DNA TEST
If 35% of an organism's DNA is thymine, what is the percentage of guanine?
15%
How does the double-helical structure of DNA explain how the molecules can be copied or replicated?
Because of base pairing, each strand has all the information to serve as a template for the other strand.
When must DNA replication occur during the cell cycle for each daughter cell to receive a complete copy of DNA?
DNA replication must occur before mitosis.
The table shows data Chargaff collected on DNA nitrogenous bases in five organisms. Which statement did Chargaff conclude based on these data? Note that a letter in brackets, such as [A] or [C], refers to the concentration of one of the nitrogenous bases.
in DNA molecules, [A] = [T], and [C ] = [G]
The picture of the double-helix model of the DNA molecule resembles a twisted ladder. The figure shows a model of the double-helical DNA molecule. What makes up the rungs of the twisted ladder?
paired nitrogenous bases
Telomeres are located near the tips of eukaryotic DNA. During DNA replication, what is the role of enzymes called telomerase?
preventing loss or damage of genes near telomeres
The diagram shows a model of DNA replication. Where is the enzyme DNA polymerase shown in the model? Select the proper location.
the circle thing
In the Hershey-Chase experiment, the components of bacteriophages were labeled with radioactive isotopes of sulfur and phosphorus. What was the Hershey-Chase experiment designed to determine?
whether cells use DNA or proteins to store genetic information
Chargaff's rules of base pairing are explained by which structural feature of DNA?
DNA is double stranded, and hydrogen bonds between base pairs hold the strands together.
The graph shows the amount of DNA in a cell during two cell cycles. A graph showing change of DNA content during the cell cycle. Which conclusion about DNA replication is supported by the graph?
DNA replication occurs only during the S phase of the cell cycle.
What would happen if a cell divides before DNA replication is completed?
Daughter cells would receive incomplete genetic information and never regain it, and they may not survive.
How does DNA replication differ between eukaryotes and prokaryotes?
Eukaryotes use multiple replication forks to replicate a larger volume of DNA.
Griffith investigated how certain types of bacteria produce pneumonia in mice. The diagram outlines his experiments. The figure shows Griffith's experiments in which he injected mice with four different samples of bacteria. When injected separately, neither heat-killed, disease-causing bacteria nor live, harmless bacteria killed the mice. The two types injected together, however, caused fatal pneumonia. What did Griffith conclude from these experiments?
The heat-killed S type bacteria transformed the harmless R type bacteria into disease-causing cells.
Griffith investigated how certain types of bacteria produce pneumonia in mice. The diagram outlines his experiments. The figure shows Griffith's experiments in which he injected mice with four different samples of bacteria. When injected separately, neither heat-killed, disease-causing bacteria nor live, harmless bacteria killed the mice. The two types injected together, however, caused fatal pneumonia. What happened when the samples of bacteria were injected into the mice? Select all that apply.
A. When heat-killed, disease-causing bacteria were injected, the mice were not killed. B. When live, harmless bacteria were injected, the mice did not die. C. When heat-killed, disease-causing bacteria and harmless bacteria were injected together, the mice were killed. E. When live, harmful bacteria were injected, the mice died.
This figure shows a section of a double-stranded DNA molecule. This figure shows a short section of a double-stranded DNA molecule. What aspects of the structure of DNA are explained by this model?
Adenine is paired with thymine, and guanine is paired with cytosine. Paired nucleotides are held together by hydrogen bonds. The two strands of DNA each have phosphate-sugar backbones
The table shows data Chargaff collected on DNA nitrogenous bases in five organisms. Percentages of Bases in Five Organisms Source of DNA A T G C Streptococcus 29.8 31.6 20.5 18.0 Yeast 31.3 32.9 18.7 17.1 Herring 27.8 27.5 22.2 22.6 Human 30.9 29.4 19.9 19.8 E.coli 24.7 23.6 26.0 25.7 Which of the following statements describe properties of the DNA molecule that are consistent with Chargaff's data? Select all of the answers that apply.
An adenine base and a thymine base on opposite strands can form hydrogen bonds between them. On a single strand, the four bases are repeated many times and in different combinations.
The result of the Hershey-Chase experiment was that radioactivity could be detected inside the bacterial cells when they were infected by bacteriophages marked with phosphorus-32.
Bacteriophages inject DNA into the bacterial cells.
A scientist uses radioactive isotopes to label a double-stranded molecule of DNA. Then the DNA undergoes replication in a non-radioactive medium. Where are the two original radioactive strands of DNA?
Both strands are intact, and each is part of a different molecule of .
Frederic Griffith used the word transformation to describe the changes in bacteria that he observed. Which is the most useful definition of transformation?
a permanent change in the genetic composition of an organism
In DNA, thymine always pairs with and cytosine always pairs with to form between the nitrogenous bases.
adenine, guanine, hydrogen bonds