The Cell Cycle
What are the stages of the cell cycle?
G1, S, G2 (all of which constitute interphase) and M
What happens in the S phase?
Synthesis of new DNA (DNA replication)
This phase of mitosis features the disintegration of the nuclear envelope and microtubules connecting to the kinetochores of sister chromatids.
(Make sure you know all of those definitions.)
Prometaphase
What phase of mitosis is this?
Prometaphase!
What are each of the checkpoints of the cell cycle? Which is the most important for regulating the cell cycle and why?
G1 checkpoint, G2 checkpoint, and M checkpoints. G1 is the most important because cells that pass through this checkpoint typically go through the entire cell cycle.
True or False: Cyclins are always present in the cell, and cyclin-dependent kinases are not.
False
How do plant and animal cells differ in regards to cytokinesis?
Animal cells divide via a cleavage furrow, whereas plant cells divide by forming a new cell plate.
At what stage of mitosis are the chromosomes lined up equidistant from the poles of the cell?
Metaphase
Nondividing cells are in what specific stage of the cell cycle?
G0
If a cell develops a mutation that allows it to bypass the checkpoints of the cell cycle, what could happen?
It could turn into a cancer cell, where it rapidly divides without normal growth signals
What process do bacteria use to divide?
Binary fission
At what stage of mitosis do cohesins become split?
Anaphase
If a cell developed a deletion mutation in the gene encoding cyclin-dependent kinase, what do you think would occur?
Think about what cyclin-dependent kinase is and what it enables.
Cyclin-dependent kinase is the enzyme that binds to cyclin to form the maturation promoting factor. The MPF allows the cell to enter into the M phase. Without CDK, the cell would be unable to divide.
A bacterium undergoes cell division by __________, a plant undergoes cell division by ______; and an animal undergoes cell division by ________.
Binary fission; mitosis; mitosis
DAILY DOUBLE! If you get this correct, add 800 to your score.
A cell has thirty-six chromosomes at the beginning of G1. How many chromosomes does it have during prophase of mitosis?
Thirty-six! The number of chromatids doubles with DNA replication in the S phase, but the number of chromosomes stay the same.
What phase of mitosis is this?
Telophase!
A cell has five chromosomes (n=5). In G1, the cell will have ____ chromosomes and ______ chromatids. In G2, the cell will have _____ chromosomes and _____ chromatids.
5 chromosomes and 5 chromatids
5 chromosomes and 10 chromatids
What is MPF (Maturation Promoting Factor)?
A cyclin-Cdk complex that triggers a cell's passage past the G2 checkpoint into the M phase
Name all of the stages of mitosis and what occurs in each. (Sorry!)
PPMAT
Prophase - Chromosomes start to condense and centrioles begin to move toward opposite ends of the cell
Prometaphase - Nuclear envelope disappears, centrioles are at the ends of the cell, and microtubules bind to kinetochores of sister chromatids
Metaphase - The pulling of the microtubules causes chromosomes to line up in the middle of the cell
Anaphase - The sister chromatids are pulled apart
Telophase (and cytokinesis) - two nuclear envelopes form around each new set of chromatids, and the cytoplasm divides, resulting in two daughter cells
When eukaryotic chromosomes are replicated in preparation for either mitosis or
meiosis, the two copies of the chromosome are connected at the ____
Centromere