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Biology Chp 12 Assessment Questions
Terms in this set (16)
1a. List the conclusions that Griffith and Avery drew from their experiments. (12.1)
Griffith - Genetic info. could be transferred from one bacterial strain to another.
Avery - Nucleic acid DNA stores and transmits genetic info. from one generation to the next.
1b. What was the experimental variable that Avery used when he repeated Griffith's work? (12.1)
Enzymes that destroyed proteins, lipids, carbohydrates, and nucleic acid RNA and enzymes that broke down nucleic acid RNA.
2a. What conclusion did Hershey and Chase draw from their experiments? (12.1)
Their experiments confirmed Avery's results; DNA was the genetic material found in genes - not in just viruses and bacteria, but in all living cells.
2b. Why did Hershey and Chase grow viruses in cultures that contained both radioactive phosphorous and radioactive sulfur? What might have happened if they had used only one radioactive substance? (12.1)
So that both the viral DNA and viral proteins would be marked; either they would not have been able to trace the location of the unmarked molecule in the bacterial cell, or the results would not have been conclusive.
3a. What are the three key roles of DNA? (12.1)
Storing, copying, and transmitting information.
3b. Why would the storage of genetic information in genes help explain why chromosomes are separated so carefully during mitosis? (12.1)
In mitosis the two sets of genetic material separate and each daughter cell receives one complete set of chromosomes.The loss of any DNA during mitosis would mean that the daughter cell would not receive a complete of chromosomes and valuable genetic information would not be transmitted from one generation to the next.
1a. List the chemical components of DNA (12.2)
Nucleotides are made up of deoxyribose, a phosphate group, and a nitrogen base: adenine, thymine, guanine, and cytosine. Nucleotides then make up nucleic acid, through the linking of phosphate groups and sugars via a covalent bond.
1b. Why are hydrogen bonds so essential to the structure of DNA? (12.2)
They keep the two strands of DNA connected. The bond is weak, allowing them to be easily disconnected and used for other functions
2a. Describe the discoveries that led to the modeling of DNA. (12.2)
Chargaff discovered base pairing rules. Franklin took X-ray photographs that revealed that DNA has a spiral structure. This finding helped Watson and Crick create a model of DNA and discover the double-helix.
2b. Why did scientists have to use tools other than microscopes to solve the structure of DNA? (12.2)
Scientists had to use tools other than microscopes because DNA is/was too small to be seen with light microscopes, the only type available at the time.
3a. Describe Watson and Crick's model of the DNA molecule. (12.2)
Watson and Crick's model is composed of two strands that are connected by bonds between nitrogen bases that has a spiral shape. The model showed that the DNA molecule is a double-helix.
3b. Did Watson and Crick's model account for the equal amounts of thymine and adenine in DNA? Explain. (12.2)
Yes. Watson and Crick's model depicted DNA as a double helix with adenine and thymine paired together. This pairing accounts for the equal amounts of thymine and adenine in DNA.
1a. How is DNA replicated? (12.3)
The DNA molecule produces two new complementary strands. Each strand of the double helix serves as a template for the new strand.
1b. What is the role of DNA polymerase in DNA replication? (12.3)
It joins individual nucleotides to produce a new strand of DNA. Then it proofreads each new DNA strand, so that each molecule is a near-perfect copy of the original.
2a. Where and in what form is prokaryotic DNA found? Where is eukaryotic DNA found? (12.3)
Prokaryotic DNA - Found in the cytoplasm of the cell. Looks like a circle.
Eukaryotic DNA - Found in the nucleus of the cell. Looks like a double helix.
2b. What could be the result of damaged DNA being replicated? (12.3)
Changes to DNA base sequences that may alter genes and produce serious consequences.
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