Lecture 10 Flashcards
What is a chromatid?
The product of DNA replication, two identical DNA molecules
What is a chromatin?
DNA + a protein complex
What is a chromosome?
One molecule of DNA
what is a centromere?
Site of attachments of chromatids and kinetochore
What is a kinetochore?
Protein complex that assembles at centromere
What are the steps of the cell cycle?
Gap 1, S phase, Gap 2 and M phase
What happens in S phase?
DNA replication, there are 2 copies of the genome after S phase
What is interphase?
G1, S phase and G2
What happens in Mitosis?
The chromatids sperate
What are the phases of Mitosis?
- Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase and Cytokinesis
What happens in Prophase?
The cell has 2 chromosomes and 4 chromatids, it also has 2 MTOC that were produced during S phase. These move to the peripheral of the cell
What is a MTOC?
Microtubule Organizing Center
What happens in Prometaphase?
Microtubules polymerizes in all directions, hoping to catch a kinetochore. They will also attach to the membrane and other Microtubules
What happens in Metaphase?
The microtubules polymerize and depolymerize to push and pull the chromosomes to the metaphase plate. Kinesin and Dynein also help move them
What are the types of Microtubules and What do they do?
Kinetochore MT attach to the Kinetochores of chromatids, Astral MT attach to the membrane for security and Polar/overlapping MT elongate around cell and help cell stretch
What happens in Anaphase?
The kinetochore MT pull the chromatids apart to make chromosomes
What happens in Telophase and Cytokinesis?
The Cell is split into two daughter cells each with the correct chromosomes. Microfilaments and myosin squeeze the center until they split.
What are the 3 checkpoints during the Cell Cycle?
- Restriction point, 2. G2 checkpoint, 3. Metaphase/Anaphase checkpoint
What happens at the restriction point?
Cell is asked: Are there signals to divide? Is there enough space? Is there enough nutrients? If the answer is yes to all of these then S Phase happens
What happens at the G2 checkpoint?
The question asked is: Is DNA replication complete?
What happens at the Metaphase/Anaphase checkpoint?
The question asked is: Are all kinetochores attached by MT?
What are the 2 main classes of cancer causing genes?
Tumor Suppressor (TSG) and Proto-oncogene
What does a TSG normally due and what happens if it mutates?
TSG usually slows the cell cycle and acts as a break pedal. If it mutates cell division can happen uncontrollably
What does a proto-oncogene normally do and what happens when it mutates?
It normally promotes the cell cycle and acts as a gas pedal to the cell cycle. When mutated it ignores any signals to stop so cells divide uncontrollably
