Proteins Flashcards
Proteins
Polymers w/amino acid monomers
Protein Functions
- structural roles (eg. keratin and collagen)
- enzymes that speed up chemical reactions
- transport substances within the body
- transport substances across cell membranes
Monomer of: Proteins
Amino Acid
Functional groups of: Protein
- amino group (H2N is nitrogen group)
- acid group (COOH can disassociate making H+, thus more acid)
- R-group (remainder group; 20 diff kinds)
Essential Amino Acids
Must be consumed in our diet since the body cannot produce it (=essential!)
Non-essential Amino Acids
Can be made in the body and therefore not essential to consume them in our diet.
Structure of Amino Acid
H H
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H-N-C-C=O
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R OH
- Amino group H2N
- Acid group COOH
- R-group
-all around central C
Dipeptide
Amino acid + amino acid = 1 dipeptide + 1 H2O (peptide bond formed by dehydration reaction)
Polymer of proteins
Polypeptide
- a single chain of amino acids w/peptide bonds (dehydration reaction)
- N-C-C-N-C-C-N-C-C
Peptide Bonds
- joins 2 amino acids covalently
- Acid group COOH reacts w/amino group of another H2N in a dehydration reaction
- links C to N creating uneven charge distribution (allowing H-bonds = shapes)
Levels of Protein Organization
- 4 structures overall
- can be complete @ 3rd or 4th
- shape of protein is very important to its function
- cannot function properly if the shape has been tampered with
Primary Structure
Polypeptide chain in linear sequence. They are differentiated from one another by their specific sequence of R-groups in the chain.
-peptide bonds
Secondary Structure
Polypeptide chain in primary changed to Alpha (helix) or Beta (pleated sheet)
-H-bonds
-peptide + H-bonds
Tertiary Structure
Single Polypeptide chain 3D in shape w/both Alpha and Beta structures in it. Can be complete at this stage.
- disulfide bonds (to condense & twist into 3D shape)
(eg. Enzymes)
-peptide + H-bonds + disulfide
Quaternary Structure
2+ tertiary polypeptide chains that have their own structure and create another when bonded together.
(eg. Hemoglobin)
How do Primary structures differ from one another?
By the sequencing of amino acid R-groups (up to 20 diff types not including combinations)
Denaturation
Occurs when a protein is exposed to extreme heat or pH so that it undergoes an irreversible change in shape.
Once its original shape is lost it can no longer perform its usual function.
Eg. heat - egg whites coagulating
Eg. pH - milk curdling
