Does RNA have proofreading?
But the RNA polymerases of RNA viruses are the kings of errors – these enzymes screw up as often as one time for every 1,000 – 100,000 nucleotides polymerized. This high rate of mutation comes from the lack of proofreading ability in RNA polymerases. These enzymes make mistakes, but they can’t correct them.
Why do eukaryotes have 3 RNA polymerases?
Eukaryotic cells contain three distinct nuclear RNA polymerases that transcribe different classes of genes (Table 6.1). RNA polymerase III transcribes the genes for tRNAs and for the smallest species of ribosomal RNA (5S rRNA).
What attaches to the DNA once it has been separated?
The initiation of DNA replication occurs in two steps. Then, a protein known as helicase attaches to and breaks apart the hydrogen bonds between the bases on the DNA strands, thereby pulling apart the two strands.
How does the ribosome know what proteins to make and make them?
The mRNA leaves the nucleus and enters the cytoplasm. Then, ribosomes attach to mRNA. A ribosome attaches to mRNA in the cytoplasm. On the ribosome, the mRNA provides the code for the protein that will be made.
Which parts of a twisted ladder are analogous?
Which parts twisted ladder are analogous to the hydrogen bonds and sugar – phosphate backbones of a double helix of DNA? Hydrogen bond of DNA ara analogous to the rungs oa the twisted ladder and sugar phosphate backbone of the double helix analogous to the side of the twisted ladder.
Why is DNA shaped like a twisted ladder?
They showed that alternating deoxyribose and phosphate molecules form the twisted uprights of the DNA ladder. The rungs of the ladder are formed by complementary pairs of nitrogen bases — A always paired with T and G always paired with C.
Why is DNA shaped like a helix?
The twisting aspect of DNA is a result of interactions between the molecules that make up DNA and water. In order to further prevent the nitrogenous bases from coming into contact with cell fluid, the molecule twists to reduce space between the nitrogenous bases and the phosphate and sugar strands.
WHO concluded that DNA was the factor that causes one bacterium to transform into another?
Cards In This Set
| Front | Back |
|---|---|
| ( ) concluded that DNA was the factor that caused one bacterium to transform into another. | Avery |
| ( ) concluded that bacteria could be transformed from harmless to disease-causing by an unknown factor. | Griffith |
| The structure of a DNA molecule can be described as a ( ) | Double helix |
What did Hershey and Chase conclude?
Hershey and Chase concluded that protein was not genetic material, and that DNA was genetic material. Unlike Avery’s experiments on bacterial transformations, the Hershey-Chase experiments were more widely and immediately accepted among scientists.
What did Avery conclude?
Because the ability to cause disease was inherited by the offspring of the transformed bacteria, he concluded that the transforming factor had to be a gene. In 1944, Oswald Avery tested the transforming ability of many substances. Only the DNA from the bacteriophage showed up in the infected bacterial cell.
What did Hershey and Chase conclude was the genetic material of the virus?
Hershey and Chase concluded that DNA, not protein, was the genetic material. They determined that a protective protein coat was formed around the bacteriophage, but that the internal DNA is what conferred its ability to produce progeny inside a bacterium.
What happened Griffith injected mice?
What happened when Griffith injected mice with a mixture of heat-killed, pneumonia- causing bacteria and live bacteria of the harmless type? The mice got pneumonia and many died. He used enzymes that destroyed various molecules from the heat-killed bacteria, including lipids, proteins, carbohydrates, and RNA.
How did Hershey and Chase use radioactivity to draw a conclusion about proteins and DNA?
Hershey and Chase studied bacteriophages which are viruses that attack bacteria. They labeled the bacteriophage with radioactive isotopes to see where it goes when a virus attacks. They discovered that nearly all the radioactivity was found in phosphorus, confirming that DNA contains genetic material, not protein.