Cell Division, Mitosis/Meiosis, Cell Cycle Regulation 1.6 Flashcards
What processes occur during Interphase?
- DNA replication
- Organelle duplication
- Cell growth
- Transcription/Translation
- Obtaining nutrients
- Respiration (cellular)
What is Interphase?
An active phase of the cell cycle where many metabolic reactipns occur.
Consists of G1, S and G2 phases
What is the M phase?
The period of a cell cycle in which the cell and contents divide.
Consists of Mitosis (P, M, A, T) and Cytokinesis.
What is Mitosis?
Mitosis is the division of a diploid nucleus into two genetically identical diploid nuclei. Mitosis is needed for:
- Tissue repair
- Organism growht
- Asexual reproduction
- Development of embryos
What occurs during PROPHASE?
PROPHASE :
- DNA supercoils and condenses to form visible chromosomes
- Nuclear membrane dissolves
- Centrosomes move to poles and begin to produce spindle fibres.
What occurs during METAPHASE?
METAPHASE :
- Centrosome spindle fibres attach to the centromere of each chromosome
- Spindle fibres contract and move the chromosomes towards the cell centre
- Chromosomes form a line along the equator of the cell
What occurs during ANAPHASE?
ANAPHASE :
- Spindle fibres continue to contract
- Sister chromatids separate and move to opposite sides of the cell
- Sister chromatids now regarded as 2 separate chromosomes
What occurs during TELOPHASE?
TELOPHASE :
- Chromosomes decondense (DNA forms chromatin)
- Nuclear membranes form around the 2 identical chromosome sets
- Cytokinesis occurs
What occurs during CYTOKINESIS?
CYTOKINESIS :
- Cytoplasm divides to form two daughter cells
- Each daughter cell contains one copy of each identical sister chromatid
- Daughter cells are genetically identical
What occurs during INTERPHASE?
INTERPHASE :
- DNA is uncondensed (chromatin)
- DNA is replicated (S Phase) to form identical sister chromatids
- Cell grows in size and organelles are duplicated (G1 & G2)
What is the mitotic index and how is it calculated?
The ratio between the number of cells in mitosis in a tissue and the total number of observed cells.
Mitotic Index = # of cells in mitosis/total # of cells
Can be used to predict how rapidly a tumour will grow and therefore what treatment is needed.
A high mitotic index indicated a fast-growing tumour.
ESSAY Q: Outline the stages of the cell cycle.
a. Interphase is the longest phase
b. Interphase includes G1, S and G2
c. In G1 and G2 phases the cell grows, organelles are duplicated, protein synthesis occurs, etc.
d. In the S phase DNA is replicated
e. Mitosis is the division of the nucleus
f. Prophase, Metaphase, Anaphase, Telophase, Cytokinesis
g. Cytokinesis is the division of the cell’s cytoplasm to form 2 daughter cells
