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Intracellular transport is unique to eukaryotic cells because they possess organelles enclosed in membranes that need to be mediated for exchange of cargo to take place. [3] Conversely, in prokaryotic cells, there is no need for this specialized transport mechanism because there are no membranous organelles and compartments to traffic between.
Macromolecules, such as RNA and proteins, are actively transported across the nuclear membrane in a process called the Ran-GTP nuclear transport cycle. G-proteins are GTPase enzymes that bind to a molecule called guanosine triphosphate (GTP) which they then hydrolyze to create guanosine diphosphate (GDP) and release energy. The RAN enzymes ...
A polypeptide chain in the cell does not have to stay linear; it can become branched or fold in on itself. Polypeptide chains fold in a particular manner depending on the solution they are in. The fact that all amino acids contain R groups with different properties is the main reason proteins fold.
The protons return to the mitochondrial matrix through the protein ATP synthase. The energy is used in order to rotate ATP synthase which facilitates the passage of a proton, producing ATP. A pH difference between the matrix and intermembrane space creates an electrochemical gradient by which ATP synthase can pass a proton into the matrix ...
Cyclins are a group of proteins that activate kinases involved in cell division. The degradation of cyclins is the key step that governs the exit from mitosis and progress into the next cell cycle. [13] Cyclins accumulate in the course the cell cycle, then abruptly disappear just before the anaphase of mitosis. The cyclins are removed via a ...
The Ran-GTP cycle, which drives the import and export of RNA and proteins through the nuclear protein complex. Scanning and illumination microscopy of nuclear pores, lamina, and chromatin. The nuclear pore complex (NPC) serves as a highly regulated gateway for the transport of molecules between the nucleus and the cytoplasm.
The main mechanism of action of the cell cycle checkpoints is through the regulation of the activities of a family of protein kinases known as the cyclin-dependent kinases (CDKs), which bind to different classes of regulator proteins known as cyclins, with specific cyclin-CDK complexes being formed and activated at different phases of the cell ...
Most eukaryotic cells have mitochondria, which produce ATP from reactions of oxygen with products of the citric acid cycle, fatty acid metabolism, and amino acid metabolism. At the inner mitochondrial membrane , electrons from NADH and FADH 2 pass through the electron transport chain to oxygen, which provides the energy driving the process as ...