Chapter Five Reading Journal

Questions:

What are the differences between fats, phospholipids, and steroids?

Fats are made from three fatty acids bonded to a glycerol by what is called an ester linkage. Fats are non-polar and used to store energy. Phospholipids are made of two fatty acids and phosphorous bonded to glycerol. They are polar at the top where the phosphorous is and non-polar at the bottom where the two fatty acids are. Phospholipids make up cell membrane. Steroids are composed of four fused rings of carbon skeletons the function of a steroid is determined by the functional group that is attached to the rings.

What is an Amino Acid and why is it important?
An Amino acid is a molecule with the amino group and carboxyl group bonded to a central carbon, this carbon is also bonded to single hydrogen. This leaves one bonding site off the carbon which bonds to one of twenty different molecules. These twenty amino acids bond together to from polypeptides and proteins are made of either one polypeptide or several polypeptides bonded together.

Why are carbs, lipids, proteins and nucleic acids called macromolecules?
They are all named this way because they are huge molecules. They are all composed of many monomers that bond together through a dehydration reactions creating polymers. Many of these organic compounds are formed from these polymers or thousands of monomers bonding to other polymers.

Facts:
- Dehydration reactions form polymers
- Hydrolysis reactions break polymers apart
- Carbohydrates are composed of saccharies
- Lipids main common property is hydrophobia
- Nucleic acids are the macromolecules that are responsible for genes





This shows the structure of Phospholipids that consist of only two fatty acids compared to fats that are composed of three fatty acids. The third bonding site of the glycerol in the phospholipids is bonded to a phosphorous. This gives phospholipids different properties than fats because instead of the whole molecule being hydrophobic, one side is hydrophilic and the “tails” of fatty acids are hydrophobic. This property is important for the cell because layers of phospholipids make up the cell membrane and the hydrophilic portions are able to interact with the aqueous portions of the cell and the hydrophilic part of the phospholipids creates a barrier between the internal and external environment of the cell.

Summary: There are four main groups of large organic molecules called macromolecules, each group is very important for the functions of life. Carbohydrates are made up of saccharides and provide energy for the cell. Lipids are mostly common in that they are hydrophobic. Fats are used for energy storage and composed of three fatty acids and a glycerol. Phospholipids form the cell membrane and are made from two fatty acids and phosphorous. Steroids are made of four fused rings of carbon structures examples: cholesterol, hormones.

Proteins are composed of twenty different amino acids that form polypeptides. Proteins are formed from one or more polypeptides. Proteins have many functions. Nucleic acids are used to store and transmit genetic information. They made up DNA, which stores the information and RNA, which transmits the information.