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

Proteins & Nucleic Acids
Also Known As…
The Worker
&
The Boss
PROTEINS
The “Rock Star” Workers!
Proteins – Basic Info
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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.
Forming “Peptide” Bonds
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Again, find the water and take it out – hook up what is left over.
Peptide bonds are the bonds that hold amino acids together.
Levels of Protein Structure (Shape)
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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 four (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
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Primary structure is the straight chain of amino acids
that has just been built. This structure can be called a
polypeptide – many peptide bonds.
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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.
The Levels of Protein Structure
Get It Right or Get Out!!!
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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:
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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…
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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:
Temperature changes – especially heat.
 Changes in pH.
 Changes in salt/ion concentration.
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NUCLEIC ACIDS
The Boss of You!!!
Nucleic Acids – Basic Info
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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. (Adenosine TriPhosphate)
Building DNA & RNA
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The monomer for the nucleic acids is the
nucleotide.
The nucleotide has three parts:
5-carbon Sugar
 Phosphate group
 Nitrogen-containing Base
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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
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RNA is a code-carrying, single-stranded
molecule made of many nucleotides.
There are several differences between RNA and
DNA.
DNA vs. RNA
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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.
DNA vs. RNA (Structurally)
ATP – Cellular Energy!!!
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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
That’s All I Got…