biologically important molecules Flashcards
Peptide bond formed between the
Carboxyl group of one amino acid and the amino group of another
hydrolysis of a protein by another protein is called _____ or ______ ______
proteolysis, proteolytic cleavage
the protein that hydrolyzes another protein is called
protease, or proteolytic enzyme
disulfide bond
the thiol (SH group) of one cysteine can react with the thiol of another cysteine to form a disulfide bond.
disulfide bond plays an important role in stabilizing _____ _____
tertiary protein structure
describe secondary structure of a protein
initial folding of polypeptide chain into shapes stabilized by hydrogen bonds between NH and CO groups
Alpha and beta sheets
describe tertiary structure of a protein
interactions between AA residues located more distantly from each other on a polypeptide chain (ex: van Der Waals between 2 AAs far apart from one another)
quaternary structure of a protein
interactions between polypeptide subunits. forces that stabilize are the same as those that stabilize tertiary structure
Carbohydrates can be broken down into ____ by the process ____ which is called burning or combustion
CO2, oxidation
the bond between 2 sugars is called
glycosidic linkage
glycosidic bonds are what type of bond
covalent
glycosidic bonds are formed by a _____ reaction
dehydration
starch is the same as glycogen (with exception of minor differences in branching) T to F
true
what are the 3 physiological roles of lipids
1) in adipose cells, triacylglyerols store energy
2) in cellular membranes, phospholipids constitute a barrier between intracellular and extracellular environments
3) cholesterol is a special lipid that serves as the building block for the hydrophobic steroid hormones
Micelle
a circular formation that lipids form in water. Hydrophobic tails on the inside and hydrophilic heads on the outside
fats are more efficient energy storage than carbohydrates
T or F?
true
why are fats more efficient energy storage
1) packaging: their hydrophobicity allows for tighter packing than carbs
2) energy content: fat molecules store much more energy than carbs
unsaturated fats increase or decrease membrane fluidity
increase, because it disrupts orderly packing of the lipid tails.
what are the 3 structural determinants that affect membrane fluidity
degree of saturation, amount of cholesterol, and tail length
how does cholesterol affect membrane fluidity
at low temps, cholesterol increases fluidity and at high temps it decreases fluidity
steroid hormones are made from _____
cholesterol
why is ATP known as a high energy structure at neural pH
it exhibits a large decrease in free energy when it undergoes hydrolytic reactions
racemic mixtures are optically ____
inactive because they consist of left and right enantiomers which reflect light in opposite ways from one another to cancel out.
which amino acids are basic
histidine, arginine, lysine
