NHM 101 Lecture Notes - Lecture 7: Hydrogen Atom, Tripeptide, Dipeptide
2 May 2018
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Chapter 6- Protein
Protein Structure
Proteins are made up of:
Amino Acids
- Contain nitrogen, carbon, hydrogen, and oxygen (N, C, H, O)
- Have same basic structure:
- Central carbon atom
- Hydrogen atom
- Acid group (COOH)
- Amino group (NH2)
- Side group varies per amino acid
Proteins are MORE complex than carbs or lipids because of their unique side groups.
● 20 different amino acids
○ Simplest amino acid is
glycine
■ Side group is a single hydrogen
○ Amino acids differ in size, shape, and other characteristics due to the unique
side group
Essential Amino Acids- the body cannot
make these itself
● 9 amino acids
● We must get these from our diet
Nonessential Amino Acids- the body can
make these itself
● 11 amino acids
● Body takes nitrogen and
fragments from carbs/fat to form
amino acid
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Protein Structure
Amino acids are linked together to form proteins
● Linked together by peptide bonds
● Condensation reactions connect amino acids
Dipeptide
● 2 amino acids bonded together
Tripeptide
● 3 amino acids bonded together
Polypeptide
● Multiple amino acids bonded together
● Most proteins contain a few dozen to hundreds of amino acids
Primary Structure
● Determined by the sequence of the amino acids
● 20 amino acids can be linked together in many different sequences
Secondary Structure
● Determined by weak electrical attractions
● Positively charged H attracts nearby negatively charged O
● Polypeptide chain twists
Tertiary Structure
● Long polypeptide chain twists that fold into complex, tangled shapes
Structural Breakdown of Proteins
Denaturation
● Loss of shape (i.e. uncoiling) of proteins due to heat, agitation, or acid
○ Ex. Hardening of an egg when it is cooked or stiffening of egg whites when
they are whipped.
○ Ex. In the body- Body proteins denature when exposed to stomach acid.
Protein Digestion
Mouth
● Proteins are crushed and moistened
Stomach
● Partial breakdown of protein through hydrolysis
● Hydrochloric acid uncoils (denatures) proteins
Small Intestine
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Document Summary
Contain nitrogen, carbon, hydrogen, and oxygen (n, c, h, o) Proteins are more complex than carbs or lipids because of their unique side groups. Amino acids differ in size, shape, and other characteristics due to the unique side group. Essential amino acids- the body cannot make these itself. We must get these from our diet. Nonessential amino acids- the body can make these itself. Body takes nitrogen and fragments from carbs/fat to form amino acid. Amino acids are linked together to form proteins. Most proteins contain a few dozen to hundreds of amino acids. Determined by the sequence of the amino acids. 20 amino acids can be linked together in many different sequences. Positively charged h attracts nearby negatively charged o. Long polypeptide chain twists that fold into complex, tangled shapes. Loss of shape (i. e. uncoiling) of proteins due to heat, agitation, or acid.
