lecture six Flashcards
why are proteins able to be so structurally and functionally diverse
there are twenty different amino acids and their sequence determines the protein’s structure and resulting function - essentially infinite combinations
What are the components of each amino acid? How do we group amino acids based on their chemical properties?
carboxyl group ( Carbon, hydrogen, hydroxide) , amino group (nitrogen and two hydrogens) , and R group.
Grouped by non polar side chains aka hydrophobic, polar side chains (hydrophilic), and electrically charged side chains (hydrophilic) (then split further into basic (+) and acidic (-))
How are polypeptide chains formed from individual Amino Acids?
Dehydration reaction, peptide bond (removes OH in carboxyl group and H from amino group - creates H2O molecule)
What does the Primary Structure tell us about the protein
peptide bonds are ______ attractions between ______
list of amino acids that make up a protein
peptide bonds - covalent attractions between N in the amino group of 1 amino acid and the C in the carboxyl functional group
What are the two types of Secondary Structures?
What is unique about the interactions that form these structures? -
where do H bonds form
Alpha helices and beta pleated sheets
formed by H bonds between the polypeptide backbone.
Weak alone but since repeated many times, keeps the shape of the protein
- amino acid 1 will be H bonded to amino acid 5 - this is what causes the helical nature: H bonds are between N in amino group and O in carbonyl
Are Amino Acid side chains involved in secondary structure
no
Tertiary Structure
What types of interactions are found in Tertiary Structures?
-H-bonding
interactions between R groups; ionic interactions, LDFs, and covalent bonds-including disulfide bridges (two S’s from sulfhydryl groups bond in cysteine amino acids)
. Quaternary Structure
What is unique about Quaternary Structure, is it found in all proteins
No, some proteins only, quaternary structure requires multiple polypeptide subunits to come together.
What type of interactions can stabilize Quaternary Structure
Noncovalents bonds -Ionic, H Bonding and LDF
What determines a protein’s final structure
Sequence of amino acids
Alpha Helices are common transmembrane (membrane-spanning) structures. How does that secondary structure allow the polypeptide chain to pass through the hydrophobic membrane region even with all the electron negative Oxygen and Nitrogen atoms in the polypeptide backbone?
The hydrophobic side chains make contact with the hydrophobic tails of the phospholipids; and the hydrophilic parts of the polypeptide backbone for H bonds with each other along the inside of the helix. Any polar R groups face inward.
able to describe how a single amino acid change from Glutamic Acid to Valine can lead to the Sickle Cell Trait.
in normal hemoglobin, the proteins that make up a red blood cell do not associate with one another, and each carries oxygen no problem. But when glutamic acid is changed to valine, it causes the shape of the beta subunit to change slightly (giving it a little divot) that causes them to attach to the other proteins, clumping them into a fiber and reducing the capacity to carry oxygen
β-Hemoglobin binds a ligand, Oxygen, through interactions of its amino acids and the heme ring, what is special about a fetus’ unique version of hemoglobin, ϒ-Hemoglobin?
-beta subunits are replaced by gamma subunits in fetal hemoglobin, and this creates a higher affinity (attraction) for oxygen. Wins “tug of war” and gets oxygen across placental membrane
