week of 2/2/09

monday:

on  monday we reviewed mitosis a little and started learning about a new kind of cell reproduction.  

what is the point of mitosis? 

mitosis---to make another cell/organism

  daughter cells have exact copy

  100% chromosomes

  CALLED A DIPLOID CELL!!

what is the point of the new kind of cell reproduction (which we learned later this week is meiosis)?

meiosis---to make another cell/organism

  daughter cell has variation-its not exactly the same as the parent cell

  50% chromosomes

  CALLED A HAPLOID CELL!!

on monday we also made a mitosis concept map!!

tuesday:

on tuesday we talked more about haploid and diploid cells

haploid-example-sperm or egg cell; definition-a cell with 50% of the chromosomes so when 2 haploid cells combine, they can make a new cell with 100% chromosomes

diploid-example-cheek cell; definition-a cell with 100% chromosomes because it is asexual and doesn't need to combine with another cell to reproduce

during interphase, the chromosomes are copied so the cell can split and have the right number of chromosomes.

this was our original prediction on how the cell divides.  BUT IT IS WRONG!!!!!!!!!  for hw that night we had to redo this meiosis web.  this is what it should look like:

wednesday:

We were wrong in our first prediction because we were splitting the chromatids when we should have been splitting the homologous pairs.  you see, in the second picture, in meiosis I we are splitting the homologous pairs first, then after that you DON'T copy the chromosomes, then split the chromatids in meiosis II.  but in our first picture, we weren't splitting the homologous pairs, we were just splitting the chromatids...if any of that makes sense

also on wednesday:

sex--delivery service-injecting cells

fertilization--combining cells

meiosis--creating sex cells (sperm, egg, pollen)

• in girls, meiosis happens in the ovaries
  
• meiosis only happens in girls when they are being born
  
• in boys, meiosis happens in the testicles
• for boys, meiosis starts during puberty
• homologous pairs have the same number chromosome.  if they didn't, then the new cell/child would have a disorder or be deformed
• the egg and sperm cell connect and cross over so that the new cell has traits from both parents

thursday:

on thursday we continued talking about meiosis and about the process.

interphase-chromosomes pair up

prophase-chromosomes cross over and the nuclear envelope starts to disolve

metaphase-homologous pairs line up parallel to the metaphase plate

anaphase-homologous pairs get pulled apart to the opposite ends of the cell by the spindle fibers 

telophase-cell membrane starts to pinch in the center and the nuclei start to reform

cytokinesis-the membrane completely closes off and nuclei completely reform

meiosis II is the EXACT SAME THING EXCEPT THE CHROMOSOMES DO NOT GET COPIED

friday:

on friday we did a simulation on meiosis and filled out a worksheet with similar information to the info i just gave you!!

see you in a couple weeks!!  i'm off to NEW ZEALAND!!!!!  WOOHOO!!!!

~*Mary*~