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Multiple Choice
Which of the following proteins are involved in the positive regulation of the cell cycle?
A
Cyclins and CDKs
B
Histones and Tubulin
C
Caspases and Bax
D
p53 and Rb
Verified step by step guidance
1
Understand the role of cyclins and CDKs: Cyclins are proteins that regulate the progression of the cell cycle by activating cyclin-dependent kinases (CDKs). Together, they form a complex that phosphorylates target proteins to advance the cell cycle.
Identify the function of histones and tubulin: Histones are proteins that package and order DNA into structural units called nucleosomes, while tubulin is a protein that makes up microtubules, which are part of the cell's cytoskeleton. Neither are directly involved in regulating the cell cycle.
Examine the role of caspases and Bax: Caspases are enzymes that play a role in apoptosis (programmed cell death), and Bax is a pro-apoptotic protein. These proteins are involved in cell death rather than cell cycle regulation.
Consider the function of p53 and Rb: p53 is a tumor suppressor protein that can halt the cell cycle in response to DNA damage, and Rb (retinoblastoma protein) is involved in inhibiting cell cycle progression. Both are involved in negative regulation of the cell cycle.
Conclude that cyclins and CDKs are the proteins involved in the positive regulation of the cell cycle, as they actively promote the progression of the cell cycle through various phases.