Monday_ December 14th_ 2009 8 Sc by fjzhangxiaoquan

VIEWS: 2 PAGES: 39

									 Today is Friday (!), November 4th, 2011

       Pre-Class:
       (it’s a simple one)

       Where do cells come
       from?

     Because they don’t come from this ---------->


http://animalsneedkisses.files.wordpress.com/2009/03/teenage_....jpg
                                           Today’s Topics

    • Chromosomes
    • Chromosomes
    • And maybe strawberries…

    • Where is this in my book?
           – P. 244 and following…
           – Also P. 341 and following…


http://www.toppstraders.org/blog/wp-content/uploads/2008/02/darryl-strawberry.jpg
    What a cell wants, what a cell needs…

• So what exactly does a cell need?
• Imagine a cell has just been “born.”
  – What do you suppose is most important?
  – What organic molecule would you pick?
                                         Of course, DNA!
       • DNA is the information of a cell.
              – The “genetic code”
       • This needs to be copied over to the new cell.
              – This stuff “codes for proteins” (like a script) and
                makes you who you are.


  DNA in pop             Not what DNA actually looks
  culture?               like…




http://static.guim.co.uk/sys-images/Film/Pix/pictures/2008/06/30/jurassicpark460.jpg
http://www.eyeondna.com/wp-content/uploads/2007/11/mrdna.jpg
         Cell Division and DNA
• There are three major methods for cell
  division:
  – Binary Fission Mainly Prokaryotes
                        Momentarily…
  – Mitosis
                Next week
                Eukaryotes
  – Meiosis
      Cell Division in Prokaryotes
• Called “Binary Fission.”
  – Simple
     • Ring of DNA copies.
     • New membrane grows across the cell, pinching it “like a
       long balloon squeezed in the middle.”
        – Holt: Biology


  – 2 cells result, both with the same DNA
     • Unless something happened.
                              Binary Fission: A View




                                                       Animated Form

http://upload.wikimedia.org/wikipedia/commons/d/d2/Binary_fission_anim.gif
                            Eukaryotic Cell Division
       • For eukaryotes, things are different. We don’t
         just have DNA. Eukaryotes have…
              – Begins with a “C…”
              – Ends in a “hromatin…”
       • Right, eukaryotes have chromatin:




http://www.reading.ac.uk/cellmigration/chromatin.jpg
                   Chromatin
• Chromatin is made of two things:
  – DNA
  – Proteins (called histones)
• The DNA is wrapped around the histones.
                           What chromatin does…
      • Chromatin in the nucleus is a lot like a bunch
        of loose fishing line.
             – It’s a bunch of long, thin, invisible strands.




http://thumb1.shutterstock.com.edgesuite.net/display_pic_with_logo/7096/7096,1231099264,4/stock-photo-a-spool-of-monofilament-fishing-
line-macro-shot-showing-all-the-dirt-and-lint-all-over-the-strands-22762768.jpg
                                                  But then…
       • When pieces of chromatin condense, they
         becomes visible under the microscope.
              – The condensed chromatin pieces are now called
                chromosomes.




http://www.koifishcareinformation.com/wp-content/uploads/2010/02/fishing-line-pond-protection-for-koi.jpg
        How big are we talkin’?
• http://learn.genetics.utah.edu/content/begin/
  cells/scale/
                    Humans
• We have 46 total chromosomes (per cell).
  – Arranged in 23 pairs.
  – One chromosome in each pair is from your
    mother, one is from your father.
     • These are called homologous chromosomes.
• Diploid
  – Diploid is an arrangement where you have pairs of
    chromosomes.
  – We describe diploid chromosome arrangements
    with the term 2n.
             Chromosomes: A Diagram View

                                                                 From Mom
                                                                 From Dad




                                           Homologous
                                          Chromosomes
http://www.macroevolution.net/images/sister-chromatids-275.jpg
Chromosomes: A “Real” View
            Other Organisms
• Dog: 78 Chromosomes (39 pairs)
• Orangutan: 48 Chromosomes (24 pairs)
• Mouse: 40 Chromosomes (20 pairs)
• Strawberry: 56 Chromosomes (7 groups of 8 -
  octoploid)
• Adders-tongue fern: 1200 or 1260
  Chromosomes
                                                          Mule
      • Horse + Donkey




http://cloud.equinenow.com/140171_1/mare_mule_horse.jpg
                                                       Liger
      • ♂ Lion, ♀ Tiger




http://2.bp.blogspot.com/__jinAaXs1i4/TGzaZyBwtmI/AAAAAAAAAI8/bMYSAFod7bw/s640/Liger4.jpg
                                                       Tiglon
      • ♂ Tiger, ♀ Lion




http://www.metrolic.com/wp-content/uploads/2010/09/Tiglon20.jpg
                                                  Zedonk
      • Donkey/Zebra




http://4.bp.blogspot.com/_p5mAt9Tofmg/TFf_sh1ENTI/AAAAAAAAAt4/ZM0AlU4z9gU/s320/zedonk+trimmed.jpg
                                                        Okapi
      • NOT a hybrid! (related to giraffes)




http://upload.wikimedia.org/wikipedia/commons/1/18/Okapi2.jpg
                                          Karyotyping
   • Arranging/looking at/analyzing chromosomes is
     a called making a karyotype (or karyotyping).
   • Chromosomes are arranged primarily by size and
     homologous chromosomes are paired.




