What are the stages of mitosis?

Mitosis involves the replication of DNA and its separation into two new daughter cells. while only four phases of mitosis are often listed. the entire process is actually comprised
of six phases:
• Interphase: Involves extensive preparation for the division process.
• Prophase: The condensation of chromosomes; the nuclear membrane disappears; formation of the spindle apparatus; chromosomes attach to spindle fibers.
• Metaphase: Chromosomes, attached by spindle fibers. align along the mid-line of a cell.
• Anaphase: The centromere splits and chromatin move apart.
• Telophase: The nuclear membrane reforms around newly divided chromosomes.
• Cytokinesis: The division of cytoplasm, cell membranes, and organelles occur. In plants. a new cell wall forms.

How do brain cells store memories?

The part of your brain responsible for processing memory is the hippocampus. It is believed that memories are formed at the level of individual nerve cells. The synapse is the point at which adjoining nerve cells touch. and it is this juncture that is the building block of memory systems. Information moves across the synapse-the information signal is carried inside a cell by a second messenger (known as CAMP), which then activates other cell machinery. The end result is the switching on of a gene that regulates memory. The product of the gene, a protein, promotes synaptic growth and can convert short term memory to long term memory.

What is the structural basis of activation of heterotrimeric G proteins?

Heterotrimeric G proteins are composed of α, β, and γ polypeptide chains. Usually, the α and γ chains are anchored to the inner leaflet of the plasma membrane by lipid anchors that consist of a fatty acid that is linked to a cysteine side chain by a thioester bond. , the binding of a signaling ligand leads to exchange of a molecule of GDP for a molecule of GTP, bound to the Gα subunit. Concurrently, the Gα subunit dissociates from the GβGγ subunit. This allows both the Gα and the GβGγ subunits to interact with other signaling molecules.There are multiple copies of the genes for the Gα, Gβ, and Gγ polypeptides in eukaryotic genomes. In the human genome there are at least 15 different Gα subunits, 5 Gβ subunits, and 10 Gγ subunits. Hence, there are potentially ~1000 different combinations of these subunits, with different possible physiological effects that depend on which G protein-coupled receptor(s) they become associated.