3.7 and 3.8: Mitosis and The cell cycle Flashcards
Mitosis
Produces two daughter cells that have the same number of chromosomes as the parent cell and each other
Daughter cells DNA
have an exact copy of the DNA of the parent cell
Mutation means
genetic make up of the two daughter nuclei is not identical to that of parent nucleus
Interphase
Period that precedes mitosis of cellular activity when the cell isn’t dividing but the replication of DNA is happening.
4 stages of mitosis
prophase
metaphase
anaphase
telophase
Prophase
stage of mitosis
Chromosomes become visible as two long thin threads, centrioles move to poles of the cell,
spindle fibres develop
nucleolus disappears and nuclear envelope breaks down
chromosomes free in the cytoplasm
Centrioles
Organelles where spindle fibres come from
Spindle apparatus
spindle fibres collectively
Opposite end of the cell
called
Poles
Metaphase
Chromosomes made up of two chromatids, the chromatids are joined by the centromere
the chromosomes are pulled along the spindle apparatus and arrange along the equator of the cell
Chromatid
each chromatid is an identical copy of DNA from the parent cell
Anaphase
the centromeres divide into two
spindle fibres pull the individual chromatids apart
chromatids move to poles and are (chromosomes now)
mitochondria provides energy for the process
Telophase
Chromosomes reach their poles become longer and thinner then disappear and leave chromatin spindle fibres disintergrate nuclear envelope and nucleolus re-form cytokinesis
Cytokinesis
the cytoplasm divides at the end of mitosis
Cell division in prokaryotes
binary fission
Binary fission
- The circular DNA molecule replicates and both copies attach to the cell membrane
- plasmids also replicate
- the cell membrane begins to grow between the 2 DNA -molecules and begins to pinch inwards,
- cytoplasm divides in 2
- new cell wall forms between the 2 molecules of DNA
- original cell divides into 2 daughter cells
Replication of viruses
Can’t undergo cell division
attach to their host cell
inject nucleic acid
genetic info. in nucleic acid provides ‘instructions’ for the cells metabolic processes
Some cells don’t divide continuously
undergo the cell cycle
Cell cycle
Regulates cycle of division with periods of cell growth
Cell cycle
3 stages
interphase
nuclear division
cytokinesis
Nuclear division
in cell cycle
when nucleus divides into either 2 (mitosis) or 4 (meiosis)
Interphase
in cell cycle
known as resting phase
occupies most of the cell cycle
no cell division occurs
