Biology Chapter 12 Test
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A strand that has the base sequence TACGTT, what would the complimentary base sequence be?
1. The two strands of the double helix separate, or "unzip", allowing two replication forks to form. 2. New bases are added following the rules of base pairing.
During DNA replication, what two processes must occur BEFORE the two strands of a DNA molecule can separate?
1. Griffith injected mice with four different samples of bacteria. 2. When injected separately, neither heat-killed, disease-causing (S strain) bacteria, nor live, harmless (R strain) bacteria killed the mice. 3. The two strains injected together, however, caused fatal pneumonia. 4. Griffith concluded that genetic information could be transferred from one bacterial strain to another. He called this process transformation.
Explain Griffith's experiment
Avery and his team extracted a mixture of various molecules from the heat-killed bacteria. They carefully treated this mixture with enzymes that destroyed proteins, lipids, carbohydrates, and some other molecules, including the nucleic acid RNA. Transformation still occurred. Clearly, since those molecules had been destroyed, none of them could have been responsible for transformation. Avery repeated the experiment one more time. This time, they used enzymes that would break down DNA. When they destroyed DNA in the mixture, transformation did not occur.
How did Avery determine that DNA was the molecule that carried the genes for transformation?
The clues/observations in Franklin's X-ray pattern enabled Watson and Crick to build a model that explained the specific structure and properties of DNA.
How did Franklin's observations contribute to DNA?
Protein coat contain sulfur and very little phosphorus. DNA contains phosphorus and no sulfur. This made it very easy to see which substance entered the bacteria. Nearly all the radioactivity in the bacteria was from phosphorus (32P), the marker found in DNA.
How did Hershey and Chase know that it was the DNA that had infected the bacterial cells in their experiment?
Franklin used a technique called X-ray diffraction to get information about the structure of the DNA molecule. Fist, she purified a large amount of DNA, then stretched the DNA fibers in a thin glass tube so that most of the strands were parallel. Next, she aimed a powerful X-ray beam a t the concentrated DNA samples and recorded the scattering pattern of the X-rays on film.
How did Rosalind Franklin study the molecular structure of DNA?
Genetic information is lost
If a piece of DNA is missing, what is the end result?
They wanted to determine which part of the virus, the protein coat or the DNA core entered the bacterial cell. Knowing that Proteins contain almost no phosphorus, and DNA contains no sulfur they knew that these substances would be easily seen.
In Hershey and Chases' experiment, what exactly was the purpose of using radioactive Sulfur and Phosphorus?
E. Griffith concluded that genetic information could be transferred from one bacterial strain to another. C. Avery and his team concluded that DNA was the transforming factor. D. Hershey and Chase showed that Genes are made of DNA B. Chargaff discovered that relative amounts of adenine [A] and thymine [T], and guanine [G] and cytosine [C] bases are almost equal in any sample of DNA. A. Franklin's X-ray diffraction photograph shows the pattern that the structure of DNA is helical. F. Watson and Crick were able to build a model of DNA that explained the specific structure and properties of DNA.
Put the following discoveries in chronological order. Who discovered what first? A. Franklin's X-ray diffraction photograph shows the pattern that the structure of DNA is helical. B. Chargaff discovered that relative amounts of adenine [A] and thymine [T], and guanine [G] and cytosine [C] bases are almost equal in any sample of DNA. C. Avery and his team concluded that DNA was the transforming factor. D. Hershey and Chase showed that Genes are made of DNA E. Griffith concluded that genetic information could be transferred from one bacterial strain to another. F. Watson and Crick were able to build a model of DNA that explained the specific structure and properties of DNA.
Transformation
The process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria is called what?
5-carbon sugar, nitrogen base and a phosphate group.
What are the three parts of a nucleotide?
Chargaff discovered that the relative amounts of A and T, and of G and C, are almost always equal. The observation that [A] = [T] and [G] = [C] became known as "Chargaff's rule." This latter contributed to the understanding of base pairing of the two strands of DNA.
What did Chargaff discover and how did this contribute to DNA?
Genes are made of DNA
What did Hershey and Chase's work show?
Hershey and Chase studied a bacteriophage that was composed of a DNA core and a protein coat. They wanted to determine which part of the virus-the protein coat or the CNA core-entered the bacterial cell. Their results would either support or disprove Avery's finding that genes were made of DNA.
What did the scientists Hershey and Chase study?
Eukaryotic chromosomes consist of DNA, tightly packed together with proteins to form a substance called chromatin.
What do Eukaryotic chromosomes consist of?
the viral genes in bacteriophage gradually destroy the bacterium.
What does bacteriophage affect?
Trying to understand the structure of DNA, Watson and Crick built three-dimensional models of the DNA molecule that were made of cardboard and wire. They twisted and stretched the models in various ways. After being shown a copy of Franklin's remarkable X-ray pattern the missing puzzle pieces were put together, and they built a double helix, in which two strands of nucleotide sequences were wound around each other.
What experiment did Watson and Crick conduct?
Franklin's X-ray diffraction photograph shows the pattern that indicated the structure of DNA is helical.
What important clue from Rosalind Franklin's work helped Watson and Crick develop their model of DNA?
telomerase helps to prevent genes from being damaged or lost during replication.
What is Telomeres' job with chromosomes?
Eukaryotic DNA is found in the nucleus, packaged into chromosomes. Eukaryotic cells have up to 1000 times more DNA than prokaryotic cells. Prokaryotic DNA is found in the cytoplasm. They have a single, circular DNA molecule.
What is the difference between eukaryotic and prokaryotic DNA?
