Upload
brook-black
View
218
Download
4
Tags:
Embed Size (px)
Citation preview
Bio 28: NutritionInstructor: Paul Nagami
Laney College
Proteins
Proteins Do Almost Everything
Proteins are the “workhouses” of the cell, making chemical reactions possible. For example, there are proteins to put together DNA and to break apart starch. A protein that runs a chemical reaction is called an enzyme.
Protein Structure
Strands of the protein keratin, a tough protein in hair. Its shape, or structure, contributes to its toughness.Let’s zoom in even closer... what are these helices (corkscrews) made out of? What holds them together?
Proteins are made of amino acids
Amino acid monomers!Proteins are
polymers, like carbohydrates!
Amino Acids
Amine functional group (has N)
Acidic functional group (like end of fatty acid)
The part in yellow is called the side chain. There are 20 different amino acid side chains in human proteins.
Assembling Proteins
Peptide bond = bond between amino acids
It’s not easy to break this bond, but we have enzymes in on our stomach that can break down proteins to harvest the amino acids.
What Makes Proteins Different from Each Other?
Proteins with different shapes can have different functions. These shapes depend on their sequence of amino acids.
Proteins Are Amino Acid Polymers (Chains)
Imagine unfolding a protein chain…You would be able to look at the individual amino acids.
Some of these amino acids would stick to each other. Others would stick to water.
Hydrophilic amino acids end up on the outside of the protein, hydrophobic amino acids end up on the inside of the protein.
The side chains (sticking out)either stick to each other or to surrounding water
DNA is the instructions for protein
DNA’s function: Instructions to make proteins, such as lactase! Differences in DNA code can lead to differences in lactase production, causing lactose intolerance.
Essential Amino AcidsAlthough there are 20 different amino acids, most people can make 11 of them.
The remaining 9 that we can’t make are called essential amino acids.
To build complete protein, you must eat all 9 of these. Meat generally has all 9.
You can get them without meat if you practice protein complementation.
By pairing foods that contain different amino acids in the same day, you can eat healthy without meat.
Making Complete Protein
Examples of complete protein: Rice + beans, rice + lentils, potatoes + milk, whole-wheat bread + peanut butter.
Dangers of Excessive Protein
If you eat too much protein, it is not stored. Instead, the body eliminates the extra amino acids in the urine.
In the long term, excessive protein consumption can lead to kidney stones and acidic blood pH.
Some carbohydrates are necessary to break down protein efficiently! If you eliminate carbs, you can’t metabolize protein well.
Protein Malnutrition
Marasmus: Lack of both protein and caloric intake in general. Leads to wasting, very common in infants.
Kwashiorkor: Lack of protein. Common after 18 months; can lead to edema/bloating, death.