I’m working out. I need to eat proteins. So I eat things like meat and beans. But who makes the proteins first and how? Why can’t I make them myself?
In: Biology
There are many thousands different protiens in your body. .
Your body builds the protiens it needs. The building blocks, the amino acids are what are actually needed. Your body break down the protiens you eat into the building blocks and builds the protiens it needs from those pieces.
There are 20 different ammino acids that we build our protiens from and your body can only make 11 of these. You must consume amino acids or protiens that break down into amino acids to get the rest.
Other orginisms are able to build different amino acids, which we then eat to get those ones we need but can’t build ourselves.
Proteins are big molecules that are made up of smaller molecules called amino acids. Your body cells are always needing specific proteins because they do all sorts of different things depending on their shape – replicate DNA, act as enzymes to catalyze reactions, carry around other molecules, act as structural elements in cells, and of course, form the primary structure of muscle cells.
Since the body needs specific proteins it doesn’t bother actually using the proteins you get in food. Instead they’re broken down into amino acids during digestion and then re-assembled into the proteins you need. The body can synthesize amino acids – which is where all the proteins in the food chain came from at some point; some plant or animal sythesized the amino acids and made them into proteins – but there are some amino acids that humans either don’t synthesize or don’t synthesize at a sufficient rate and are so called ‘essential’ because getting them in your diet is important. Plants can synthesize all these amino acids, but animals evolved not to because they can just eat plants to get them and it wasn’t worth the energy.
So to answer your question: plants, ultimately. And animals to some extent
You do make proteins. All of your enzymes and antibodies that you use to survive are examples of proteins. There are regions of your DNA known as exons which are read by specialized enzymes in your cells. These enzymes essentially copy a mirror image (known as mRNA) that gets sent to a large protein unit called a ribosome which translates that mRNA into an amino acid sequence called a peptide. Peptides join together to make a protein. Those single building blocks known as amino acids can’t always be made by us, so when you eat protein, you give your body a lot more access to a bunch of amino acids to use to make the proteins we need!
Living things make proteins, and are made in part of proteins. Eating more proteins than normal enables making more proteins than normal, which helps when building muscle. Specifically, the proteins you eat are broken down to their amino acid building blocks, and reassembled to new proteins as needed.
Proteins are made in every cell. But the cells need amino acids to build the proteins. When you eat proteins you are not after the actual proteins but rather the amino acids. There are various different types of amino acids, the sequence of the various amino acids is what gives proteins their shapes and therefore their function.
The cells can make their own amino acids. But this takes a lot of energy as well as the biological infrastructure. Plants can make all their own amino acids. And there is a difference in the amino acids made by herbivores and carnivores to complement their diet. So while humans can make enough of most of the amino acids we need we do need some protein in our diet. When we are growing though we often need to compensate with additional protein in our diet because the body is not able to make enough, even of the amino acids it normally produce enough of.
So technically you don’t need to eat proteins. You need to eat amino acids. However we don’t typically find amino acids by themselves, so the easiest way to get them is to eat proteins and let your body break down the protein into individual amino acids.
As for why your body can’t make them by itself, well.. for some of them it can. Your body can make 6 of them under normal circumstances, and 6 of them sometimes. The remaining 9 you have to consume from food. These 9 are called ‘essential amino acids’, and when you’re planning your diet, you want to make sure that you get all 9, otherwise your body will be deficient in one or more of them.
Foods that contain all 9 are considered ‘complete’ proteins, which is a term that you’ll hear sometimes. For example, pork rinds have a lot of protein, but the protein that they contain do not have all 9 essential amino acids. You’ll also want to make sure you get enough of each 9, but that’s a lot harder to calculate because we don’t exactly know how much of each one our body needs per day.
https://en.wikipedia.org/wiki/Essential_amino_acid
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