Who demonstrated that DNA is the genetic material?
Who demonstrated that DNA is the genetic material?
Alfred Hershey
Which enzyme catalyzes the elongation of a new DNA strand in the 5 → 3 direction?
DNA polymerase III
Which process results in DNA being copied into DNA?
Replication
What did Griffith observe in his transformation experiments?
In his transformation experiments, what did Griffith observe? Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form. Which observations would provide the best evidence that the ability to fluoresce is a heritable trait?
What did Griffith conclude transformed the harmless bacteria in his experiment?
In Griffith’s experiment, he mixed heat-killed S-strain bacteria with live, harmless bacteria from the R-strain. When this mixture was injected into mice, the mice developed pneumonia, died. He was able to conclude that genes from the harmful bacteria transferred to the harmless bacteria, and transformed them.
Why does a new DNA strand elongates only in the 5 to 3 direction?
why does a new DNA strand elongates only in the 5′ to 3′ direction? DNA polymerase can only add nucleotides to the free 3′ end. relieving strain in the DNA ahead of the replication fork. What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
What is the difference between the leading strand and the lagging strand in DNA replication?
Within each fork, one DNA strand, called the leading strand, is replicated continuously in the same direction as the moving fork, while the other (lagging) strand is replicated in the opposite direction in the form of short Okazaki fragments.
What is the basis for the difference in how the leading and lagging strands of DNA are synthesized?
What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized? DNA polymerase can join new nucleotides only to the 3′ end of a growing strand.
What is the function of DNA polymerase III?
The main function of the third polymerase, Pol III, is duplication of the chromosomal DNA, while other DNA polymerases are involved mostly in DNA repair and translesion DNA synthesis. Together with a DNA helicase and a primase, Pol III HE participates in the replicative apparatus that acts at the replication fork.
What are the two primary functions of DNA polymerase III?
In Escherichia coli, five DNA polymerases have been found and designated as DNA polymerase I–V, in order of their discovery. The main function of the third polymerase, Pol III, is duplication of the chromosomal DNA, while other DNA polymerases are involved mostly in DNA repair and translesion DNA synthesis.
What is the difference between DNA polymerase 1 and 3?
The main difference between DNA polymerase 1 and 3 is that DNA polymerase 1 is involved in the removal of primers from the fragments and replacing the gap by relevant nucleotides whereas DNA polymerase 3 is mainly involved in the synthesis of the leading and lagging strands.
Is DNA polymerase III found in eukaryotes?
The chloroplast also has DNA pol γ. On top of the pols α, δ and ε eukaryotes have lots of repair enzymes: pols β, η, ι, κ and ζ. Not only do we have different enzymes but eukaryotic cells have more copies of these enzymes than do prokaryotes. coli has 10 to 20 molecules of DNA pol III.
Which side of DNA has continuous replication?
Figure 3: Replication of the leading DNA strand is continuous, while replication along the lagging strand is discontinuous. After a short length of the DNA has been unwound, synthesis must proceed in the 5′ to 3′ direction; that is, in the direction opposite that of the unwinding.
Is DNA replication faster in prokaryotes or eukaryotes?
Prokaryotic cells possess one or two types of polymerases, whereas eukaryotes have four or more. Replication also happens at a much faster rate in prokaryotic cells, than in eukaryotes.
What happens if DNA polymerase is not present?
When strand slippage occurs during DNA replication, a DNA strand may loop out, resulting in the addition or deletion of a nucleotide on the newly-synthesized strand. But if this does not occur, a nucleotide that is added to the newly synthesized strand can become a permanent mutation.
What mistakes can occur when DNA is replicated?
DNA replication is a highly accurate process, but mistakes can occasionally occur, such as a DNA polymerase inserting a wrong base. Uncorrected mistakes may sometimes lead to serious consequences, such as cancer. Repair mechanisms correct the mistakes.
Does DNA polymerase 1 need a primer?
To initiate this reaction, DNA polymerases require a primer with a free 3′-hydroxyl group already base-paired to the template. They cannot start from scratch by adding nucleotides to a free single-stranded DNA template. RNA polymerase, in contrast, can initiate RNA synthesis without a primer (Section 28.1. 4).
How does DNA polymerase make mistakes?
Most of the mistakes during DNA replication are promptly corrected by DNA polymerase which proofreads the base that has just been added. In proofreading, the DNA pol reads the newly-added base before adding the next one so a correction can be made. This is performed by the exonuclease action of DNA pol III.
How important is the DNA proofreading step?
Proofreading, which corrects errors during DNA replication. Mismatch repair, which fixes mispaired bases right after DNA replication. DNA damage repair pathways, which detect and correct damage throughout the cell cycle.
What is the main job of DNA polymerase?
The primary role of DNA polymerases is to accurately and efficiently replicate the genome in order to ensure the maintenance of the genetic information and its faithful transmission through generations.
What foods help repair DNA?
In a study published in the British Journal of Cancer (published by the research journal Nature) the researchers show that in laboratory tests, a compound called indole-3-carinol (I3C), found in broccoli, cauliflower and cabbage, and a chemical called genistein, found in soy beans, can increase the levels of BRCA1 and …
How can I make my DNA stronger?
Start here:
- Remove the Five Food Felons from your diet: added sugars and sugar syrups, saturated fat, trans fats and any grains that aren’t 100 percent whole.
- Move for at least 30 minutes daily, heading for a goal of 10,000 steps or more!
- Take time to relax daily.
Which vitamin helps with DNA repair?
Vitamin B12 and folate have also been found as essential for DNA metabolism. In short folic acid and B12 are required for the maintenance of DNA conformation and methylation patterns.
Can damaged DNA repair itself?
Most damage to DNA is repaired by removal of the damaged bases followed by resynthesis of the excised region. Some lesions in DNA, however, can be repaired by direct reversal of the damage, which may be a more efficient way of dealing with specific types of DNA damage that occur frequently.
What happens if DNA gets damaged?
The DNA in just one of your cells gets damaged tens of thousands of times per day. Because DNA provides the blueprint for the proteins your cells need to function, this damage can cause serious issues—including cancer. Fortunately, your cells have ways of fixing most of these problems, most of the time.
What are DNA damaging agents?
DNA damaging agents are widely used in oncology to treat both hematological and solid cancers. Some commonly used modalities include ionizing radiation, platinum drugs (cisplatin, oxaliplatin, and carboplatin), cyclophosphamide, chlorambucil, and temozolomide.
What causes DNA damage?
DNA damage can be subdivided into two types: (1) endogenous damage caused by reactive oxygen species (ROS) that are derived from metabolic byproducts and (2) exogenous damage caused by radiation (UV, X-ray, gamma), hydrolysis, plant toxins, and viruses.
What is the difference between DNA damage and mutation?
DNA damage is distinctly different from mutation, although both are types of error in DNA. DNA damage is an abnormal chemical structure in DNA, while a mutation is a change in the sequence of standard base pairs. While most DNA damages can undergo DNA repair, such repair is not 100% efficient.
What is the most dangerous type of DNA damage?
Double-strand DNA breaks
How do you treat damaged DNA?
4. DNA Repair Pathways
- 4.1. Fanconi Anemia (FA) Pathway. Several natural or artificial compounds might promote crosslinking of two DNA strands.
- 4.2. Nucleotide Excision Repair (NER)
- 4.3. Base Excision Repair (BER)
- 4.4. Mismatch Repair (MMR)
- 4.5. DNA Double-Stranded Break Repair Pathways.
