Cell growth and division Flashcards
Define cell division.
Cell division is the process required for the growth of the human and replacement of dead cells. Two processes are involved: mitosis and meiosis. Cells are reproduced as part of a cell cycle.
What are the two processes involved in cell division?
Mitosis and Meiosis
What is mitosis?
The production of genetically identical cells for growth and replacement of cells
What is meiosis?
For the creation of genetic variable gametes
What is interphase?
This is the phase which occurs between cell divisions, this step is subdivided into G1, S and G2 phase (G stands for gap and S for synthesis).
What happens during G1?
The cell grows and the cellular contents are duplicated
What happens during the S phase?
The 46 chromosomes are replicated called DNA replication
What happens during G2?
Further growth and checking of contents
What are the four stages of mitosis?
Prophase, metaphase, Anaphase, Telophase
What happens during prophase stage of mitosis?
Chromatin condenses into chromosomes. Spindles are microtubules act like a rope pulling the chromosomes around the cell.
What happens during metaphase stage of mitosis?
Chromosomes align at equatorial plate pulled by the spindles
What happens during anaphase stage of mitosis?
The chromatids break apart and pulled to opposite ends of the cell.
What happens during telophase stage of mitosis?
New nuclear membranes form around each of the two chromosomes set.
Summarise the 4 stages of mitosis?
PMAT
Prophase - PAIRS of chromosomes become visible
Metaphase - chromosomes line up in the MIDDLE of the cell
Anaphase - chromosomes pulled APART
Telophase - TWO nuclear membranes formed
What is cytokinesis?
Cytoplasm divides two separate cells form. Each cell has 46 different chromosomes.
Define the terms haploid, diploid and zygote?
Haploid is 23 chromosomes
Diploid is 46 chromosomes
Zygote when two haploid cells come together (sperm and egg) they make a diploid
What is independent assortment?
The Principle of Independent Assortment describes how different genes independently separate from one another when reproductive cells develop.
What is the crossing over stage?
It is when the chromosomes come together and fragments of chromosomes containing genes are exchanged between chromatids. This takes place in Prophase I.
What are the steps of meiosis.
- Interphase
- Prophase I
- Metaphase I
- Anaphase I
- Telophase I
What happens during interphase in meiosis.
growth of cell and DNA replication.
What happens during Prophase I in meiosis.
Chromatin condenses into chromosomes. Spindles are microtubules act like a rope pulling the chromosomes around the cell.
And homologus chromosome pairs from bivalents (they crossover and genes to be exchanged).
What happens during Metaphase I in meiosis.
Homologous pairs align at the equatorial plate, pulled by spindles.
What happens during Anaphase I in meiosis.
The sister chromatids do not break apart, instead the homologous chromosomes separate, with one going to each end of the cell.
What happens during Telophase I in meiosis.
New nuclear membranes form around each of the two chromosomes set.
