Chapter 10 HW

Enter the complementary sequence to the DNA strand shown. 5′- TACAGACAG -3′

3'- ATGTCTGTC -5'

What is the key feature of DNA that allows it to be copied?

complementary base pairing

Which relations will be found in the percentages of bases of a double‑stranded DNA molecule? A+C=G+TA+C=G+T A+T=G+CA+T=G+C A/C= G/TA/C= G/T A/T=G/CA/T=G/C (A+G)/(C+T)=1.0

A+C=G+T A/T=G/C (A+G)/(C+T)=1.0

Which of the statements describes purines and pyrimidines in DNA molecules? Pyrimidines form hydrogen bonds with pyrimidines. Purines consist of a two-ring structure. Thymine and cytosine are purines. Purines form covalent bonds with pyrimidines. Purines form hydrogen bonds with pyrimidines

Purines consist of a two-ring structure. Purines form hydrogen bonds with pyrimidines

What evidence supports the hypothesis that RNA was the genetic material early in evolutionary history? RNA can self‑replicate. Some viruses have RNA genomes. RNA has been isolated from more ancient sources than DNA. Some archaea have RNA genomes.

RNA can self‑replicate. Some viruses have RNA genomes.

Which of these is an example of a sequence of bases in an RNA molecule that will produce a hairpin structure? (A hairpin structure occurs when a single strand of nucleotides can base‑pair with itself.) Select all that apply. UGCGAUACUCAUCGCA AUCGGGCCCAAGUCG CGCGCAAAGCGCG TGCGATACTCATCGCA AAUAAUUUCGGAGCGC

UGCGAUACUCAUCGCA CGCGCAAAGCGCG

Identify the key structural features of a DNA molecule: - DNA is most often found as a left-handed helix, commonly referred to as A‑DNA. - DNA contains the nucleotide bases adenine, thymine, guanine, cytosine, and uracil. - DNA bases are always paired using Watson-Crick base pairing. - Strong ionic bonds and hydrophobic interaction hold DNA together. - The backbone of DNA is made of a sugar and a phosphate molecule. - DNA strands are antiparallel and include a 5′5′ end and a 3′3′ end.

- DNA bases are always paired using Watson-Crick base pairing. - The backbone of DNA is made of a sugar and a phosphate molecule. - DNA strands are antiparallel and include a 5′5′ end and a 3′3′ end

There are two types of nucleic acids, DNA and RNA. Nearly all organisms use DNA, not RNA, as the central repository for genetic information. Choose the statements that explain this phenomenon. - DNA is flexible and forms complex catalytic structures. - DNA contains adenine as one of its nitrogenous bases. - DNA is more resistant against enzymes that degrade nucleic acids. - DNA has a double‑stranded structure that ensures an accurate mechanism of duplication. - DNA contains an −OH−OH group at the 2′2′ carbon.

DNA is more resistant against enzymes that degrade nucleic acids. DNA has a double‑stranded structure that ensures an accurate mechanism of duplication.

What is the reason scientists think DNA was selected over RNA as the most common genetic material? DNA has more total codons. DNA is easier to replicate. DNA has the nucleotide thymine. DNA is more stable than RNA.

DNA is more stable than RNA.

DNA has unique properties that allow it to accurately retain genetic information, even after multiple rounds of replication. One aspect of DNA that allows it to accurately store genetic information is the base pairing from Chargaff's first rule of the four nucleotide bases. If the C content of a DNA molecule is 22%,22%, what are the percentages of the remaining bases? G? T? A?

G = 22% T = 28% A = 28%

Select each of the characteristics that are key features of genetic material. It must be able to store and express information. It must be able to replicate and transmit to progeny. It must have heritable traits that can be passed to offspring. It must periodically mutate to generate variation. It must differentiate in each cell type.

It must be able to store and express information. It must be able to replicate and transmit to progeny. It must periodically mutate to generate variation.

Scientists have reportedly isolated short fragments of DNA from fossilized dinosaur bones hundreds of millions of years old. The technique used to isolate this DNA is the polymerase chain reaction, which is capable of amplifying very small amounts of DNA a million‑fold. Critics have claimed that the DNA isolated from dinosaur bones is not purely of ancient origin but instead has been contaminated by DNA from present‑day organisms, such as bacteria, mold, or humans. What precautions, analyses, and control experiments could be carried out to ensure that DNA recovered from fossils is truly of ancient origin? - The DNA from people involved in the procedure, material at various locations around the site, and isolated microorganisms from the area should be tested to see if amplification occurs. - The design of the primers used for amplification should be considered carefully and should be executed considering the sequences of potential dinosaur descendants, such as birds or reptiles. - The sample DNA should be washed in ethanol or heated to 300 °C because it will destroy any contaminating DNA. - The scientists should wear gloves and masks, and instruments used in the sampling should be sterilized. - This DNA should be compaired to DNA from previous dinosaur samples because low similarity would rule out that the sample DNA came from a dinosaur.

- The DNA from people involved in the procedure, material at various locations around the site, and isolated microorganisms from the area should be tested to see if amplification occurs. - The design of the primers used for amplification should be considered carefully and should be executed considering the sequences of potential dinosaur descendants, such as birds or reptiles. - The scientists should wear gloves and masks, and instruments used in the sampling should be sterilized.

My Attempt In 1953, the scientists James Watson and Francis Crick published their landmark findings on the structure of DNA. Watson and Crick deduced the structure of DNA by unifying evidence that they collected from several scientists who were also seeking to answer this important question. Identify the pieces of evidence describing the features of DNA that Watson and Crick used to determine the structure of DNA. - The sugar-phosphate backbones of each DNA helix run antiparallel to one another. - A purine base forms covalent bonds with a pyrimidine base located on the opposite DNA helix. - DNA forms a right‑handed double helical structure with two polynucleotide chains coiled around a central axis. - The two chains are parallel, both running in a 5′5′ to 3′3′ direction. - The diameter of the DNA double helix is 2 nanometers, with each purine-pyrimidine base pair spanning an equivalent distance between the two chains. - A purine base forms hydrogen bonds to pair with a pyrimidine base located on the opposite DNA strand. Specifically, A pairs with T, and C pairs with G.

- The sugar-phosphate backbones of each DNA helix run antiparallel to one another. - DNA forms a right‑handed double helical structure with two polynucleotide chains coiled around a central axis. - The diameter of the DNA double helix is 2 nanometers, with each purine-pyrimidine base pair spanning an equivalent distance between the two chains. - A purine base forms hydrogen bonds to pair with a pyrimidine base located on the opposite DNA strand. Specifically, A pairs with T, and C pairs with G.

What is the average wavelength, in nanometers (nm), at which protein absorbs UV light?

280

What results would you expect if the Hershey-Chase experiment were conducted on tobacco mosaic virus? - The radioactive protein would have entered the cells, and the radioactive RNA genome would have remained outside in the surrounding medium. This would demonstrate that protein was the genetic material. - Both the radioactive protein coat and the radioactive RNA genome would have entered the cells, making it difficult to determine which of them was the genetic material. - The radioactive protein would have entered the cells, and the radioactive RNA genome would have remained outside in the surrounding medium. This would demonstrate that RNA was the genetic material. - The radioactive RNA genome would have entered the cells, and the radioactive proteins would have remained outside in the surrounding medium. This would demonstrate that protein was the genetic material. - The radioactive RNA genome would have entered the cells, and the radioactive proteins would have remained outside in the surrounding medium. This would demonstrate that RNA was the genetic material.

Both the radioactive protein coat and the radioactive RNA genome would have entered the cells, making it difficult to determine which of them was the genetic material.