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TAKS Objective 2 Review Reading the DNA Code

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TAKS Objective 2 Review Reading the DNA Code

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    1. TAKS Objective 2 Review Reading the DNA Code Protecting and Reading the DNA Code

    2. Where is DNA found in a cell? DNA is the coiled molecules that form the chromosomes. Since chromosomes are in the nucleus, so is the DNA. The genetic code is the instructions on how to make the cell, and what its function is, so it never leaves the nucleus.

    3. Why is it important to copy DNA exactly? Each cell has unique properties and functions. It must make a cell to replace itself before it dies. Example: skin cells die on average every 3 days, you wouldn’t want a liver cell to replace your skin cell.

    4. Replication This means to make an exact copy of something. DNA replicates so that new cells are identical to the ones being replaced. To replicate, DNA opens up or ‘unzips’ along the base pairs, and then repairs with a new set of bases, so that the new DNA forms inside the old. Base pairs are A with T and C with G.

    5. What is the structure of DNA? The sides are made of alternating sugar and phosphate groups. Attached to each sugar is a nitrogen base: Adenine, Thymine, Cytosine or Guanine. These pair to form the rungs of the ladder. A to T and C to G. Lines to lines and round to round.

    6. To practice replication: Roll the die three times and record the letter each time. Using the base pair rule, determine what the other side of the DNA would look like. This is done in 3’s since that is the number of bases in a mRNA codon which pairs for a single amino acid. Complete 10 triplet DNA base pair sets.

    7. How does DNA tell the cell what to do? Each chromosome is composed of many genes. One gene is made of the coiled DNA strand necessary to make 1 protein. 1 gene = 1 protein. Proteins form enzymes that control chemical reactions in the cell, they also make cell parts By controlling the types of protein the cell makes, DNA can control the function of the cell.

    8. Cell parts used in Transcription DNA is found in the nucleus, it is read by messenger RNA (mRNA), which carries the code in sets of 3. The mRNA codon travels out of the nucleus by way of the endoplasmic reticulum, and goes to a ribosome to be read and assemble the protein.

    9. Steps of Transcription The DNA unzips by releasing the hydrogen bonds between the base pairs. The mRNA pairs to one side of the DNA by forming A to U and C to G base pairs. The mRNA leaves the nucleus. . . And the DNA rezips and recoils back into the chromosome.

    10. Your turn! Roll the di 3 times, recording each letter. This is the DNA code. Base pair to form a mRNA codon. Remember there is no T in RNA, so A pairs with U and C pairs with G. Repeat this process 10 times, so you have 10 mRNA codons. Use the table on your handout to determine which amino acid each codon indicates. Transfer RNA or tRNA circulates in the cytoplasm of the cell to find that amino acid and bring it to the ribosome. This is TRANSLATION. The process of forming a chain of amino acids is called PROTEIN SYNTHESIS.

    11. Time to apply what you have learned… 1. Part of a DNA strand is represented in the diagram above. In order for DNA to replicate, the strand must separate at which of the following locations? F Between every phosphate-sugar pair G Between the eight sugar-base pairs H Between the four nitrogenous base pairs J Between any two chemical bonds

    12. 2. This illustration is an example of a normal DNA sequence. Which of the following represents a single base change in the sequence?

    13. 3. Proteins are produced according to a special code found in the control center of the cell. Which of these molecules carries this code? A DNA B ATP C Glucose D Lipid

    14. 4. Which of the following must occur before DNA replication can take place? A Translation of DNA into amino acids B Separation of the DNA molecule into codons C Transformation of DNA into RNA D Separation of the DNA double helix

    15. 5. In all plant and animal cells, the nucleus contains long molecules of DNA. Which of the following best describes the function of DNA? F DNA provides the shape and structure of the nucleus. G DNA packages materials for transport through the nucleus. H DNA carries materials into and out of the nucleus. J DNA contains the blueprint for producing the whole organism.

    16. And the answers are. . . H; It must come apart at the rungs or steps of the ladder, which are the nitrogen bases. D; the center A has been changed to a C. A; it is the DNA, 1 gene = 1 protein D; the first step in replication is to untwist the double helix, and then unpair the bases. J; what the cell does and how it works is information from the genes, which are made of DNA.

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