Topics for TodayTopics for Today

Natural Curls?Natural Curls?

Topics for TodayTopics for Today

How do proteins get their shape?How do proteins get their shape?

Chapter 12Chapter 12

12.3 Cracking the chemical code 12.3 Cracking the chemical code

(p. 539 on proteins only)(p. 539 on proteins only)

Chapter 5Chapter 5

5.6 The role of hydrogen bonding 5.6 The role of hydrogen bonding   

Topics for FridayTopics for Friday

Closing RemarksClosing Remarks Quiz #11 (Don’t be late!)Quiz #11 (Don’t be late!)

Topics for FridayTopics for Friday

If you are > 5 minutes late… If you are > 5 minutes late…

No quiz for you!

Announcements!Announcements!

HW 5 due tomorrow

Psst… easy 10 points!

Announcements!Announcements!

Final Exam

Friday, May 18 at 12:25 pm in 113

Psychology!

NOT here!

Announcements!Announcements!

Final Exam

Don’t forget about the

essay!

Ever wondered how we measure

metals in atmospheric PM?

NO!

Still, you’re all invited to a special

talk on Friday!!!

Dr. Majestic Talks About His Dr. Majestic Talks About His Research!Research!

12:05 pm THIS Friday; 102

Water Science and Engr Lab!!

Topics for TodayTopics for Today

How do proteins get their shape?How do proteins get their shape?

ReviewReviewWhat is a protein??

A polymer of amino acids!!

…amide-ala-amide-gly-amide-leu-amide-ile-amide-glu-amide-arg-amide-asp-amide-ala…

Keratin, …Keratin, …

A protein that contains a A protein that contains a high content of cysteine.high content of cysteine.

Glycine (gly) Glycine (gly) Alanine (Ala) Valine (Val) Alanine (Ala) Valine (Val)

Leucine (Leu) Leucine (Leu) Isoleucine (Ile) Proline (Pro) Isoleucine (Ile) Proline (Pro)

Tryptophan (Trp) Tryptophan (Trp) Phenylalanine (Phe)Phenylalanine (Phe)

Serine (Ser) Serine (Ser) Threonine (Thr) Tyrosine Threonine (Thr) Tyrosine (Tyr)(Tyr)

Aspartic acid (Asp) Glutamic acid (Glu)Aspartic acid (Asp) Glutamic acid (Glu)

Asparagine (Asn) Glutamine (Gln)Asparagine (Asn) Glutamine (Gln)

Lysine (Lys) Lysine (Lys) Arginine (Arg) Arginine (Arg) Histidine(His)Histidine(His)

Cysteine (Cys) Methionine (Met)Cysteine (Cys) Methionine (Met)

CysteineCysteine

R = –CHR = –CH22––SS–H–H

MethionineMethionine

R = –CHR = –CH22–CH–CH22––SS–CH–CH33

Contains sulfur!!

Keratin, …Keratin, …

Where is keratin found?Where is keratin found? Hair!

HairHair

~90% protein (keratin)~90% protein (keratin)

HairHair

Also contains melaninAlso contains melanin

Skin pigment

KeratinKeratin

The chains of amino acids form a coilThe chains of amino acids form a coil

Why a coil?

The side chains give

the protein its shape!

KeratinKeratin

Nonpolar R groups on the outside of Nonpolar R groups on the outside of the coilthe coil

R

R

R

R

R

Water repelling (hydrophobic)

KeratinKeratin

R

R

R

R

R

What about the R groups inside?

KeratinKeratin

R

R

R

R

R

What about the R groups inside?

These help give hair its

structure

R groups that …R groups that …

(1) contain –SH and form disulfide (1) contain –SH and form disulfide bondsbonds

(2) are ionic and attract each other(2) are ionic and attract each other

(3) hydrogen bond to each other(3) hydrogen bond to each other

What gives hair its structure?What gives hair its structure?

R groups that …R groups that …

(1) contain –SH and form disulfide (1) contain –SH and form disulfide bondsbonds

(2) are ionic and attract each other(2) are ionic and attract each other

(3) hydrogen bond to each other(3) hydrogen bond to each other

What gives hair its structure?What gives hair its structure?

1) It’s bent1) It’s bent 2) 2) It’s polarIt’s polar 3) Polar things dissolved in water3) Polar things dissolved in water 4) Formed from acid-base reactions4) Formed from acid-base reactions 5) Formed from making Nylon and PET5) Formed from making Nylon and PET 6) Anywhere from ½ to ¾ of our body6) Anywhere from ½ to ¾ of our body 7) Forms ions in small amounts7) Forms ions in small amounts

OHH

.. ..What do we know about

water?

ReviewReview

What else do we know

about water?

Fig.05.10Hydrogen

bonds!

What are H-bonds?

Fig.05.10

δ-

δ+ δ+

δ-

δ+ δ+

δ-

δ+ δ+

δ-

δ+ δ+

δ-

δ+ δ+

Fig.05.10

Hydrogen bondsHydrogen bonds

Not really bonds, at all!Not really bonds, at all!

Just a strong attraction!

Need a dipole!!

Can non-water molecules H-

bond?

Fig.05.10

N

H

..

