BCH 100 Lecture #2 NLM

What two functional groups define an α-amino acid?

An amino group (-NH₃⁺) and a carboxylic acid group -(COO^-) attached to the same central (α) carbon.

What does “α” mean in α-amino acid?

the amino group is on carbon #2 - one carbon away from the carboxyl carbon

*What four things are bonded to the α-carbon in a standard amino acid?

*An amino group, a carboxyl group, a hydrogen atom, and a variable side chain R.

What is a zwitterion?

A single molecule that has both a positive and a negative charge but is overall electrically neutral

At physiological pH (~7), what is the charge on the amino group?

the amino group is protonated and positively charged (−NH3+)

At physiological pH (~7), what is the charge on the carboxyl group?

The carboxyl group is deprotonated and negatively charged (−COO−)

At pH 7, which is the dominant form for the molecule (the form you should assume on an exam

Zwitterionic

Describe how many amino acids are used in proteins?

There are 20 basic amino acids in proteins (coded in RNA)

Explain what the slide says about amino acids found in nature

There are many, many more in nature.

Describe what the α-carbon is and list the four groups attached to it

• carboxyl group

• amino group

• hydrogen atom

• R group

What does the lecture say about chirality in amino acids

The α carbon is the chiral center, and one amino acid is not chiral

Explain what configuration naturally occurring amino acids have.

They are in the L-configuration

State the average molecular weight of an animo acid.

110 g/mol

Which configuration does this isomer have?

L configuration

Which configuration does this isomer have?

D configuration

Explain what a Fischer projection is.

a two-dimensional way to depict molecule with chiral centers

Describe what the horizontal lines represent in the Fischer projection. (think “on the horizon”)

bonds projecting forward

Describe what the horizontal lines represent in the Fischer projection.

bonds projecting backward

Describe what the two diagrams of alanine on the slide are showing.

One diagram shows a 3D stereochemical rendering of alanine, and the other shows its Fischer projection

What molecule is chirality determined from (not imp)

Glyceralydehyde

What is the relationship between D-glyceraldehyde and L-glyceraldehyde

They are enantiomers

State the natural configuration of carbohydrates

D-configuration

State the natural configuration of amino acids

L-configuration

What two forms of alanine are shown here?

L and D configuration

Which amino acid is the only one that is not chiral?

Glycine

What feature make the other 19 amino acids chiral?

They have a stereocenter at the Cα (alpha carbon)

List the five categories of naturally occurring amino acids

• nonpolar aliphatic

• aromatic

• polar uncharged

• positively charged

• negatively charged

How many nonpolar, aliphatic amino acids are there

7

How many aromatic amino acids are there?

3

How many p5lar, uncharged amino acids are there?

5

How many positively charged amino acids are there?

3

How many negatively charged amino acids are there

2

Name the amino acids in the nonpolar, aliphatic group

Valine

Alanine

Glycine

Methionine (sep)

Proline (sep)

Isoleucine

Leucine

What is the mnemonic for nonpolar aliphatic amino acids?

VAGMPIL

List the aromatic amino acids

• Phenylalanine

• Tyrosine

• Tryptophan

What is the mnemonic for aromatic amino acids

Romantic = FYW = find your wife

Name the polar, uncharged amino acids

Serine, Cysteine, Threonine, Asparagine, Glutamine

think uncharge = smthn wrong with cstm/system, she thinks shes QN = queen.

List out the positively charged amino acids

• Histidine (H)

• Arginine (R)

• Lysine (K)

think I am positive that this class “HRKs” me

List out the negatively charged amino acids

• Aspartate (D)

• Glutamate (E)

think “Luca tells me “don’t eat” = negative vibes”

What type of Amino acid is proline?

Nonpolar, aliphatic

What type of Amino acid is Glycine?

Nonpolar, aliphatic

What type of amino acid is Alanine?

Nonpolar, aliphatic

What type of amino acid is Alanine?

Nonpolar, aliphatic

What type of amino acid is Valine?

Nonpolar, aliphatic

What type of amino acid is Leucine?

Nonpolar, aliphatic

What type of amino acid is Methionine?

Nonpolar, aliphatic

What type of amino acid is Isoleucine?

Nonpolar, aliphatic

What type of amino acid is Serine?

Polar, uncharged

What type of amino acid is Threonine?

Polar, uncharged

What type of amino acid is Cysteine?

Polar, uncharged

What type of amino acid is Asparagine?

Polar, uncharged

What type of amino acid is Glutamine?

Polar, uncharged

What type of amino acid is lysine?

Basic (polar + positively charged)

What type of amino acid is Arginine?

Basic (polar + positively charged)

What type of amino acid is Histidine?

Basic (polar + positively charged)

What type of amino acid is Aspartate?

Acidic (polar + negatively charged)

What type of amino acid is Glutamate?

Acidic (polar + negatively charged)

What type of amino acid is Phenylalanine?

Nonpolar, aromatic

What type of amino acid is Tryptophan?

Nonpolar, aromatic

What type of amino acid is Tyrosine?

Nonpolar, aromatic AND polar, uncharged

What is the one letter abbreviation for Glycine

G

What is the one letter abbreviation for Alanine

A

What is the one letter abbreviation for Valine

V

What is the one letter abbreviation for Leucine

L

What is the one letter abbreviation for Isoleucine

I

What is the one letter abbreviation for Proline

P

What is the one letter abbreviation for Serine

S

What is the one letter abbreviation for Threonine

T

What is the one letter abbreviation for Cysteine

C

What is the one letter abbreviation for Methionine

M

What is the one letter abbreviation for Tyrosine

Y

What is the one letter abbreviation for Phenylalanine

F

What is the one letter abbreviation for Trypotophan?

W

What is the one letter abbreviation for Lysine?

K

What is the one letter abbreviation for Arginine?

R

What is the one letter abbreviation for Histidine?

H

What is the one letter abbreviation for Aspartate?

D

What is the one letter abbreviation for Glutamate?

E

What is the one letter abbreviation for Asparagine?

N

What is the one letter abbreviation for Glutamine?

Q

Draw a proline

Draw an Alanine

Draw a Glycine

Draw a valine

Draw a Leucine

Draw an isoleucine

Draw a phenylalanine

Draw a tyrosine

Draw a tryptophan

Tryptophan

Draw a serine

Draw a threonine

Draw a cysteine

Draw a methionine

Draw an asparagine

Draw a glutamine

What is the 3 letter abbreviation for Glycine?

Gly

What is the 3 letter abbreviation for Alanine?

Ala

What is the 3 letter abbreviation for Valine?

Val

What is the 3 letter abbreviation for Leucine?

Leu

What is the 3 letter abbreviation for Isoleucine?

Ile