokinesis cannot occur because of the cell wall. What happens instead?
- The cell wall deposits vesicles through the center of the cell and forms a cell plate
- This cell plate becomes a new cell wall, and the cell is divided
Name the 4 types of signaling that could tell a cell when to divide.
- GPCR (g protein coupled receptors)
- RTK (receptor tyrosine kinase)
- Intracellular
- Ion Channels
Explain the concept of checkpoints, cyclins and cdks.
- Cdks (cyclin-dependent kinases) are always inactive and present in the cell
- When a cell passes a checkpoint and everything looks ok, Cdks are activated by specific cyclins
- Cdks phosphorylate proteins, which allow DNA replication / mitosis
What are two causes of cancer?
- Uncontrolled cell growth
- Damaged cells pass the checkpoints (leading to more reproduction of these cells and more mistakes are made)
What are 3 possible reasons for uncontrolled cell growth?
- signaling from a GPCR even though there’s no stimulating ligand present
- RTKs that are stuck in dimerized form
- Over expression of cyclin that regulates entry into mitosis