δ-

δ+ δ+

δ-

δ+ δ+

δ-

δ+ δ+

δ-

δ+ δ+

δ-

δ+ δ+δ+

Hydrogen bonds?

Fig.05.10

Hydrogen bonds…

N

H

..

δ-

δ+ δ+

δ-

δ+ δ+

δ-

δ+ δ+

δ-

δ+ δ+

δ-

δ+ δ+δ+

H bondsH bonds

Occur when H is attached to an Occur when H is attached to an electronegative atom such as O, electronegative atom such as O, N or F.N or F.

page 231

Amino AcidsAmino AcidsGlycine (gly) Glycine (gly) Alanine (Ala) Valine (Val)Alanine (Ala) Valine (Val)Leucine (Leu) Leucine (Leu) Isoleucine (Ile) Proline (Pro)Isoleucine (Ile) Proline (Pro)Tryptophan (Trp) Tryptophan (Trp) Phenylalanine (Phe)Phenylalanine (Phe)Serine (Ser) Serine (Ser) Threonine (Thr) Tyrosine Threonine (Thr) Tyrosine

(Tyr)(Tyr)Aspartic acid (Asp) Glutamic acid (Glu)Aspartic acid (Asp) Glutamic acid (Glu)Asparagine (Asn) Glutamine (Gln)Asparagine (Asn) Glutamine (Gln)Lysine (Lys) Lysine (Lys) Arginine (Arg) Arginine (Arg)

Histidine(His)Histidine(His)Cysteine (Cys) Methionine (Met)Cysteine (Cys) Methionine (Met)

Which amino acids will H-

bond?

Hydrogen bonds

NH

– O

R groups that …R groups that …

(1) contain –SH and form disulfide (1) contain –SH and form disulfide bondsbonds

(2) are ionic and attract each other(2) are ionic and attract each other

(3) hydrogen bond to each other(3) hydrogen bond to each other

What gives hair its structure?What gives hair its structure?

H O H O

| // | //

HH22N — C — C N — C — C

| \ | \

CHCH22 OH OH

||

SHSH

CysteineCysteine

R R = = CHCH22 – – SHSH

– SH HS –

– SH HS –

– SH HS –

– SH HS –

Amide Backbone

Disulfide bondsDisulfide bonds

– S – S –

– S – S –

– S – S –

– S – S –

Not easily broken!!

Disulfide bondsDisulfide bonds

– S – S –

– S – S –

– S – S –

– S – S –

A “permanent”

– SH HS –

– SH HS –

– SH HS –

– SH HS –

Reset the strands

Break the disulfide bonds!

– S – S –

– S – S –

– S – S –

– S – S

–

SummarySummary

A permanentA permanent– BreakBreak the S the S – – SS bonds bonds– Wrap hair around a curlerWrap hair around a curler– Reform Reform SS – – SS bonds to bonds to

permanently change the shapepermanently change the shape

R groups that …R groups that …

(1) contain –SH and form disulfide (1) contain –SH and form disulfide bondsbonds

(2) are ionic and attract each (2) are ionic and attract each otherother

(3) hydrogen bond to each other(3) hydrogen bond to each other

What gives hair its structure?What gives hair its structure?

(3) Acidic(3) Acidic

R group contains carboxylic acidR group contains carboxylic acid REVIEW

Aspartic acidAspartic acid REVIEW

Aspartic acidAspartic acid N

EW

COOH can ionize to COO—

and H+

(4) Basic(4) Basic

R contains an amine groupR contains an amine group REVIEW

LysineLysine REVIEW

LysineLysine N

EW

NH2 can gain H+ to become NH3

+

Ionic bondIonic bond

The acidic groups, –COOH, can lose The acidic groups, –COOH, can lose a Ha H+ + and become –COOand become –COO––

The basic groups, –NHThe basic groups, –NH22, , can gain a can gain a HH++ and become –NH and become –NH33

++

+ and – attract!

ProteinsProteins

Polymers of amino acids

But how are they made?

Protein synthesis video!!

Hippies reenact protein synthesis - A Protein Primer

The JabberwockyThe Jabberwocky

The JabberwockyThe JabberwockyTwas brillig, and the slithy toves

  Did gyre and gimble in the wabe:All mimsy were the borogoves,  And the mome raths outgrabe.

"Beware the Jabberwock, my son!  The jaws that bite, the claws that catch!

Beware the Jubjub bird, and shun  The frumious Bandersnatch!"

He took his vorpal sword in hand:  Long time the manxome foe he sought --

So rested he by the Tumtum tree,  And stood awhile in thought.

And, as in uffish thought he stood,  The Jabberwock, with eyes of flame,

Came whiffling through the tulgey wood,  And burbled as it came!

One, two! One, two! And through and through

  The vorpal blade went snicker-snack!

He left it dead, and with its head  He went galumphing back.

"And, has thou slain the Jabberwock?

  Come to my arms, my beamish boy!

O frabjous day! Callooh! Callay!'  He chortled in his joy.

`Twas brillig, and the slithy toves  Did gyre and gimble in the wabe;

All mimsy were the borogoves,  And the mome raths outgrabe.