Chap 6
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Draw the basic structure of an amino acid. Identify the central carbon. Identify the four groups attached to the central carbon. Which group is responsible for the amino acids specific properties?
Carbon is attached to amino group (left) , carboxyl group (right), R group (up), and hydrogen (low) the R group (side chain) is what determines the unique characteristics of a particular amino acid
What are beta and gamma forms of amino acids?
beta: beta amino acids = two carbons, beta carbon is the one bonded to the amino group gamma: gama amino acids = 3 carbons, gamma carbon is the one bonded the amino group
Why are some amino acids biological buffers? How do they maintain pH levels? What is a zwitterion?
because they contain a carboxyl and a amino group pH high : amino and carboxyl donate a proton pH low: amino group and carboxyl accept a proton zwitterion : dipolar ionic state (physiological pH)
List the 3 classes of amino acids based on their chemical properties. Classify an amino acid into one of those groups based on the chemical structure of its side chain.
hydrophobic: R group is non-polar (leucine) hydrophilic: charged or simply electronegative (R group is polar (serine))
What is an essential amino acid?
amino acid animals/us don’t synthesize in enough quantities so need to get form diet.
Define a polypeptide and state the type of bond involved in linking monomers.
polypeptide: many amino acids linked together via peptide bonds has a N terminus and a C terminus = gives polarity to polypeptide
Define a protein. Describe the difference between a polypeptide and a protein.
consists of one or more polypeptides twisted, folded, and coiled into a unique shape structure determines function
Describe some of the overall distinct shapes of proteins.
globular = compact combinations of alpha helices and beta sheets = roughly spherical fibrous: consisting of alpha helices
Describe the four levels of protein structure (primary, secondary, tertiary, quaternary). For each level, indicate the type of interactions and which parts of the protein are involved.
primary: specific and unique sequence of amino acids -through peptide bonds between the amino group and the carboxyl group of two amino acids secondary: alpha helix (coils) or beta pleated sheet (folded) -h-bonds in alpha hold helix cells in shape -h-bonds in beta hold neighbouring strands of sheet together tertiary: 3-dimensional shape of the folded protein resulting from the interaction among the r-groups -determined by primary structure - h-bonds, disulfide bridges, hydrophobic interactions (van der waals), and ionic bonds. quaternary: interaction among the polypeptide chains - h-bonds, disulfide bridges, van der waals, and ionic bonds.
Discuss the relationship between protein structure and function. Explain how sickle cell disease highlights this point.
the structure of a protein is what gives it its function. For example, the change of a single amino acid in the sequence of hemoglobin can change the rest of the structures (2nd, 3rd, 4th) and change its whole function and shape
Describe the function of molecular chaperones in cells.
when cell synthesizes polypeptides, they must fold into their correct shape or conformation = happens in chaperonins, which separate new polypeptides from the potentially disruptive chemical conditions within the cytoplasm chaperonins found in ER and cytoplasm
Define a prion and discuss how they highlight the importance of proper protein folding.
prions are misfolded proteins that have become an infectious agent prion diseases occur when the prion interacts with the normal version = denatures the normal one and keep denaturing the rest prion diseases affect the structure of the brain or neural tissue = always fatal
Define denaturation of a protein and list some environment conditions that will promote denaturation.
denaturation is the disruption and possible destruction of both the secondary and tertiary and sometimes quaternary structures uncoils it into a random shape heat, pH, alcohol, and diseases
Why do biologists want to determine the structure of proteins?
allows us to determine it’s function …
Describe the eight major functional classes of proteins. List some specific examples for each
enzyme: accelerate chemical reactions storage: provide a source of amino acids for developing embryos or developing infants ex: ovalbumin, protein that composes egg chemical messengers: hormones and neurotransmitters ex: insulin contractile proteins: function in movement ex: actin and myosin (muscle movement) defensive proteins: defensive substances within the body ex: antibody proteins in response to the proteins, antigens, found on the surface of the foreign substance transport proteins: move substances within the body or in and out of cells ex: hemoglobin receptor proteins: function to regulate the response of the cell to chemical stimuli ex: receptors that detect chemical signals released by other nerve cells structural proteins: provide support ex: collagen and elastin (fibrous)