Biological Molecules: Protein Function

Proteins

Proteins are like the structure of life.  First of all, all your DNA is is a big cookbook of protein recipes: melaninA brown-black pigment made by melanocytes in the stratum basal and given to keratinocytes as melanos, epinephrineadrenaline): Fight-or-flight hormone from the adrenal medulla., insulin, lactase and a bunch of other names ending in –ase.  Cells have only two jobs: make more of themselves, something we talk about in later parts of this course, and making proteinsLarge molecules made of amino acids with various functions in the body..  There are cellsThe basic structural and functional units of life. called melanocytesCells in the stratum basale that produce melanin, the pigment responsible for skin color. that only make melanin…and melanomaA dangerous form of skin cancer that originates in melanocytes. if you are unlucky.  There are cells in your pancreasA gland that produces digestive enzymes and hormones like insulin and glucagon. destinated to make enzymesProteins that speed up chemical reactions in the body. that will then be squirted into your small intestine as food joins it form the stomach. 

Enzymes

One of the major types of proteins are enzymes.  These are like chaperones for chemical reactions.  These are not living things, they are just biological moleculesGroups of atoms bonded together. or proteins. This diagram shows you how an enzyme called sucrase can help two glucoseA simple sugar that is the main source of energy for cells. and fructose molecules to bind together to make sucrose.  These two monosaccharides and being made into a disaccharide.  This is a process called anabolismThe metabolic process that builds complex molecules from simpler ones, requiring energy., a word that means “to grow.”  Opposite to this is catabolismThe metabolic process that breaks down molecules to release energy., which means “to break down.”  This enzyme comes away from the reaction unscathed and ready to anabolize more sucrose. 

Enzymes, as do all proteins, have a very specific shape allowing them to interact with one substate and be a catalyst for only one reaction.  So, if you don’t make the lactase enzyme to digest milk products, it’s not like another enzyme is going to be like, “Oh, yeah, I can do that job too.”  Enzymes get this specificity from their active siteThe specific region of an enzyme where a substrate binds and a reaction occurs..  This is a location on the protein that is specifically shaped for the substrates of the reaction. 

Communication

I have a picture here of the unfortunately shaped pituitary glandEndocrine gland at the brain’s base controlling many hormones. which is an organ that’s located kind of like at the center of your headRounded proximal end that fits into the acetabulum of the hip bone.. This organ secrets a whole bunch of protein based hormones one of them being the thyroid stimulating hormone. On the right I have proteins that are being used as neurotransmittersChemicals released by neurons to transmit signals across a synapse. to send electricity between two nervous cells or two neuronsThe functional cells of the nervous system that transmit signals.. Many neurotransmitters like serotoninA monoamine neurotransmitter involved in mood, sleep, and sensory perception. dopamineA catecholamine neurotransmitter involved in motor control, motivation, and reward. and epinephrine are protein based substances made by neurons and then spew out into a tiny space called a synapseThe junction between two neurons where communication occurs. in order to communicate with the next cell.

Transport and Defense

We will see proteins function in many types of transport. There are multiple types of proteins inserted into cell membranes. Many of them are channelsProtein passages in the cell membrane that allow specific molecules to pass through. gated channels free tunnels carriersMembrane proteins that transport substances across a cell membrane. and a whole bunch of different ways that molecules can pass through the cell membrane. I have a picture here of an ion channel which means that it’s allowing something like the sodium(Na⁺): Major ECF cation; important for fluid balance, nerve function. cation or the potassium(K⁺): Major ICF cation; essential for muscle and nerve function. cation to flow through it. And this cation is flowing from an area of high concentration to an area of less concentration.

Antibodies more specifically known as immunoglobulins(Ig) Antibodies: Proteins produced by the immune system to target specific antigens. are pro teens that are made by plasma cellsImmune cells that develop from B cells and produce antibodies. in the bone marrow. These proteins are made very specifically in order to target a virus a bacteria or some other type of invader in your body.

Structure and Contractions

Almost everything in your body is made-up of structural proteins. The most common structural proteins are collagenA structural protein in the dermis that provides strength and elasticity., which we usually associate with our skinThe body’s largest organ, providing protection and regulation., but our the basicA solution with a pH above 7, having a lower concentration of H⁺ ions. structures of other tissues such as tendons and ligaments. Your hair is made of a fibrous protein called keratinA strong, fibrous protein that forms the structure of skin, hair, and nails. which is also present as a waterproofing protein in your skin and other mucous membranes that are exposed to the outside.

You have three types of muscle in your body cardiac muscle which is obviously in your heart, smooth muscle which surrounds a lot of your squishy organs like your small intestine, and the last one is skeletal muscle which is attached to your bones and his phone voluntarily controlled by you. Within your skeletal muscle exist 2 little tiny proteins that we’ve never actually been able to see but we’ve been able to project their shadows and X-ray them in an effort to find out what their structures are. The first one is called actin and the other one is called myosin. It’s the assembly of these two proteins that allow you to have contractile proteinsProteins (actin and myosin) responsible for muscle contraction. as those in your skeletal muscle. And this is what makes us different from a jellyfish. A jellyfish has no contractile proteins or way of swimming in any willful direction. However our contractile proteins in our skeletal muscle give us voluntary control over our body.

Storage

Eggs are storage proteins. The yolk is full of a protein called Oval albuminA plasma protein that helps maintain osmotic pressure and transport substances. and your blood in general is full of a protein called albumin but the ovalbumin serves as of food reserve for the growing embryo. Coconuts are actually coconut tree seeds. Coconuts float on waterThe universal solvent essential for life. because they’re full of coconut milk which is the substance high in fat. Fat floats. The luscious juicy coconut milk is the reserve for the embryo as that embryo and its casing float from 1 island to the next