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Name______________________________________________Period__________Date______________ The Chromosomes of a Frimpanzee Lab Introduction In the last unit you created your Frimpanzees. You showed how DNA coded for an amino acid chain or protein and that this protein is seen as a trait. DNA mRNA amino acids (protein) trait This unit is all about reproduction. Frimpanzees grow by making identical cells. Mitosis is a form of asexual reproduction that allows organisms to grow and make identical cells. When frimpanzees are grown they reproduce sexually. To do this they must create sex cells called gametes. Frimpanzees do not give all of their chromosomes to their offspring. They only give half. During fertilization the baby gets half of its chromosomes from its mom and the other half from its dad. The process of creating sex cells with half the number of chromosomes is meiosis. Recap: Mitosis – creates diploid body (somatic) cells – for growth. Cells are identical to parent Meiosis – creates haploid sex cells (gametes) – for reproduction. Cells have half the number of chromosomes. Fertilization – two haploid sex cells (egg and sperm) join to form a diploid cell (start of a baby). The purpose of this activity is to see how mitosis and meiosis occurs in Frimpanzees. To do this we will use colored paper to make models of the chromosomes in a cell of your Frimpanzees. Frimpanzees have a total of 6 chromosomes per cell. Part 1 - Making your chromosome models 1. Your teacher will tell you if you have a boy or a girl frimpanzee. If you have a boy you will work with blue chromosomes. If you have a girl you will work with pink chromosomes. 2. Each partner should fold the sheet of chromosomes in half lengthwise (along the solid line). 3. Keeping the sheet folded, cut on the dotted lines – Keep the three folded pieces of paper that have a shape that looks like <. You should end up with 6 pieces that have the < shape. For now keep them folded. These are the chromosomes in a normal Frimpanzee cell. 1. What does the folded model represent ( < )? __________________________________________ 2. Draw in the centromeres on the folded models. How many chromosomes does the Frimpanzee have? __________ For each trait below, circle the one that represents your Frimpanzee: Straight Hair (Aa) or Curly hair (aa) No Spots (Bb) or Spots (bb) Long nose (Cc) or Short nose (cc) No antennae (Dd) or 2 antennae (dd) Blue skin (Ee) or Yellow skin (ee) Pointy Ears (Ff) or Floppy ears (ff) Notice there are letters written next to each trait. These letters represent the genes on the chromosomes. Now write the appropriate letters on one side only of your folded chromosome. Use the following example to help you. Let’s say your Frimpanzee has straight hair (Aa), spots its skin (bb), a short nose (cc), 2 antennae (dd), blue skin (Ee) and pointy ears (Ff). You would write the following letters on your chromosomes: A & B genes are on the large chromosomes. C & D genes are on the medium chromosomes. E & F genes are on the small chromosomes. 3. Notice for every trait there are two copies. One of the copies comes from _____________ and the other copy comes from __________________. 4. We are now going to complete Interphase. Unfold the chromosome so that it is in the shape of an X. What is the name of the process that the unfolding would represent? _________________________________ 5. Extend the centromeres onto the other side of the unfolded models. How many chromosomes does the frimpanzee have now? __________ How many sister chromatids? _____________ 6. Write in the same exact letters on the other half of the X. Remember when DNA copies it makes an exact copy of itself. 7. Your Frimpanzee is young and needs to grow and mature. S/he has to make new cells that are identical to the other cells. In order to make more cells mitosis must occur. Follow the mitosis directions to fill in the chart below. Part 2 – Mitosis Mitosis Interphase Prophase # of Chromosomes = 6 # of Chromosomes = Metaphase Anaphase # of Chromosomes = # of Chromosomes = Telophase/Cytokinesis # of Chromosomes per cell = ___________ Are the cells produced by mitosis identical to the original cell or different? _____________ Part 3: Modeling Meiosis – Follow the steps on the instruction sheet and draw the chromosomes in below. YOU DO NOT HAVE TO WRITE THE LETTERS ON THE CHROMOSOMES FOR EACH PHASE. JUST DRAW THE CHROMOSOMES OF DIFFERENT SIZES. Meiosis I Prophase I Telophase I/Cytokinesis # of Chromosomes = ___________ # of Chromosomes = ___________ Meiosis II Prophase II # of Chromosomes per cell = ________ Telophase II/ Cytokinesis # of Chromosomes per cell = ___________ 1. Look at all 4 cells. Are the same exact letters written on all four cells? 2. Which process, mitosis or meiosis, allows for genetic diversity (differences)? _______________ 3. In humans we have 46 chromosomes. 