Cell Division Flashcards
G1 stage
Synthesis of rna and protein
Preparing to replicate dna
Cell grows larger
S stage
Replication of dna is completed
Duplication of histone proteins
Generates sister chromatids, attached by a centromere
G2 stage
Cell grows larger
How is chromatic formed
DNA is packaged by histones
Order of dna organisation
Chromatin has a lower order
Chromosomes has a higher order
Prophase
Chromosomes condense and become visible inside the nuclear membrane
Nucleolus disappears
Centrioles migrate to opposite sides
Microtubules form
Cohesion forms rings that hold chromatids
Condensing forms rings that coil the chromosomes into highly compact forms
Pro-metaphase
Phosphorylation of nuclear lamins by M-CDK causes the nuclear membrane to break down into small vesicles
Microtubules connect to each chromosome at its kinetochore (proteins at the centromere)
Metaphase
Nuclear membrane disappears
DNA content has doubled
Chromosomes line up at the equator
Anaphase
Centromeres split
Enzymatic breakdown of cohesion = separation
Anaphase a- the kinetochores Microtubules shorten and draw the chromosomes towards the spindle poles
Anaphase b- the astral Microtubules pull the poles further apart and the inter polar microtubules slide past each other
Telophase
Chromatids assemble at the poles
Nuclear membrane forms
Nucleoli reform
Meiosis
2 nuclear divisions
Number of chromosomes is halved (haploid)
Meiosis
2 nuclear divisions
Number of chromosomes is halved (haploid)
Differences in prophase in mitosis and meiosis
Meiosis
synapsis= pairing of homologous chromosomes
Crossing over
