Chapter 4 - Macromolecules

• Oxygen and sulfur both have six valence electrons and normally form two bonds.
• Oxygen may be present in all macromolecules.
• %%Sulfur is frequently present in proteins.%%
• Nitrogen and phosphorus have five valence electrons apiece, and they normally form three bonds.
• Nucleic acids and proteins contain nitrogen.
• %%Phosphorus may be present in nucleic acids as well as certain lipids.%%
• Hydrogen contains a single valence electron and just one bond.
• Hydrogen may be present in all macromolecules.
• In fact, hydrogen atoms are so common that they are frequently overlooked in molecular structures.
• Carbon serves as the molecules' "backbone."
• Carbon contains four valence electrons and may connect to a wide variety of other elements.
• It has the ability to create single, double, and even triple bonds.
• Carbon can also take the form of linear, branching, or ring-shaped formations.
• Carbon can be present in all macromolecules.
• Carbohydrates are sugar monomer polymers."
• The structure and function of carbohydrate are determined by the type of sugars utilized to form it and how the sugars are connected.
• Sugars can be linked in either linear or branched chains.
• Carbohydrates can be utilized to store energy (as in starch or glycogen) as well as provide structural roles (such as in cellulose).
• ^^The types of connections found between sugars in carbs that store energy differ from those found in carbohydrates that have a structural purpose.^^
• Lipids are nonpolar polymers that have important roles in energy storage, cell membranes, and insulation." (As seen in the image attached below.)
• Fatty acids are one of the building components of lipids.
• Saturated fatty acids have the greatest amount of C–H single bonds, are solid at room temperature, and are often derived from animals.
• 
• Unsaturated fatty acids have at least one C=C double bond, are liquid at room temperature, and are often derived from plants.
• The saturation level of a lipid determines how it operates in a cell.
• Phospholipids play a critical role in cell membranes.
• A glycerol molecule, two fatty acids, and a phosphate group make up their structure.
• Because the fatty acids are nonpolar and the phosphate is polar, phospholipids are amphipathic, which means they have both hydrophobic and hydrophilic properties.
• The term Nucleic acids refer to polymers of nucleotides and function as the carriers of genetic information.
• Nucleotides will be discussed in more detail later in this chapter.”
• Steroids are another kind of lipid.
• Steroids are nonpolar, rather flat molecules.
• Many steroids are created by altering the molecules of cholesterol.
• Estradiol, testosterone, and cortisol are examples of steroids.
• Proteins are amino acid polymers.
• As illustrated in the image above, amino acids have an amino group, a carboxylic acid group, a hydrogen atom, and a side chain (R-group) connected to a central carbon.
• The R-group is unique to each amino acid; it defines the amino acid's identity as well as whether it is nonpolar, polar, acidic, or basic.
• Proteins have roles in enzyme catalysis, cell structure maintenance, cell signaling, cell recognition, and other processes.
• Peptide bonds connect amino acids, as seen in the image attached above.
• The resultant polypeptide chains have a carboxyl (COOH) terminus and an amino (NH2) terminus.
• The main structure of the protein is determined by the order of the amino acids in the polypeptide chain.
• Tertiary structure refers to the protein's three-dimensional folded form, which is frequently governed by hydrophobic/hydrophilic interactions between R-groups in the polypeptide.
• The most stable tertiary structures will feature hydrophilic R-groups on the protein's surface (in touch with the aqueous environment of the cell's cytosol), whereas hydrophobic R-groups will be found in the protein's core (away from the watery cytosol).
• Disulfide bridges between sulfur atoms may also be seen in tertiary structures.

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