organelle

newscientist.com
Exclusive: World’s first baby born with new “3 parent” technique
A five-month-old boy is the first baby to be born using a new version of a controversial technique that uses DNA from three people
By Jessica Hamzelou

This headline pops up just about EVERY YEAR. How can the world’s first 3-parent baby keep getting born over and over again? Let me explain to you why that’s not really what you might think it is based on the headline.

1. This basic technique was first carried out in the 90′s. THOSE KIDS HAVE GRADUATED HIGH SCHOOL. They called it 3-parent then, and now they’re calling this almost-identical procedure 3-parent. The difference now is just when the sperm fertilizes the egg, being after the egg nucleus is implanted in the egg of a donor, as opposed to before. 

2. This is not a situation where each parent gives a third of their DNA. What’s really happening is that there are TWO parents, and one person, a donor, who is donating the cytoplasm and the non-nucleus organelles of the egg. The donor’s egg nucleus–with all of her ribosomal DNA–is discarded. Then, yes, there is like 0.03% of her DNA that is still there, in the mitochondria. Mitochondira convert ATP into energy but they do not have any fun traits on them like your hair color, personality, predisposition to cancer, or basically anything that you would consider getting from your parents. 

3. GMO Babies? If not 3-parent, people call these Genetically modified. I guess they are sort of, but listen. This is not some CRISPR-CAS9 shit where you can cut and paste traits here and there and across individuals and organisms. This is all about this one little organelle. I should also note that, in places where this procedure is legal, there is a focus on discarding the female blastocysts, so that only males are born, who do not pass on mitochondria to their own kids.

In short, it is weirdly common for assisted reproductive technology to be blown out of proportion in headlines. And Mitochondria is the powerhouse of the cell.

The Golgi Apparatus is a membrane-bound organelle in the cell that receives proteins and lipids from the rough endoplasmic reticulum. It modifies some of them and sorts, concentrates and packs them into sealed droplets called vesicles. This organelle can be seen using an electron micrograph. 

Eukaryotes: A Breakdown of Organelles

Organelles are unique to eukaryotes and act like organs in the cell, each performing their own specific functions to keep the whole cell running. Since they’re all in their own little sealed-off membrane-bound areas, they can provide the ideal environment for whatever function they perform—for example, they can adjust the pH or temperature—and thus this allows for much more complexity in the cell.

Most organelles fit into a single functional unit called the Endomembrane system, because they evolved in the same way. The only organelles that don’t fit into this category are the mitochondria and chloroplast—for reasons that will become clear in the next article.

So let’s take a look at the functions of the organelles in the Endomembrane system:

  • Nuclear envelope: This compartment contains the cell’s genetic material—the DNA. Its main function is to protect and package the DNA, but it also synthesises RNA, another kind of genetic material.
  • Endoplasmic reticulum: Interconnected with the outer membrane of the nuclear envelope, the ER consists of flattened tubes and sacs called cisternae. The endoplasmic reticulum is subdivided into two: the rough ER, where protein synthesis and packaging takes place, and the smooth ER, where lipid and carbohydrate synthesis takes place. Basically, the endoplasmic reticulum uses the information in DNA to create the building blocks of the cell.
  • Golgi body: This is composed of a group of flat, membranous sacs that deal with the goods produced in the endoplasmic reticulum. Proteins are transported by vesicles from the cis face (the part facing the nucleus) and a trans face (the part facing away from the nucleus), being packaged, modified and matured along the way. When they emerge the proteins are sent out into the wider environment.
  • Lysosome: This is the recycling plant of the cell, containing digestive enzymes that sort, degrade and recycle waste products. It’s actually a perfect example of how organelles can create niche environments: the lysosome maintains an acidic pH of 5, which is ideal for the breakdown of products.
  • Vesicle: Membrane-bound sacs used to store and transport material.
  • Vacuole: A large, fluid-filled “bubble” in plant cells, where food and waste products are
  • Cell membrane: Made mostly of lipids, this encloses the cell and separates it from the outside world. It’s selectively permeable, meaning that only some substances are allowed passage in and out.

And now the functions of those loners not in the Endomembrane system:

  • Mitrochondria: This is where cellular respiration takes place—where the cell’s energy (ATP) is extracted from glucose (a sugar). It’s present in all plant and animal cells.
  • Chloroplast: Present in plants, the chloroplast takes in light energy and converts it into chemical energy through the process of photosynthesis, ready for use in the mitochondria.

I know I’ve just dumped a whole host of terms onto you, and if they’re totally unfamiliar then they might be difficult to juggle. But trust me, we’ll come back to almost all of these in more detail later, so you’ll have time to digest and memorise.

Further resources: An interactive look at animal, plant, and bacterial cells

The Rationals as cellular organelles

INTJ: Lysosome. Contains enzymes that neutralize all the bullshit coming their way.

INTP: Centrosome. Only manifests itself during cellular division or when somebody mentions Star Wars.

ENTJ: Mitochondria. The powerhouse of the cell.

ENTP: Golgi apparatus. Continuously spits out vesicles filled with random facts.

4

Photonic crystals cause active colour change in chameleons. “Many chameleons, and panther chameleons in particular, have the remarkable ability to exhibit complex and rapid colour changes during social interactions such as male contests or courtship. It is generally interpreted that these changes are due to dispersion/aggregation of pigment-containing organelles within dermal chromatophores. Here, combining microscopy, photometric videography and photonic band-gap modelling, we show that chameleons shift colour through active tuning of a lattice of guanine nanocrystals within a superficial thick layer of dermal iridophores.”

Watch on somberfawn.tumblr.com

MY BIOLOGY TEACHER MADE A RAP ABOUT CELLS