DNA & Replication Flashcards
Ch. 12, 16
What is the cell cycle
Life of a cell from the time of formation to its own division into 2 daughter cells
What is a genome
The totality of an organisms DNA
What is cohesin
Cohesin is a multi-protein complex that mediates cohesion between replicated sister chromatids (like a binder ring between sister chromatids)
What is a gamete
A reproductive cell with half as many chromosomes
When do chromosomes condense
After DNA replication
What is a centromere
The region of repetitive sequences in DNA where sister chromatids are connected
The “waist” of a duplicated chromosome
Define mitosis
Division of genetic material in the nucleus of a cell
*Not cell division
Define cytokinesis
Division of cell into 2 daughter cells
What are each of the following phases in cell division
1. G1
2. S
3. G2
4. M
5. Cytokinesis
- G1 = growth
- S = DNA replication
- G2 growth
- M = distribution of daughter chromosomes into 2 daughter nuclei
- Cytokinesis = division of cytoplasm into 2 daughter cells
What are 3 main properties of prophase
- Chromosomes condense
- Nucleoli disappear
- Miotic spindles begin to form
What are 3 main properties of prometaphase
- Nuclear envelop begins to fragment
- Microtubules extend from centrosome
- Kinetochores form at centromeres
What are 3 main properties of metaphase
- Centrosomes can now be found at opposite poles of cell
- Chromosomes have moved to metaphase plate
- Microtubules attach to kinetochores
What are 3 main properties of anaphase
- Sister chromatids separate
- Kinetochore tubules shorten at centrosome end
- Cell elongates as nonkinetochore mictotubules lengthen
What are 3 main properties of telophase
- Two daughter nuclei form in the cell
- Nuclear envelop arise from fragments
- Nucleoli reappear and chromosomes uncoil
What is the 1 main property of cytokinesis
- Formation of cleavage furrow
Where does spindle microtubule assembly occur
Centrosome
What is a centrosome
A subcellular region containing materials that function throughout the cell cycle to organize microtubules
Where are the centrioles located
The center of the centrosome
What happens to the centrosomes during the cell cycle
Interphase = Centrosomes duplicate
Prophase = Centrosomes move apart
Prometaphase = Spindle microtubules begin to grown out of Centrisomes
What is an aster
An array of short microtububles that extend from the centrosomes
What is a kinetochore
A protein structure at chromosome centromere that binds with kinetochore microtubules during prometaphase
What is the metaphase plate
The imaginary line where chromosomes align in the cell during metaphase
What is separase
An enzyme that separates sister chromatids
How does cytokinesis occur
With help from vesicles that come from the golgi
These vesicles move along microtubules to the middle of the cell (aka cell plate). The materials in the vesicles are used and the cell wall grows until a new plasma membrane arises from vesicles
How does binary fission work
- 1 OR moves to opposite side of cell. Chromosome replication begins at the origin of replications (OR).
- Cell elongates
- Replication finishes and plasma membrane is pinched inward until 2 cells are produced
What are cell cycle checkpoints
Stop and go signals that regulate the cell cycle
What is a maturation promotion factor
A.k.a. M-phase promotion factor
A cyclin-Cdk complex which regulated the passage of a cell from the G2 phase to the M phase
Explain how cyclin and Cdk levels rise and fall in regards to the cell cycle
Cyclin levels begin to rise during S phase and fall abruptly during anaphase. Cyclins associate with Cdk at the end of G2 phase, activating MPF which phosphorylates certain proteins that trigger mitosis. During anaphase, MPF switches itself off by destructing cyclin. Noncyclin Cdk remains in cell, inactive.