IPS1- Classification of Amino acid Based on Structure

300 amino acids

Over _____ amino acids exist in nature

20

Over 300 amino acids exist in nature, but proteins are made mainly from ____special ones called L-α-amino acids

L-α-amino acids

Over 300 amino acids exist in nature, but proteins are made mainly from 20 special ones called_____

True

[Amino Acid]

[T/F] 

Out of these 20 amino acids ,

• 10 are essential (we must get them from food)

• 10 are nonessential (our bodies can make them).

7 types

Amino acids are grouped into ____ types based on their structure

3-letter code and a 1-letter code

These amino acids are grouped into 7 types based on their structure. Each one has a _____ and ____ to represent it. 

Selenocysteine

The 21st protein L-α-amino acid

Selenocysteine

____- is a special amino acid found in many living things

Selenocysteine

It’s like cysteine, but it has selenium instead of sulfur

Selenocysteine

_____-

• Is added directly to proteins during translation (when RNA is turned into protein), not after the protein is made.

• Is only in translation not in transcription

Selenocysteine

Unlike the other 20 amino acids, it doesn't use a regular 3-letter codon in the genetic code.

Amino acids with nonpolar side chains

[CLASSIFICATION OF AMINO ACID ACCORDING TO SIDE CHAIN]

These amino acids don’t give or take protons and don’t form hydrogen or ionic bonds

hydrophobic (don’t mix with water).

[CLASSIFICATION OF AMINO ACID ACCORDING TO SIDE CHAIN]

Amino acids with nonpolar side chains  are like oil or fat, so they are____ [hydrophillic /hydrophobic]

• Glycine

• Alanine

• Valine

• Leucine

• Isoleucine

• Methionine

• Phenylalanine

• Tryptophan

• Proline 

Examples of Amino acids with nonpolar side chains [9]

• Phenylalanine

• Tryptophan

• Proline 

[CLASSIFICATION OF AMINO ACID ACCORDING TO SIDE CHAIN]

Most Amino acids with nonpolar side chains  are ALIPATHIC HYDROCARBON  except ___ [3] which are CLOSED RING HC STRUCTURE 

Amino acids with uncharged POLAR side groups

[CLASSIFICATION OF AMINO ACID ACCORDING TO SIDE CHAIN]

These amino acids are having zero net charge at neutral pH.

• Serine

• Threonine

• Cysteine

• Aspargine

• Glutamine

Example of Amino acids with uncharged POLAR side groups [5]

True

[CLASSIFICATION OF AMINO ACID ACCORDING TO SIDE CHAIN]

[T/F]

Amino acids with uncharged POLAR side groups

• In the case of Cysteine and Tyrosine , they can lose proton at alkaline pH.

Amino acids with acidic side chains

[CLASSIFICATION OF AMINO ACID ACCORDING TO SIDE CHAIN]

____-

• These amino acids are proton donors

• They are fully ionized in neutral pH forming a negatively charged carboxylate group (-COO- )

• Aspartic acid

• Glutamic acid 

Example of Amino acids with acidic side chains [2] 

UNDERSTAND

Ionization of aspartic and glutamic acid

• The acid group (shown in the green box) loses a proton, which is typical acid behavior. 

UNDERSTAND

This turns it into a carboxylate group (COO⁻), 

Amino acids with basic side chains

[CLASSIFICATION OF AMINO ACID ACCORDING TO SIDE CHAIN]

These amino acids accept protons, based on the Bronsted-Lowry theory.

• Lysine

• Arginine

• Histidine

Example of Amino acids with basic side chains [3]

True 

[T/F]

Lysine (Lys) and Arginine (Arg) are fully charged and positive. 

Histidine (His)

_____- is a weak base. By itself, it’s not charged, but in proteins, its side chain can be positive or neutral.

• Arginine

• Asparagine

• Aspartic acid

• Cysteine

• Glutamic acid

• Glutamine

• Glycine

• Histidine

• Lysine

• Serine

• Threonine

🧬 Hydrophilic Amino Acids [11]

• Alanine

• Isoleucine

• Leucine

• Methionine

• Phenylalanine

• Proline

• Tryptophan

• Tyrosine

• Valine

💧 Hydrophobic Amino Acids [9]

R-groups (side chains)

The _____of amino acids help enzymes do their jobs.

imidazole ring

The______ ring in histidine can give or take protons at normal body pH. This makes it important for enzyme reactions and for balancing H⁺ ions in red blood cells.

• alcohol groups

• nucleophiles

The ____groups in serine and threonine, and the -SH group in cysteine, let these amino acids act as____ during enzyme reactions

nucleophiles

____- attack other molecules during enzyme reactions

• –SH group

• disulfide bonds

The______ groups in cysteine can form _____ with another cysteine, helping shape and stabilize proteins

–OH groups

The ___ groups in serine, tyrosine, and threonine help control enzyme activity.

• 300 natural amino acids

• 20

There are over _____ natural amino acids, but only____make up proteins.

True

[T/F]

• Humans and animals can’t make 10 of these 20 amino acids in enough amounts for growth and health.

• essential

• non-essential 

Amino acids are called : 

• [essential / non-essential] ______- if we must get them from food

• [essential / non-essential] _____ - if our body can make them 

True

[T/F]

• We can’t make essential amino acids because our DNA doesn’t have the instructions for them.

Aspartic acid

Amide of Asparagine (Asn)

Glutamic acid

Amide of Glutamine