What is the difference between mismatch repair and nucleotide excision repair quizlet?
What is the difference between mismatch repair and nucleotide excision repair? In mismatch repair, one nucleotide is replaced, whereas in nucleotide excision repair several nucleotides are replaced. You just studied 29 terms!
What is the difference between base excision repair and mismatch repair?
In base excision repair, just the damaged base is removed. In nucleotide excision repair, as in the mismatch repair we saw above, a patch of nucleotides is removed.
What does nucleotide excision repair fix?
In nucleotide excision repair (NER), damaged bases are cut out within a string of nucleotides, and replaced with DNA as directed by the undamaged template strand. This repair system is used to remove pyrimidine dimers formed by UV radiation as well as nucleotides modified by bulky chemical adducts.
What are the two types of DNA repair?
The different types of DNA repair include direct repair, base excision repair, nucleotide excision repair (NER), double-strand break repair (including homologous recombination and nonhomologous end joining), and crosslink repair (Sancar et al., 2004).
What are the steps of DNA repair?
At least five major DNA repair pathways—base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination (HR) and non-homologous end joining (NHEJ)—are active throughout different stages of the cell cycle, allowing the cells to repair the DNA damage.
What enzyme is in base excision repair?
DNA glycosylase
What is the correct order for the following events in excision repair of DNA?
What is the correct order for the following events in excision repair of DNA? (1) DNA polymerase I adds correct nucleotides by 5′-to-3′ replication; (2) damaged nucleotides are recognized; (3) DNA ligase seals the new strand to existing DNA; (4) part of a single strand is excised.
Which statement is true with respect to mismatch repair and nucleotide excision repair NER )?
Which statement is true with respect to mismatch repair and nucleotide excision repair (NER)? Mismatch repair fixes thymine dimers caused by exposure to UV light, while NER fixes errors in DNA replication.
What is a thymine dimer?
Cyclobuthane thymine dimer is a photolesion produced by UV radiation in sunlight and is considered as a potential factor causing skin cancer. It is formed as a covalently bonded complex of two adjacent thymines on a single strand of DNA.
Which of the following prevents hydrogen bonding between DNA strands during replication?
| Table 1. The Molecular Machinery Involved in Bacterial DNA Replication | |
|---|---|
| Enzyme or Factor | Function |
| Single-stranded binding proteins | Bind to single-stranded DNA to prevent hydrogen bonding between DNA strands, reforming double-stranded DNA |
| Sliding clamp | Helps hold DNA pol III in place when nucleotides are being added |
Are phosphodiester bonds broken during DNA replication?
When the bond between the phosphates is broken, the energy released is used to form the phosphodiester bond between the incoming nucleotide and the growing chain….Summary.
| Prokaryotic DNA Replication: Enzymes and Their Function | |
|---|---|
| Enzyme/protein | Specific Function |
| Primase | Synthesizes RNA primers needed to start replication |
Why DNA replication is bidirectional?
In bidirectional, none of the two ends will be stationary and both will be moving. Therefore, bidirectional replication involves replicating DNA in two directions at the same time resulting in a leading strand and a lagging strand.
Is DNA replication bidirectional or unidirectional?
Bidirectional replication of DNA is the mechanism employed in all eukaryotic and most prokaryotic cells. Unidirectional replication is rare and appears to occur in only a limited number of prokaryotes.
Is DNA replication always bidirectional?
DNA replication is bidirectional from the origin of replication. To begin DNA replication, unwinding enzymes called DNA helicases cause short segments of the two parent DNA strands to unwind and separate from one another at the origin of replication to form two “Y”-shaped replication forks.
What is unidirectional DNA replication?
A replication eye may represent unidirectional replication (when only one end moves) or a bidirectional replication (when both ends move). Fig. 26.10. The difference between unidirectional and bidirectional replications in the movement of replication forks.
How replication is termination in prokaryotes?
Termination of DNA replication occurs when two oppositely orientated replication forks meet and fuse, to create two separate and complete double‐stranded DNA molecules. Failure to terminate bacterial chromosome replication correctly results in chromosome over‐replication and genome instability.
How is DNA replication in prokaryotes?
DNA Replication in Prokaryotes: A replication fork is formed when helicase separates the DNA strands at the origin of replication. The DNA tends to become more highly coiled ahead of the replication fork. DNA ligase seals the gaps between the Okazaki fragments, joining the fragments into a single DNA molecule.
Is prokaryotic DNA replication Semiconservative?
DNA synthesis is a process that all living organisms must perform. For most eukaryotes and prokaryotes, the process of DNA synthesis is done semiconservatively. Semiconservative replication for E. Coli is initiated by way of a replicon structure which behaves as an autonomous unit of DNA replication.
Is DNA replication in prokaryotes conservative?
The genetic material must be faithfully replicated to assure heredity. Unlike in eukaryotes, pyrimidine deoxyribonucleotides are synthesized from ribonucleotide diphosphates rather than triphosphates. The replication takes place in a semi-conservative manner semi-conservative replication.
Which one is useful in prokaryotes replication?
Mesosomes serve in DNA replication and guide distribution of duplicated bacterial chromosomes into the two daughter cells during cell division. They also carry the enzymes for aerobic respiration and increase the surface area for the same.
What is unique about prokaryotic DNA replication?
The origin of replication is approximately 245 base pairs long and is rich in AT sequences. This sequence of base pairs is recognized by certain proteins that bind to this site. An enzyme called helicase unwinds the DNA by breaking the hydrogen bonds between the nitrogenous base pairs.
Why does DNA replication occur from 5 to 3?
DNA is always synthesized in the 5′-to-3′ direction, meaning that nucleotides are added only to the 3′ end of the growing strand. As shown in Figure 2, the 5′-phosphate group of the new nucleotide binds to the 3′-OH group of the last nucleotide of the growing strand.