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How are prokaryotes producing daughter cells?
What are the three steps of binary fission in prokaryotic cells?
1. Chromosome replication begins; 2. The two origin of replication are at the polar ends of the cell; 3. Replication finishes, and cell divide.
What is a chromosome before replication?
It is one chromatid
What is a chromosome after replication?
It is the X structure resulting by the joining of two sister chromatids.
What is a chromatid?
The thread-like strands into which a chromosome divides longitudinally during celll division.
What is chromatin?
The complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells.
What is a centromere?
The point on the chromosome which attaches the chromosome to a spindle fiber during cell division
What is a kinetochore?
A protein structure which attaches the spindle fiber to the chromosome.
What is mitosis?
The division of genetic material between two daughter cells
Where in the cell does mitosis happen?
What are the 4 phases of the cell cycle?
1. G1; S (DNA synthesis); G2; M (mitotic phase)
What happens during G1?
The cell grows until it is big enough to replicate it's chromosomes.
What hapens during the mitotic phase?
Mitosis and cytokinesis
What are the 5 stages of mitosis?
1. Prophase; 2. prometaphase; 3. metaphase; 4. anaphase and 5. telophase
What is a centrosome?
It is the region in the animal cell where the microtubules of the spindle are organized.
What happens during prophase?
The chromatic fibers become condensed and therefore more visible, and the mitotic spindle begins to form.
What happens during prometaphase?
The nuclear envelope breaks down. Kinetochore proteins are now attached to the centromere of the chromosomes.
What happens during metaphase?
The chromosomes become attached to the spindle fibers and are localized at the metaphase plate, equidistant from the spindle's poles.
What happens during anaphase?
The mitotic stage when chromatids are moved away from one another towards oposite poles of the spindle.
What happens during telophase?
The chromosomes move to the oposite ends of the cells and two nuclei are formed.
What happens during cytokinesis in animal cells?
A cleavage furrow is formed which pinches the cell in two and ultimately the cytoplasm of the two daughter cells is separated by new cell membranes.
What happens during cytokinesis in plant cells?
Along the old metaphase plate, a cell plate from membrane vesicles is formed and ultimately the cell wall is formedalong this plate.
What proteins are involved in controlling the cell cycle?
Cyclins and cyclin-dependent kinases.
What triggers the cell to pass the G1 checkpoint towards replication?
If the environment is favorable and the cell is grown enough.
What triggers the cell to pass the G2 checkpoint towards mitosis?
If the DNA was replicated in its entirety, and if all the DNA damage was repaired.
What triggers the cell to pass the M checkpoint?
If chromosomes are attached to the mitotic spindle.
How are cyclins degraded when not required?
By ubiquitinilation (ubiquitin-addition), which signals the cell that the ubiquitinilated protein is ready to be degraded by the proteasome.
What protein controls cyclins which subsequently control the cell cycle?
What does p53 do in a normal cell?
p53 will arrest the cell cycle by not permiting production of certain cyclins, which signal the cell to pass checkpoints it shouldn't.
What does p53 do in a mutated p53 cell?
p53 will permit the cell cycle to continue and finally replicate a mutated cell.