A
learned this in bio last ye
The plasma membrane or the cell
membrane is the one that protects the cytoplasm of a cell. It is mostly
composed of lipids and proteins. It has a phospholipid bilayer that controls
the entering and exiting of molecules in the cell and at the same time,
provides protection for the cell or plasma membrane. It has polar head and a
nonpolar tail. Proteins embedded within the phospholipid bilayer have the same
function of the plasma membrane that includes selective transport. The
phospholipid bilayer consists mainly of the lipid molecules.
Loss of Rb, an important part of the G1-S transition checkpoint, can result in uncontrolled cell cycle progression and cancer. All of the following would mimic loss of Rb except constitutively active Ras GTPase activating protein. Correct answer: letter E.
Constitutively active Ras GTPase activating protein would not mimic loss of Rb, because it would not directly result in uncontrolled cell cycle progression.
<h3>What is Retinoblastoma (RB)?</h3>
Rb is an important tumor suppressor protein that works to inhibit cell cycle progression by preventing the activation of E2F transcription factors. Constitutively active Ras GTPase activating protein would not directly interfere with the Rb-E2F pathway, which is necessary for uncontrolled cell cycle progression and cancer.
Learn more about the cell cycle:
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Answer and Explanation:
The interphase is the previous step before mitosis occurs. The interphase is conformed of the G1, S, and G2 stages.
- During the G1 stage, it occurs a high intense biochemical activity. The cell duplicates its size, and the organelles and other molecules and cytoplasmatic structures duplicate too. Some structures, such as microtubules and actin filaments, are synthesized from zero. The endoplasmic reticulum increases in size and produces a membrane for the Golgi apparatus and vacuoles, lysosomes, and vesicles. During this stage, the pair of centrioles separate, and each centriole duplicates. Mitochondria and chloroplasts also replicate.
The stages S and G2 follow the G1. Once the whole interphase is completed, mitosis occurs.
- During the S stage occurs the DNI replication process. At this point, it also occurs the synthesis of histones and other associated proteins. This is the only stage where the DNI molecule is replicated.
- G2 stage is the final one before the cellular division. Here it begins the slow process of DNI condensation. Duplication of centrioles completes. Structures such as spindle fibers are assembled.
