Did you get the question correct from the previous entry?  If yes, then you are definitely rolling.  If not, that's okay. 

Let's begin by reviewing the DNA structure.

Source: http://ghr.nlm.nih.gov/handbook/basics/dna

First, the double helix structure in DNA is composed of the "sugar phosphate backbone".  DNA is consisted of 4 different nucleotides (chemical building blocks).  They are Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).  However, why are they called base pairs?  As the picture suggests, Adenine pairs with Thymine while Guanine pairs with Cytosine.  Therefore, Adenine and Thymine are one of the base pairs.  Another base pair will be Guanine pairs with Cytosine.  If you are having trouble remember the names for each nucleotides, then try to remember the shorthand for each one.  A pairs with T and G pairs with C (Aunt Tina is Going to Circus).  Can you believe it?  The DNA in your cells have information for your whole body!!! 

Where can you find DNA?  DNA is found inside a special area of the cell called the nucleus.  Due to the size of the cell, each DNA molecule must be tightly packed and condensed because there are many DNA molecules in a cell.  Therefore, the condensed form of the DNA is called a chromosome.  Humans have 23 pairs of chromosomes in each cell.  22 of these pairs are called autosomes which are the same for both male and female.  However, the last pair of chromosome is called the sex chromosome which is different for both female and male.  Do you know the difference between a female and a male sex chromosome?  It's okay If you don't know the answer to this question.  We will discuss this more in details during class.  If you do know the answer, please reply under the "Comments" section.



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    Ms. Pan is a 7th grade Science teacher at XXX Middle School. 

    Ms. Pan is both a scientist and an educator, but she likes the role of a teacher more than anything else. 

    The purpose of this blog is to provide online learning discussion and stimulate thinking prior classroom activities.
    For students, please check this blog on a daily basis to participate in discussion.
    For parents, please check this blog on a regular basis to see what your children are learning in the classroom.


    April 2009

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