http://www.genomenewsnetwork.org/gnn_images/whats_a_genome/karyotype.gif
   Two Types of Chromosomes

• Autosomes
  – The 22 “body”
    chromosomes.
  – They’re responsible
    for non-gender
    things in the body.
         Two Types of Chromosomes

• Sex chromosomes
   – The one pair of chromosomes
     that contains information
     linked to gender.
      • And some stuff not linked to
        gender.
• Two X chromosomes = XX
   – Female
• One X, One Y = XY
   – Male
• Y chromosome is relatively
  small.
         Let’s do some karyotyping…
• Visit this website:
• http://learn.genetics.utah.edu/content/begin/traits/karyot
  ype/
• You will first just practice karyotyping on this
  website.
• When you are finished, LEAVE YOUR COMPUTERS
  OUT.
   – We’re going to discuss some chromosome-based
     diseases.
 Sex Chromosome-Linked Conditions
• XX - ♀
• XY - ♂
• XXX - Trisomy X
  – Female, otherwise healthy.
• XXY - Klinefelter’s Syndrome
  – Male, reduced sex characteristics, some female
    characteristics.
• XO - Turner’s Syndrome
  – Female, appear normal but sterile.
                  Aneuploidy
• An abnormal number of chromosomes is
  called aneuploidy.
  – Trisomy X, Klinefelter’s, and Turner’s are all
    aneuploidies, as are the conditions we will discuss
    on the next slides.
  – Aneuploidies can be autosomal or sex
    chromosome-linked.
                             Autosomal Conditions
      • Trisomy 21
             – Three copies of the 21st chromosome instead of
               two.
             – 47 total chromosomes instead of 46.
             – Leads to Down’s Syndrome.




http://kittymowmow.files.wordpress.com/2008/01/whitetigerdeformed1.jpg
                             Autosomal Conditions
• Trisomy 13
      – Three copies of the 13th
        chromosome instead of two.
      – 47 total chromosomes instead of
        46.
      – Leads to Patau Syndrome.




http://www.diagnosticpathology.org/content/figures/1746-1596-2-48-1.jpg
http://myummah.co.za/site/wp-content/uploads/2009/02/image-801.jpg
 Let’s do some more karyotyping…
• Now visit Quia and open the quiz called
  “Karyotyping” and follow the directions.
  – You’ll need a different website for the second
    activity.
     • On this website, just click where the match should go.
       No dragging.
  – Linked on my website under University of Arizona
    – Karyotyping.
     • http://www.biology.arizona.edu/human_bio/activities/
       karyotyping/karyotyping.html
                   Gametes
• In autosomal cells, there are 23 pairs of
  chromosomes, including one pair of sex
  chromosomes.
  – You’ve probably already written this.
• In sperm and egg cells (gametes), there are
  only 23 chromosomes total.
  – Haploid.
  – Only one sex chromosome.
  – 1n
                 Gametes
            Egg and Sperm Cells

• Egg cells are produced by females.
  – Made by cells that have XX karyotype.
  – Therefore, eggs always have one X sex
    chromosome.
• Sperm cells are produced by males.
  – Made by cells that have XY karyotype.
  – Therefore, sperm could have either one X or one Y
    sex chromosome.
           Class Baby Pictures
• And now, let’s take a look at some class baby
  pictures.
  – Seriously.
  – And please thank your parents for cooperating
    (and keeping this a secret).
                      Zygote
• Your first diploid cell:




                             http://www.alphascientists.org/images/uploads/images/Zygote_1.jpg
                           Gametes
• Sperm and egg cells (each haploid) combine to
  form a zygote (first cell - diploid).
  – 23 chromosomes from egg + 23 chromosomes
    from sperm = 46 chromosomes in zygote.




                          http://images-cdn01.associatedcontent.com/image/A6498/649888/150_649888.jpg

          http://www.ncbi.nlm.nih.gov/bookshelf/picrender.fcgi?book=cell&part=A5406&blobname=ch20f4.jpg
              Henry the VIII
                          I even
• Six wives.             look like
                          I’m an
• Really wanted a son.     idiot.
• Whose fault was it?
  Eukaryotic Cell Division Preview
• The rest of this unit will be discussing how
  eukaryotes divide.
• As we said, this process is more complicated
  than for prokaryotes.
• We’re going to wrap today up with a preview
  of what’s to come next week.
  Eukaryotic Cell Division Preview
• Step 1: Chromatin/DNA must be copied
• Step 2: Chromatin/DNA condenses to form
  chromosomes
• Step 3: Chromosomes, one from Mom and
  one from Dad, pair up
• Step 4: Copies joined by centromere
• Step 5: Chromatids separate as the cell splits
  into two new cells
                  Exit Ticket
• Exit Ticket: Humans have ___ total chromosomes, or
  ___ pairs of chromosomes.

• You must show me your answer on your way out the
  door.

								
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