74. A study is done on a mammalian cell line that has a doubling time of 24 hours. These cells are synchronized in G1 and then labeled for 2 days with BrdU (an analog of thymidine that increases the density of DNA into which it is incorporated). At the end of the labeling period, chromosomal DNA is isolated from the cells and its density analyzed by equilibrium centrifugation in cesium chloride gradients. Which of the following patterns would be expected to be seen? (H=heavy, L=light) a. 100% H/H b. 111% H/L c. 50% H/H, 50% H/L d. 50% H/H, 50% L/L e. 25% H/H, 50% H/L, 25% L/L 78. Diarrhetic shellfish poisoning is caused by okadaic acid. Dr. Mollusca finds that okadaic acid increases the phosphorylation of Cl- channels in intestinal epithelial cells, causing the channels to open. Dr. Mollusca concludes that okadaic acid activates a kinase that phosphorylates the Clchannels. Based on the given evidence, do you agree or disagree with Dr. Mollusca’s conclusion, and why? a. Agree, it is the most obvious conclusion and based on evidence of increased phosphorylation. b. Disagree, since kinases do not phosphorylate Cl- channels. c. Disagree, because it is more likely that okadaic acid inhibits a phosphatase. d. Disagree, because based on the evidence you can’t conclude which enzyme is being affected by the okadaic acid
DNA and RNA
Deoxyribonucleic acid (DNA) is usually called the blueprint of life. Deoxyribose is a monosaccharide that has a key function in the synthesis of deoxyribonucleic acid. One less oxygen-containing hydroxyl group occurs in deoxyribose sugar. Nucleic acid, deoxyribonucleic acid, is one of the natural components. Deoxyribonucleic acid is a double-stranded molecule. Watson and Crick postulated the double-stranded model of the helix. A deoxyribonucleic acid is a molecular group that carries and transmits genetic information from parents to offspring. All eukaryotic and prokaryotic cells are involved.
DNA as the Genetic Material
DNA, or deoxyribonucleic acid, is a long polymeric nucleic acid molecule discovered in the late 1930s. It is a polymer; a long chain-like molecule made up of several monomers connected in a sequence. It possesses certain characteristics that qualify it as a genetic component. Certain organisms have different types of nucleic acids as their genetic material - DNA or RNA.
Genetics
The significant branch in science which involves the study of genes, gene variations, and the organism's heredity is known as genetics. It is also used to study the involvement of a gene or set of genes in the health of an individual and how it prevents several diseases in a human being. Thus, genetics also creates an understanding of various medical conditions.
DNA Replication
The mechanism by which deoxyribonucleic acid (DNA) is capable of producing an exact copy of its own is defined as DNA replication. The DNA molecules utilize a semiconservative method for replication.
74. A study is done on a mammalian cell line that has a doubling time of 24 hours. These cells are
synchronized in G1 and then labeled for 2 days with BrdU (an analog of thymidine that increases
the density of DNA into which it is incorporated). At the end of the labeling period, chromosomal
DNA is isolated from the cells and its density analyzed by equilibrium centrifugation in cesium
chloride gradients. Which of the following patterns would be expected to be seen? (H=heavy,
L=light)
a. 100% H/H
b. 111% H/L
c. 50% H/H, 50% H/L
d. 50% H/H, 50% L/L
e. 25% H/H, 50% H/L, 25% L/L
78. Diarrhetic shellfish poisoning is caused by okadaic acid. Dr. Mollusca finds that okadaic acid
increases the phosphorylation of Cl- channels in intestinal epithelial cells, causing the channels to
open. Dr. Mollusca concludes that okadaic acid activates a kinase that phosphorylates the Clchannels. Based on the given evidence, do you agree or disagree with Dr. Mollusca’s conclusion,
and why?
a. Agree, it is the most obvious conclusion and based on evidence of increased
phosphorylation.
b. Disagree, since kinases do not phosphorylate Cl- channels.
c. Disagree, because it is more likely that okadaic acid inhibits a phosphatase.
d. Disagree, because based on the evidence you can’t conclude which enzyme is being
affected by the okadaic acid
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