Chapter 11

Section 1


Objectives:

• Describe Griffith's experiments and conclusion.
• Describe Avery's experiments and conclusion.
• Explain how experiments with viral DNA further supported Avery's conclusion.

1. Describe Griffith's experiments and conclusion.

He injected four mice with four different strains of bacteria. One strain was pneumonia, one strain was harmless, one strain was heated pneumonia, and the last one was a mixture of the heated pneumonia strain and the harmless bacteria. The strain of pneumonia and the mixture of the heated pneumonia and the harmless bacteria killed the mice. The harmless strain alone, and the heated pneumonia had no affect on the mouse. 

2. Describe Avery's experiments and conclusion.

Avery treated Griffith's mixture of the heat treated pneumonia and the harmless bacteria with protein-destroying enzymes. Bacterial colonies in the mixture were still transformed. Then he treated the mixture with DNA-destroying enzymes. The colonies failed to transform. He concluded that DNA was the genetic material of the cell. 

3. Explain how experiments with viral DNA further supported Avery's conclusion.

Two scientists, Hershey and Chase, knew that the bacteriophage (phage) had two basic components: DNA inside, and the proteins were on the outside. They conducted the following experiment:

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Section 2

Objectives:

• Identify the building blocks of DNA.
• Describe DNA's structure and the rules for base pairing in DNA. 

1. Identify the building blocks of DNA.

Nucleotides are really the building blocks of DNA. They are monomers that make nucleic acid polymers. Each nucleotide has three parts: 

1. Deoxyribose, a ring shaped sugar.
2. A phosphate group.
3. A nitrogenous base.

2. Describe DNA's structure and the rules for base pairing in DNA. 

DNA is a double-helix made up of nitrogenous bases. The rules of base pairings are so:

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Section 3


Objectives:

• Explain how the template mechanism is important in DNA replication.
• Describe the process of DNA replication.

1. Explain how the template mechanism is important in DNA replication.

The template mechanism is important because it provided a basis for how the DNA molecule replicates.

2. Describe the process of DNA replication.

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Section 4


Objectives:

• Explain the "one gene–one polypeptide" hypothesis.
• Trace the information flow from DNA to protein.
• Describe how amino acids are coded.

1.  Explain the "one gene–one polypeptide" hypothesis.
The function of an individual gene is to dictate the production of a specific protein.


2. Trace the information flow from DNA to protein.
DNA first must convert into RNA, or ribose nucleic acid. RNA is slightly different than DNA, because it has uracil instead of thymine, and its sugar is ribose, not deoxyribose. After the DNA is converted to RNA, it goes through a process called transcription, when a DNA template is used to produce a single-stranded RNA molecule. After the RNA is transcribed, nucleic acid information is converted to amino acid information. 


3. Describe how amino acids are coded.
They are coded using the triplet code.

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Section 5


Objectives:

• Describe the process of DNA transcription.
• Explain how an RNA message is edited.
• Describe how RNA is translated to a protein.
• Summarize protein synthesis. 

1. Describe the process of DNA transcription.

Messenger RNA (mRNA) is transcribed to the DNA template. It is similar to the process of DNA replication, but only one of the DNA strands is used as a template. Then, the DNA strands separate at the location of transcription. Finally, RNA nucleotides pair up with DNA nucleotides using a transcription enzyme called RNA polymerase.


2. Explain how an RNA message is edited.
Introns are removed from the RNA, and the exons are joined together, right before it leaves the nucleus. It produces a mRNA molecule with a continuous coding sequence. It is now ready for translation. 


3. Describe how RNA is translated to a protein.

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4. Summarize protein synthesis.
DNA is a template, which controls the transcription of the mRNA. The mRNA show the order of amino acids in a polypeptide, which is constructed with the help of tRNA and rRNA. Lastly, the proteins control the function of the cell.  


Section 6


Objectives:

• Describe the types of mutations that can affect genes.
• Explain what can cause a mutation.

1. Describe the types of mutations that can affect genes.
There are two types of mutations that can affect genes: substitutions and insertions/deletions. A substitution is when a base or nucleotide is switched to another. It may affect a protein. An insertion/deletion is when either an extra base is added or removed. This is mutation is more harmful, because of errors made in chromosome crossovers.


2. Explain what can cause a mutation.
DNA replication or when errors are made in chromosome crossovers. There are also environmental factors, such as radiation, that can cause mutations.