Amino acids - are ter building blocks of proteins.

Amino acids - They belong to an important class of organic compounds that contain both the amino (-NH2) and carboxyl (-COOH) groups.

alpha – amino acids: what do you call the 20 most important amino acids?

the alpha – carbon atom: the amino and carboxyl groups are both attached to a single carbon atom, which is called?

D-(dextrorotatory) or L-(levorotatory): Amino acids may either be?

D-serine: present in the forebrain

D-aspartate: present both in brain and periphery

Amino acids: may have positive, negative or zero net charge.

ionic character: The solubility and melting points of amino acids reflect their?

polar solvents such as water and ethanol: Amino acids are soluble in

nonpolar such as benzene, hexane, or ether: Amino acids are insoluble in?

ALIPHATIC AMINO ACIDS – possess hydrocarbon side chains arranged in chain-like structures otherwise known as the monoamino – monocarboxylic acids

ALIPHATIC AMINO ACIDS: otherwise known as monoamino – monocarboxylic acids

AROMATIC AMINO ACIDS – possess the benzene ring (C6H6) in their side chains

HYDROXYAMINO ACIDS – possess the hydroxyl group (-OH) in their side chains

ACIDIC AMINO ACIDS – possess an additional carboxyl group (-COOH)

AMIDES OF ACIDIC AMINO ACIDS – possess an amide group (-CONH2) in their side chains

BASIC AMINO ACIDS – possess an additional amino group (-NH2) in their side chains

SULFUR-CONTAINING AMINO ACIDS – possess a thiol group (-SH) in their side chains

IMINO ACIDS – they have a cyclic imino group in their structure

NON – POLAR (HYDROPHOBIC) AMINO ACIDS - They prefer to contact with one another than water.

NON – POLAR (HYDROPHOBIC) AMINO ACIDS - Generally found buried in the interior of proteins, where they can associate with one another and remain isolated from water.

POLAR (HYDROPHILIC) AMINO ACIDS: They attached to water and are often found on the surfaces of protein.

Polar, neutral amino acids: have R groups that have a high affinity for water but are not ionic.

Negatively charged amino acids: have ionized carboxyl group in their side chains. At pH 7, these amino acids have a net charge of -1

Positively charged amino acids: have a positive net charge of + 1 because their side chains contain a positive group

ESSENTIAL AMINO ACIDS – are those that cannot be synthesized by the body and are required in the diet.

NON – ESSENTIAL AMINO ACIDS – are those that can be synthesized by the body and need not be included in the

diet

Histidine: is an essential amino acid for infants but not for adults.

Cysteine and Tyrosine: are considered to be semi-essential amino acids.

Cysteine and Tyrosine: They are required by premature infants and adults who are ill.