DNA And Protein Synthesis (8.1-8.4)
Objectives: Identify the 4 properties required of every genetic material, Summarize the classic experiments determining that DNA is genetic material
DNA was first described by Mischer, who determined the following:
DNA is not a protein
DNA is rich in nitrogen and phosphorus
Never learned DNA function
Griffin got a hint of DNA’s function (hereditary information)
Studied 2 bacteria, one harmless and one harmful, and found that heat destroyed the harmful bacteria’s ability to cause disease but not its hereditary material
Oswald, Avery, MacLeod, and McCarty identified that the principle must be a nucleic acid. It used enzymes that destroyed DNA and RNA to decide which one it was, and came to the conclusion it was DNA.
Prior to this, scientists believed that proteins controlled heredity, not nucleic acids
DNA was assumed to be too simple
They published their findings and concluded that DNA must be genetic material
Their discovery prompted new scientists to do further research:
Confirmed DNA’s ability to carry genetic information
Realized that any molecule had to have a certain set of properties to store hereditary information. These are the following:
Hereditary information must be passed on from one generation to the next
Cells of a certain species should contain the same amount of it
Not susceptible to major change
Must be able to encode a huge amount of information to build life
How does DNA fulfill these requirements?
Transmits full hereditary information
Body cells of certain species had all the same amounts of DNA
DNA is not involved in metabolism, therefore, its content does not change over time
DNA’s structure allows it to encode large amounts of genetic information
Objectives: Summarize the events that led to the discovery of DNA’s structure, identify the subunits of DNA and how they combine into a DNA molecule, explain how DNA holds information, describe base pairing
DNA is a polymer of 4 different nucleotides:
Adenine
Guanine
Thymine
Cytosine
Each has 3 phosphate groups, deoxyribose sugar, and a nitrogenous base.
Chargaff made 2 important discoveries about DNA’s structure:
Amounts of thymine and adenine are identical in any DNA molecule, and Amounts of cytosine and guanine are identical in any DNA molecule
Chargaff’s First RUle
DNA of different species differs in proportion of adenine and guanine
Watson and Crickhat been theorizing about DNA’s structure.
Used an X-ray to decipher shape, size, spacing between elements
Since DNA was large, it was hard to crystallize w/ techniques of the time
Identified a repeating pattern and length
Thus, DNA is characterized by the following:
2 chains/strands of nucleotides in opposite directions, in a double helix
Covalent bonds link deoxyribose to phosphate groups, leading to sugar-phosphate backbone
Hydrogen bonds hold the pair of strands together
Only Adenine to Thymine and Cytosine to Guanine
DNA sequence is the order of nucleotides bases, greatly differ from organism to organism. DNA molecules can hold hundreds of millions of nucleotides, thus, a sequence of nucleotides can hold a lot of information.
Objectives: Identify the 4 properties required of every genetic material, Summarize the classic experiments determining that DNA is genetic material
DNA was first described by Mischer, who determined the following:
DNA is not a protein
DNA is rich in nitrogen and phosphorus
Never learned DNA function
Griffin got a hint of DNA’s function (hereditary information)
Studied 2 bacteria, one harmless and one harmful, and found that heat destroyed the harmful bacteria’s ability to cause disease but not its hereditary material
Oswald, Avery, MacLeod, and McCarty identified that the principle must be a nucleic acid. It used enzymes that destroyed DNA and RNA to decide which one it was, and came to the conclusion it was DNA.
Prior to this, scientists believed that proteins controlled heredity, not nucleic acids
DNA was assumed to be too simple
They published their findings and concluded that DNA must be genetic material
Their discovery prompted new scientists to do further research:
Confirmed DNA’s ability to carry genetic information
Realized that any molecule had to have a certain set of properties to store hereditary information. These are the following:
Hereditary information must be passed on from one generation to the next
Cells of a certain species should contain the same amount of it
Not susceptible to major change
Must be able to encode a huge amount of information to build life
How does DNA fulfill these requirements?
Transmits full hereditary information
Body cells of certain species had all the same amounts of DNA
DNA is not involved in metabolism, therefore, its content does not change over time
DNA’s structure allows it to encode large amounts of genetic information
Objectives: Summarize the events that led to the discovery of DNA’s structure, identify the subunits of DNA and how they combine into a DNA molecule, explain how DNA holds information, describe base pairing
DNA is a polymer of 4 different nucleotides:
Adenine
Guanine
Thymine
Cytosine
Each has 3 phosphate groups, deoxyribose sugar, and a nitrogenous base.
Chargaff made 2 important discoveries about DNA’s structure:
Amounts of thymine and adenine are identical in any DNA molecule, and Amounts of cytosine and guanine are identical in any DNA molecule
Chargaff’s First RUle
DNA of different species differs in proportion of adenine and guanine
Watson and Crickhat been theorizing about DNA’s structure.
Used an X-ray to decipher shape, size, spacing between elements
Since DNA was large, it was hard to crystallize w/ techniques of the time
Identified a repeating pattern and length
Thus, DNA is characterized by the following:
2 chains/strands of nucleotides in opposite directions, in a double helix
Covalent bonds link deoxyribose to phosphate groups, leading to sugar-phosphate backbone
Hydrogen bonds hold the pair of strands together
Only Adenine to Thymine and Cytosine to Guanine
DNA sequence is the order of nucleotides bases, greatly differ from organism to organism. DNA molecules can hold hundreds of millions of nucleotides, thus, a sequence of nucleotides can hold a lot of information.
