Download Proteins & Nucleic Acids - St. Mary Catholic Secondary School

Proteins & Nucleic Acids
Also Known As…
The Workers & Directors
Proteins
Also Known As…
The “Rock Star” Worker Molecules
Protein – Basic Info
Proteins are the “working” molecules of the body. They
can act as enzymes, aiding in chemical reactions, or be
structural components such as fingernails.
 Proteins have a very specific 3-D shape which relates
directly with their function – if this shape is not exact in
every way, the protein may not function at all.
 On top of this, if the conditions in which the proteins
must function are not just right – the protein may function
at a lower capacity or not at all – even if it had the right
shape to start.
 Think of proteins as the spoiled rock stars of the body –
if they are not feeling right or the stage or dressing room
they have to perform in is a little off – the show may be
cancelled altogether.

Protein Building Blocks
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The monomer for the proteins is the amino acid.
There are 20 different amino acids. They have the same
“body” with a different “head”.
The “body” of an amino acid, that is common to all 20 of
them, has the following parts:


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
An alpha (α)carbon – the central carbon that holds it all
together. There is always a hydrogen bonded to this alpha
carbon.
An amino group – NH2.
A carboxyl group – COOH.
There is also an R-Group – this is the head of the amino
acid that is used to identify which of the 20 amino acids it
happens to be.
Making Proteins

Amino acids are bonded together using a
dehydration synthesis reaction – remove the
water and connect the leftovers.
 The water comes from a “H” on the amino group
and the “OH” of the carboxyl group.
 The bond that is made between the amino acids
is called a peptide bond.
 This means, of course, that proteins are taken
apart by hydrolysis – stick the water back in and
break it up. This is what you do when you eat a
hamburger and break down the protein of the
beef.
Protein Making
Protein Structure (Shape)

Structural proteins tend to be linear.
 The proteins that act as enzymes have a more
pronounced 3-D that is absolutely necessary for
the proper function of the enzyme – damn rock
stars!
 There are 4 levels of protein structure…


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Primary – straight line.
Secondary – α-helix or β-pleated sheet.
Tertiary – “Kinky slinky” with folds.
Quaternary – A bunch of tertiary proteins acting as
one.
Primary & Secondary Structure

Primary structure is the straight chain of amino
acids that has just been built. This structure can
be called a polypeptide – many peptide bonds.


aa-aa-aa-aa-aa-aa-aa-aa-aa-aa-aa-etc…
Secondary structure sees this chain assume the
α-helix (corkscrew) shape or a β-pleated sheet
(fan) shape.
 The secondary structure is held together by
hydrogen bonding between nearby carboxyl and
amino groups within the polypeptide chain.
Tertiary & Quaternary Structure
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Tertiary structure occurs when the helix and sheet
interact and twist around each other – it’s like a slinky
and a fan getting mangled together.
Tertiary shape is held together by R-group bonding
within the chain and R-group interactions with the
environment.
Tertiary structure is also aided by prosthetic groups
that are inorganic compounds that act as a central point
for bonding within the protein.
Quaternary structure occurs when a few tertiary
structures fit together to act as one functional unit.
Go Exact Or Go Home!!!

Proteins are the rock stars of the body but they
are very specific in their construction – if they
are not built exactly right – they may not work.
 This need for the exact 3-D shape is known as
specificity and it is based on two things:



The number of amino acids.
The order of the amino acids.
If the protein is built exactly right it will function
properly unless environmental conditions get to
tough.
I Fall To Pieces…
If the environment is too tough – the protein may
denature – fall apart and lose that special 3-D
shape.
 Denaturing may occur is response to:


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Temperature changes – especially heat.
Changes in pH.
Changes in salt/ion concentration.
In your body, a protein may denature but
chaperone proteins will help reassume the
proper shape.
 In a lab, there are no chaperone proteins so
once the protein denatures – it is gone for good!
Nucleic Acids
Also Known As…
The Directions on How to Make
Proteins Just Right.
Nucleic Acids – Basic Info

They carry genetic information. This information
determines all of your structural and functional
characteristics.
 DNA – Deoxyribonucleic Acid - houses the
genetic code within the nucleus of the cell.
 RNA – Ribonucleic Acid - carries a copy of the
code to the protein-making areas of the cell in
the cytoplasm.
 ATP – the cell’s energy – is also made from a
nucleic acid building block.
Building DNA & RNA
 The
monomer for the nucleic acids is the
nucleotide.
 The nucleotide has three parts:



5-carbon Sugar
Phosphate group
Nitrogen-containing Base
 It‘s
the sequence of the nitrogenous bases
that provides the code/instructions for
making the proteins.
DNA
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Double helix composed of two strands of nucleotides
held together by hydrogen bonds. The two strands are
antiparallel to each other and are made of millions of
nucleotides.
Ladder shape – Rails - A series of alternating
phosphates and sugars linked by covalent bonds known
as phosphodiester bonds. Rungs of the ladder are
made of the nitrogenous bases and their hydrogen
bonds.
The nitrogenous bases involved with DNA are adenine,
cytosine, guanine and thymine.
The adenine and thymine pair up using two hydrogen
bonds and cytosine and guanine pair up using three
hydrogen bonds (Chargaff’s Base-Pair Rule).
The nitrogenous bases can be either purines (A & G) or
pyrimidines (C & T or U in RNA).
DNA Structure
RNA
 RNA is
a code-carrying, single-stranded
molecule made of many nucleotides.
 There are several differences between
RNA and DNA.
RNA vs. DNA

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DNA
Double-stranded.
A, C, G & T.
Deoxyribose - sugar.
H-bonds present.
Works in nucleus.
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RNA
Single-stranded.
A, C, G, & U.
Ribose - sugar.
No H-bonds
Works in cytoplasm –
built in nucleus.
RNA vs. DNA (Diagram)
ATP
 ATP
(Adenosine Triphosphate) is the
cellular form of energy.
 It is composed of three phosphates, a
ribose sugar and an adenine base.
 The energy of the molecule is found in the
bonds between the phosphate groups.
ATP Structure
FIN!