D2.1 Cell and Nuclear Division

Cell cycle vs Mitosis

Interphase - cell growth and normal function (NOT Mitosis)
Prophase - The Chromosomes condense and the nucleus dissolves

Metaphase - The Chromosomes align on the equator

Anaphase - The Chromosomes are pulled apart to the poles by spindle fibers (microtubules)

Telophase - The Chromosomes are at the poles and the nuclei reform. 

Cytokinesis - The cell splits (NOT Mitosis)

Mitosis

PMAT

Mitotic Index

Cells in mitosis / total number of cells

Histones and gene expression

Histone proteins have tails that bind to the DNA and hold it around the nucleosome

Acetylation and methylation can affect how tightly the DNA is bound and this can influence gene expression

Cytokinesis

Not part of mitosis

Animal cells have a ring of contractile actin and myosin proteins, pinches a cells membrane together to spit the cytoplasm.

Meiosis recap

Meiosis results in the formation of genetically individual cells that are haploid.

Meiosis and variation + crossing over

Random orientation of bivalents, (random assortment), means we do not know which of the maternal or paternal chromosomes will go into which gamete.

Crossing over occur when the chromosomes align on the equator, the end sections of chromosomes can become tangled and so there can be an exchange of genes between chromosomes, meaning that the final version of that chromosome is not the same as the original copy