Other answers from study sets
- G1: Cells do most of their growing. Cells increase in size and synthesize new proteins and organelles. S: Follows the G1 phase. During the S phase, new DNA is synthesized as the chromosomes are replicated.
- G2: A period of intense growth and activity. The preparation for mitosis.
What happens when a cell is stuck in S phase?
What Happens at the S-Phase of Interphase?
- Interphase. The interphase portion of the cell cycle is relatively long compared to mitosis. ...
- DNA Replication. During the S phase, the chromosomes enter a relaxed state that allows the enzyme DNA polymerase to access the DNA double helix inside each chromosome.
- Chromatids. ...
- Exiting the S Phase. ...
What are the 7 stages of mitosis in order?
What are the 7 stages of mitosis in order?
- Interphase. Cell performs normal functions, Cell growth (G1 and g2), Synthesizes new molecules and organelles.
- Prophase.
- Prometaphase.
- Metaphase.
- Anaphase.
- Telophase.
- Cytokinesis.
What happens during telophase stage?
There are three main stages of telophase:
- The chromosomes move to opposite ends of the poles and begin to unwind. ...
- A nuclear envelope forms around each set of chromosomes, the nucleoli reform and ribosomes are assembled.
- As the nucleoli forms, the cell’s cytoplasm begins to divide. This division of the cytoplasm is referred to as cytokinesis. ...
What happens to energy added during phase change?
The energy that is changing during a phase change is potential energy. During a phase change, the heat added (PE increases) or released (PE decreases) will allow the molecules to move apart or come together. Heat absorbed causes the molecules to move farther apart by overcoming the intermolecular forces of attraction.
What happens in the S phase?
S phase is the period of wholesale DNA synthesis during which the cell replicates its genetic content; a normal diploid somatic cell with a 2N complement of DNA at the beginning of S phase acquires a 4N complement of DNA at its end.
Which of the occurs during S phase?
In the eukaryotic cell cycle, chromosome duplication occurs during "S phase" (the phase of DNA synthesis) and chromosome segregation occurs during "M phase" (the mitosis phase).
What happened during the S phase of interphase?
S Phase (Synthesis of DNA) Throughout interphase, nuclear DNA remains in a semi-condensed chromatin configuration. In the S phase, DNA replication results in the formation of identical pairs of DNA molecules, sister chromatids, that are firmly attached to the centromeric region.
What is the S phase in simple terms?
Definition of S phase : the period in the cell cycle during which DNA replication takes place — compare g1 phase, g2 phase, m phase.
What is the S phase of cell cycle and what happens in this phase?
S phase (Synthesis Phase) is the phase of the cell cycle in which DNA is replicated, occurring between G1 phase and G2 phase. Since accurate duplication of the genome is critical to successful cell division, the processes that occur during S-phase are tightly regulated and widely conserved.
What occurs during the S phase of the cell cycle quizlet?
S phase. DNA replication occurs during S phase. Each chromosome is duplicated and thereafter consists of two sister chromatids (the products of DNA replication). The sister chromatids remain joined together until mitosis, when they segregate into two daughter cells.
What is the purpose of the S phase of the cell cycle?
Cell cycle has different stages called G1, S, G2, and M. G1 is the stage where the cell is preparing to divide. To do this, it then moves into the S phase where the cell copies all the DNA. So, S stands for DNA synthesis.
What happens during the S phase of interphase quizlet?
The S phase of interphase involves the replication of DNA, which produces identical sister chromatids. Without this process of replication, there would be no way for cells to continually go through the cell cycle. They would run out of DNA.
What is the end result of S phase?
During the S phase, the chromosomes enter a relaxed state that allows the enzyme DNA polymerase to access the DNA double helix inside each chromosome. Replication begins when helicase enzymes unzip various locations along the chromosome, separating the two complementary strands of DNA.
Does the cell grow during S phase?
S phase is the period during which DNA replication occurs. The cell grows (more...)
How does DNA replication begin in S phase?
DNA synthesis begins in S phase as the replicative helicase unwinds and separates the two strands of the DNA double helix [7]. As the helicase unwinds DNA, DNA polymerase synthesizes DNA utilizing the exposed single stranded DNA as a template.
Is S phase the same as interphase?
S Phase is a part of interphase of the cell cycle. It is a crucial step of cell division. During this step, the cell replicates its DNA so that it has two complete copies of its genome. Loose DNA known as chromatin gathers and condenses into chromatids with the help of histone proteins.
Which of the following occurs in S phase quizlet?
Which of the following is a function of the S phase in the cell cycle? The synthesis of sister chromatids, DNA replication occurs during S phase and results in two sister chromatids for each original chromosome.
What changes occur in DNA content during S phase?
S phase is marked by replication of DNA and the amount of DNA per cell is doubled.
Which of the following is synthesized during S phase of cell cycle?
Both DNA and histone proteins are synthesized during the S phase of interphase.
What is the purpose of the S phase of the cell cycle?
