Tony Berardi Metabolism 1 Exam 2 1 Know the general structure of an amino acid Amino acids are the simplest unit of a protein just like monosaccharide s are of glycogen If you take a protein and break it down completely you will get one of the 20 amino acids that there are An amino acid contains a center carbon with a hydrogen attached called the alpha carbon There is a carboxylic acid attached to this to give the amino a negative charge an amine group a NH2 with a positive charge and a side chain The side chain differs for every amino acid but they all have that carboxy and NH2 groups If you see nitrogen always think amino acid and then think protein 2 Know the groups of amino acids and know which amino acids belong in each In this class the 20 amino acids are separated by their side chains There are the aliphatic side chains hydroxyl side chains sulfur containing side chains carboxyl side chains basic side chains aromatic and the imino side chains isoleucine glycine and alanine have a negative charge The aliphatic side chains have different combinations of CH groups such as valine leucine The hydroxyl amino acids are serine and threonine The hydroxyl gives them the ability to The sulfur side chains are methionine and cysteine The sulfur gives them the unique ability to form strong di sulfur bonds with other amino acids The carboxyl chains are aspartic and glutamic acid These have a strong negative charge The amide groups are asparagine and glutamine These have strong positive charge The basic charge The basic amino acids are arginine lysine and histidine These also have a strong positive Then the aromatic amino acids are phenylalanine tyrosine and tryptophan The one amino acid with a imino group is proline The reason I m explaining all these is because you will need to know them all for higher level classes such as biochemistry Helps to at least get familiar with them 1 Tony Berardi 3 Know the functions we discussed in class and some examples of those functions Most structures in the body are made of proteins such as all the enzymes that you are learning about some of the hormones antibodies are made of proteins muscle hair nails the transporters in the body and some neurotransmitters Our body depends on proteins for growth and maintenance repair and energy They can give us energy by undergoing gluconeogenesis if needed That was the cycle we went over on the previous test where the body makes glucose from other substrates but for protein it will only form glucose if nothing else is available otherwise you are breaking down muscle It can also form fat if the body already has enough energy 4 Know the essential and non essential amino acids and conditionally essential and why they are designated as such its own For proteins the classification of essential and non essential don t refer to the importance of the amino acid the body needs all equally Essential simply means that the body cannot make them on 11 of the amino acids are non essential and the body can make them and the other 9 are essential as we must get them from our diet These are histidine leucine lycine isoleucine phenylalanine valine methionine tyrosine and threonine You will need to know these Then there are two that are considered conditionally essential because the body can only make them with other essential amino acids These are cysteine and tyrosine Cysteine is made from methionine and tyrosine is made from phenylalanine So this means that if you are lacking in methionine you will have a deficiency in cysteine Likewise for tyrosine 5 Understand and be able to describe the structure of proteins primary secondary tertiary and quaternary Be able to give examples where relevant A protein is a line of amino acids connected by peptide bonds which formed when the nitrogen on the amine group combines with the C of the carboxyl of an adjacent amino acid This releases a water molecule of the protein The chains of amino acids are called the primary structure of the protein this is the backbone Then the chain starts to bind and fold onto itself It can either form an alpha helix hair and muscles as example or a beta sheet depending on the structure of the bonds The forces that 2 Tony Berardi cause the primary structure to bind are hydrogen bond van de walls forces and disulfide bonds The most important one to know to hydrogen bonds though a lot of forces in the body At this point the protein will start to loop and fold even more onto itself The forces that cause this binding are hydrogen bonds disulfide bonds again This folding determines the final are from hydrogen bonds structure of the protein Then in some cases two or more proteins with interact and you will have a quaternary structure An classic example is hemoglobin and antibodies 6 Know the different functions of proteins in the body be able to give examples The functions of proteins in the body are all that was explained above but to go into some specific example All enzymes are made of proteins a majority of the hormones such as insulin are made of proteins The contractible proteins actin and myosin are what gives muscles their appearance and ability to contract and fibrous proteins such as collagen reinforce our ligaments All the membrane transporters are proteins also such as the glucose transporters on the previous test and also all the receptors in the body The last specific example she gave was the plasma protein albumin The protein helps maintain the osmotic pressure in the blood This pressure keeps the blood in the veins since fluid moves from high to low pressure albumin keeps the pressure high in the veins 7 Know the digestive secretions related to protein digestion ie gastrin HCL pepsinogen Following what we know about carbohydrate digestion protein digestion doesn t differ too much The main thing to understand is that protein digestion begins in the stomach unlike carbohydrate digestion which starts in the mouth with salivary amylase Once in the stomach gastrin is stimulated and releases HCl via the parietal cells Gastrin is stimulated by the presence of food or merely by the thought of food at times As said before the HCl mixes with the food to start digestion and starts to denature the chemical bonds HCl also serves the role of activating pepsinogen to pepsin Pepsin is the main enzyme that starts the specific digestion of the protein Pepsinogen is the inactive enzyme that is released from the gastric cells in the stomach Once the HCl cleaves it to
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