F211 Cell Division, Cell Diversity, Cellular Organisation Flashcards
Interphase
Phases
Growth 1
Synthesis
Growth 2
Cell Cycle
Nuclear division, mitosis, is only a very small part of the cycle, a third of the other three phases
Growth 1, Synthesis, Growth 2, take up a third each of the rest of the cycle
Interphase
Growth 1
First and longest growth stage
Organelles produced
Cytoplasm volume increases
46 chromosomes
Interphase
Synthesis
Chromosome replication
DNA content doubles
92 chromosomes
Interphase
Growth 2
Second growth phase
Cytoskeleton breaks down
Checks that the copied DNA is correct
Mitosis
Phase
Prophase
Metaphase
Anaphase
Telophase
Prophase
Chromosomes shorten and thicken, coil around histones
Nuclear envelope breaks down and disappears
Centriole divides in two
Each daughter centriole moves to the opposite poles of the cell
Centrioles organise the spindle, a 3D structure made of microtubles
Metaphase
Chromosomes move to the central region of the spindle, the equator
Each chromosome becomes attached to a spindle thread by its centromere
Anaphase
Replicated chromatid pairs separate when the centromere holding them together splits
Spindle fibres shorten pulling the sister chromatids away from each other towards the poles
They assume a V shape because they are pulled by their centre
Telophase
The separated chromatids reach the poles of the cell
A new nuclear envelope forms around each set of chromosomes
The spindle breaks down and disappears
The chromosomes uncoil
Cytokinesis
Cell division
Takes place after mitosis
Cytokinesis
In Animal Cells
The membrane constricts around the middle of the cell
A ring of protein filaments bound to the surface of the cell membrane contract until the cell is divided into two, actin and myosin
The daughter cell is genetically identical to the parent cell
Cytokinesis
In Plants
Only happens at meristems
A new cell wall plate is synthesised between the two new cells where the spindle was
Homologous Pair of Chromosomes
Chromosomes that have the same genes at the same loci
Pair up during meiosis
One chromosome from each parent
Made up of genes that code for the same thing
Purposes of Mitosis
Produces cells which are genetically identical to the parent and can therefore perform the same function. This is used for: Asexual Reproduction Growth Repair Replacement