Amino Acids & Proteins Flashcards
How many naturally occuring amino acids are there?
20.
Amino acids are joined together in what type of chains to form proteins?
Polypeptide chains.
How long are the polypeptide chains that form proteins?
From a few hundred to over a thousand amino acids long.
Every amino acid has the same structure, except for…?
The R group.
What part of a protein is involved in reactions with a substrate?
The R group.
If the R group is changed, what effect can this have on a protein?
It can destroy the protein.
What FOUR atoms or groups are attached to the central carbon atom of an amino acid?
- A hydrogen atom.
- A carboxyl group (COOH).
- An amino group (NH2).
- An R group.
Of the carboxyl group and amino group in an amino acid, which is an organic acid and which is an organic base?
Organic acid - carboxyl group.
Organic base - amino group.
What are the three groups of amino acids?
- Non-polar side chains and hydrophobic.
- Polar with uncharged side chains.
- Polar with charged (acidic or basic) side chains.
Which group of amino acids is this?:
Alanine, valine, leucine, isoleucine, glycine, proline, methionine, phenylalanine and tryptophan.
Non-polar side chains and hydrophobic.
Which two amino acids are aromatics, with ring structures that can be involved in fluorescence?
Phenylalanine and tryptophan.
What type of bond joins individual amino acids to form proteins?
Peptide bonds.
Methionine contains sulphur. This means that it can be involved in what sort of bonding?
Metal bonding.
Which group do these amino acids belong to?:
Serine, threonine, cysteine, tyrosine, asparagnine, glutamine and histidine.
Polar with uncharged side chains.
Which group do these four amino acids belong to?:
Aspartate, glutamate, lysine, and arginine.
Polar side chains (charged, either acidic or basic).
Name the nine essential amino acids.
Phenylalanine, tryptophan, isoleucine, valine, methionine, lysine, threonine, leucine and histidine.
Why are the nine essential amino acids so-called?
They are essential for physiological functions but cannot be synthesised by humans.
Kwashiorkor is a condition caused by a diet adequate in ………………. but lacking ……………… .
Carbohydrates, amino acids.
All amino acids have chiral centres and are optically active, but are they all R-enantionmers or L-enantiomers?
Amino acids are all L-enantiomers.
Are only R-enantiomers or L-enantionmers of amino acids used to make proteins?
Only L-enantiomers of amino acids are used to make proteins.
Give an example of why chirality can be important.
Chirality is very important in drug design. For example, the R-enantiomer of prozac is effective, but the L-enantiomer is dangerous.
Amino acids are important physiological buffers. What is the function of a buffer?
Buffers are solutions that resist changes in pH upon addition of an acid or a base, keeping enzymatic reactions at a constant pH.
What do buffers take up or release in order to maintain enzymatic reactions at a constant pH?
H+ ions.
If a solution has a high pH, does it have a lot of H+ ions or very few pH ions in solution?
It has very few H+ ions in solution so it is very basic.