L1 Amino acids Flashcards
What is the central dogma of Biology?
DNA makes RNA and RNA makes proteins.
How does DNA go to RNA?
DNA goes to RNA via the process of transcription.
How does RNA go to Protein?
RNA goes to protein via the process of translation.
Messenger RNA carries coded info to ribosomes during protein synthesis.
What is the basic structure of an amino acid?
Amino group, carboxylate group, hydrogen, alpha carbon and R group.
Groups covalently attached to tetrahedral alpha carbon
Describe the general structure of an amino acid.
Tetrahedral structure.
How do amino acids differ? By what group?
Amino acids differ by the R group that is attached to them. Each amino acid has a different R group.
Why are amino acids categorized as zwitterions?
They act as either an acid or base.
Describe amino acids in relation to chirality?
Amino acids have a tetrahedral alpha carbon bonded to four different chemical groups
Which amino acid doesn’t display chirality?
Glycine
R group is hydrogen
How are amino acids classified or group?
According the physiochemical properties of their R-group
What is polarity defined as?
Polarity is defined as the magnitude of the dipole induced in the presence of an external electromagnetic field
What are the four classifications of amino acids?
- Polar
- Non-polar
- Positively charged
- Negatively charged
Name the non polar amino acids. (9)
Alanine Valine Leucine Isoleucine Phenylalanine Tryptophan Glycine Methionine Proline
Name the polar uncharged amino acids. (6)
Threonine Serine Cysteine Glutamine Asparagine Tyrosine
What type of R groups do polar uncharged amino acids have?
hydroxyl
thiol
carboxyamide
Which three polar uncharged amino acids are often involved in enzymatic reactions?
Threonine
Serine
Cysteine
What type of R groups do non polar amino acids have?
Nonpolar R groups (aliphatic and aromatic with hydrophobic properties)
R group is a hydrocarbon
What are the sulfur containing amino acids?
Functions?
cysteine- disulfide bridges
methionine- first a.a. when building a protein
What are the polar charged amino acids? (5)
Arginine lysine Glutamate Aspartate Histidine
What type of R groups do polar charged amino acids have?
carboxylate
amine
What charge do amines have?
Neutral or positive
What charge do carboxylates have?
Neutral or negative
What are free amino acids?
Free amino acids have 2 or more acid/base groups and produce complex acid/base titration curves.
What is an isoelectric point?
Isoelectric point is the pH at which the total charge of the amino acid and peptide or protein is zero.
What is the isoelectric point for amino acids without ionizable R groups?
The PI is the average of the pkas
What is the isoelectric point for amino acids with ionizable R groups?
The average of the pka of the amino acids on either side of species that has net charge of 0.
What are peptide bonds? What does it involve?
Peptide bond is formed via a condensation reaction.
It is a covalent bond formed between the carboxyl end of one amino acid residue and the amino end of another amino acid residue.
Describe the direction of amino acid sequences.
Start at amino end and end at carboxylate
What are the characteristics of peptide bonds? (4)
- Partial double bond character
- Rigid and planar
- Trans configuration
- Uncharged but polar
