Protein Structure and Function — Flashcards

Flashcard 41: The acidic amino acids _____ and glutamate are negatively charged at physiological pH.

Answer: aspartate

Extra: Aspartate and glutamate have side chain carboxylic acid groups ($pK_a \approx 4$). At physiological pH (~7.4), which is above their $pK_a$, these groups are deprotonated ($COO^-$) and carry a negative charge.

Flashcard 42: Prion proteins have two isoforms: _____ that causes disease and PrPc, the normal prion protein, found in human cells

Answer: PrPSc

Flashcard 43: In the Golgi apparatus, _____ is added to proteins for trafficking to lysosomes

Answer: mannose-6-phosphate

Flashcard 44: Prion disease arises with conversion to a _____ conformation, known as PrPsc

Answer: β-pleated

Flashcard 45: There are four superfamilies of proteins namely _____, dynein, myosin, dynamins referred to as molecular motors.

Answer: kinesin

Flashcard 46: Sickle cell anemia occurs due to a point mutation that substitutes _____ (hydrophilic) with valine (hydrophobic)

Answer: glutamic acid

Flashcard 47: While being packed into secretory granules, proteases cleave the _____ of proinsulin, yielding insulin

Answer: connecting peptide

Flashcard 48: One normal type of hemoglobin is _____ which is composed of two alpha and two beta chains

Answer: HbA

Flashcard 49: Compounds that have the same chemical formula but different structures are called _____ of each other

Answer: isomers

Flashcard 50: Which oxygen-binding protein exhibits a **hyperbolic** dissociation curve?

Answer: Myoglobin

Extra: Myoglobin exhibits a **hyperbolic** oxygen dissociation curve, reflecting its high affinity for oxygen and lack of cooperativity. In contrast, hemoglobin exhibits a **sigmoidal** curve due to positive cooperativity between its four subunits.