A Little Blog About AP Bio

Key Concepts: Meiosis

In a world where the first bit of meiosis is different than mitosis, Prophase I forms tetrads instead of pairs…and then Metaphase-Telophase I proceed with these tetrads, forming two haploid cells.

but then…

• the second bit happens, and is also very much like mitosis, only the sister chromatids separate and we have a cell with only n chromosomes
• Dun
• Dun
• DUN

Blips: C4 Pathway

• Normal plants go through the C3 pathway
• C4 is for plants in extremely dry climates where the concentration of CO2 is low
• CO2 first combines with “PEP” to form oxaloacetate (4C) 
• PEP Carboxylase then fixes the CO2 because it has a high affinity for it, even at low concentrations
• Oxaloacetate is then converted to malate which enters cells around the leaf vein (bundle sheath cells)
• It is converted to pyruvate and CO2 and then fed into the Calvin cycle
• This prevents Rubisco from fixing O2 and destroying the Calvin cycle