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.
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