CHMA11H3 Lecture Notes - Lecture 38: Protein Structure, Peptide, Cell Nucleus

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CHMA11 Lecture 35: Protein structure and Intro to Nucleic Acids
- There are 4 levels of protein structure
o Primary Structure: sequence of amino acids in a protein
A simple list of all the amino acids in the protein linked by peptide bonds
Identifies the N and C terminals of proteins
o Secondary Structure: regular periodic patterns in the amino acid chain
Stabilized by hydrogen bonds between close by amino acids on
neighboring amino acid chains
Two key distinct structures
Alpha Helix: twisted polypeptide chain
o Hydrogen bonds from lower levels twist upward to form a
twist helix shape
Beta Sheet: polypeptide chain that makes a U turn
o Involves hydrogen bonds between 2 parallel amino acid
chains
Overall hydrogen bonds play a major role in stabilizing the
secondary structure elements
o Tertiary Structure: interactions within proteins that give it its shape
Refers to the overall structure of the entire polypeptide chain
Determined by interactions between the R groups of the amino acids and
their surroundings
Causes the proteins to fold in certain unique ways
Key structures
Disulfide Link: link between two sulfur molecules
Salt Bridge: form bridge between acidic and basic site groups in
amino acids
Proteins with one single polypeptide chain will end at the tertiary
structure
o Quaternary Structure: structural relationship between two or more polypeptide
chains within a protein
Essentially just a combination of two or more polypeptide chains within a
proteins
- Nucleic Acids: contains the genetic information needed to make proteins
o Third form of macromolecule
o Central Dogma: outlines the flow of genetic information
Claims that genetic information flows from DNA into RNA via
transcription and then RNA to protein via translation
DNA sequences therefore are codes for the amino acid sequences of
proteins
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