Embedded Files
From http://www.bio.miami.edu/dana/226/226F08_21.html
Pictured above is a diagram of a simple signal transduction pathway. Imagine the receptor is a protein -- without an adequate protein intake, many of the body's vital reactions would be inhibited.
Pictured above is a diagram of a simple signal transduction pathway. Imagine the receptor is a protein -- without an adequate protein intake, many of the body's vital reactions would be inhibited.
Hormones
Hormones
Proteins are responsible for a lot of hormone synthesis.
Signal transduction pathways for stimulating endocrine (hormonal) glands involve enzymes, many of which are proteins. G-proteins and tyrosine-kinases are common protein-based receptors.
Many hormones, such as insulin, growth hormone, and oxytocin are made from proteins or protein components (oxytocin is a peptide hormone, which does not contain as many amino acids as a protein) [16]
Structure and Motion
Structure and Motion
The most abundant structural protein in the human body (out of over one hundred!) is collagen. It makes up about 6 percent of total body weight, 30 percent of bone tissue, and comprises large amounts of tendons, ligaments, cartilage, skin, and muscle [17].
Keratin, another fibrous protein, makes up skin, hair and nails.
Contractile parts of muscles, responsible for motion, are actin and myosin, whose interaction is depicted on the bottom right.
Consuming protein allows your body to create all of these essential components. This is why it is important to consume protein after exercise; microscopic tears are created in your muscles during a vigorous workout, and consuming adequate protein (and carbs to restore glycogen) after putting physical stress on your body helps recovery and promotes muscle growth!
From https://biologydictionary.net/concentration-gradient/
The dotted line in the diagram above represents the semi-permeable membrane of a cell. It is more difficult for sodium ions to cross the cell membrane because of their size and charge, whereas water molecules have special channels, known as aquaporins, through which they can passively cross the membrane. In the picture, the water molecules flow with a concentration gradient to maintain a healthy water balance. This same concept can be applied to the role of circulating proteins.
The dotted line in the diagram above represents the semi-permeable membrane of a cell. It is more difficult for sodium ions to cross the cell membrane because of their size and charge, whereas water molecules have special channels, known as aquaporins, through which they can passively cross the membrane. In the picture, the water molecules flow with a concentration gradient to maintain a healthy water balance. This same concept can be applied to the role of circulating proteins.
This role is especially important because acidic conditions can cause proteins to denature, and therefore lose their functional abilities, possibly hindering many reactions.
Fluid and Acid-Base Balance
Fluid and Acid-Base Balance
To keep water evenly distributed between blood and cells, proteins continuously circulate at high concentrations in the blood. This works for balance because of water and solute potential rules: water moves toward areas with higher concentrations of solutes.
In particular, albumin is circulated to maintain a balanced pH. Albumin, the most abundant protein in the blood, is slightly acidic and negatively charged, so it balances the many positively charged molecules such as H+, Ca2+, K+, and Mg2+ that are also circulating. In other words, albumin acts as a buffer against abrupt changes in the concentrations of these molecules. Hemoglobin, another abundant protein, also participates in this balance by binding H+ [17].
TRansport
TRansport
Albumin also has a role in transporting hormones, fatty acids, some vitamins, essential minerals, and drugs. It does so by binding them, then moving through circulatory system where they can perform specific tasks for the body [17]. Proteins perform similarly during the second phase of detoxification in the liver, during which they to waste molecules and escort them out of the body.
Each red blood cell contains millions of hemoglobin molecules that bind oxygen in the lungs and transport it to all the tissues in the body!
The plasma membranes of the body’s cells aren’t really permeable to large, polar molecules, so for your cells to obtain the necessary nutrients and molecules, many transport proteins exist in the membrane.
Channels, one-way taxis that require energy, etc.
Enzymes
Enzymes
Enzymes are catalysts for biochemical reactions. They work by providing an alternative pathway for the reaction that requires less energy to activate.
Proteins are ideal for forming enzymes because their chemistry enables specific structures in folding, and enzymes exist in very specific shapes. This specificity is required for precise targeting between an enzyme and its substrate, which then goes on to elicit a certain reaction in the body.
Four stages of protein folding
Four stages of protein folding
From http://www.bio.miami.edu/dana/226/226F08_21.html
Here is a diagram depicting, in very simple terms, how enzymes work. Catabolizing (breaking down) a molecule of maltose into two molecules of glucose can be done more efficiently with the help of an enzymatic reaction.
Something to note is the specificity of the shapes of enzyme and substrate. This lock-and-key fit is attributed to protein folding. Various chemical interactions between atoms along the protein cause it to form a distinct shape.
Here is a diagram depicting, in very simple terms, how enzymes work. Catabolizing (breaking down) a molecule of maltose into two molecules of glucose can be done more efficiently with the help of an enzymatic reaction.
Something to note is the specificity of the shapes of enzyme and substrate. This lock-and-key fit is attributed to protein folding. Various chemical interactions between atoms along the protein cause it to form a distinct shape.
From https://home.apu.edu/~jsimons/Bio101/protein-tertiary.gif
Closeup of tertiary structure, showing how protein shape is formed. Quaternary structure, which not all proteins have, is created from similar interactions.
Closeup of tertiary structure, showing how protein shape is formed. Quaternary structure, which not all proteins have, is created from similar interactions.
Energy Production
Energy Production
Some of the amino acids in proteins can be disassembled and used to make energy (though only about 10 percent of dietary proteins are catabolized each day for cellular energy; glucose is still preferred). The liver can break down amino acids to their carbon skeletons, which can then be fed into the citric acid cycle for cellular respiration. Here is a more comprehensive article on the specific steps and components that can be used in this process, complete with diagrams!
If one’s diet doesn’t contain enough carbs and fats, their body will use more amino acids to make energy, which compromises the synthesis of new proteins and destroys muscle. Conversely, if their diet contains more proteins than their body needs, the extra amino acids will be broken down and transformed into fat, which can also be harnessed for energy.
Protection
Protection
The skin’s dense network of the collagen fibers serves as a barrier against harmful foreign substances such as bacteria and viruses.
The immune system’s attack and destroy abilities are dependent on enzymes and antibodies, both of which are proteins
Certain proteins circulating in the blood can be directed to build a molecular “knife” that stabs the cellular membranes of foreign invaders, killing them (remember the specific shapes that proteins can form!) [17].
Wound Healing & Tissue Regeneration
Wound Healing & Tissue Regeneration
Wound healing process has three phases: inflammatory, proliferative, and remodeling
I: Begins with proteins such as bradykinin, which dilate blood vessels at the site of injury
I: Additional protein called fibrin helps to secure platelets that form a clot to stop the bleeding
P: Cells move in and mend injured tissue by building collagen fibers to pull the wound edges together
R: More collagen is deposited, forming a scar
Tissue regeneration is an ongoing process that rebuilds an exact structural and functional copy of the lost tissue, unlike scar formation. Skin, hair, nails, and intestinal cells regenerate very quickly, while others, such as heart-muscle cells and nerve cells, do not regenerate at levels that are even noticeable [17].
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