DNA polymerase
What is the enzyme involved in DNA replication?
Bacteriophage
What is the kind of virus that infects bacteria called?
Griffith
What is the name of scientist(s) responsible for the discovery of bacterial transformation?
Base pairing
What is the principle that says that bonds in DNA can form only between adenine and thymine and between guanine and cytosine?
Replication
What is the process of copying DNA prior to cell division called?
Telomere
What is the repetitive DNA at the end of a eukaryotic chromosome called?
Francis Crick was British and he was a physicist.
What nationality was Francis Crick and what did he do for work?
He was British, studying how bacteria made people sick.
What nationality was Frederick Griffith? and what was he studying?
James Watson was American and he was a biologist.
What nationality was James Watson and what did he do for work?
Avery was Canadian and he was studying which molecule in the heat-killed bacteria from Griffith's experiments was most important for transformation.
What nationality was Oswald Avery? and what was he studying?
Rosalind Franklin was a British scientist who began to study the molecular structure of DNA.
What nationality was Rosalind Franklin and what did she study?
DNA
What stores information in a cell?
Nearly all the radioactivity in the bacteria was from phosphorus (32P), the marker found in DNA. Hershey and Chase concluded that the genetic material of the bacteriophage was indeed DNA, not protein, confirming Avery's results. This convinced many scientists that DNA was the genetic material found in genes-not just in viruses and bacteria, but in all living things.
What was the conclusion of Hershey and Chase's experiment? How did it contribute to DNA?
Watson and Crick were able to build a model of DNA that explained the specific structure and properties of DNA. This double-helix model explains Chargaff's rule of base pairing and how the two strands of DNA are held together.
What was the conclusion of Watson and Crick's experiment? How did this contribute to DNA?
Avery and his team extracted a mixture of various molecules from the heat-killed bacteria. They carefully treated this mixture with enzymes that destroyed proteins, lipids, carbohydrates, and some other molecules, including the nucleic acid RNA. Transformation still occurred. Clearly, since those molecules had been destroyed, none of them could have been responsible for transformation. Avery repeated the experiment one more time. This time, they used enzymes that would break down DNA. When they destroyed DNA in the mixture, transformation did not occur.
What was the experiment that Avery conducted?
Wanting to find out how bacteria made people sick, Griffith 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 strains injected together, however, cause fatal pneumonia. (How could this happen if the S-strain cells were dead?) Griffith inferred that genetic information could be transferred from one bacterial strain to another, calling this process transformation.
What was the experiment that Griffith conducted?
Alfred Hershey and Martha Chase used different radioactive markers to label the DNA and proteins of bacteriophages. They used the radioactive isotopes of phosphorus-32 (32P) and sulfur-35 (35S), knowing that proteins contain almost no phosphorus, and DNA contains no sulfur, enabling the scientists to easily tell which molecules actually entered the bacteria, carrying the genetic information of the virus. if they found radioactivity from sulfur-35 in the bacteria, it would mean that the virus's protein coat had been injected into the bacteria. If they found phosphorus-32, then DNA core had been injected. Protein coat contain sulfur. DNA contains phosphorus.
What was the experiment that Hershey and Chase conducted?
Erwin Chargaff was Austrian-American and he was a biochemist.
What was the nationality of Erwin Chargaff and what did he do?
They were trying to understand the structure of DNA
What were Watson and Crick trying to understand in their studies?
By itself, Franklin's X-ray pattern does not reveal the structure of DNA, but it does carry some very important clues: *The X-shaped pattern shows that the strands in DNA are twisted around each other like the coils of a spring, a shape known as a helix. *The angle of the X suggests that there are two strands in the structure. *The nitrogenous bases are near the center of the DNA molecule.
What were the conclusions of Franklin's studies?
Avery and his team concluded that DNA was the transforming factor. These conclusions contributed to DNA by discovering that the nucleic acid DNA stores and transmits genetic information from one generation of bacteria to the next.
What were the conclusions that Avery drew from his experiments? How did these conclusions contribute to DNA?
Griffith concluded that genetic information could be transferred from one bacterial strain to another. Because the ability to cause disease was inherited by the offspring of the transformed bacteria, Griffith concluded that the transforming factor had to be a gene. It was later concluded that the "gene" that was responsible for transformation was DNA.
What were the conclusions that Griffith drew from his experiments? How did these conclusions contribute to DNA?
In the viral genes.
Where does a bacteriophage have genetic material?
Eukaryotic cells is found in the nucleus, packaged into chromosomes.
Where is DNA found in Eukaryotic cells?
Most prokaryotes have a single, circular DNA molecule in the cytoplasm.
Where is DNA found in prokaryotic cells?
The circles on the edges are the phosphate groups. The octagon shapes are the 5-carbon sugars. The rectangles in the center are the bases of Adenine, Guanine, cytosine and Thymine. Adenine and paired with Thymine. Guanine and paired with cytosine.
Where is the phosphate group? Where is the sugar? Where are the bases? What are the pairs?
Alfred Hershey and Martha Chase
Which researchers used radioactive markers in experiments to show that DNA was the genetic material in cells?
Because of structural problems of being too long or too short. If Adenine paired with Cytosine or Guanine it would be too long. If Cytosine paired with Thymine it would be too short.
Why can Adenine only pair with Thymine, and Cytosine only pair with Guanine?
The book contains instructions. It stores information that can be copied and information can be transmitted. These three tasks, storing, copying and transmitting are also the main functions of DNA. DNA has stored information, that can be copied and passed on just like a book.
Why do we refer to DNA as a book?
