Which process results in offspring that are genetically identical?
Asexual reproduction involves one parent and produces offspring that are genetically identical to each other and to the parent. Sexual reproduction involves two parents and produces offspring that are genetically unique.
Which process occurs in their body somatic cells?
How do the number of chromosomes in a female scorpion’s egg cells compare with the number in her somatic cells?
How do the number of chromosomes in a female scorpion’s egg cells compare with the number in her body (somatic) cells? There are twice as many chromosomes in egg cells. There are half as many chromosomes in egg cells.
Which process must occur before mitosis and meiosis can occur?
The S phase of a cell cycle occurs during interphase, before mitosis or meiosis, and is responsible for the synthesis or replication of DNA. In this way, the genetic material of a cell is doubled before it enters mitosis or meiosis, allowing there to be enough DNA to be split into daughter cells.
What must occur before meiosis takes place?
Before meiosis actually begins, the DNA that is packaged into chromosomes must be fully copied. These two chromosomes are independent but very similar, and are termed homologues of each other. DNA replication occurs in the same fashion as it does during mitosis.
What must occur before mitosis takes place?
Mitosis itself consists of five active steps, or phases: prophase, prometaphase, metaphase, anaphase, and telophase. Before a cell can enter the active phases of mitosis, however, it must go through a period known as interphase, during which it grows and produces the various proteins necessary for division.
What are the four steps of mitosis in order?
These phases are prophase, prometaphase, metaphase, anaphase, and telophase. Cytokinesis is the final physical cell division that follows telophase, and is therefore sometimes considered a sixth phase of mitosis.
What triggers mitosis?
Abstract. Entry into mitosis is triggered by the activation of cyclin-dependent kinase 1 (Cdk1). This simple reaction rapidly and irreversibly sets the cell up for division.
What are the 3 steps of interphase?
Interphase is composed of G1 phase (cell growth), followed by S phase (DNA synthesis), followed by G2 phase (cell growth). At the end of interphase comes the mitotic phase, which is made up of mitosis and cytokinesis and leads to the formation of two daughter cells.
What major event occurs during interphase?
During interphase, the cell grows and the nuclear DNA is duplicated. Interphase is followed by the mitotic phase. During the mitotic phase, the duplicated chromosomes are segregated and distributed into daughter nuclei. The cytoplasm is usually divided as well, resulting in two daughter cells.
What is uncoiled stringy DNA called?
Which condition is evaluated at the G2 M checkpoint?
The G2 checkpoint ensures all of the chromosomes have been replicated and that the replicated DNA is not damaged before cell enters mitosis. The M checkpoint determines whether all the sister chromatids are correctly attached to the spindle microtubules before the cell enters the irreversible anaphase stage.
Is CDK present in G1 checkpoint?
Right panel (+G1/S cyclin): the G1/S cyclin is present and binds to the Cdk. The Cdk is now active and phosphorylates various targets specific to the G1/S transition. The phosphorylated targets cause the activation of DNA replication enzymes, and S phase begins.
Is CDK present in G2 checkpoint?
Cyclin B-CDK 1 Activity CyclinB-CDK1 activity is specific to the G2/M checkpoint. The combined activity and complex of Cdc2, Cdc25, and Plk1 with the accumulation of cyclin B activates the CyclinB-Cdc2 complex, promoting entry into mitosis.
Why is there a G1 S checkpoint?
The primary G1/S cell cycle checkpoint controls the commitment of eukaryotic cells to transition through the G1 phase to enter into the DNA synthesis S phase. Importantly, a multitude of different stimuli exert checkpoint control, including TGF-β, DNA damage, replicative senescence, and growth factor withdrawal.
What happens at G1 S checkpoint?
The G1 checkpoint is located at the end of G1 phase, before the transition to S phase. At the G1 checkpoint, cells decide whether or not to proceed with division based on factors such as: Cell size. Nutrients.
What is the purpose of G2 checkpoint?
Abstract. The G2 checkpoint prevents cells from entering mitosis when DNA is damaged, providing an opportunity for repair and stopping the proliferation of damaged cells. Because the G2 checkpoint helps to maintain genomic stability, it is an important focus in understanding the molecular causes of cancer.
What happens at the S checkpoint?
The hallmark of the S-phase DNA damage checkpoint is the slowing of replication in response to DNA damage. Bulk replication can be slowed by inhibiting origin firing or reducing the rate of replication fork progression and both mechanisms appear to be used (Figure 1).
What is the purpose of a checkpoint?
The primary purpose of checkpoints is to deter impaired driving, not to increase arrests. Police generally arrest impaired drivers detected at checkpoints and publicize those arrests, but arrests at checkpoints should not be used as a measure of checkpoint effectiveness.
Which is the main reason cells are replaced in the body?
Explanation: Cells are replaced by new cell because every cell have some life span after this they become older and damage, so cells divide to replace old and damage cells. Cells are further divided so that , living things can grow.
How are G1 and G2 different?
How are G1 and G2 different? In G1, the cell prepares to synthesize its DNA and in G2 it synthesizes the proteins needed for cell division. External signals such as hormones and growth factors can stimulate a cell to go through the cell cycle.
Does a cell have more DNA in G2 than G1?
Not only does the DNA need to be divided, but so do the organelles. G2 is the last chance for the cell to make more protein in preparation for division. The cell has twice the amount of DNA during G2 than it did during G1.
Does DNA replication occur in G2?
S Phase: To produce two similar daughter cells, the complete DNA instructions in the cell must be duplicated. DNA replication occurs during this S (synthesis) phase. Gap 2 (G2): During the gap between DNA synthesis and mitosis, the cell will continue to grow and produce new proteins.
What is G2 phase in mitosis?
G2 phase, Gap 2 phase, or Growth 2 phase, is the third subphase of interphase in the cell cycle directly preceding mitosis. G2 phase is a period of rapid cell growth and protein synthesis during which the cell prepares itself for mitosis.
How many chromosomes are in G2 phase of mitosis?
What is the importance of G2 phase?
The last part of interphase is called the G2 phase. The cell has grown, DNA has been replicated, and now the cell is almost ready to divide. This last stage is all about prepping the cell for mitosis or meiosis. During G2, the cell has to grow some more and produce any molecules it still needs to divide.
What is M phase basically for?
M phase involves a series of dramatic events that begin with nuclear division, or mitosis. As discussed in detail in Chapter 18, mitosis begins with chromosome condensation: the duplicated DNA strands, packaged into elongated chromosomes, condense into the much more compact chromosomes required for their segregation.
What are the stages of the M phase?
The Principal Stages of M Phase (Mitosis and Cytokinesis) in an Animal Cell. The five stages of mitosis—prophase, prometaphase, metaphase, anaphase, and telophase—occur in strict sequential order, while cytokinesis begins in anaphase and continues through telophase.
What does the M in M phase stand for?
What is the longest phase of a cell?