35 Questions
What is the first visible change of cytokinesis in an animal cell?
Appearance of a cleavage furrow
Which structure is responsible for the division of an animal cell during cytokinesis?
Contractile ring
What triggers the assembly and contraction of the contractile ring during cytokinesis?
Activation of RhoA by RhoGEF
What is the function of RhoA in cytokinesis?
Control of contractile ring assembly
Which protein is involved in the formation of the contractile ring in animal cells?
Actin filaments
What is the role of a guanine nucleotide exchange factor (RhoGEF) during cytokinesis?
Stimulation of RhoA activation
Which process occurs just beneath the plasma membrane during anaphase?
Assembly of the contractile ring
What is the main structure underlying cytokinesis in an animal cell?
Contractile ring
Where does the contractile ring assemble during cytokinesis?
Just beneath the plasma membrane
What is the function of RhoA during cytokinesis?
Activating the contractile ring assembly and function
Which protein is essential for the contraction of the contractile ring during animal cell cytokinesis?
Myosin II
What triggers the formation of the cleavage furrow during cytokinesis in animal cells?
Contractile ring
Which factor stimulates the release of GDP and binding of GTP to RhoA during cytokinesis?
RhoGEF
What is the role of actin filaments in the contractile ring during cytokinesis?
Cell division contractility
During which cell cycle phase does the contractile ring assemble in preparation for cell division?
Anaphase
What is the role of cyclins in the activity of Cdks?
Binding to Cdks to activate them
Which class of cyclins helps govern the activities of G1/S-cyclins in late G1?
G1-cyclins
When do M-cyclin levels decrease?
Mid-mitosis
Which type of cyclin stimulates entry into mitosis at the G2/M transition?
M-cyclins
What happens to S-cyclin levels until mitosis begins?
They stay elevated until mitosis
What is the role of securin destruction at the end of metaphase?
Leads to the separation of sister chromatids
What is the consequence of APC/C targeting S- and Mcyclins for destruction?
Inactivation of Cdk activity in anaphase
How does APC/C activation occur?
Phosphorylation of the APC/C
What is the significance of M-Cdk promoting Cdc20–APC/C activity?
Creates a negative feedback loop for cyclin destruction
What occurs when Cdk becomes inactivated in the cell cycle?
Activation of phosphatases for Cdk phosphorylation
What is the role of the Anaphase-Promoting Complex/Cyclosome (APC/C) in late M phase events?
Facilitates the destruction of cyclins
What is the function of Cdk-activating kinase (CAK) during M-Cdk activation?
Phosphorylates Cdk at an activating site
What triggers the activation of the 'stockpile' of M-Cdk at the end of G2 phase?
Suppression of inhibitory phosphates by Cdc25
What is the role of protein phosphatase Cdc25 in M-Cdk activation?
Removes inhibitory phosphates from M-Cdk
How does positive feedback loops contribute to M-Cdk activation during mitosis?
Inhibits its own inhibitor Wee1 and activates its activator Cdc25
What is the role of cyclin in the activation of Cdk?
Directs Cdk to specific target proteins
Which type of phosphorylation inhibits the activity of a cyclin–Cdk complex?
Phosphorylation by Wee1
What structural change occurs in the Cdk protein upon binding with cyclin?
Loop moves away from the active site, partially activating the enzyme
Which protein phosphorylates an amino acid near the entrance of the Cdk active site for full activation of the cyclin–Cdk complex?
CAK
What effect does dephosphorylation by Cdc25 have on a cyclin–Cdk complex?
Increases Cdk activity
Test your knowledge on the cell-cycle control system and SCF ubiquitin ligase, including their functions and roles in regulating the cell cycle phases. This quiz covers topics such as dephosphorylation of Cdk targets, proteolysis by SCF, and the ubiquitylation process controlled by SCF.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
