Chapter 16: The Molecular Basis of Inheritance Flashcards
During the 1940s, people believed that proteins were the genetic material. Why?
People believed that proteins were the genetic material because proteins are very complex and diverse. They have a lot of different functions, and they have 20 amino acids.
What was Frederick Griffith working with and why?
He was working with Streptococcus pneumonia and was trying to find a cure.
What observations did Frederick Griffith make?
He found that harmless bacteria mixed with heat-killed remains of bacteria caused disease in mice. He figured out that the substance was passed from dead bacteria to live bacteria–> transforming factor.
What is the transformation that occurred during Griffith’s experiments?
The transformation that was discovered was that something in heat-killed bacteria could still transmit disease-causing properties.
What were MacLeod, McCarthy, and Avery trying to figure out?
They knew that there was a transformation occurring, so they were trying to figure out what that transforming factor was.
What was MacLeod, McCarthy, and Avery’s experiment?
They used enzymes that destroyed each component independently and checked for transformation.
What did DNAase do?
DNAase is an enzyme that destroys DNA, which leaves the protein to be injected into bacteria. The result of this experiment is that there was no effect or transformation, meaning that the protein is not the transforming factor.
What did Protease do?
Protease destroys proteins, which leaves DNA to be injected into the bacteria. The result of this experiment is that it transformed harmless bacteria into virulent bacteria.
Who were the scientists that confirmed that the transforming factor is DNA?
Hershey and Crick confirmed that the transforming factor is DNA.
Why did Hershey and Chase use radioactive Sulfur to label the proteins and radioactive Phosphorus to label the DNA in their experiment?
They used radioactive sulfur because sulfur is unique to proteins, so when the radioactive sulfur is found, they know that it came from proteins and not DNA. They used radioactive phosphorus because phosphorus is unique to DNA. When the phosphorus is shown, they know that it came from DNA and not proteins.
What was Hershey and Chase’s experiment?
They had the classic “blender” experiment. They worked with bacteriophage (virus that infect bacteria). The two phage viruses were grown in two medias (liquids). When the bacteriophages went to infect the bacterial cells, the bacteriophage that had radioactive sulfur was not found in the bacteria, but found in the medium, meaning the proteins didn’t move from the bacteriophage into the bacteria cell. However, the radioactive phosphorus was found inside the bacterial cell. This means that the DNA moved from the bacteriophage into the bacterial cell.
What are Chargaff’s rules?
Amount of thymine= Amount of adenine
Amount of cytosine= Amount of guanine
Who developed the double helix model of DNA?
Rosalind Franklin was the person who created the image of the double helix of DNA. She used an x-ray crystallographer to study the structure of DNA. Her images allowed for Watson to deduce that DNA is helical and he was able to determine the width of the helix and the spacing of the bases.
What did James Watson and Francis Crick find from Franklin’s pictures?
They found that the structure of DNA is a double helix. They also found that the backbone of DNA consists of alternating phosphate and sugar units. He also deduced that the nitrogenous bases were paired in the interior. He also founds that the backbones of strands were antiparallel. Their research suggested that there may be a copying mechanism for genetic material.
Why can’t two purines bind together?
They are too wide to be consistent with the DNA x-ray data.