Cell cycle has different stages called G1, S, G2, and M. G1 is the stage where the cell is preparing to divide. To do this, it then moves into the S phase where the cell copies all the DNA. So, S stands for DNA synthesis.
What phase of the cell cycle is chromosome duplication?
In the eukaryotic cell cycle, chromosome duplication occurs during " S phase " (the phase of DNA s ynthesis) and chromosome segregation occurs during "M phase" (the m itosis phase). During S phase, any problems with DNA replication trigger a ‘' checkpoint " — a cascade of signaling events that puts the phase on hold until the problem is resolved. The S phase checkpoint operates like a surveillance camera; we will explore how this camera works on the molecular level. The last 60 years of research in bacterial species (specifically, Escherichia coli) and fungal species (specifically, Saccharomyces cerevisiae ), have continually demonstrated that several major processes during DNA replication are evolutionarily conserved from bacteria to higher eukaryotes.
Why is DSB a catastrophic event?
A DSB is a catastrophic event because it ruins the replication fork. Under these circumstances, cells activate the ATM kinase (Figure 4, on the right). As mentioned above, ATM and ATR are related to each other as they share some amino acid sequences (Shiloh 2003), but ATM has a different function: it works exclusively to repair DSBs (Cimprich & Cortez 2008). It does so by phosphorylating checkpoint kinase 2 (Chk2), a protein that triggers a cascade of phosphorylation events that ultimately result in the repair of the DSB. Only if the DSB is successfully repaired can DNA replication resume.
What are the components of the DNA helicase?
In eukaryotes, the DNA helicase is comprised of a structural core and two regulatory subunits. The core, which contains the ATP hydrolysis activity, is a hexameric complex formed of the m ini c hromosome m aintenance proteins 2-7, called Mcm2-7 (Bochman & Schwacha 2008; Bochman & Schwacha 2009; Schwacha & Bell 2001). Mcm2-7 encircles dsDNA (Remus et al. 2009), but remains inactive until two additional regulatory subunits assemble onto it. Those factors are cell division cycle protein 45 (Cdc45) and GINS (Go, Ichi, Ni, and San; Japanese for "five, one, two, and three," which refers to the annotation of the genes that encode the complex). Scientists call this resulting functional DNA helicase a CMG complex (formed by Cdc45, Mcm2-7, GINS) (Moyer, Lewis, & Botchan 2006). In principle, any of these assembled components could be linked to pol-a/primase by a hypothetical connector protein. Scientists have actually identified two candidate connector proteins that directly bind to both helicase and primase: 1) Mcm10 (another Mcm protein that, despite its name, has no functional resemblance to any of the Mcm2-7 proteins) (Solomon et al. 1992.; Merchant et al. 1997) and 2) c hromosome t ransmission f idelity protein 4 (Ctf4) (Kouprina et al. 1992). Specifically, both of these proteins interact with pol-a/primase (Fien et al. 2004; Ricke & Bielinsky 2004; Warren et al. 2009; Miles & Formosa 1992) and CMG complex subunits (Merchant et al. 1997; Gambus et al. 2009). In budding yeast, Mcm10 is essential for replication to occur. However, in these same cells DNA replication can function normally without Ctf4, which means that Ctf4 is not absolutely required (Kouprina et al. 1992). What about higher eukaryotes? Other experiments in human cells have shown that both proteins seem to be necessary, and work together during replication (Zhu, et al. 2007). Scientists are still actively investigating these complex mechanisms.
How does ATR affect replication?
ATR kinase acts in several ways to keep the replication process intact. There is evidence that ATR also stabilizes replication forks that contain ssDNA (Katou et al. 2003). How this happens remains largely unclear, but recent evidence suggests that ATR may affect the Mcm2-7 proteins, the inner core of the CMG helicase mentioned above (Cortez, Glick, & Elledge 2004; Yoo et al. 2004). One hypothesis is that phosphorylation of one or several of the Mcm2-7 subunits prevents the CMG complex from unwinding more and more DNA. This action effectively stops the process so that it can be repaired before proceeding. Currently, many researchers are trying to better understand the mechanisms of crosstalk between ATR and the replication machinery (Forsburg 2008; Bailis et al. 2008).
Why is coordination between DNA unwinding and synthesis important?
Why is coordination between DNA unwinding and synthesis important? What would happen if you lose this coordination? Because pol-a/primase always requires CMG function to create the ssDNA template, it could never surpass the DNA helicase ( Figure 2b ). Without a connecting link, the CMG complex could just "run off" and leave pol-a/primase behind. This would create long regions of vulnerable ssDNA. Therefore, the second rule in DNA replication is that DNA unwinding and DNA synthesis have to be coordinated.
What happens to DNA strands during replication?
During DNA replication, the unwinding of strands leaves a single strand vulnerable. How does the cell protect these strands from damage?
Which direction does DNA synthesis occur?
As a rule, none of the known DNA polymerases adds a nucleoside triphosphate onto a free 5' end. This brings us to the first rule of DNA replication: DNA synthesis only occurs in one direction, from the 5' to the 3' end .
