2026-08-12 12:06:56: proteins

biology/Chemistry of Life/Nucleic Acids.md

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+[[Macromolecules]]

biology/Chemistry of Life/Proteins.md

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+[[Macromolecules]]
+# General Overview
+first thing to think of when hearing proteins is "everything"
+
+1. carry out most cellular functions
+2. unlike the other macromolecules, proteins use all of chnops
+
+# Structure of Amino Acids:
+monomers are called amino acids, polymers are polypeptides
+![[Pasted image 20260812110332.png]]
+structure of proteins is pretty similar, the have an alpha carbon, a hydrogen, an amino group, a carboxyl group, and a r group.
+the r group differs and is what determines a proteins function, r groups can be hydrophobic, hydrophilic, or ionic
+
+# Structure of Polypeptides:
+proteins have 4 structural levels, primary secondary tertiary and quaternary, describes order of which proteins formed
+
+![[Pasted image 20260812112259.png]]
+amino end has a presence of ammonia, carboxyl end has a carboxyl group
+
+the primary structure is a long chain of amino acids that determine the overall shape of the protein. each amino acid in a protein is connected by a covalent bond, called peptide bonds
+
+long chains of amino acids first form in one of two shapes through hydrogen bonding in the peptide backbone, a spiral or a folded sheet, called alpha helices and beta pleated sheets, and represent the proteins secondary structure. 
+
+" Interactions (such as **hydrogen bonds**, **disulfide bridges**, **ionic bonds**, and **hydrophobic interactions**) between the polypeptide’s R-groups cause the helices and sheets to fold into a new shape, which is called the tertiary structure."
+
+for some proteins, tertiary is their final structure, meaning that once it's achieved the protein is fully functional, some more complex proteins require multiple tertiary structures to combine, called a quaternary structure.
+![[Pasted image 20260812114439.png]]
+first step to making a protein is creating appropriate amino acid sequence.
+amino acids fold into alpha helices or beta pleated sheets which come together to form a tertiary structure.
+some proteins require multiple tertiaries/polypeptides to come together to form a quaternary structure.
+
+"_**Key Takeaway:** Proteins are responsible for most cellular functions. All proteins have a central alpha carbon with a hydrogen, an amino group, and a carboxyl group. Where they differ is the R-group. Proteins cycle through three to four structures before becoming fully functional._"
+
+although proteins have multiple structures, they're dependent on the previous one.
+the protein structures are derived from the folding of the primary structure. proteins can fold back into the primary structure, called denaturation
+![[Pasted image 20260812120344.png]]
+denaturation can be caused by:
+1. heat
+2. ph changes
+3. mechanical agitation (stirring, shaking)
+
+renaturation can also occur. eg pepsin enzyme. pepsin is one of the enzymes of the stomach, if ph is too high, it denatures, if it's brought back down, it renatures.
+# Function
+
+Proteins have a bunch of different functions
+1. Enzymes: speed up chemical reactions
+2. Defensive proteins: antibodies help the immune system recognize viruses
+3. Transport proteins: facilitate transport of large/polar molecules across cell membranes
+4. Storage proteins: store amino acids, such as in milk
+5. Receptor proteins: used in cell signaling
+6. Contractile/ Motor proteins: helps muscles contract and cells with tails move
+7. Structural proteins: makes up hair, nails, and scars
+
+# Summary
+|Structure|Monomer / Polymer Name|Function|
+|---|---|---|
+|All proteins have a central alpha carbon with a hydrogen, an amino group, and a carboxyl group. However, they have different R-groups, which lead to structural and functional differences.|Monomer: Amino Acid  <br>Polymer: Polypeptide|Most cellular and body functions|