Mitosis Flashcards
Memorise what Mitosis is, when it occurs, important structures during mitosis and the phases.
What is Mitosis?
The division of a cell’s nucleus. It replaces old and dead cells in an organism.
When does Mitosis occur?
Mitosis occurs for:
- Growth and development
- Repair to tissues/organs that have been damaged
- Asexual reproduction
- Growth after fertilization if reproduction is sexual
What are the important structures during Mitosis?
- Chromosome: structure in the nucleus that house genetic material, consisting of DNA and protein
- Chromatid: a strand of a chromosome
- Centromere: a region on each chromatid that joins with the centromere of its sister chromatid
What is Interphase?
Between phases:
- Nucleus visible
- Chromosomes are copied and remain attached to each other
- Chromosomes appear as sister chromatids by the end of the phase
- Centrioles and other organelles replicated
What is Prophase?
Before (division) phase:
- Centrioles begin to move to opposite ends of the cell
- Spindle fibres form between the poles in the cytoplasm
- Nuclear envelope breaks down
What is Metaphase?
Sharing phase:
- Nuclear membrane breaks apart
- Pairs of chromatid attach to the spindle fibres
- Chromatids move along the spindle fibres to the ‘equator’ in the middle of the cell
What is Anaphase?
A new phase:
- Chromatids separate and move to opposite ends of the cell along the spindle fibres
What is Telophase?
Reproduction phase:
- Two new nuclei form
- Chromosomes appear as chromatin threads
- Nuclear membrane forms around each of the two sets of chromosomes
- Spindle breaks down
What is Cytokinesis?
Cell movement (separation):
- Cell membrane moves inward to create two daughter cells
- Each new cell has its own nucleus and contains identical chromosomes
What is Meiosis?
Produces new ‘individuals’ of a species (reproduction)
What is Spindle?
Fibres that separate the chromosomes into the daughter cells during cell division
What is Centriole?
A ring of microtubules associated with the spindle apparatus
What is cell division?
Contact inhibition:
Cells appear to divide until they fill a space and then stop
What about cancer cells?
Cancer cells do not stop dividing, they have lost their contact inhibition
