Biology DNA Unit HW Packet #1 Name Date Hour DUE: Lab Nucleotide Completed Daisy Analysis Completion Chain HW Completion Genetics Disorders #5 5 total 1
DNA Daisy Chain and Analysis of Replication Background: DNA structure, once hypothesized by Watson and Crick, led directly to speculation about the mechanisms of DNA s storage of genetic material. The proposal of a two stranded molecule with complementary (G-C,.A-T) bases strongly hinted at a mechanism for replicating (copying) DNA. Today we will build a model of the double helix. Analyze its replication and join our molecules together, 5 end to 3 end to build one large DNA molecule. Procedure Follow the instructions on the DNA Daisy Chain handout to cut out a template for your model. Use this template and the folding instructions to cut out your own DNA molecule. Be sure to color your bases the correct color. A = red T = yellow G = green C = blue Phosphate = white Deoxyribose Sugar = Orange Template: Orange A, T, G or C one color White 2
DNA Daisy Chain Cut-Out Questions 1. What are the three parts of a nucleotide? a. deoxyribose (sugar) b. phosphate c. nitrogen base (adenine, thymine, guanine, cytosine) 2. Which bases are connected? Adenine connects with thymine. Guanine connects with cytosine. 3. How many total bases did you draw? 12 bases total in DNA daisy chain. 4. How many bases would there be in one human cell? There are 6 billion bases in one human cell. 5. Where in the cell would these bases be stored? Bases are stored in the nucleus of the cell. 6. In terms of DNA structure, what determines whether you have blue eyes or brown eyes? The order of the nucleotides determines your eye color. 3
DNA Homework DNA is a polymer composed of many monomers. Think of monomers as the many boxcars that are linked together to form a long train. Each train (polymer) is composed of different cars (monomers) and is a different length. The monomers in DNA are the nucleotides. A nucleotide is joined to the next nucleotide in the chain by a phosphodiester bond. Each nucleotide is in turn made up of the joining of a nitrogenous base, a pentose sugar and a phosphate group. 1. Label the following cartoon of a nucleotide with these three parts: base, sugar, and phosphate. (Hint: Use your notes to help) sugar base phosphate Many of these nucleotides can be hooked together to form a nucleic acid like deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). 2. Let us build a very short RNA molecule by joining three nucleotides together with the bases: cytosine, guanine, and adenine. Draw your own bases using the model in question one; replace the base with the three bases listed above. (First one included) C G A DNA is a double stranded polymer. These two strands run in an anti-parallel direction. The force holding one strand to another is hydrogen bonding between the bases. We can use a simplified model to convey this complex structure. A key rule to follow is that certain bases are complementary, pairing together like puzzle pieces, to build the ladder-like structure of DNA. Adenine pairs with Thymine (or Uracil in RNA) and Guanine pairs with Cytosine. [A with T or U and G with C] G T G A C 4
DNA STRUCTURE (Use Text book - pg 228 233) 1. DNA is an abbreviation for deoxyribonucleic acid. 2. In the 1920 s, P.A. Levine showed that DNA is made of what 3 parts? A. sugar (deoxyribose) B. phosphate C. nitrogen base 3. There are 4 nitrogenous bases. Their full names are: A. adenine B. thymine C. cytosine D. guanine 4. When a nitrogenous base, a sugar, and a phosphate group are put together, the resulting molecule is called a nucleotide_. 5. The sugar in DNA is named deoxyribose. 6. While studying the chemical makeup of DNA, Erwin Chargaff found that the nitrogen bases do not occur in equal proportions. Later, scientists used this information to help determine the structure of DNA. How did this information help determine the structure of DNA? (What did they figure must be true about the nitrogen bases?) Because adenine and thymine occurred in equal amounts and cytosine and guanine occurred in equal amounts, adenine and thymine must be paired and guanine and cytosine must be paired. 5
7. In 1953, two scientists determined the structure of DNA. A. Who were these two scientists? James Watson and Francis Crick B. What scientific term describes DNA s shape? Double helix C. How many strands does DNA have? 2 D. Which nitrogen bases pair together? 1. adenine and thymine 2. guanine and cytosine 8. How are the rungs of DNA held together? The rungs of the DNA ladder (made of the bases) are held together with hydrogen bonds. 9. How many base pairs are in a single human cell? There are 3 billion base pairs in a single human cell. 10. If the sequence of DNA is C T A C G T, the sequence of nucleotides on the other strand of DNA would be G A T G C A. 11. In your own words, describe the importance of DNA. Please write approximately 3 4 complete sentences. Answers will vary. 6
GENETIC DISORDER RESEARCH PACKET PART V My assigned genetic disorder is Answer in complete sentences. Be sure to attach a copy of your references to the homework packet. GENETIC DISORDER PROJECT ASSIGNMENT #5 Genetic disorders are caused by your DNA. Since your DNA is inherited from your parents (and your parents inherited this DNA from their parents), any changes to the DNA sequence can be passed from one generation to the next. In general, genetic disorders can be classified into two groups: chromosome disorders and gene disorders. In chromosome disorders, an entire chromosome is missing or an extra one has been added. As a result, humans with chromosome disorders may only have 45 chromosomes or could have as many as 47 chromosomes in each of their cells. In gene disorders, only a small section of a chromosome (a gene) is changed. However, even a small change can have a huge effect on the person who has a gene disorder. 1. Define the following terms: - Chromosome Disorder: A genetic disorder caused by large changes to DNA. An entire chromosome may be missing (monosomy) or an extra chromosome may be added (trisomy). - Gene Disorder: A genetic disorder caused by small changes to the DNA sequence of gene(s). 7
