An overview of the structures inside a sperm cell:
Acrosome: Contains hydrolytic enzymes.
Nucleus: Holding DNA.
Centriole: Forming the axoneme.
Mitochondria: Generate ATP for movement.
Axoneme: Propels the sperm cell.

The image shows an internal, cytoplasmic perspective, highlighting the protein complex that connects the cytoskeleton to the structures responsible for cell-cell adhesion.

The bean is a lie!
After bringing up my pet peeve - left-handed DNA - in my Halloween video, I want to pivot to a quick rant about the real shape of mitochondria.

Inside the cell, you can see organelles and components: microtubules, a centriole, the endoplasmic reticulum (ER), the Golgi apparatus, mitochondria, and ribosomes (both free-floating and ER-bound), along with a nuclear pore complex.

This simple simulation lets you visualize ion concentrations in various cellular compartments, such as the cytoplasm, extracellular space, and sarcoplasmic reticulum. I hope it helps you better understand the ion density across these different environments.

Voltage-gated calcium channels allow Ca++ influx following membrane depolarization. The channel complex consists of several subunits:
The red forms the central pore through which Ca++ ions pass.
The extracellular and intracellular proteins regulate channel activation and inactivation.

The spookiest thing for me? When a scientific organization uses left-handed DNA in an illustration.
And yes, I'm well aware of Z-DNA. But that's not an excuse if you don't have a zig-zag backbone. Speaking of the backbone, why didn't I use "spinal cord" there? Ugh!
Anyway, happy Halloween!

The GABA-B receptor functions as a neuronal inhibitor, distinct from its counterpart, the GABA-A receptor. It operates as a G-protein-coupled receptor (GPCR), meaning that upon activation, it initiates a cellular signaling cascade rather than acting as a direct ion channel.

Meet the protagonists of this week's video: GABA-A (as the ligand-gated ion channel), GABA-B (as the long-winded GPCR), G-Proteins alpha, beta, and gamma (as the mischievous trio), GIRK (as the potassium bouncer), and KCTD (as the clean-up crew).

A synaptic vesicle waiting to be released into the synapse. It's filled with neurotransmitters
The V-ATPase maintains an electrochemical gradient, which the VAChT uses to load the vesicle with acetylcholine. Synaptobrevin teams up with Syntaxin and SNAP-25 on the membrane.

The GABA-A receptor is a protein complex made of five subunits that acts as the brain's main brake, receiving inhibitory signals from neurons. When the neurotransmitter GABA binds, it opens a channel, allowing chloride ions to flow into the cell and quiet down its electrical activity.

All of our body's cells possess the same genes, yet they perform wildly different functions. Epigenetics determines which of these genes are expressed, thereby dictating the cell's role. DNA methylation is a crucial part of this process.

The sodium-potassium pump is a protein in the neuron's membrane that uses ATP to move three sodium ions out and two potassium ions into the cell, thereby restoring the resting potential necessary for nerve impulses.

ATP-synthase, the tiny machine that powers cells by spinning at 20'000 rpm.

The Type IV secretion system is a complex bacterial structure that extends across the inner and outer membranes

An Escherichia coli bacterium navigating a milky environment. This scene is a segment of an upcoming animation illustrating the fascinating Lac Operon. Stay tuned for the complete animation! I thank all my Patreon supporters who make projects like this possible.