Mitosis Flashcards
What does mitosis produce?
2 daughter cells that have the same number of chromosomes as the parent cell.
What does meiosis produce?
4 daughter cells, each with half the number of chromosomes of the parent cell.
What do daughter cells have in mitosis?
An exact copy of DNA from the parent cell.
What happens during interphase?
Organelles double, the cell grows and DNA replicates.
What is the centromere?
The centre where 2 chromatids are joined.
What are the 4 stages of mitosis?
Prophase, metaphase, anaphase, and telophase and cytokinesis.
What happens to the chromosomes in prophase?
They first become visible as long thin threads.
What are centrioles?
Cylindrical organelles.
What happens to the centrioles in prophase?
They move to opposite poles of the cell.
What develops from centrioles?
Spindle fibres.
What do the spindle fibres do in prophase?
Span the cell from pole to pole.
What are spindle fibres collectively called?
Spindle apparatus.
What happens to the nucleus in prophase?
The nucleolus disappears and the nuclear envelope breaks down.
What happens to the chromosomes after the nuclear envelope breaks down in prophase?
They are left free in the cytoplasm.
What are the chromosomes drawn to the equator of the cell by?
The spindle fibres attached to the centromere.
What are the chromosomes seen as in metaphase?
Chromatids.
What is each chromatid?
An identical copy of DNA from the parent cell.
What is attached to the centromere in metaphase?
Some microtubules from the poles.
What happens to the chromosomes in metaphase?
They are pulled along the spindle apparatus and arrange themselves across the equator of the cell.
What happens to the centromeres in anaphase?
They divide into two.
What happens to the spindle fibres in anaphase?
They pull the individual chromatids of the chromosome apart.
What happens to the chromatids in anaphase?
They move rapidly to their opposite poles of the cell, and are then referred to as chromosomes.
Where is the energy for the process in anaphase from?
Mitochondria.
Where do the mitochondria needed gather in anaphase?
Around the spindle fibres.
What happens if cells are treated with chemicals in anaphase?
The spindle fibres are destroyed and the chromosomes remain at the equator, unable to reach their poles.
What happens to the chromosomes in telophase?
They reach their poles and become longer and thinner, finally disappearing and leaving only widely spread chromatin.
What happens to the spindle fibres in telophase?
They disintegrate.
What re-forms in telophase?
The nuclear envelope and nucleolus.
What happens in cytokinesis?
The cytoplasm divides.
What does cell division in prokaryotic cells take place by?
Binary fission.
What is the first stage of binary fission in prokaryotic cells?
The circular DNA molecule replicates and both copies attach to the cell membrane, plasmids also replicate.
What happens in the second stage of binary fission in prokaryotic cells?
The cell membrane begins to grow and pinch inward between the two DNA molecules, dividing the cytoplasm into two.
What happens in the last stage of binary fission in prokaryotic cells?
A new cell wall forms between the two DNA molecules, dividing the original cell into two daughter cells, each with a single copy of DNA and copies of plasmids.
Why can’t viruses undergo cell division?
They are non-living.
How do viruses replicate?
By attaching to their host cell with the attachment proteins on their surface.
What do viruses inject into their host cell?
Their nucleic acid.
What is on the injected nucleic acid from a virus?
The genetic information.
What does the genetic info on the nucleic acid from a virus provide?
The instructions for the host cells metabolic processes to start producing the viral components, nucleic acid, enzymes and structural proteins, to then be assembled into new viruses.
What is mitosis essential for?
Growth, repair and reproduction.