2. In all cases, you were assigned a gene disorder. To be a gene disorder, one or more genes are affected. What is the name of the gene that is causing this genetic disorder? NOTE: There may be more than one gene. If so, select two (your choice) to focus your attention. NAME OF GENE(S): 3. Each gene can be found on a chromosome. For the gene(s) you listed in question #2, what chromosome contains this gene? WHICH CHROMOSOME: 4. Each chromosome can be divided into p and q sections which are simply halves of a chromosome that are on one side or the other of a centromere. Centromere p q Scientists have likely gone through a process to try to narrow the location of this gene to a region of that chromosome the numbers which follow the p or q. For example, a gene found on 11q13.3 which means that this gene is on chromosome 11, the q section, 13.3 units away from the centromere. WHERE ON THE CHROMOSOME IS THE GENE LOCATED: 8
5. Each gene serves as a set of instructions to help a cell make a protein. What is the name of the protein encoded by this gene? NAME OF PROTEIN: 6. Each protein has a job in a cell or in the body. What is your protein supposed to do? You will be asked to explain this to everyone else in class during your presentation to begin to summarize the protein s function or job in your own words. JOB OF PROTEIN: 7. In the first packet, you were asked to find the symptoms of this disorder. Regardless of which genetic disorder you were assigned, the gene involved is not the normal set of instructions. As a result, the protein encoded by that gene is not doing what it is supposed to be doing. How does this lead to the traits or symptoms of this disorder? EXPLAIN HOW PROTEIN NOT WORKING RIGHT LEADS TO TRAITS/SYMPTOMS OF THIS DISORDER: 9
8. This is a genetic disorder and scientists may have determined whether the disorder is dominant, recessive, incomplete dominant, co-dominant, sex-linked, or a different possibility. Research to find how this genetic disorder is passed from one generation to the next. (NOTE: You will typically see that the disorder is sex-linked or autosomal. Remember, sex-linked genes are either on the X or the Y chromosome. Autosomal genes are on one of the other chromosomes (1 22). You should know the specific chromosome number of this gene. Once you find an answer, you may want to check one of the chromosome posters in my room to find this gene). WHAT TYPE OF GENETICS IS INVOLVED IN INHERITING THIS DISORDER? - (NOTE: If this disorder is dominant, then you MUST revise your answer to the Hardy Weinberg problem in packet #4.) 10
9. You have recently learned about pedigrees. Imagine that you are a doctor or genetics counselor for a family that has just learned that their child has inherited your assigned genetic disorder. Draw a pedigree that shows how this child has inherited this disorder and write a paragraph to explain the family history (a story with your pedigree). Your pedigree must include the following: - three generations - at least two children in the second generation - at least 4 people in the third generation - must be accurate for the genetics of the disorder - must have the correct genotypes for each person PEDIGREE: STORY: 11
The following websites may aid your search: DON T JUST TYPE IN THE WEB ADDRESSES. READ THE SUMMARIES THEY MAY CONTAIN HELPFUL DIRECTIONS! www.genetests.org at this site, you can click on Gene Reviews, type in the name of the disorder, select reviews, and then select molecular genetics. If known, the name of the gene, the name of the protein, and the position on a chromosome (chromosomal locus will be given. Click on the name of the protein and it will tell you the protein s function. Select genetic counseling and you will find the genetics of this disorder (mode of inheritance such as dominant or recessive). You can also enter the name of the disorder and select testing to find out how tests are done to know if someone has this disorder. www.ncbi.nlm.nih.gov/disease/ - AWESOME website. If you know the chromosome that your gene is on, choose that chromosome and click on the name of the gene. If you don t know which chromosome to start with, choose the green click here button for the BOOKSHELF. This will take you to a page that has a listing of genetic disorders. These are grouped by type of disorder. Search the page by selecting Find on the toolbar and entering the name of your assigned genetic disorder. Great summaries! www.ygyh.org not available for all genetic disorders, but does contain AWESOME information and animations for a select few. If you find your assigned genetic disorder here, congratulations! www.geneclinics.org/profiles - find your assigned genetic disorder from an alphabetical listing of a large number of genetic disorders. Click on the name and be taken to a description of the disorder. Most often, the link is to the www.genetests.org site (see above). ghr.nlm.nih.gov/ghr/ - FANTASTIC SITE! If you are having any trouble with your research, you should be accessing this site. This is the one above all others that you should use. Great place to begin. www.nlm.nih.gov/medlineplus/geneticdisorders.html - links to a variety of sites about genetic disorders; designed by the National Institutes of Health. gslc.genetics.utah.edu/units/disorders/whataregd/ - if you are struggling to understand the difference between chromosome and gene disorders, this website will help you. www.ncbi.nlm.nih.gov/science96/genelist.cgi - an alphabetical listing of a limited number of genes and genetic disorders. Interesting to compare what was known less than 10 years ago with the wealth of information available today. 12