1. What is a linear polymer made up of 4 letters that forms 3 letter words with a total of 20 possible words?
2. The Human Genome has it been completed?
3. The Human Genome does it have free open-source access on a public database?
4. Roughly how many species have been partially sequenced?
a. 5,500 b. >100,000 c. 500 d. 25 Rollover answer
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DNA Primer
a. Rollover images blank to answer DNA deoxyribonucleic acid is found in the nucleus of human cells.
b. DNA has four bases - adenine(A), thymine(T), cytosine(C), guanine(G) arranged along double strands of sugar-phosphate molecules.
c. The bases on the two strands are complementary, with A always opposite T and C always opposite G. These combinations are called complementary base pairs.
d. The double-stranded DNA molecule has the shape of a ladder. The base pairs are the rungs, and sugar-phosphate molecules are the rails. This ladder twists up tightly, forming a "double helix".
e. DNA is duplicated or copied when its strands separate and new bases bind to their complements on each strand. An enzyme, DNA polymerase, helps add bases to build a new strand.
f. The order or sequence of bases in the DNA molecule carries the message or "meaning" of DNA's instructions.
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Genetics Primer
a. There is more than one variety of most genes. Some genes have disease varieties and healthy varieties.
b. The variants of the gene can be dominant, recessive, or co-dominant.
c. Some traits are caused by a single gene, others by a combination of genes.
d. Genes are arranged in a specific order along chromosomes.
e. Each of us has 23 pairs of chromosomes. We inherit one chromosome in each pair from each parent.
f. The chromosomes we inherit from our mother contain a combination of genes from her parents. Likewise, our dad's chromosomes contain a combination of genes from his parents. This recombination of genes leads to the infinite variety of individuals.
g. Genes located on different chromosomes are inherited independently of each other.
h. Genes and markers located near each other on the same chromosome are often inherited together, so they are linked when passed from parent to child.
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DOE Gene Gateway Workbook Answers
Chapter 1 Solutions Even-number Problems
1.2 What is the complementary sequence to the following string of nucleotides? Be sure to label the 5' and 3' end of the sequence that you write. 5'-GGATCGTAGCCTA-3'
5'-TAGGCTACGATCC-3'
1.4 Organic molecules that contain hydroxyl groups (-OH) are called alcohols. Would you expect such molecules to be hydrophobic or hydrophilic? Why?
Alcohols are generally hydrophilic because the oxygen atom is more electronegative than the hydrogen and carbon atoms to which it is covalently bonded. The resulting partial separation of charges (slightly negatively charged oxygen and slightly positively charged hydrogen and carbon) allows hydrogen bonds to be formed with water molecules.
1.6 How frequently would you expect to find the sequence of nucleotides provided in Question 1.2 in a DNA molecule simply as a result of random chance? Assuming that each of the four nucleotides occurs with the same frequency.
The nucleotide sequence shown in Question 1.2 is 13 nucleotides long. If each of the four nucleotides can be expected to occur with the same frequency (0.25) then it should be found approximately once for every 413 (67,108,864) sequences that are 13 nucleotides long.
1.8 Distinguish between positive and negative regulation of gene expression.
In positive regulation of gene expression, the action of a regulatory molecule assists in the expression of a gene (i.e., the binding of a protein to the promoter of a gene that makes it more likely that RNA polymerase will initiate transcription). Negative regulators of gene expression inhibit the expression of genes when they are active.
1.10 A circular piece of DNA known to be 4,000 bp long is cut into two pieces when treated with the restriction enzyme EcoRI: one is 3,000 bp long and the other is 1,000 bp long. Another restriction enzyme, BamHI, cuts the same DNA molecule into three pieces of the following lengths: 2,500, 1,200, and 300 bp. When both EcoRI and BamHI are used to cut the DNA molecule together, fragments of the following sizes are generated: 1,600, 1,200, 900, 200, and 100 bp. Use this information to make a restriction enzyme map of this circular DNA molecule.
From one of the EcoRI sites, it is 900 bp to the closest BamHI site. Continuing around the circular DNA molecule, it is 100 bp to the second EcoRI site, then 200 bp to the next BamHI site, then 1,200 bp to the next BamHI site, then 1,600 bp back to the first EcoRI site.
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