In a bacterial cell, a protein is synthesized at random location in the cytoplasm. The protein has to reach one pole of the cell for its appropriate function. The protein reaches the pole by
random movement
Protein Movement in Bacterial Cells
In a bacterial cell, many processes occur within the cytoplasm. Proteins are synthesized by ribosomes, which are located throughout the cytoplasm. For a protein to carry out its specific function, it often needs to be located at a particular place within the cell, such as the cell membrane, cell wall, or at one of the cell poles.
The question describes a situation where a protein is made at a random spot in the cytoplasm and needs to get to one of the cell poles.
How Proteins Reach Specific Locations
There are several ways molecules, including proteins, move within a cell:
- Directed Transport: Some proteins have specific signals that are recognized by cellular machinery which actively moves them to the correct location. This is like a targeted delivery system.
- Random Movement (Diffusion): Molecules move randomly due to thermal energy, colliding with other molecules and the surrounding cellular components. This random motion allows them to spread out over time. In small spaces like the cytoplasm of a bacterial cell, diffusion can be quite effective for molecules to travel short distances relatively quickly.
Let's consider the given options in the context of a protein synthesized at a random location needing to reach a pole:
- Chemical attraction: While chemical signals or gradients can direct movement in some cases, simply needing to reach a pole from a random location doesn't inherently imply a strong chemical gradient pulling the protein across the entire cytoplasm, especially if it's a general case for a randomly synthesized protein.
- Random movement: A protein moving randomly through the cytoplasm will explore the available space. Given enough time, this random motion will eventually lead the protein to reach the cell pole, especially in the confined space of a bacterial cell. This is a fundamental process called diffusion.
- Enzymatic action: Enzymatic action typically refers to the chemical reactions catalyzed by enzymes, not a general mechanism for protein transport across the cytoplasm.
- Attraction between opposite charges: Electrostatic interactions based on charge can play a role in specific binding events or localization near charged surfaces, but they are not the primary, general mechanism for a randomly synthesized protein to navigate the bulk cytoplasm to reach a specific pole.
Since the protein is synthesized at a random location and simply needs to reach the pole, without mention of specific targeting signals or machinery, the most fundamental and likely process enabling it to eventually arrive at the pole from anywhere in the cytoplasm is random movement, or diffusion.
Therefore, the protein reaches the pole by random movement within the bacterial cytoplasm.
Important Questions from Cell Division and Cell Cycle
During cell cycle, entry in the S-phase is tightly regulated. This is possible because:
A. APC/C promotes ubiquitination of S-phase cyclins and mitotic cyclins, marking them for proteolyses at the mitotic exit.
B. Cyclin B1 helps in the activation of S-phase CDKs only in late G1.
C. As mitotic CDK activity declines in late mitosis, cdc14 phosphatase activates APC/C by dephosphorylating Cdh1, thus promoting formation of APC/CCdh1
D. Securin keeps S-phase cyclins in inactive state till late G1.
Which one of the options represents all correct statements?
Following statements were made about cell cycle regulation:
A. De novo synthesis and destruction of Cyclin B are essential for cell cycle progression in yeast.
B. De novo synthesis and destruction of Cyclin B and the related Cyclin dependent Kinase (CDK) are essential for cell cycle progression.
C. CDK activity is regulated by both activating and inhibitory phosphorylation.
D. Retinoblastoma (Rb) functions as an inhibitor of G2 to M transition.
E. Inactivation of Sic 1 is essential for transition into S phase.
Which one of the following represents the combination of the correct statements?
The table below lists cell cycle regulatory proteins and their known functions
Which one of the following options represents the correct match between cell cycle regulatory proteins with their known functions?Cell Cycle regu latory proteins Function A Cdk-activating kinase (CAK) (i) Suppresses G1/S-Cdk and S-Cdk activation in G1; helps cells withdraw from cell cycle when they terminally differentiate; phosphorylation by Cdk2 triggers its ubiquitylation by SCF. B Wee1 kinase (ii) Suppresses G1/S-Cdk and S-Cdk activities following DNA damage C p27 (mammals) (iii) Phosphorylates inhibitory sites in Cdks: primarily involved in suppressing Cdk1 activity before mitosis D p21 (mammals) (iv) Phosphorylates an activating site in Cdks Following statements were made about the characteristics of cyclin proteins:
A. Synthesis of M-cyclin is dependent on the cyclin mRNA that is newly transcribed after every cycle.
B. Destruction of M-cyclin toward the end of mitosis is driven by ubiquitin independent proteolytic system.
C. G1 cyclins can be activated by mitogenic factors.
D. Retinoblastoma (Rb) is a key target of the activated cyclin D - Cdk 4/6 complex.
E. While cyclin A1 expression is ubiquitous, cyclin A2 expression is restricted to the germ cell lineages.
Which one of the following options contains a combination of all correct statements?
To test the impact of cAMP on protein kinase A conformation in cells, an investigator made FRET biosensor by fusing two fluorescent proteins at the N-and C-terminus of protein kinase A. In the absence of cAMP in the cellular milieu, no FRET signal was detected. However, upon cAMP addition, a strong emission at 530 nm was observed. What could be the best configuration of fluorophores that were used by the investigator?
