3. 2. 2 All Cells Arise from other Cells Flashcards
Within multicellular organisms, do all cells retain the ability to divide?
Not all cells retain the ability to divide, Eukaryotic cells that do divide show a cell cycle
What happens to Eukaryotic cells that do divide during a cell cycle?
1 - DNA replication occurs during the interphase of the cell cycle
2 - Mitosis is the part of the cell cycle in which an Eukaryotic cell divides to produce two daughter cells, each with identical copies of DNA produced by the parent cell during replication.
What are the 5 stages the cell cycle?
The 5 stages of cell cycle are -
1 - Interphase
2 - Prophase
3 - Metaphase
4 - Anaphase
5 - Telophase of Mitosis
What happens to the behaviour of Chromosomes during Interphase?
1 - During the interphase the cell prepares for mitosis by growing larger.
2 - DNA replicates so that each chromosome now consists of two sister chromatids, connected by a structure called the centromere.
3 - The mitochondria produce more ATP which will provide the energy for cell division.
What happens to the behaviour of Chromosomes during Prophase?
During the Prophase the Chromosomes condense (they become shorter & fatter) and the nuclear envelope disintegrates.
The centrioles move to opposite poles of the cell & form spindle fibres.
What happens to the behaviour of Chromosomes during Metaphase
The chromosomes line up along the middle of the cell.
They attach to the spindle fibre by their centromere.
What happens to the behaviour of chromosomes during Anaphase?
The centromere splits & the chromatids are pulled to the opposite poles of the cell.
What happens to the behaviour of Chromosomes during the Telophase of Mitosis?
During the telophase of mitosis the two groups of chromosomes decondense (they become long & thin) & a nuclear envelope reforms around them forming two nuclei.
What happens during Cytokinesis?
During Cytokinesis the cytoplasm divides (cytokinesis) and the plasma membrane pinches off to form two new genetically-identical cells.
What is the role of spindle fibres attached to centromeres in the separation of chromatids?
The chromosomes break apart at the centromere.
The spindle fibres begin pulling the sister chromatids away from each other to opposite poles of the cell.
This splits the chromosome into two V-shaped sister chromatid structures.
What type of process is Mitosis?
Mitosis is a controlled process.
Uncontrolled cell division can lead to the formation of tumors & of cancers.
Many cancer treatments are directed at controlling the rate of cell division.
What does Binary Fission in prokaryotic cells involve?
Binary fission in prokaryotic cells involve -
1 - Replication of the circular DNA & of plasmids.
2 - Division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA & a variable number of copies of plasmids.
Do viruses undergo cell division?
Being non-living, viruses do not undergo cell division.
Instead, they infect a host cell (injection of their nucleic acid) & use the host cell to replicate themselves & to produce new viral particles.
The viruses life-cycle depends on its ability to successfully infect a host cell so that it may reproduce.
