B1.2 ProteinsIB Biology SL: Flashcards

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What four things are bonded to the alpha carbon of an amino acid?

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What four things are bonded to the alpha carbon of an amino acid?: An amine group, a carboxyl group, a hydrogen atom and an R-group.
Which part of an amino acid differs between amino acids?: The R-group.
Word equation for forming a dipeptide?: Amino acid + amino acid → dipeptide + water.
Which groups react to form a peptide bond?: The carboxyl group of one amino acid and the amine group of the other.
How many water molecules are released making a chain of n amino acids?: n − 1 (one per peptide bond).
What is an essential amino acid?: One that cannot be synthesized in the body and must be obtained from food.
What is a non-essential amino acid?: One that can be made in the body from other amino acids.
Why do vegans need to plan their protein intake?: Plant proteins may be low in some essential amino acids, so a range of plant proteins must be combined.
How many amino acids are coded for in the genetic code?
Why is there an almost infinite variety of polypeptides?: 20 amino acids, in any order, in chains of any length: 20ⁿ possible sequences.
Give two examples of polypeptides.: Insulin (hormone, 51 amino acids); titin (muscle elasticity); oxytocin (hormone, 9 amino acids).
What is denaturation?: A change in the three-dimensional shape of a protein caused by heat or pH, usually permanent, so it loses its function.
How does high temperature denature a protein?: Increased vibration breaks the bonds holding the three-dimensional shape.
How does pH denature a protein?: It changes the charges on amino acids, disrupting the bonds holding the shape.