23 chromosomes come from mom and 23 come from dad. Frimpanzees have 6 chromosomes. How many chromosomes will each Frimpanzee parent give to its baby?____________ Part 4 – Fertlization Now choose ONE of your four sex cells (gametes). You can put the other sex cells aside. Your teacher will have two groups join sex cells. Place the chromosomes you received from the other group with the chromosomes from your sex cell. This represents random fertilization. Random fertilization is another thing that leads to genetic diversity. 4. What is the male sex cell (gamete) called? ______________ female sex cell ________________? 5. Fill in the chart below with the traits of your new offspring. Trait Type of hair (A) Letters of the Baby Trait Baby Received Spots on skin or no spots (B) Type of nose (C) Antennae (D) Color of Skin (E) Type of Ear (F) 6. Who does the baby look more like, mom or dad, or is the baby a nice blend between the two parents? _____________________________________________________________ 7. Are there any traits that neither of the parents have but the baby has? (Ex: Baby has yellow skin but both parents have blue skin) ___________. How is it possible for the baby to show a trait that neither parents show? _____________________________________ Extension Activity Using your baby Frimpanzee work backwards to determine the DNA sequence for each trait Does your Frimpanzee have straight or curly hair? GENE A Does your Frimpanzee have spots on its skin? GENE B Trait Trait Amino Acids Amino Acids mRNA mRNA DNA DNA Does your Frimpanzee have a long or short nose? GENE C Does your Frimpanzee have antennae or not? GENE D Trait Trait Amino Acids Amino Acids mRNA mRNA DNA DNA Does your Frimpanzee have blue or yellow skin? GENE E Does your Frimpanzee have pointy or floppy ears? GENE F Trait Trait Amino Acids Amino Acids mRNA mRNA DNA DNA Part 3 Meiosis Instructions. Prophase I – On your desk take a piece of yarn and form a circle. This circle represents the nucleus. Place the chromosomes inside the yarn circle and arrange them by size by placing the same size chromosomes next to each other.. Chromosomes that are the same size with the same type of genes are called homologous chromosomes. These chromosomes are still inside the nucleus but the nucleus is beginning to break down. Metaphase I – Remove the yarn from the desk. Move the homologous chromosomes so they line up in the middle of your desk. The same size chromosomes should be right next to each other forming a double file line down the center of the desk. Anaphase I – Move the homologous chromosomes apart to opposite sides of the desk. The entire X moves to the other side of the desk. Telophase I / Cytokinesis- Take two pieces of yarn and form two circles around the chromosomes on opposite sides of the desk. Two new cells form. MEIOSIS II - This will be a separate process in each of the two new cells. Place a piece of yarn down the center of the desk to represent the separation of each of the cells. One partner will work with one set of chromosomes on one side of the desk and the other partner works with the other set. Prophase II – Create a yarn circle to represent the nucleus. Place the chromosomes you are working with inside the yarn circle. The chromosomes are inside the nucleus. Metaphase II – Remove the yarn circle. Line the chromosomes up single file in the middle portion of your part of the desk. . Anaphase II - Chromosomes split at centromere. Cut each one of your chromosomes in half through the centromere. Now move the chromatids to opposite sides of your portion of the desk. Telophase II - Create two yarn circles around the chromosomes on your part of the desk. Two new cells form. However remember your partner is doing the same things so you should have total of 4 cells on your desk. These cells are called gametes - they are the sex cells that will become either frimpanzee sperm or egg cells. Part 2 – Mitosis Instructions Interphase – Create a yarn circle to represent the nucleus. A major step during this phase is DNA replication. I have drawn the picture of interphase for you. Remember DNA appears as chromatin during this phase. Prophase –Place the chromosomes you are working with inside the yarn circle. The chromosomes are inside the nucleus. Metaphase – Remove the yarn circle. Line the chromosomes up single file in the middle portion of your part of the desk. . Anaphase - Chromosomes split at centromere. Cut each one of your chromosomes in half through the centromere. Now move the chromatids to opposite sides of your portion of the desk. Telophase - Create two yarn circles around the chromosomes on your part of the desk. Two new cells form. Before replacing your chromosomes back inside of the baggie, tape the chromosomes back together at the centromere and fold them in half.