All Cells Arise From Other Cells (3.2.2) Flashcards
1
Q
What is the cell cycle?
A
- The entire sequence of events that a cell undergoes to grow, prepare for division and divide
- Interphase → Mitosis → Cytokinesis
2
Q
What is mitosis?
A
- The type of cell division occurring in all eukaryotic cells, except sex cells, resulting in two genetically identical daughter cells
3
Q
What is mitosis essential for?
A
- Growth of an organism
- Replacement of damaged or dead cells
4
Q
What happens during interphase?
A
- DNA is replicated
- Increase in protein synthesis and replication of organelles
5
Q
What is the evidence for interphase?
A
- Chromosomes are not visible
- Nuclear membrane and nucleolus are still present
6
Q
What happens during prophase?
A
- Chromosomes condense, becoming shorter and thicker
- Centrioles move to opposite poles of the cell
- The nuclear envelope breaks down
- NOTE: Centrioles are not present in plant cells
7
Q
What is the evidence for prophase?
A
- Chromosomes are visible
8
Q
What happens during metaphase?
A
- Spindle fibres form from the centrioles and centromeres attach to them
- Chromosomes align along the equator of the cell
9
Q
What is the evidence for metaphase?
A
- Chromosomes are aligned along the equator of the cell
10
Q
What happens during anaphase?
A
- Centromeres divide into two and sister chromatids separate
- Spindle fibres begin to shorten pulling the chromatids towards opposite poles of the cell
11
Q
What is the evidence for anaphase?
A
- Two sets of chromatids are at opposite ends of the cell
12
Q
What happens during telophase?
A
- Chromosomes de-condense and become longer
- Spindle fibres disintegrate
- Nuclear envelope reforms
13
Q
What is the evidence for telophase?
A
- Two cells appearing, two nuclei visible
14
Q
What is cytokinesis?
A
- The splitting of the cytoplasm into two, forming two new cells
15
Q
What is the formula to calculate the time taken for each stage in mitosis?
A
- (Cells in that phase / The total total number of cells undergoing mitosis) x Total time of 1 cell cycle
16
Q
What is the formula for the mitotic index?
A
- (The number of cells undergoing mitosis / The total number of cells)
17
Q
What does binary fission involve?
A
- Replication of circular DNA
- Replication of plasmids
- Division of the cytoplasm to produce daughter cells
18
Q
How do viruses reproduce?
A
- Since they are non-living, they can only replicate in host cells
- The viruses inject their nucleic acid into the host cells
- The genetic material is used to code for more viruses which are produced using the organelles of the host cell
