Control of the cell cycle, Biology

Assignment Help:

The cell cycle is controlled by a cyclically operating set of reaction sequences that both trigger and coordinate key events in the cell cycle

• The cell-cycle control system is driven by a built-in clock that can be adjusted by external stimuli (chemical message).

• Checkpoint - a critical control point in the cell cycle where stop and go-ahead signals can regulate the cell cycle
o Animal cells have built-in stop signals that halt the cell cycles and checkpoints until overridden by go-ahead signals.
o Three Major checkpoints are found in the G1, G2, and M phases of the cell cycle.

• The G1 checkpoint - the Restriction Point
o The G1 checkpoint ensures that the cell is large enough to divide, and that enough nutrients are available to support the resulting daughter cells.
o If a cell receives a go-ahead signal at the G1 checkpoint, it will usually continue with the cell cycle
o If the cell does not receive the go-ahead signal, it will exit the cell cycle and switch to a non-dividing state called G0
o Actually, most cells in the human body are in the G0 phase.

• The G2 checkpoint ensures that DNA replication in S phase has been completed successfully.
• The metaphase checkpoint ensures that all of the chromosomes are attached to the mitotic spindle by a kinetochore. 


Related Discussions:- Control of the cell cycle

Respiration, explain why expired air contain co2

explain why expired air contain co2

Pain receptors, What information does the pain receptor relay to the brain ...

What information does the pain receptor relay to the brain about stimuli below threshold

What percentage of acid is not ionized, A weak acid (HA) has a pKa of 4.691...

A weak acid (HA) has a pKa of 4.691. If a solution of this acid has a pH of 4.920, what percentage of the acid is not ionized? (Assume all H in solution came from the ionization of

What are passive and active immunization, What are passive and active immun...

What are passive and active immunization? According to the duration of the protection how do these types of immunization differ? Active immunization is that in which an antigen

What is reaction specificity, Reaction specificity Some  enzymes  catal...

Reaction specificity Some  enzymes  catalyze only one  reaction  acting  on  a specific substrate. Example: urease  and  catalase  acts  only  on  urea and  hydrogen peroxide,

Hepatic portal system and the pulmonary circuit, Trace the flow of blood th...

Trace the flow of blood through the systemic circuit (hepatic portal system) and the pulmonary circuit, beginning and ending in the left ventricle .  You will be using named chamb

#Erosion, In what ways does over-grazing lead to soil erosion?

In what ways does over-grazing lead to soil erosion?

Explain kingdom protista, Kingdom Protista The protistans are a complex a...

Kingdom Protista The protistans are a complex and diverse group of organisms that are placed together simply because they are all single celled eukaryotes but some form rather sp

Define most probable number (mpn) method, Define Most Probable Number (MPN)...

Define Most Probable Number (MPN) Method? The MPN method is like agar shake tube method where no agar is used. The dilutions of the microbial suspension are made in liquid medi

What is the normal duration of the menstrual cycle, Q. What is the normal d...

Q. What is the normal duration of the menstrual cycle? How does the calendar contraceptive method work? The normal duration of the menstrual cycle is 28 days but it can vary am

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd