Cell division Flashcards
(30 cards)
When are daughter cells not identical to the parent cell in mitosis?
In the rare event of mutation
What period precedes mitosis?
Interphase
What happens during interphase?
The cell carries out normal functions and the DNA is unravelled and replicated, the organelles grow
What’s the function of the centromere?
Joins together the two copies of DNA after replication
What are the stages of mitosis?
Prophase, metaphase, anaphase and telophase/cytokinesis
What happens to the chromosomes during prophase?
Become visible, initially as long thin threads, they are drawn to the equator of the cell by the spindle fibres attached to the centromere
What are centrioles?
Two cylindrical organelles in animal cells, that move to the poles of the cell
What do the centrioles do during prophase?
Spindle fibres develop and span the cell from poles, collectively this is called the spindle apparatus
What happens to the nucleus during prophase?
Nucleolus disappears and nuclear envelope break down, leaving the chromosomes free in the cytoplasm
When are chromosomes made to be seen as two chromatids?
Metaphase
What happens during metaphase?
The chromosomes are pulled across the spindle apparatus towards the equator of the cell
What happens during anaphase?
Centromeres divide into two and the spindle fibres pull the individual chromatids to poles where they are now considered chromosomes
Where is the energy for anaphase provided from?
Mitochondria
What happens if cells are treated with chemicals that destroy the spindle fibres?
The chromosomes remain at the equator, unable to reach the poles
What happens to the chromosomes during telophase?
The chromosomes reach their respective poles and become longer and thinner, finally disappearing altogether, leaving widely spread chromatin
What happens to the spindle fibres and nucleus during telophase?
Spindle fibres disintegrate and nucleolus and nuclear envelope reform
What is cytokinesis?
The division of the cytoplasm
How do prokaryotic cells divide?
Binary fission
What happens to DNA during binary fission?
Circular DNA molecule replicates and both copies attach to the cell membrane, plasmids also replicate
What happens to the cell membrane of binary fission?
Cell membrane begins to grow and pinch inwards, dividing into two
What are the daughter cells of binary fission?
Identical circular DNA with variable number of copies of the plasmids
How do viruses replicate?
Attaching to the host cell with attachment proteins on the surface and injecting nucleic acid with info to replicate it
What do host cells produce to replicate the virus?
Viral components, nucleic acids, enzymes and structural proteins
What are the three stages of the cell cycle?
Interphase, nuclear division and cytokinesis
